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Crossingham, Grant James. "A digital laser slopemeter". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481690.
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Ranély-Vergé-Dépré, Claude-Alban. "Digital laser and Coherent Beam combination". Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAX131.
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La combinaison cohérente de lasers (CBC) est une approche architecturale innovante permettant la conception de sources laser efficaces associant puissances moyennes et crêtes élevées (kW/GW) tout en offrant une grande liberté quant à la mise en forme spatiale du faisceau résultant.Les amplificateurs à fibre dopée Ytterbium (Yb) permettent une très bonne gestion thermique grâce au rapport surface/volume élevé de la fibre (facilitant le refroidissement) et au rendement élevé rendu possible par les grandes longueurs d’interaction accessibles et le faible défaut quantique du dopant Yb. De plus, ces fibres présentent une largeur spectrale de gain supportant des durées d’impulsion allant jusqu’à quelques centaines de femtosecondes.Il est ainsi possible d’amplifier des trains d’impulsions femtosecondes à fort taux de répétition.Les deux prototypes étudiés dans cette thèse utilisent l’association de cette brique technologique avec l’architecture CBC. Le premier repose sur une pupille composite de 61 faisceaux juxtaposés offrant des caractéristiques de contrôle individuel de ses canaux et ayant permis d’introduire le concept de laser digital. Sa durée d’impulsion est réduite par une technique dite de “post-compression” non-linéaire permettant de conserver néanmoins ses propriétés digitales. Le second prototype à superposition de 7 pupilles est étudiée et développé pour son efficacité théorique plus importanteCoherent Beam Combining (CBC) is an innovative architectural approach to designing efficient laser sources combining high average power and high peak power (kW/GW), while offering great flexibility in the spatial shaping of the resulting beam. Ytterbium (Yb)-doped fiber amplifiers offer excellent thermal management thanks to the fiber's high surface-to-volume ratio (facilitating cooling) and high efficiency made possible by the long interaction lengths accessible and the low quantum defect of the Yb dopant. Moreover, these fibers feature a gain spectral width that supports pulse durations of down to a few hundred femtoseconds. This makes it possible to amplify femtosecond pulse trains at high repetition rates. The two prototypes studied in this thesis use the combination of this technology with CBC architecture. The first is based on a composite pupil with 61 tiled beams, offering individual control of its channels and introducing the concept of digital laser. Its pulse duration is reduced by a non-linear "post-compression" technique, enabling it to retain its digital properties. The second prototype, with its superposition of 7 pupils, is being studied and developed for its greater theoretical efficiency
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Mosayebi, Mahshad. "Digital Laser Speckle Image Correlation". OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2131.
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This thesis examines the feasibility of combining Digital Image Correlation (DIC) with laser speckle based methods to form a new hybrid deformation measurement method called Digital Laser Speckle Image Correlation (DilSIC). Consequently, this method does not require any sample preparation and allows for the measurement of displacement of micro structures in addition to large displacements. In this technique, a coherent 30mW-632nm laser beam is expanded with 40X lens and then illuminated on the target surface to produce a fine, homogenous laser speckle pattern. Images were captured before and after deformation due to external load and the whole field displacement and strain were determined by the DIC method. This technique could measure displacement less than 30-μm with high accuracy when a 120mm × 80mm area of the surface was inspected. Up to 10% strain was measured by this technique with high accuracy during the whole range. Eventually the sub-surface crack was located successfully, which is a revolutionary achievement in NDT optical methods. This method was tested in different material, with different roughness. Aluminum sheet and rubber material were used mostly. This method could broaden the capability of displacement measurement and subsurface crack detection in wide range of materials.
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Heath, Daniel. "Digital micromirror devices and femtosecond laser pulses for rapid laser micromachining". Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/417275/.
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Laser machining techniques are almost ubiquitous in industry for micro- to nanoscale fabrication. It is essential for the advancement of the field that faster, cheaper processes be developed. Enhancements in speed and fidelity of production can be made to both additive and subtractive writing techniques by using Digital Micromirror Devices (DMD), particularly when coupled with femtosecond laser pulses. The objective of this thesis is the demonstration of DMDs used in conjunction with ultrafast laser pulses for both novel and rapid machining applications; primarily image-projection based techniques, using DMDs as dynamic intensity masks, will be used for subtractive patterning, laserinduced transfer, multi-photon polymerisation and centimetre-scale micro-machining. The dynamic nature of the DMD enables its application to the field of multiple exposures, and the centimetre-scale machining is applied to functional biological assays. Adaptive mask techniques are used to enhance the image reproduction achieved, correct for positional errors introduced by translation stages, as well as to attain greyscale intensity control with a DMD in single ultrashort pulses. A new technique for producing digital holograms is developed, and will form the basis of future work. Image projection-based patterning using DMDs as dynamic intensity masks is shown via ablation, multiphoton polymerisation and Laser-Induced Transfer (LIT). Ablation was achieved in a range of materials (including, but not limited to: gold, graphite, diamond, bismuth telluride and antimony telluride, glass, nickel, glucose, and gelatin), with 2 micron resolutions in samples and overall sizes of 1cm2. A multiple exposure technique reduced final structure resolution by 2.7 compared to the diffraction limit possible in a single exposure – from 1m to 370nm on one experimental setup, and from 727nm to 270nm on a second setup. The first demonstration of shaped, solid-phase LIT deposits has been made, both in forward and backward directions of transfer. Adaptive optics techniques have been developed for DMD mask corrections, and have reduced the positional error of samples introduced by translation stages. Greyscale intensity patterns have been projected at samples using the strictly binary-style DMD display technology, and the loss of intensity in high spatial frequencies at the sample has been addressed. A novel method for the generation of binary holograms is introduced, which allows for several additional degrees of control over spatial intensity patterns when using DMDs, such as the effective mask position relative to imaging optics, greyscale control, the formation of images at multiple planes, phase control, and overall lateral shifts of the intensity distribution below a single DMD pixel width.
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Newberry, Shawn. "Laser Speckle Patterns with Digital Image Correlation". OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2885.
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Digital Laser Speckle Image Correlation (DiLSIC) is a technique that utilizes a laser generated speckle pattern with Digital Image Correlation (DIC). This technology eliminates the need to apply an artifact speckle pattern to the surface of the material of interest, and produces a finer speckle pattern resulting in a more sensitive analysis. This investigation explores the parameters effecting laser speckle patterns for DIC and studies DiLSIC as a tool to measure surface strain and detect subsurface defects on pressure vessels. In this study a 632.8 nm 30 mW neon-helium laser generated the speckle pattern by passing through the objective end of an objective lens. All experiments took place in a lab setting on a high performance laminar flow stabilizer optical table.This investigation began with a deeper look at the camera settings that effect the effectiveness of using laser speckles with DIC. The first studies were concentrated on the aperture size (f-stop), shutter speed, and gain (ISO) of the camera. Through a series of zero-correlation studies, translation tests, and settings studies, it was discovered that, much like white light DIC, an increased gain allowed for more noise and less reliable measurements when using DiLSIC. It was shown that the aperture size and shutter speed will largely depend on the surface composition of the material, and that these factors should be investigated with each new sample of different surface finish.To determine the feasibility of using DiLSIC on pressure vessels two samples were acquired. The first was a standard ASTM filament wound composite pressure vessel (CPV) which had an upper load limit of 40 psi. The second was a plastic vessel that had internal subsurface defects added with the use of an air pencil grinder. Both vessels were put under a pressure load with the use of a modified air compressor that allowed for multiple loading cycles through the use of a pressure relief valve. The CPV was mapped out in 10-degree increments between the 90° and 180° markings that were on the pressure vessel, occurring in three areas, each one inch apart. The CPV had a pressure load applied to at 10, 20, 30,and 40 psi. DiLSIC was able to measure increasing displacement with increased loading on the surface of the CPV, however with a load limit of 40 psi no strains were detected. The plastic vessel had known subsurface defects, and these areas were the focus of the investigation. The plastic vessel was loaded with a pressure load at 5, 10, 12, 15, 17, and 20 psi. The 5 psi loaded image was used as a reference image for the correlation and decorrelation consistently occurred at 20 psi. This investigation proved that DiLSIC can detect and locate subsurface defects through strain measurement. The results were verified with traditional white light DIC, which also showed that the subsurface defects on pressure vessels were detectable. The DIC and DiLSIC results did not agree on maximum strain measurement, with the DiLSIC prediciting much larger strains than traditional DIC. This is due to the larger effect out-of-plane displacement has on DiLSIC. DiLSIC was able to detect subsurface defects on a pressure vessel. The median measured hoop strain was in agreement for DiLSIC, DIC and the predicted hoop strain for a wall thickness of 0.1 inches. However, DiLSIC also produced unreliable maximum strain measurements. This technique shows potential for future applications, but more investigations will be needed to implement it for industrial use. A full investigation into the parameters surrounding this technique, and the factors that contribute the most to added noise and unreliability should be conducted. This technology is being developed by multiple entities and shows promising results, and once further advanced could be a useful tool for rapid surface strain measurement and subsurface defect detection in nondestructive evaluation applications. Therefore, it is recommended to continue further investigations into this technology and its applications.
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Amer, Eynas. "Pulsed laser ablation studied using digital holography". Doctoral thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18194.
