Dissertations / Theses on the topic 'Laser scanning technique'
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1
Tam, Chung-yan Candy. "Study of rock joint roughness using 3D laser scanning technique." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/b40203487.
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Tam, Chung-yan Candy, and 譚頌欣. "Study of rock joint roughness using 3D laser scanning technique." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203487.
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Yahyavi, Zanjani Matin, Henning Zeidler, André Martin, and Andreas Schubert. "Application of Laser Scanning as a Pre-machining metrology technique in Jet-ECM." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-227104.
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In Electrochemical Machining (ECM), where the material removal takes place based on the anodic dissolution of the workpiece material, the working distance is one of the most important parameters. Especially in Jet Electrochemical Machining (Jet-ECM), where a micro nozzle is moved over the initial surface of the workpiece in order to apply an electrolytic free jet to produce the desired shapes, the distance between the nozzle and the workpiece becomes even more important. On the one hand a small working distance is aspired to achieve high current densities resulting in a high efficiency of the process. On the other hand the working distance needs to be large enough to avoid damages on the micro nozzle caused by electrical discharges or mechanical contact. Hence, the adjustment of the working gap is essential to realize a precise, effective and secure Jet-ECM process.
The control of the gap size is done based on the data gathered before machining by surface measurement. Until now, the initial surface has been detected by electrostatic probing through moving the nozzle stepwise to the work piece surface and detect the voltage drop between the nozzle and the work piece. With this strategy, only a limited number of points can be detected within adequate time. Hence, in most cases only three points of the initial surface are detected in order to adjust the working distance according to the planar inclination of the workpiece. The coordinates of the three detected points are used to calculate the normal vector of the initial surface. In recent studies, another strategy was analysed, which is realized by dividing the surface into smaller areas and respectively calculating the normal vector of each area in order to obtain more accurate data of the initial surface. A further strategy is to use probing along the machining path of the tool and to gather the coordinates of a number of points along the path.
The above mentioned methods usually do not ensure the precise control of the gap size especially for the surfaces with complex geometry with locally confined convex and concave shapes and are highly affected by the size of the probe. In this study, the application of a laser scanner is investigated for the measurement of the workpiece surface before machining to gather the required data for the adjustment of the working distance during Jet-EC machining of complicated surfaces.
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Favey, Etienne. "Investigation and improvement of airborne laser scanning technique for monitoring surface elevation changes of glaciers /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14045.
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Yildiz, Bilge Can. "Imaging Of Metal Surfaces Using Confocal Laser Scanning Microscopy." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613641/index.pdf.
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Optical imaging techniques have improved much over the last fifty years since the invention of the laser. With a high brightness source many imaging applications which were once inaccessible to researchers have now become a reality. Among these techniques, the most beneficial one is the use of lasers for both wide-field and
confocal imaging systems.
The aim of this study was to design a laser imaging system based on the concept of laser scanning confocal microscopy. Specifically the optical system was based on optical fibers allowing the user to image remote areas such as the inner surface of rifled gun barrels and/or pipes with a high degree of precision (+/- 0.01 mm). In order to build such a system, initially the theoretical foundation for a confocal as well as a wide-field imaging system was analyzed. Using this basis a free-space optical confocal system was built and analyzed. The measurements support the fact that both the objective numerical aperture and pinhole size play an important role in the radial and axial resolution of the system as well as the quality of the images obtained.
To begin construction of a confocal, optical-fiber based imaging system first an all fiber wide-field imaging system was designed and tested at a working wavelength of 1550 nm. Then an all fiber confocal system was designed at a working wavelength of 808 nm. In both cases results showed that while lateral resolution was adequate, axial resolution suffered since it was found that the design of the optical system needs to take into account under-filling of the objective lens, a result common with the use of laser beams whose divergence is not at all like that of a point source.
The work done here will aid technology that will be used in the elimination process of faulty rifling fabrication in defense industry. The reason why the confocal technique is preferred to the conventional wide-field one is the need for better resolution in all directions. Theoretical concepts and mathematical background are discussed as well as the experimental results and the practical advantages of such a system.