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Pulsed digital holographic interferometry has been used to study the plume and the shock wave generated in the laser ablation process on different targets under atmospheric air pressure. A pulsed Nd-YAG laser system (pulse duration 12 ns) has been used both for ablating the material (wavelength 1064 nm) and for measurement (wavelength 532 nm). Digital holograms were recorded for different time delays using collimated laser light passed through the volume along the target. Numerical data of the integrated refractive index field were calculated and presented as phase maps. The Radon inversion has been used to estimate the 3D refractive index fields measured from the projections assuming rotational symmetry. Intensity maps have been calculated from the recorded digital holograms and used to calculate the attenuation of the probing laser beam by the ablated plume. Qualitative and quantitative information have been extracted from both the phase map and the intensity map to help describing the laser ablation process. Also 3D information about the induced plume has been obtained by numerical reconstruction of the digital holograms at different planes along the plume. The amount of released energy due to laser impact on a PCBM target has been estimated using the point explosion model. The released energy is normalized by the incident laser pulse energy and the energy conversion efficiency between the laser pulse and the target has been calculated and it seems to be constant around 80 %. The 3D refractive index fields have been used to calculate the shock wave front density and the electron number density distribution within the induced plasma. The electron number densities are found to be in the order of 1018 cm-3 and decay at a rate of 3x1015 electrons/cm3ns. The effect of the laser spot diameter on the shock wave generated in the ablation process of a Zn target has been studied. The induced shock wave has an ellipsoidal shape that approaches a sphere for decreasing spot diameter. A model was developed that approaches the density distribution that facilitates the derivation of the particle velocity field. The method provides quantitative results that are discussed; in particular a comparison with the point explosion theory. The effect of the physical properties of the target on the laser ablation process has been studied. The comparison of the laser ablation of Zn and Ti shows that different laser ablation mechanisms are observed for the same laser settings and surrounding gas. At a laser fluence of 5 J/cm2, phase explosion appears to be the ablation mechanism in case of Zn, while for Ti normal vaporisation seems to be the dominant mechanism. The results show that pulsed digital holographic interferometry is a promising technique to give a physical picture and increase the understanding of the laser ablation process in a time resolved manner.Godkänd; 2009; 20091018 (eyname); DISPUTATION Ämnesområde: Experimentell mekanik/Experimental Mechanics Opponent: Reader in Laser Engineering Bill O’Neill, University of Cambridge, UK Ordförande: Professor Mikael Sjödahl, Luleå tekniska universitet Tid: Fredag den 20 november 2009, kl 10.00 Plats: E 231, Luleå tekniska universitet
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Cronin, Christopher Joseph. "Digital frequency demodulation for a laser vibrometer". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-11102009-020344/.
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Amer, Mohamed Eynas. "Pulsed laser ablation studied using digital holography /". Luleå : Department of Applied Physics and Mechanical Engineering, Luleå University of Technology, 2009. http://pure.ltu.se/ws/fbspretrieve/3315450.
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Larsson, Ola. "Digital Implementation of a Laser Doppler Perfusion Monitor". Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7091.
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Under 20 års tid har Perimed AB utvecklat och tillverkat LDPM- och LDPI-instrument som är baserade på en analog filterkonstruktion. De analoga komponenterna i konstruktionen är komplexa och icke-linjära med hänsyn till frekvens och de driver även med temperaturen. Funktionen hos konstruktionen beror också kraftigt av att de analoga komponenterna trimmas in under produktionen.
Det här examensarbetet syftar till att ta fram en alternativ design baserad kring en digital signal processor. Den digitala signalbehandlingsmetod som beskrivs baseras på väl förankrade laser-Doppler perfusionsteorier. Den implementerade signalbehandlingsalgoritmen beräknar perfusionen ur en samplad fotodetektorström, som har filtrerats till AC- och DC-komponenter med hjälp av ett analogt detektorkort. Algoritmen producerar en råperfusionssignal genom att beräkna en frekvensviktad summa av fotodetektorströmmens effektspektrum. Kompensation för detektorns brus och normalisering med ljusintensitet har också implementerats.
Den presenterade implementationen har verifierats mot ett exemplar av LDPM-enheten PF 5010 som har använts som referensinstrument vid alla mätningar. Mätningar in vitro har påvisat liknande mätresultat som referensinstrumentet för en referensvätska med hög perfusion och även för ett statiskt mätobjekt. Vidare har implementationen verifierats med mätningar in vivo på hud, vilket har påvisat nära nog identiska signalnivåer och gensvar på värmeprovokationer som referensinstrumentet.
Den demonstrerade uppfinningen förenklar tillverkningen av instrumenten eftersom antalet komponenter reduceras avsevärt och därmed antalet produktionstester. Användandet av en DSP reducerar dessutom instrumentets temperaturkänslighet eftersom den ersätter flera temperaturkänsliga komponenter.
For 20 years Perimed AB have been developing and manufacturing LDPM and LDPI instruments based on an analog filter construction. The analog components in the construction are complex and suffer from non-linear frequency dependency and temperature drifts. The functionality of the design is also heavily depending on analog components which need to be trimmed in the production.
In this thesis, an alternative design employing a digital signal processor is presented. The signal processing method used is based on well established laser Doppler perfusion theories. The implemented signal processing algorithm calculates the perfusion from a sampled photodetector current, pre-filtered into AC and DC components by an analog detector card. The algorithm produces a raw perfusion signal by calculating a frequency weighted sum of the power spectral density, PSD, of the photocurrent. Detector noise compensation and light intensity normalization of the signal has also been implemented.
The presented digital implementation has been verified using the PF 5010 LDPM unit as a reference. In vitro measurements have shown similar behaviour as the reference in a highly perfused reference fluid as well as for a static scatterer. Furthermore, the DSP implementation has been verified on in vivo measurements of skin, showing nearly identical signal levels and response to heat provocation as the reference.
The demonstrated invention improves the manufacturability of the instruments since it reduces the number of electronic components significantly and thus, the amount of manufacturing tests. The DSP also reduces the temperature sensitivity of the instrument since it replaces several analog components sensitive to temperature changes.
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Erk, Patrick P. (Patrick Peter). "Digital signal processing techniques for laser-doppler anemometry". Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/43026.
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Manivannan, Ayyakkannu. "Digital fundus imaging with a scanning laser ophthalmoscope". Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602038.
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A prototype scanning laser ophthalmoscope was constructed based on the original principles of Webb et al (1987 and 1990). The basic design was, however, altered in a number of ways to give the flexibility needed for what was primarily a research instrument with a requirement to use lasers of various wavelengths and to carry out confocal imaging with a variety of slice thicknesses. Some of the performance characteristics of the prototype SLO, such as modulation transfer function, axial resolution and uniformity of illumination were measured and are presented. The SLO can operate in three different modes; direct, confocal and indirect. The direct mode imaging has a large depth of focus and collects light from all layers of the fundus. High contrast imaging is possible due to scattered light being significantly reduced as only a single spot is illuminated at a time. Confocal imaging further improves the contrast by collecting light only from a small slice of the fundus. The capacity to carry out confocal imaging is a significant advantage over fundus cameras. By moving the confocal aperture, light from different layers could be collected enabling the visualisation of various lesions. The indirect mode collects only the scattered light, avoiding the directly reflected light. The clinical value of the equipment was evaluated with a small number of patients with various pathological conditions from the Eye Out-patient Clinic of the Aberdeen Royal Infirmary. The images from the SLO were compared with fundus photographs. The confocal capability, together with the penetrating capacity of near infrared illumination, was utilised to demonstrate the ability to visualise deep lying structures such as choroidal vessels and intra- retinal abnormalities. Near infrared illumination was found useful for imaging through media opacities, such as cataracts. The indirect mode was found useful for visualising structures such as drusen and epiretinal membrane. It is concluded that near infrared monochromatic imaging with the SLO offers a 'new' picture of the fundus. The confocal capability provides the ability to produce 3-D images of the fundus. The near infrared reflective characteristics of many normal and pathological tissues appear to offer new clinical insights into fundal pathology. However, more work is needed to fully appreciate the clinical potential of this new imaging modality.
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Amer, Eynas. "Pulsed laser ablation studied using digital holographic interferometry". Licentiate thesis, Luleå : Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1757/2008/55/.
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Montes, Felix G. "Digital data acquisition for laser radar for vibration analysis". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA350185.
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Thesis (M.S. in Applied Physics) Naval Postgraduate School, June 1998.Thesis advisor(s): Robert C. Harney, D. Scott Davis. "June 1998." Includes bibliographical references (p. 45-46). Also available online.
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Hunter, David MacKenzie. "Digital radiography by laser-scanned readout of amorphous selenium". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ45465.pdf.
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Olsson, Erik. "Digital holographic reconstructions of ultrasound from laser vibrometry recordings /". Luleå, 2004. http://epubl.luth.se/1402-1757/2004/024.
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Doneddu, Daniele. "The use of novel digital power supply to drive laser systems". Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa42441.
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Light-based therapies are becoming increasingly important and widely applied within the clinical practice. Their advantages over more traditional therapies have created an expanding market which is driving the development of more efficient and sophisticated devices. These devices allow a more precise control of the characteristics of the optical output to maximise benefits of the treatment. Although many studies have been conducted on light, and more specifically lasers, both from a therapeutic and a technological perspective, there is still much research to be undertaken. Laser systems have been used for more than two decades for the treatment of vascular lesions. Indeed the application of selective photothermolysis utilising the monochromaticity of the laser system has become the treatment of choice. However the treatment of larger blood vessels remains problematic. Many workers have, for theoretical and clinical reasons, elected to choose the YAG laser for the treatment of larger thread veins and vascular lesions containing larger vessels. The therapeutic output has been mixed and the need for further work identified. This thesis describes the design of a novel approach to the control of the temporal profile of the YAG laser. The design aspect of the work includes a computer modelling study which shows that careful control of the temporal parameters can in principle improve the therapeutic output. A novel approach to the digital control of the flashlamps pumping the YAG crystal is also described. The digital control of the flashlamp translates to sensitive control of the temporal profile of the laser output in a way that has not been described to date. The thesis therefore concludes that control of the temporal output of the YAG laser, if possible, should give improved therapeutic output and that the necessary level of control can be achieved by advanced digital techniques. Future clinical work should prove improved therapeutic results.
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LYLES, ALBERT Anthony. "AN ADVANCED APPROACH VERIFICATION TO DIGITAL LASER SPECKLE IMAGE CORRELATION". OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2458.
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This research project on the campus of Southern Illinois University Carbondale is an extension to the inquiry into the feasibility and reliability of the technology known as Digital Laser Speckle Image Correlation (DiLSIC). This is a hybrid approach of combining two existing technologies. The first being Digital Image Correlation (DIC) which is a nondestructive evaluation commonly used to find displacement, in-plane strain, as well as deformation. The second being the of laser speckle patterns. This hybrid has achieved level of resolution measured to be 3.4μ. DiLSIC increases the application ability of the DIC technique to situations that generally would not be an option to use. DiLSIC needs no artifact speckle patterns to be applied to the specimen as a preparation for nondestructive testing. In DIC testing, the surface of a specimen must artifact speckles applied to the subject surface. Often the application of artifact speckles is not desirable or possible. DiLSIC is an acceptable alternative to the previously discussed industry-wide practice. This method broadens the usage of the DIC technique to situations which previously were not possible. This technology can identify, quantify, and detect the distribution of strain and stress concentrations in composite structures. For this study, a honeycomb-backed glass fiber reinforced polymer (GFRP) panel from a Cessna aircraft exterior luggage door was obtained and a defect panel is created. The panel is constructed with one area containing a repair compliant with manufacturer standardized methods and a repair area is not compliant and consists of multiple incorrect repair steps. An area with no repair is also tested to act as a control for comparison and quantification. The results for the inspected areas showed a linear strain increase in the noncompliant repair. The data plot for the compliant repair showed a trend of following the same basic curve as the no repair area. A verification process follows the DiLSIC testing consisting of using Infrared Thermography, Air-coupled ultrasonic, and white light artifact speckle DIC. These tests show DiLSIC is a viable alternative to the testing that is available in the industry. DiLSIC can detect defect location, size, geometry and map strain to determine the difference between compliant and noncompliant repairs when compared to a base level non-repair area
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Akiwowo, Kerri. "Digital laser-dyeing : coloration and patterning techniques for polyester textiles". Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19180.
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This research explored a Digital Laser Dye (DLD) patterning process as an alternative coloration method within a textile design practice context. An interdisciplinary framework employed to carry out the study involved Optical Engineering, Dyeing Chemistry, Textile Design and Industry Interaction through collaboration with the Society of Dyers and Colourists. In doing so, combined creative, scientific and technical methods facilitated design innovation. Standardized polyester (PET) knitted jersey and plain, woven fabrics were modified with CO2 laser technology in order to engineer dye onto the fabric with high-resolution graphics. The work considered the aesthetic possibilities, production opportunities and environmental potential of the process compared to traditional and existing surface design techniques. Laser-dyed patterns were generated by a digital dyeing technique involving CAD, laser technology and dye practices to enable textile coloration and patterning. An understanding of energy density was used to define the tone of a dye in terms of colour depth in relation to the textile. In doing so, a system for calibrating levels of colour against laser energy in order to build a tonal image was found. Central to the investigation was the consideration of the laser beam spot as a dots-per-inch tool, drawing on the principles used in digital printing processes. It was therefore possible to utilise the beam as an image making instrument for modifying textile fibres with controlled laser energy. Qualitative approaches employed enabled data gathering to incorporate verbal and written dialogue based on first-hand interactions. Documented notes encompassed individual thought and expression which facilitated the ability to reflect when engaged in practical activity. As such, tacit knowledge and designerly intuition, which is implicit by nature, informed extended design experiments and the thematic documentation of samples towards a textile design collection. Quantitative measurement and analysis of the outcomes alongside creative exploration aided both a tacit understanding of, and ability to control processing parameters. This enabled repeatability of results parallel to design development and has established the potential to commercially apply the technique. Sportswear and intimate apparel prototypes produced in the study suggest suitable markets for processing polyester garments in this way.
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Sopeña, i. Martínez Pol. "Laser-induced forward transfer for printed electronics applications". Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/670919.
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Printed electronics appeared in the 1980s as a cost-effective alternative to silicon-based electronics. Employing the techniques from the graphics industry, such as rotogravure or screen printing, it was possible to print metals, ceramics, and polymers on a wide variety of materials, including flexible and organic substrates. However, these techniques became not adequate when customization or short runs were considered since the production costs of the components and devices substantially increased. To overcome these issues, direct-write techniques, such as inkjet printing, allowed depositing materials on-demand in a digital fashion. Nonetheless, the ink was ejected in the form of droplets from a nozzle, which small diameter limited the range of printable inks; only those with low viscosity (few mPa·s) and small particle size (~100 nm) could be routinely printed without resulting in nozzle clogging. Alternatively, laser-induced forward transfer (LIFT), another digital technique, has barely any of these constraints.
LIFT is a printing technique capable of depositing almost every kind of ink in a digital fashion independently of its rheology. In LIFT, a thin layer of ink is extended on a transparent donor substrate, which is placed facing the receiver substrate through a certain gap. Using a laser pulse focused on the ink donor film, a cavitation bubble is induced. The high pressure within results in its expansion, propelling the material forward towards the receiver, where it is finally deposited. Since the ink is not ejected from an output nozzle, the range of printable viscosities extends from a few mPa·s to hundreds of Pa·s, and the particles in suspension can feature sizes of up to tens of micrometers, non-achievable with other direct-write techniques. Furthermore, both the resolution of the printed features and the printing speeds are similar to those of other digital printing techniques.
In this thesis, the use of LIFT is investigated with the aim of printing inks for printed electronics applications. Special attention is devoted to the transfer of conductive pads to be used as interconnects. To demonstrate the potential and possibilities of LIFT, different inks used in printed electronics applications are chosen. These inks exhibit diverse rheologies: from low to high viscosity, and with particle sizes ranging from nano- to micrometers, characteristics that make them unprintable with most of the other direct-write methods. Finally, to prove the versatility and compatibility of the technique with the desired applications, several functional components and devices are entirely printed with LIFT.
The work is divided in three main sections. The first aims at the production of transparent electrodes by means of the LIFT of two silver nanowire inks on rigid and flexible substrates. The main laser parameters are varied to find the optimum compromise between the optical and electrical properties, to finally print a device consisting of conductive and transparent electrodes. The second focuses on the LIFT of high solid content silver screen printing ink. The study is divided in the fundamental study of the deposits and its correlation with the transfer dynamics, and the ability to obtain conductive interconnects on non-planarized regular paper. As a proof-of-concept, a radio-frequency inductor is printed on paper. The third consists of performing LIFT using continuous-wave laser sources for printing inks, with the aim of reducing the capital investment associated to pulsed LIFT. The laser parameters are varied to determine the optimum printing conditions and the transfer mechanism is investigated. As a final remark, a gas and temperature sensor is printed using this approach.
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Novotny, Robert A. "Analysis of smart pixel digital logic and optical interconnections". Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/1275.
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Drollinger, Cy Taylor. "Frequency stabilization of an external cavity diode laser employing digital control". Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/drollinger/DrollingerC0806.pdf.
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Khmaladze, Alexander. "Three-dimensional microscopy by laser scanning and multi-wavelength digital holography". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002638.
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Brucoli, Henrique Cesar Purchio. "Análise da imagem radiográfica de raízes apicetomizadas e irradiadas com laser de Nd:YAG por meio do processamento de imagem de radiografias digitais diretas". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-24102009-112749/.