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Barnier, Fabien. "Fibre Bragg grating techniques." Thesis, University of Hull, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322570.
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Liu, Yan. "Comparison of tactile probe CMM and laser scanning techniques for reverse engineering." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30955.pdf.
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Monte, Jamie Marie, and 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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Doukoglou, Tilemachos D. "Non-parametric system identification techniques for numerical deconvolution of scanning laser microscope images." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61889.
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Meadway, Alexander. "Combinations of techniques for the advancement of scanning laser ophthalmology and optical coherence tomography." Thesis, University of Kent, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653049.
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In this thesis methods of eye imaging are investigated, primarily optical coherence tomography (OCT) and scanning laser ophthalmology (SLO). These are two well established technologies. This thesis investigates the combination of techniques to improve resolution, sensitivity and the amount of information that can be extracted from a device. There are three systems presented in the thesis. The first generates on-axis and off axis confocal retinal images simultaneously by way of a drilled mirror. Off-axis imaging provides greater depth penetration, but at the cost of resolution. The second system combines three technologies; SLO, time domain (TD) OCT and adaptive optics (AO). The system is able to generate simultaneous en-face SLO and OCT images, whilst the AO closed loop corrects for aberrations enhancing the intensity and resolution of the images in both modes. This system is used in several investigative directions; the effect of deformable mirror dynamics on the acquired image; the OCT channel is used to investigate the confocal profile; the performance of the deformable mirror with regards to its focus control is investigated; the focus control is used to generate 3D confocal images. Finally, the system is converted to a balanced Fourier domain (FD) OCT system. It has previously been assumed that excess photon noise (that balanced detection is used to remove) is not significant due to the limitations of the CCD camera used in an FD system's spectrometers, however, CCD cameras have since been developed, with increased depths of quantum wells and balanced detection offers other advantages, such as the removal of auto correlation terms from an image. The third system investigated is a TD-OCT system that spectrally separates the broadband source into discrete channels at detection. It can be viewed as a hybrid system, combining TD and FD OCT. A system such as this may be used to reduce the shot noise of a time domain system, or it may be used to make spectroscopic measurements. Both are investigated in this thesis, dispersion was measured as well as absorption profiles and a preliminary investigation into the noise reduction is also presented.
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Göbel, Werner. "3D laser-scanning techniques for two-photon calcium imaging of neural network dynamics in vivo /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17655.
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Dalgleish, Gordon Fraser. "A study of laser-based scanning techniques for defect recognition in sintered cutting tool inserts." Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389285.
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Acharya, Dabit. "COMPARATIVE EXPERIMENTAL STUDIES FOR GLOBAL DAMAGE DETECTION IN PLATES USING THE SCANNING LASER VIBROMETER TECHNIQUES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1155079600.
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TORTAROLO, GIORGIO. "Laser Scanning Microscopy with SPAD Array Detector: Towards a New Class of Fluorescence Microscopy Techniques." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1000654.
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Laser scanning microscopy is one of the most common architectures in fluorescence microscopy. In a nutshell: the objective lens focuses the laser beam(s) and generates an effective excitation spot which is scanned on the sample; for each pixel, the fluorescent image is projected into a single-element detector, which – typically – spatially and temporally integrates the fluorescent light along its sensitive area and the pixel dwell-time, thus providing a single-intensity value per pixel. Notably, the integration performed by the single-element detector hinders any additional information potentially encoded in the dynamic and image of the fluorescent spot. To address this limitation, we recently upgraded the detection unit of a laser scanning microscope, replacing the single-element detector with a novel SPAD (single photon avalanche diode) array detector. We have shown at first that the additional spatial information allows to overcome the trade-off between resolution and signal-to-noise ratio proper of confocal microscopy: indeed, this architecture represents the natural implementation of image scanning microscopy (ISM). We then exploited the single-photon-timing ability of the SPAD array detector elements to combine ISM with fluorescence lifetime imaging: the results show higher resolution and better lifetime accuracy with respect to the confocal counterpart. Moreover, we explored the combination of our ISM platform with stimulated emission depletion (STED) microscopy, to mitigate the non-negligible chance of photo-damaging a sample. Lastly, we showed how the SPAD array-based microscope can be used in the context of single-molecule/particle tracking (SMT or SPT) and spectroscopy. Indeed, we implemented a real-time, feedback based SMT architecture which can potentially correlate the dynamics of a bio-molecule with its structural changes and micro-environment, taking advantage of the time-resolved spectroscopy ability of the novel detector.