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Nesta pesquisa foi realizada a análise da imagem radiográfica digital da técnica periapical de raízes cujos ápices foram irradiados com laser de Neodymium Yttrium Aluminum Garnet (Nd:YAG) após a ressecção apical. Com intuito de encontrar alterações da imagem radiográfica digital das raízes causadas pela irradiação laser, desenvolvemos um modelo experimental in vitro. Foram realizadas as apicectomias de 39 raízes de dentes unirradiculares a dois milímetros do limite apical, com posterior fixação dos dentes em dispositivo que conferiu uma rígida padronização das radiografias, cujas imagens foram capturadas por meio de um sistema de radiografia digital direta (Dixi® Planmeca). Com a fixação das raízes no dispositivo de padronização, realizamos uma radiografia inicial, irradiamos os ápices radiculares com o laser de Nd:YAG e em seguida fizemos uma radiografia final, sem manipulação do sistema de padronização durante todo o processo. Os parâmetros de irradiação laser utilizados foram baseados no protocolo de pesquisa clínica para cirurgias apicais desenvolvido no Laboratório Especial de Laser em Odontologia (LELO-FOUSP). Foram eles 100mJ, 15Hz, 1,5W e diâmetro da fibra óptica de 320m. As radiografias foram obtidas com três tempos de exposição diferentes (0,05s, 0,08s e 0,14s). As imagens radiográficas antes e depois a irradiação laser, obtidas em 12 bits, foram convertidas para 8 bits e exportadas para o programa de análise de imagens ImageTool 3.0.0. A análise das imagens digitais foi executada por meio de histogramas e subtração de imagem digital quantitativa. Foi possível detectar por meio dos dois métodos uma menor quantidade de dentina na superfície apical após a irradiação com o laser de Nd:YAG. A variável tempo de exposição não apresentou diferenças estatísticas significantes, porém foi observada uma tendência de melhor desempenho dos métodos com imagens obtidas com exposição de 0,05s. Apesar de termos observado remoção de tecido dentinário, não foi possível detectar a presença de uma camada de dentina mais radiopaca nas imagens radiográficas da superfície irradiada.In this research, we carried out an evaluation of the digital radiographic image of dental root-ends irradiated with Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser after apical resection. With the intention of founding alterations in the digital radiographic image of the roots caused by laser irradiation, we developed an in vitro experimental model. We made apicectomy in 39 single-root teeth, 2 milimeters below the apical limit and then we fixed these teeth in a standardization device. The radiographic images were captured thru a direct digital radiographic system (Dixi® Planmeca). After positioning of the teeth in the standardization device, we made an initial radiograph, Nd:YAG laser irradiation of the apex and a final radiograph, without manipulation of the standardized system during the whole process. The laser parameters applied in this research followed the clinical research protocol for apical surgeries developed in the LELO- FOUSP. They were 100mJ, 15Hz, 1,5W and a 320m diameter optic fiber. The radiographs were made within three different exposure times (0,05s, 0,08s and 0,14s). The obtained 12 bit radiographic images before and after laser irradiation were converted to 8 bit images and exported to the ImageTool 3.0.0 image analysis software. With this software wee analyzed the digital images in the methods of histogram analysis and quantitative digital image subtraction. The two methods indicated less amount of dentin in the apical surface after Nd:YAG laser irradiation. The variable exposure time did not present statistical differences. However, we observed a tendency of better performance of the methods with images obtained with 0,05s exposure time. Although we observed dental tissue ablation, it was not possible to detect the presence of a more radiopac dentin layer in the irradiated surface radiographic images.
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Li, Peng. "A vehicle-based laser system for generating high-resolution digital elevation models". Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3890.
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Lin, Yu-Ching. "Digital Terrain Modelling from Small-Footprint Full-Waveform Airborne Laser Scanning Data". Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515066.
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Monte, Jamie Marie y Jamie Marie Monte. "ROCK MASS CHARACTERIZATION USING LASER SCANNING AND DIGITAL IMAGING DATA COLLECTION TECHNIQUES". Thesis, The University of Arizona, 2004. http://hdl.handle.net/10150/621370.
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The primary focus of this research is to evaluate whether laser scanning and
digital imaging can provide a reliable means to collect essential rock mass data.
Simulated and field case studies were conducted to determine if fracture orientation data
(dip angle and dip direction) can be accurately estimated from a laser generated three -
dimensional point cloud. Orientations measured with a Brunton Compass were compared
to values derived from point clouds. The difference in dip direction was within three
degrees and as high as twelve degrees for the dip angle. When fracture sets were
estimated for both field and laser data, good correlation in mean set orientation and set
distribution was observed. Some sets recorded during field mapping were absent in stereo
plots of laser derived data due to a shadow zone created during scanning. This indicated
that scanning from multiple locations is necessary to reduce potentially missed data. This
thesis also investigated whether the newly proposed Digital Rock Mass Rating (DRMR)
system could classify rock masses similar to established systems such as the Geological
Strength Index (GSI). The seven DRMR parameters, fracture spacing, length, large -scale
roughness, block volume, rock bridge percent, and rock mass texture were calculated for
images of poor to good rock masses. When DRMR values were compared to GSI ratings
estimated during field work, good correlation was seen for good quality rock masses (GSI
between 40 and 60). The DRMR overestimated ratings for outcrops with GSI values less than 40, indicating that the rating system may not be applicable for poor quality rock
masses. Additional case studies are needed to further validate the DRMR classification
system.
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Mikail, Solange Corrêa. "Avaliação da terapia por laser de arsenito e gálio em tendinite de cavalos Puro Sangue Inglês de corrida". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/10/10136/tde-23122008-101158/.
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Para avaliar a eficácia do laser de arsenito de gálio em acelerar a cicatrização tendínea em cavalos PSI de corrida com lesão no tendão flexor digital superficial, foram realizados dois experimentos, primeiro (E1) com 14 casos clínicos onde as lesões foram decorrentes do esporte em um dos membros torácicos, o segundo (E2) com cinco casos experimentais, onde as lesões foram induzidas com colagenase em ambos os membros torácicos. No E1, após a detecção da lesão no tendão flexor digital superficial por exame ultra-sonográfico, todos os animais receberam antiinflamatório não esteróide associado à dimetilsulfóxido por via intravascular, crioterapia no local da lesão, e caminharam ao passo duas vezes ao dia por 15 minutos durante os 30 dias de acompanhamento. Os membros tratados pertenceram a onze animais que receberam uma sessão diária de laser de arsenito de gálio na dose de 20 J/cm2, realizadas durante 10 dias consecutivos, após término do antiinflamatório e da crioterapia. Os membros controle pertenceram a três animais, os quais não foram tratados com laser. No E2, após identificação das lesões, foram escolhidos aleatoriamente um membro torácico controle e outro a ser tratado por laser em cada animal. Da mesma forma, estes animais foram mantidos a passo e receberam o mesmo protocolo de laserterapia que os membros tratados do E1. Todos os membros foram avaliados através de exames ultra-sonográficos, utilizando-se como parâmetros o paralelismo das fibras tendíneas em corte longitudinal; a ecogenicidade, a área do tendão, a área da lesão e a porcentagem de ocupação da lesão em corte transversal. No E1, os membros controle não apresentaram diferença significativa (P>0,05) nos parâmetros avaliados entre os dias 0 e 30. Nos membros tratados, a área do tendão também não apresentou diferença significativa (P>0,05) entre os dias analisados, porém houve diminuição muito significativa nos escores de ecogenicidade e paralelismo (P<0,001), assim como diminuição no tamanho da lesão (P<0,05) e na porcentagem de ocupação da lesão (P<0,05). No E2 também não houve diferença significativa entre os dias em todos os critérios avaliados nos membros controles (P>0,05). Nos membros tratados a ecogenicidade, o paralelismo e o tamanho do tendão, não sofreram alterações significativas (P>0,05) entre os dias avaliados, porém o tamanho da lesão (P<0,05) e a porcentagem de ocupação da lesão (P<0,01) apresentaram diminuição significativa. O laser de arsenito de gálio na dose de 20 J/cm2 mostrou-se eficaz em acelerar a reparação da lesão tendínea nos membros tratados em relação aos membros controle, tanto no grupo de casos clínicos quanto no grupo experimental, quando comparados aos 30 dias do aparecimento da lesão. Esses resultados sugerem a participação positiva do laser de arsenito de gálio nos resultados e a validação do mesmo no tratamento da tendinite do flexor digital superficial de cavalos Puro Sangue Inglês de corrida.This study conducted two trials to evaluate the efficacy of Gallium Arsenide Laser in the speed of the healing process of superficial digital flexor tendon (SDFT) lesions in thoroughbred horses. One trial group (T1) comprises 14 horses with lesions, which resulted from the sport, in the SDFT in one of the front limbs. The other trial group (T2) was formed by five horses that had lesions induced in both front limbs by collagenase injection. In the T1, after the detection of the lesion in the SDFT by ultrasonography all horses were treated by intravenous injection, once a day, over five days, with an association of two AINS: phenylbutazone and dimethylsulfoxide. Cryotherapy was also applied on the affected tendon (three times a day over five days) and the horses were kept in stalls and allowed controlled exercise (hand-walked twice daily for 15 minutes) during the 30 days of the study. The treated limbs belong to 11 horses that received laser sessions once a day for ten days at a dosage of 20J/cm2. These sessions started after the AINS association and cryotherapy. The control limbs belong to the other three horses that received the same treatment, except by the laser sessions. In the T2, after the detection of the lesion, a limb from each horse was randomly chosen to be the control limb and the other limb was treated by laser. These horses were also kept in stall under controlled exercise and the treated limb was under the same laser protocol that T1. All horses were evaluated by two ultrasonographic exams with a 30-day interval. The parameters evaluated were: the fiber alignment, the echogenicity, the tendon area, the lesion area and the proportion of the cross sectional area involved. In the T1, the control limbs showed no significant difference (p>0,05) in the echogenicity, the fiber alignment, the tendon area, the lesion area or the proportion of the cross sectional area involved, between the day 0 and 30. The treated limb, didn´t show any significant difference of the tendon area, but showed a significant difference on the echogenicity (P<0,001), the fiber alignment (P<0,001), the lesion area (P<0,05) and the proportion of the cross sectional area involved (P<0,05). In the T2, only one limb received the laser treatment, the other limb acted as a control. The control limbs showed no significant difference (P>0,05) in the echogenicity, the fiber alignment, the tendon area, the lesion area and the proportion of the cross sectional area involved between the day 0 and 30. The treated limbs showed no significant difference (P>0,05) in the echogenicity, the fiber alignment and the tendon area, but showed significant difference in the lesion area (P<0,05) and the proportion of the cross sectional area involved (P<0,01). The treatment dose of 20J/cm2 of gallium arsenide laser was efficient in speeding the healing process of SDFT lesions of the laser treated limbs in both groups (T1 and T2), when compared with the control limbs, at 30 days of the onset of the lesion. The group which lesions occurred due to the sport (T1) had a better response to the treatment than the group which lesions were induced by collagenasis (T2). The limbs treated by laser showed a positive response which validates the use of the Gallium Arsenide laser for the treatment of tendinitis in the Superficial Digital Flexor in race horses.
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Ferrier, Adrian Jon. "Processing techniques for flow images obtained by planar laser-induced fluorescence". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/24097.
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Morgan, Laura. "Laser textile design : the development of laser dyeing and laser moulding processes to support sustainable design and manufacture". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/23176.
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This research developed new creative opportunities for textile design by investigating CO2 laser processing technology to achieve surface design and three-dimensional effects. A practice based and interdisciplinary textile design methodology was employed, integrating scientific and technical approaches with a reflective craft practice. It was found that the synthesis of design and science was imperative to achieving the research goal of evolving techniques that have opened new design opportunities for textile design whilst being viable and communicable for industrial and commercial application. Four distinct Laser Textile Design techniques were developed in this research including: a laser enhanced dyeing technique for wool and wool blends; Peri-Dyeing, a laser dye fixation technique; a laser moulding technique; and a laser fading linen technique.
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Hansel, Thomas. "Anwendung ultrakurzer Lichtimpulse in der digital-holographischen Interferometrie". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16194.
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In dieser Arbeit wird die digital-holographisch-interferometrische Zwei-Wellenlängen-Formerfassung sehr schnell bewegter Objekte behandelt und dafür unter Nutzung einer Ultrakurzpuls-Laserquelle mit der digitalen Einzelimpuls-Mehr-Wellenlängen-Holographie ein neuartigen Ansatz der digital-holographischen Aufnahme und Auswertung entwickelt. Mit der Entwicklung spezieller Methoden zur Formung der spektralen Signatur einer Ultrakurzpuls-Laserquelle hoher Leistungsdichte wurde zum ersten Mal die Voraussetzung für eine Zwei-Wellenlängen-Formerfassung hochdynamischer Objekte geschaffen. Die intrinsisch kurze Belichtungszeit unter einer Pikosekunde macht das Verfahren absolut stabil gegenüber Umwelteinflüssen. Für die simultane Aufnahme werden die spektral verschiedenen Hologramme mit einem eigens entwickelten Prinzip der Polarisationskodierung räumlich getrennt und zum ersten Mal mit zwei synchron laufenden Kameras gespeichert. Mit den in der digital-holographischen Einzelimpuls-Mehr-Wellenlängen-Interferometrie zusammengefassten numerischen Routinen zur Rekonstruktion und Phasenauswertung wird eine Zwei-Wellenlängen-Formerfassung mit mehreren Kameras möglich. In Anwendung des neuartigen Verfahrens an verschiedenen dynamischen Mikrosystemen konnte eine Genauigkeit von einem Zwanzigstel der erzeugten synthetischen Wellenlänge, bei der Auswertung der spektralen Differenzphase an Objekten in Reflexion erreicht werden. In einer digital-holographischen Hochgeschwindigkeitsformerfassung in Transmission wurden erstmals Bildfolgefrequenz von mehr als 0,4 kHz erreicht und der interferometrische Eindeutigkeitsbereich auf mehr als das 60-fache der optischen Wellenlänge ausgedehnt. Es wurden die Voraussetzungen für eine digitale Vier-Wellenlängen-Holographie geschaffen. Zukünftig wird eine Formerfassung mit einer Genauigkeit von 10nm über einen eindeutigen interferometrischen Bereich einiger 10 μm und die Untersuchungen von Prozessen auf einer Pikosekunden-Zeitskala möglich sein.This work deals with the digital holographic interferometric two-wavelength contouring of very fast moving objects and develops with the digital single pulse multiwavelength holography a novel approach of digital holographic recording and analysis, using an ultrashort pulse laser source. The development of several methods to shape the spektral signature of an high power ultrashort pulse laser source provides the precondition for a two-wavelength contouring of highly dynamic objects for the first time. The intrinsically short exposure time shorter than a picosecond makes the system stable regarding external impacts. For the simultaneous recording the spektral different holograms are spatially separated in novel interferometric setups by the especially developed principle of polarization encoding and stored with two synchronized cameras for the first time. The digital holographic single pulse multi-wavelength interferometry combines the numeric routines of reconstruction and phase evaluation that make a two-wavelength contouring possible using more than one camera. The novel approach is successfully demonstrated on several dynamic microsystems. Evaluating the spectral phase difference for objects in reflection an accuracy of 2 μm, which corresponds to the twentieth of the realized synthetic wavelength, could be achieved. In a digital holographic high speed contouring in transmission a frame rate higher than 0,4 kHz was achieved for the first time and the interferometric range of unambiguity was extended larger than sixty times the optical wavelength. Furthermore, the developed digital holographic single pulse multi-wavelength interferometry is not limited to the evaluation of two wavelength. The principles of the method allow to perform digital four-wavelength holography. Future a contouring with an accuracy of 10nm over the unambiguous interferometric range of several 10 μm and the investigation of processes on a picosecond time scale will be possible.
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Dias, Paulo Miguel de Jesus. "Reconstrução tridimensional de ambientes reais usando dados laser e de intensidade". Doctoral thesis, Universidade de Aveiro, 2003. http://hdl.handle.net/10773/2203.
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O objectivo do trabalho apresentado nesta tese é a criação de modelos
tridimensionais completos e de alta resolução de ambientes reais (informação
geométrica e de textura) a partir de imagens passivas de intensidade e de
sensores de distância activos. A maior parte dos sistemas de reconstrução 3D
são baseados em sensores laser de distância ou em câmaras fotográficas,
mas muito pouco trabalho tem tentado combinar estes dois tipos de sensores.
A extracção de profundidade a partir de imagens de intensidade é complicada.
Por outro lado, as fotografias fornecem informação adicional sobre os
ambientes que pode ser usada durante o processo de modelação, em
particular para definir, de uma forma precisa, as fronteiras das superfícies. Isto
torna os sensores activos e passivos complementares em varios modos e é a
ideia de base que motivou o trabalho apresentado nesta tese.
Na primeira parte da tese, concentramo-nos no registro entre dados oriundos
de sensores activos de distância e de câmaras digitais passivas e no
desenvolvimento de ferramentas para tornar este passo mais fácil,
independente do utilizador e mais preciso. No fim, com esta técnica, obtém-se
um mapa de textura para os modelos baseado em várias fotografias digitais. O
modelo 3D assim obtido é realizado baseado nos dados de distância para a
geometria e nas fotografias digitais para a textura. Com estes modelos, obtémse
uma qualidade fotográfica: uma espécie de fotografia de alta resolução em
3D dum ambiente real.
Na segunda parte da tese, vai-se mais longe na combinação dos dados. As
fotografias digitais são usadas como uma fonte adicional de informação
tridimensional que pode ser valiosa para definir com precisão as fronteiras das
superfícies (onde a informação de distância é menos fiável) ou então
preencher falhas nos dados ou aumentar a densidade de pontos 3D em áreas
de interesse.The objective of the work presented in this thesis is to generate complete, highresolution three-dimensional models of real world scenes (3D geometric and texture information) from passive intensity images and active range sensors. Most 3D reconstruction systems are based either in range finders or in digital cameras but little work tries to combine these two sensors. Depth extraction from intensity images is complex. On the other hand digital photographs provide additional information about the scenes that can be used to help the modelling process, in particular to define accurate surface boundary conditions. This makes active and passive sensors complementary in many ways and is the base idea that motivates the work in this thesis. In the first part of the thesis, we concentrate in the registration between data coming from active range sensors and passive digital cameras and the development of tools to make this step easier, more user-independent and more precise. In the end, with this technique, a texture map for the models is computed based on several digital photographs. This will lead to 3D models where 3D geometry is extracted from range data, whereas texture information comes from digital photographs. With these models, photo realistic quality is achieved: a kind of high-resolution 3D photograph of a real scene. In the second part of the thesis, we go further in the combination between the datasets. The digital photographs are used as an additional source of threedimensional information that can be valuable to define accurate surface boundary conditions (where range data is less reliable) or even to fill holes in the data or increase 3D point density in areas of interest.
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Gouveia, Fahim. "Projeto de um transceptor óptico para comunicação digital em espaço livre". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-04072007-133531/.