We believe that this novel laser scanning microscopy architecture has everything in its favour to substitute current single-element detector approaches; it will enable for a new class of fluorescence microscopy techniques capable of investigating complex living biological samples with unprecedented spatial and temporal characteristics and augmented information content.
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GASPARONI, ANDREA. "Tracking and continuous-tracking scanning laser doppler vibrometer: innovative techniques for the operational characterization of rotating blades." Doctoral thesis, Università Politecnica delle Marche, 2010. http://hdl.handle.net/11566/242169.
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Paul, Sanjoy. "CHARGE TRANSPORT IN LIQUID CRYSTALLINE SMECTIC AND DISCOTIC ORGANIC SEMICONDUCTORS: NEW RESULTS AND EXPERIMENTAL METHODOLOGIES." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1469836810.
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Lewark, Erick A. "Automated techniques in anthropometry using a three dimensional laser scanner." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176485676.
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Benaud, Pia Emma. "Exploring the multiple techniques available for developing an understanding of soil erosion in the UK." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/32939.
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Accelerated soil erosion and the subsequent decline in soil depth has negative environmental, and consequently financial, impacts that have implications across all land cover classifications and scales of land management. Ironically, although attempts to quantify soil erosion nationally have illustrated that soil erosion can occur in the UK, understanding whether or not the UK has a soil erosion problem still remains a question to be answered. Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible, fluvial pathways and the subtle nature of the less-visible, diffuse pathways, across varying spatial and temporal scales. Accordingly, as we move towards a national-scale understanding of soil erosion in the UK, this thesis aims to explore some of the multiple techniques available for developing an understanding of soil erosion in the UK. The thesis first explored the information content of existing UK-based soil erosion studies, ascertaining the extent to which these existing data and methodological approaches can be used to develop an empirically derived understanding of soil erosion in the UK. The second research chapter then assessed which of two proximal sensing technologies, Terrestrial Laser Scanning and Structure-from-Motion Multi-view Stereo (SfM-MVS), is best suited to a cost-effective, replicable and robust assessment of soil erosion within a laboratory environment. The final research chapter built on these findings, using both Rare Earth Oxide tracers and SfM-MVS to elucidate retrospective information about sediment sources under changing soil erosion conditions, also within a laboratory environment Given the biased nature of the soil erosion story presented within the existing soil erosion research in the UK, it is impossible to ascertain if the frequency and magnitude of soil erosion events in the UK are problematic. However, this study has also identified that without ‘true’ observations of soil loss i.e. collection of sediment leaving known plot areas, proxies, such as the novel techniques presented in the experimental work herein and the methods used in the existing landscape scale assessments of soil erosion as included in the database chapter, are not capable of providing a complete assessment of soil erosion rates. However, this work has indicated that despite this limitation, each technique can present valuable information on the complex and spatially variable nature of soil erosion and associated processes, across different observational environments and scales.
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Fekrmandi, Hadi. "Development of New Structural Health Monitoring Techniques." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/cgi/viewcontent.cgi?article=2923&context=etd.
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During the past two decades, many researchers have developed methods for the detection of structural defects at the early stages to operate the aerospace vehicles safely and to reduce the operating costs. The Surface Response to Excitation (SuRE) method is one of these approaches developed at FIU to reduce the cost and size of the equipment. The SuRE method excites the surface at a series of frequencies and monitors the propagation characteristics of the generated waves. The amplitude of the waves reaching to any point on the surface varies with frequency; however, it remains consistent as long as the integrity and strain distribution on the part is consistent. These spectral characteristics change when cracks develop or the strain distribution changes. The SHM methods may be used for many applications, from the detection of loose screws to the monitoring of manufacturing operations.