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Os sistemas de comunicação óptica por espaço livre, comumente denominados sistemas FSO (Free Space Optics), servem para estabelecer enlaces de comunicação do tipo wireless, ponto-a-ponto, a uma elevada taxa de dados e com alcances que podem variar de algumas centenas de metros a alguns quilômetros. O interesse pela tecnologia FSO tem sido estimulado pela necessidade de se fornecer soluções complementares às tradicionais (e.g. fibra óptica e RF) visando a atender à crescente demanda por conexões de banda larga. Algumas de suas aplicações mais importantes são a conexão de redes locais de computadores, a conexão de estações rádio base de telefonia móvel às centrais e o acesso de última milha. Embora a tecnologia FSO venha sendo empregada em pequena escala no Brasil, vislumbra-se o potencial de maior aplicação desta tecnologia em um futuro próximo, razão pela qual se propõe este estudo, focado no projeto de sistemas FSO. A principal contribuição deste trabalho é demonstrar uma possível solução para a realização de um enlace óptico operando em espaço livre, destinado a conectar duas redes locais de computadores Ethernet Rápida (100 Mbps). As seguintes atividades foram desenvolvidas: estudo das questões mais relevantes pertinentes ao projeto de sistemas FSO; projeto, construção e caracterização eletro-óptica de circuitos; montagem e demonstração do funcionamento de uma versão de testes do sistema, realizadas em laboratório; estudo de características associadas à transferência de radiação óptica de transmissor para receptor, envolvendo o balanço de potência para estimativa do alcance do enlace, sob condições atmosféricas ideais. Como resultado, obtivemos um sistema de comunicação do tipo full-duplex, operando no comprimento de onda de 850 nm em formato de modulação OOK, a uma taxa de dados efetiva de 125 Mbps. Com base na experiência obtida, melhoras ao sistema são sugeridas no final do trabalho.Free space optical communication systems (FSO systems) provide wireless, point-to-point communication links at high data rates, at maximum distances ranging from hundreds of meters to several kilometers. The growing interest in FSO technology arises from the necessity of providing complementary and alternative solutions to those already adopted (eg. fiber optics and RF), aiming to satisfy the increasing demand for broadband connections. Some of its most important applications are connecting local area networks (LANs), backhauling wireless networks and providing last mile access. Although today FSO is not widely adopted in Brazil, the technology has the potential for being adopted in a greater scale in the near future, which is the reason we propose a study focused on issues related to the design of FSO systems. This work\'s main contribution is to demonstrate a possible solution for the construction of a FSO system intended to connect two Fast Ethernet LANs (100 Mbps). For this purpose, the following activities were developed: study of the main aspects related to FSO system design; design, construction and electrooptical characterization of circuits; mounting and demonstration, in the lab, of a test version of the system; study of characteristics related to radiation transfer from transmitter to receiver, involving the use of the link power budget for an estimation of the maximum distance achievable under ideal atmospheric conditions. The result is a full-duplex communication system that employs the 850 nm wavelength in OOK modulation format, operating at an effective bit rate of 125 Mbps. Based on the knowledge achieved, improvements to the system are suggested at the end of this work.
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Pejchang, Darawan. "Measurement of nanoparticles by digital in-line holography". Rouen, 2015. http://www.theses.fr/2015ROUES052.
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Dans cette thèse, nous proposons une nouvelle méthode pour mesurer la taille et la forme de nanoparticules en utilisant l'holographie numérique dans l’axe en association un processus photo-thermique d’échauffement induit par laser. Une suspension de nanoparticules en très faible concentration et en milieu dilué dans une goutte d’eau, est chauffée par un laser impulsionnel. Une bulle de vapeur d’eau, stable, entourant la nanoparticule secondaire à l’échauffement est créée. La transposition de taille de l’échelle nanométrique à l’échelle micrométrique est alors obtenue. Ce processus photo-thermique est utilisé pour relier la taille de la bulle à la taille de la nanoparticule. On obtient les relations fonctionnelles entre le rapport d'aspect et le volume de la bulle et ceux de la nanoparticule. Ces fonctions dépendent des caractéristiques de l'impulsion laser, de la température initiale de la nanoparticule et l’indice optique de l'eau et sont également spécifiques à la matière et à la forme de la nanoparticule. Une nanoparticule sphérique de TiO2 est utilisée dans cette démonstration. Le diamètre mesuré expérimentalement est en bon accord avec le diamètre moyen de l'échantillon. Cela signifie que la mesure indirecte utilisant la bulle de vapeur d’eau obtenue par cavitation autour de la nanoparticule peut être considéré comme efficace pour obtenir la taille d'une nanoparticuleIn this thesis we study and develop a new methodology to measure the size and shape of individual nanoparticles by using digital in-line holography (DIH) microscopy in association with a photothermal process. Due to the limited resolution of the direct DIH technique at the nanoscale, an indirect measurement is treated. Instead of recording the hologram of a nanoparticle directly, the nanoparticle suspension is suddenly heated by a powerful pulse laser. Then a vapor bubble cavitation surrounding the nanoparticle is formed in order to increase the object size from the DIH point of view. The photothermal process is used to link the size of the bubble to the size of the nanoparticle. We obtain the functional relations between the aspect ratio and volume of the bubble and those of the nanoparticle from this process. These functions are dependent on the characteristics of the laser pulse, the initial temperature of the nanoparticle and the water medium, and are also specific to the material and shape of the nanoparticle. A spherical nanoparticle of TiO2 is used in this demonstration. The measured diameter is in good agreement with the average diameter of the sample. This means that the indirect measurement employing the cavitation vapor bubble around the nanoparticle can be considered as efficient to obtain the size of a nanoparticle. This technique has the ability to take into account the shape (ellipticity) of the bubble
34
Sriram, P. "Whole field optical methods for structural mechanics : digital speckle correlation and laser Doppler velocimetry". Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/11751.
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Chen, Xiaoran. "Computational and Experimental Approach for Non-destructive Testing by Laser Shearography". Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/928.
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"Non-destructive testing (NDT) is critical to many precision industries because it can provide important information about the structural health of critical components and systems. In addition, NDT can also identify situations that could potentially lead to critical failures. Specifically, NDT by optical methods have become popular because of their non-contact and non-invasive nature. Shearography is a high-resolution optical NDT method for identification and characterization of structural defects in components and has gained wide acceptance over the last decade. Traditional workflow of NDT by shearography has been determined to be inefficient, due to the requirements of having experienced operators that must determine the most suitable loading methods to identify defects in samples under testing as well as to determine the best system arrangement for obtaining the maximum measuring sensitivity. To reduce the number of experiments that are required and to allow inspectors to perform NDT by laser shearography in a more efficient way, it is necessary to optimize the experimental workflow. The goal of the optimization would be an appropriate selection of all experimental variables including loading methods, boundary conditions, and system¡¯s sensitivities, in order to avoid repeating experiments several times in the processes of components characterization and health monitoring. To achieve this goal, a hybrid approach using shearographic fringe prediction with Finite Element Analysis (FEA) has been developed. In the FEA simulations, different loading conditions are applied to samples with defects, and in turn, the shearographic fringes are predicted. Fringe patterns corresponding to specific loading conditions that are capable of detecting defects are chosen and experimental tests are performed using those loading conditions. As a result, using this approach, inspectors could try different combinations of loading methods, and system¡¯s sensitivities to investigate and select appropriate experimental parameters to improve defect detection capabilities of the system by using low-cost computer simulations instead of lengthy and expensive experiments. In addition, to improve the identification of defects on the sample, camera calibration and image registration algorithms are used to project the detected defects on the sample itself to locate and visualize the position of defects during shearographic investigations. This hybrid approach is illustrated by performing NDT of a plate made of acrylic that has a partial hole at the center. Fringe prediction with finite element analysis are used to characterize the optimized experimental procedures and in turn, corresponding measurements are performed. A multimedia projector is employed to project the defects on the surface of the plate in order to visualize the location of the partial hole (defect). Furthermore, shearographic system is used for other applications including NDT of a composites plate and of a thin latex membrane. The procedures shows the effectiveness of the approach to perform NDT with shearography methods. "
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Alves, Hélder Nuno Vieira. "Intraferência : hacktivismo urbano digital, uma forma de preservação do património e promoção artística". Master's thesis, Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa, 2012. http://hdl.handle.net/10362/7769.
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WebEste trabalho de projecto pretende incentivar o uso da tecnologia e dos open standards num contexto de hacktivismo urbano, preservação do património cultural e promoção artística. A questão central teórica abordada visa um exercício de reflexão sobre de que forma as tecnologias digitais combinadas com a internet produzem mudanças no quotidiano pessoal e profissional, num quadro de evolução e criação permanente. Reimaginar a forma como o graffiti comunica e integra paisagem urbana é o principal desafio. O processo de criação e partilha recorre à aplicação de código aberto laser tag para intervir e comunicar no espaço urbano, numa relação criada entre o graffiti analógico e digital, street art experimental e os novos média. O processo de concretização consiste na criação de uma célula do Graffiti Research Lab em Portugal, para criar e trocar experiências e conhecimentos bem como contribuir para um entendimento mais abrangente desta expressão artística.
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Hadi, Muhammad Usman. "Digital predistortion for compensation of nonlinearities in Radio over Fiber Links". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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In order to cope up with the ever increasing demand for larger transmission bandwidth, Radio over Fiber technology is a very beneficial solution. These systems are expected to play a major role within future fifth generation wireless networks due to their inherent capillary distribution properties.
Nonlinear compensation techniques are becoming increasingly important to improve the performance of telecommunication channels by compensating for channel nonlinearities. Indeed, significant bounds on the technology usability and performance degradation occur due to nonlinear characteristics of optical transmitter, nonlinear generation of spurious frequencies, which, in the case of RoF links exploiting Directly Modulated Lasers , has the combined effect of laser chirp and optical fiber dispersion among its prevailing causes.
The purpose of the research is to analyze some of the main causes of harmonic and intermodulation distortion present in Radio over Fiber (RoF) links, and to suggest a solution to reduce their effects, through a digital predistortion technique.
Predistortion is an effective and interesting solution to linearize and this allows to demonstrate that the laser’s chirp and the optical fiber’s dispersion are the main causes which generate harmonic distortion. The improvements illustrated are only theoretical, based on a feasibility point of view. The simulations performed lead to significant improvements for short and long distances of radio over fiber link lengths.
The algorithm utilized for simulation has been implemented on MATLAB. The effects of chirp and fiber nonlinearity in a directly modulated fiber transmission system are investigated by simulation, and a cost effective and rather simple technique for compensating these effects is discussed. A detailed description of its functional model is given, and its attractive features both in terms of quality improvement of the received signal, and cost effectiveness of the system are illustrated.
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Ross, Mark. "An embedded control and display system for a laser-based mid-infrared hyperspectral imager /". St Andrews, 2008. http://hdl.handle.net/10023/731.
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Brugière, Charlotte. "L'invasion péri-nerveuse des carcinomes épidermoïdes cutanés humains". Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC193.
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Le carcinome épidermoïde cutané (CEC) représente un enjeu important par sa fréquence et sa gravité potentielle.L’agressivité de ce cancer est liée à l’invasion péri-nerveuse (IPN), mode d’envahissement tumoral reconnu comme un facteur de mauvais pronostic.L’objectif de ce travail est de s’intéresser aux mécanismes favorisant l’IPN, en comparant 2 groupes appariés de CEC humains, avec et sans IPN.Pour cela nous avons réalisé une étude de facteurs et récepteurs neurotrophiques, de marqueurs de la transition épithélio-mésenchymateuse (TEM), et de la molécule NCAM1, par analyse immunohistochimique à partir de pièces chirurgicales de CEC et par analyse moléculaire en droplet digital PCR sur des cellules tumorales microdisséquées.L’analyse immunohistochimique a trouvé une forte expression de BDNF, TrkB, p75NGFR, Snail 1 et NCMA1 dans les cellules tumorales péri-nerveuses, contrastant avec une faible expression de ces marqueurs dans les cellules tumorales à distance du nerf. L’E-cadhérine était diminuée dans les cellules tumorales péri-nerveuses.L’analyse moléculaire en ddPCR montrait une diminution d’expression de l’E-cadhérine et une surexpression de BDNF, TrkB, p75NGFR, Snail1, Slug, Zeb2, Twist1 et NCAM1 dans les cellules tumorales péri-nerveuses par rapport aux cellules tumorales distantes du nerf.Nous avons démontré dans ce travail que l’invasion péri-nerveuse dans les CEC humains est liée aux neurotrophines, à la TEM et implique NCAM1Cutaneous squamous cell carcinoma (SCC) is an important issue because of its frequency and potential severity.The aggressiveness of this cancer is related to perineural invasion (PNI), a mode of tumor dissemination recognized as a poor prognosis factor.The aim of this work is to study the mechanisms of PNI, comparing 2 matched- groups of human SCC with and without PNI.For this, we studied neurotrophins, epithelial-mesenchymal transition (EMT) markers, and the NCAM1 molecule, by immunohistochemistry analysis on surgical pieces of SCC and by molecular analysis with digital-droplet PCR on laser-microdissected tumor cells.Immunohistochemistry analysis found strong expression of BDNF, TrkB, p75NGFR, Snail 1 and NCMA1 in perineural tumor cells, contrasting with weak expression of these markers in tumor cells distant from the nerves. E-cadherin was decreased in perineural tumor cells.Molecular analysis in ddPCR showed decreased expression for E-cadherin and overexpression of BDNF, TrkB, p75NGFR, Snail1, Slug, Zeb2, Twist1 and NCAM1 in perineural tumor cells compared to tumor cells distant from the nerves.We have demonstrated in this work that PNI in human SCC is linked to neurotrophins and EMT, and involves NCAM1
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Rahn, Christian D. [Verfasser]. "Towards Automated Processing and Analysis of Digital Laser Scanning Micrographs of Human Skin / Christian D Rahn". Aachen : Shaker, 2008. http://d-nb.info/1162793198/34.
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Kebrle, John Michael. "Texture measurement and skid number prediction using laser aata acquisition, digital signal processing, and neural networks". Arlington, TX : University of Texas at Arlington, 2008. http://hdl.handle.net/10106/931.
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Rhodes, Matthew. "DIGITAL CONTROLLER IMPLEMENTATION FOR DISTURBANCE REJECTION IN THE OPTICAL COUPLING OF A MOBILE EXPERIMENTAL LASER TRACKING SYST". Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2891.
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Laser tracking systems are an important aspect of the NASA space program, in particular for conducting research in relation to satellites and space port launch vehicles. Often, launches are conducted at remote sites which require all of the test equipment, including the laser tracking systems, to be portable. Portable systems are more susceptible to environmental disturbances which affect the overall tracking resolution, and consequently, the resolution of any other experimental data being collected at any given time. This research characterizes the optical coupling between two systems in a Mobile Experimental Laser Tracking system and evaluates several control solutions to minimize disturbances within this coupling. A simulation of the optical path was developed in an extensible manner such that different control systems could be easily implemented. For an initial test, several PID controllers were utilized in parallel in order to control mirrors in the optical coupling. Despite many limiting factors of the hardware, a simple proportional control performed to expectations. Although a system implementation was never field tested, the simulation results provide the necessary insight to develop the system further. Recommendations were made for future system modifications which would allow an even higher tracking resolution.M.S.Cp.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Engineering
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Rosa, Rogério Hadid. "Efeitos dos lasers de diodo de alta e baixa potência no processo de reparo de reabsorções radiculares após reimplante tardio: análise clínica e radiográfica em ratos". Universidade de Taubaté, 2012. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=408.
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Objetivo: Avaliar clínica e radiograficamente os efeitos da irradiação com laser de diodo de alta potência e de baixa potência em dentes de ratos, reimplantados tardiamente. Método: Foram utilizados incisivos direitos de cinquenta ratos (Wistar) com peso entre 250 a 350g. Os dentes foram extraídos, permanecendo em meio ambiente durante 60min. Em seguida, realizou-se a remoção da polpa, bem como o preparo químico-cirúrgico e o preenchimento dos canais radiculares com pasta de hidróxido de cálcio. Após a extração, os espécimes foram divididos aleatoriamente em cinco grupos (n = 10). G1 e G2 foram os controles (sem tratamento para reparação periodontal) e nesses grupos foram realizados, respectivamente, o reimplante imediato e o reimplante tardio (sessenta minutos após a extração). G3, G4 e G5 receberam tratamento para reparação antes do reimplante tardio: G3 condicionamento das superfícies radiculares com laser de diodo de alta potência (810nm, modo contínuo, fibra óptica de 600μm, 1,5W, 30s); G4 condicionamento da superfície radicular com laser de diodo de baixa potência no alvéolo (780nm, 40mW por um minuto) e na superfície radicular (660nm, 30mW por três minutos) e G5 associação do laser de alta potência e de baixa nos mesmos parâmetros dos grupos 3 e 4. Após sessenta dias do reimplante, os animais foram anestesiados para análise clínica e, posteriormente eutanasiados para preparo das peças e análise por meio de radiografias digitais das reabsorções radiculares encontradas nos grupos. Resultados: os melhores resultados quanto à análise clínica foram observados respectivamente de forma decrescente em: G1=G3>G4>G2>G5; e quanto a análise radiográfica os melhores resultados ocorreram em G1,G3 e G5 respectivamente. Conclusão: a utilização do laser de alta potência associado ou não ao laser de baixa promoveu a diminuição da ocorrência de reabsorções externas quando comparada aos grupos isentos de tratamento de superfície radicular, e o laser de baixa potência, isoladamente, não favoreceu o controle das reabsorções radiculares.Study hypothesis: The external root resorptions control and the peridontal ligaments regeneration when using the high and low laser power in associate or not in case of delayed reimplant in rats. Objective of the study : Evaluate clinically and radiographically the radiation effects using diodo laser with high and low power in the rats teeth those had delayed reimplant. Methodology: We used incisors rights from fifty rats (Wistar) with weight between 250 a 350g. The teeth were extracted and remained in the environment during 60min. After this, the extraction, the surgical chemical preparation and the filling of root conducts were made with calcium hydroxide paste. Then, the animals were divided randomly in five groups (n=10). G1 and G2 were the controls ( those didnt have treatmet for peridontal repair) and in those groups were realized respectively the immediate reimplant and the delayed reimplant (sixty minutes after the extraction). G3, G4 and G5 had received treatment for reparation before the delayed reimplant; G3- The root surfaces conditioning using diodo high power(810nm,continuos mode, optical fiber 600μm, 1.5W, 30s);G4 The root surface conditioning using diodo low power in alveolar wounds(780nm, 40mW during one minute) and in the root surface (660nm, 30mW during three minutes). G5 - the association with the high and low power in the same way that in the groups 3 and 4. After sixty days, the animals were anesthezied for clinical analisys, and euthanized in order to prepare the parts and to analyse throught the digital x-rays the root resorptions those were found in both groups. Results: The best results about clinical analysis were obtained respectively in decreasing order in G1=G3>G4>G2>G5; and about the radiography analysis the best results occurred in G1,G3 e G5 respectively. Conclusion: The high laser power utilization in association or not with low laser power promoted the decreasing of root resorptions when it compared with the groups that didnt have the same treatment, and the low laser power when was used alone it didnt result in the root resorptions control.
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Marquard, Jonas [Verfasser] y Stefan W. [Akademischer Betreuer] Hell. "Digital Light Deflection and Electro-Optical Laser Scanning for STED Nanoscopy / Jonas Marquard ; Betreuer: Stefan W. Hell". Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://d-nb.info/1177384167/34.
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Fitch, Andrew William. "Characterisation of flow in an oscillatory baffled column using digital particle image velocimetry and laser induced fluorescence". Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/375.
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Marquard, Jonas [Verfasser] y Stefan [Akademischer Betreuer] Hell. "Digital Light Deflection and Electro-Optical Laser Scanning for STED Nanoscopy / Jonas Marquard ; Betreuer: Stefan W. Hell". Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-239568.
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Doheny, David A. "Real Time Digital Signal Processing Adaptive Filters for Correlated Noise Reduction in Ring Laser Gyro Inertial Systems". [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000306.
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Lim, Kwanthar. "Semi-automated registration with direct linear transformation and quality evaluation of digital photogrammetry and terrestrial laser scanning". Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/2592.
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Photogrammetry and Laser Scanning can be used to complement one another, during instances where digital images are taken of the object of interest with the intention to merge the 3D data and image in order to reconstruct photorealistic virtual models with photo quality and metric realism. Laser scanning acquires 3D data points and intensity information of objects but is unable to directly obtain photorealistic colour in most cases. To get photorealistic colour, some laser scanners come with an onboard camera, or alternatively a separate camera is used, and registration is required for both cases. One example uses a specially designed camera mounting for the laser scanner and another is to transfer colour information from 2D images captured from near the scanner to the 3D points using close-range photogrammetry. Currently limited methods exist for the registration of the data from multiple-sensors. This research outlines the evaluation and semi-automated registration of a single colour image to laser scanning point cloud data, using the canonical transformation and Direct Linear Transformation (DLT) methods for registration.The method presented in this thesis is to directly reconstruct three dimensional data from a single image with the assistance of estimated depth information. Laser scanning point cloud information is used to supplement the recovery of the estimated depth information, which is then assigned to the image data. Two primary aspects for this research are (1) the Synthetic Camera Image, following on from previous work reported in the literature on utilising synthetic imagery created from point-clouds, and (2) the Direct Linear Transformation model, which is used to provide the transformation parameters between the 2D and 3D datasets.Synthetic datasets were used to provide an indication of expected results in terms of range, incidence angle and image resolution. The image resolution is an important factor to consider. It should be as high as possible as it affects the outcome of precision. Testing with real data, the proposed method resulted in a precision of 2 mm for the data of a model T-Rex dinosaur dataset, and 19mm for a typical indoor scene. The variations in precision levels are due to different values for range, incidence angle and image resolution. Overall the results achieved the expectations producing a colour point cloud with metric assessment.
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Nissinen, I. (Ilkka). "CMOS time-to-digital converter structures for the integrated receiver of a pulsed time-of-flight laser rangefinder". Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514295478.
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Abstract The aim of this thesis was to develop time-to-digital converters (TDC) for the integrated receiver of a pulsed time-of-flight (TOF) laser rangefinder aiming at cm-level accuracy over an input range of 10 m – 15 m. A simple structure, a high integration level and low power consumption are the desired features for such a TDC. From the pulsed TOF laser rangefinder point of view an integrated receiver consisting of both the TDC and the receiver channel on the same die offers the possibility of manufacturing these laser rangefinders with a high integration level and at a low price to fulfil the needs of mass industrial markets. The heart of the TDC is a CMOS ring oscillator, the clock frequency of which is used to calculate the full clock cycles between timing signals, the positions of the timing signals inside the clock period being determined by storing the state of the phase of the ring oscillator for each timing signal. This will improve the resolution of the TDC. Also, additional delay lines are used to generate multiple timing signals, each having a time difference of a fraction of that of the ring oscillator. This will further improve the resolution of the whole TDC. To achieve stable results regardless of temperature and supply voltage variations, the TDC is locked to an on-chip reference voltage, or the resolution of the TDC is calibrated before the actual time interval measurement. The systematic walk error in the receiver channel caused by amplitude variation in the received pulse is compensated for by the TDC measuring the slew rate of the received pulse. This time domain compensation method is not affected by the low supply voltage range of modern CMOS technologies. Three TDC prototypes were tested. A single-shot precision standard deviation of 16 ps (2.4 mm) and a power consumption of 5.3 mW/channel were achieved at best over an input range of 100 ns (15 m). The temperature drifts of an on-chip voltage reference-locked TDC and a TDC based on the calibration method were 90 ppm/°C and 0.27 ps/°C, respectively. The results also showed that a pulsed TOF laser rangefinder with cm-level accuracy over a 0 – 15 m input range can be realized using the integrated receiver with the time domain walk error compensation described hereTiivistelmä Väitöskirjatyön tavoitteena oli kehittää aika-digitaalimuunninrakenteita valopulssin kulkuajan mittaukseen perustuvan lasertutkan integroituun vastaanottimeen. Tavoitteena oli saavuttaa senttimetriluokan tarkkuus 10 m – 15 m mittausalueella koko lasertutkan osalta. Aika-digitaalimuuntimelta vaaditaan yksinkertaista rakennetta, korkeaa integroimisastetta ja matalaa tehonkulutusta. Integroitu vastaanotin sisältää sekä aika-digitaalimuuntimen että vastaanotinkanavan ja tarjoaa mahdollisuuden korkeasti integroidun lasertutkan valmistukseen halvalla teollisuuden massamarkkinoiden tarpeisiin. Aika-digitaalimuuntimen ytimenä toimii monivaiheinen CMOS-rengasoskillaattori. Aika-digitaalimuunnos perustuu rengasoskillaattorin täysien kellojaksojen laskentaan laskurilla ajoitussignaalien välillä. Lisäksi rengasoskillaatorin jokaisesta vaiheesta otetaan näyte ajoitussignaaleilla niiden paikkojen määrittämiseksi kellojakson sisällä, jolloin aika-digitaalimuuntimen erottelutarkkuutta saadaan parannettua. Erottelutarkkuutta parannetaan lisää viivästämällä ajoitussignaaleja viive-elementeillä ja muodostamalla näin useita erillisiä ajoitussignaaleja, joiden väliset viive-erot ovat murto-osa rengasoskillaattorin viive-elementin viiveestä. Aika-digitaalimuunnin stabiloidaan käyttöjännite- ja lämpötilavaihteluja vastaan lukitsemalla se integroidun piirin sisäiseen jännitereferenssiin, tai sen erottelutarkkuus määritetään ennen varsinaista aikavälinmittausta erillisellä kalibrointimittauksella. Vastaanotetun valopulssin amplitudivaihtelun aiheuttama systemaattinen ajoitusvirhe integroidussa vastaanotinkanavassa kompensoidaan mittaamalla vastaanotetun valopulssin nousunopeus aika-digitaalimuuntimella. Tällainen aikatasoon perustuva kompensointimetodi on myös suorituskykyinen nykyisissä matalakäyttöjännitteisissä CMOS-teknologioissa. Työssä valmistettiin ja testattiin kolme aika-digitaalimuunninprototyyppiä. Muuntimien kertamittaustarkkuuden keskihajonta oli parhaimmillaan 16 ps (2,4 mm) ja tehonkulutus alle 5,3 mW/kanava mittausetäisyyden olessa alle 100 ns (15 m). Sisäiseen jännitereferenssiin lukitun aika-digitaalimuuntimen lämpötilariippuvuudeksi mitattiin 90 ppm/°C ja kalibrointimenetelmällä saavutettiin 0,27 ps/°C lämpötilariipuvuus. Työssä saavutetut tulokset osoittavat lisäksi, että valopulssin kulkuajan mittaukseen perustuvalla lasertutkalla on saavutettavissa senttimetriluokan tarkkuus 0 – 15 m mittausalueella käyttämällä tässä työssä esitettyä integroitua vastaanotinta ja aikatason ajoitusvirhekompensointia
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Moussa, Wassim [Verfasser] y Dieter [Akademischer Betreuer] Fritsch. "Integration of digital photogrammetry and terrestrial laser scanning for cultural heritage data recording / Wassim Moussa. Betreuer: Dieter Fritsch". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/105038900X/34.
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