A scanning laser vibrometer was used in this study to investigate the characteristics of the spectral changes at different points on the parts. The study started with detecting a load on a plate and estimating its location. The modifications on the part with manufacturing operations were detected and the Part-Based Manufacturing Process Performance Monitoring (PbPPM) method was developed. Hardware was prepared to demonstrate the feasibility of the proposed methods in real time.
Using low-cost piezoelectric elements and the non-contact scanning laser vibrometer successfully, the data was collected for the SuRE and PbPPM methods. Locational force, loose bolts and material loss could be easily detected by comparing the spectral characteristics of the arriving waves. On-line methods used fast computational methods for estimating the spectrum and detecting the changing operational conditions from sum of the squares of the variations. Neural networks classified the spectrums when the desktop – DSP combination was used. The results demonstrated the feasibility of the SuRE and PbPPM methods.
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Graves, Rosemarie Rachel. "Can a hemispherical scanning imaging differential optical absorption spectroscopy technique be used to improve understanding of the emissions, dynamics and chemistry of nitrogen dioxide in the urban boundary layer?" Thesis, University of Leicester, 2014. http://hdl.handle.net/2381/28636.
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Air quality is an international issue which has been the subject of several European directives on pollution levels as atmospheric pollutants can have significant effects on human health, ecosystems and climate change, especially at high levels. In the UK the largest sources of atmospheric pollutants are products of combustion from power generation and motor vehicles including NO[subscript x] (NO and NO[subscript 2]), CO, VOCs and particulate matter. Hence it is becoming increasingly important to measure changes in these air pollutants especially in urban areas where these pollutants are at the highest levels. Differential Optical Absorption Spectroscopy is now commonly used as an air quality tool; primarily through the measurements of nitrogen dioxide (NO[subscript 2]). CityScan is a Hemispherical Scanning Imaging Differential Optical Absorption Spectrometer (HSI-DOAS) which has been optimised to measure concentrations of NO[subscript 2]. This thesis will describe the development and subsequent deployment of three CityScan instruments and the first results from these deployments. CityScan has a 95° field of view (FOV) between the zenith and 5° below the horizon. Across this FOV there are 128 resolved elements which are measured concurrently, the spectrometer is rotated azimuthally 1° per second providing full hemispherical coverage every 6 minutes. Three CityScan instruments were built between 2009 and 2012 and deployed in various locations, including Leicester, London and Bologna. Data from one of these instruments has been validated with a MAX-DOAS instrument (TROPOGAS) and in situ monitors. The comparison with the TROPOGAS instrument produced gradient values between 0.7 and 1 with R² values rarely lower than 0.7. An NO[subscript 2] detection limit of CityScan has been calculated to be 4 x 10[superscript 15] mol cm[superscript -2]. The extensive field of view of the CityScan instruments has allowed NO[subscript 2] concentrations to be mapped on city-wide scales allowing areas of high and low pollution to be identified with a spatial resolution which has never been possible before without the use of models.
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SUZUKI, SELLY S. "Avaliação histomorfométrica, imunoistoquímica e microtomográfica da ação da terapia laser de baixa potência no processo de reabsorção radicular durante movimentação ortodôntica induzida em ratos." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26832.
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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T17:46:50Z
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A movimentação dentária induzida é um processo biológico complexo mediado por estímulos mecânicos, levando a um subsequente processo de remodelação óssea, podendo haver reabsorção indesejada da raiz dentária provocada pelo excesso de força. Uma vez que a movimentação ortodôntica se baseia em um processo inflamatório localizado, o propósito deste estudo foi avaliar os efeitos do laser de baixa potência no processo de remodelação óssea e reabsorção radicular, buscando correlacionar as mudanças metabólicas observadas a nível celular ocorridas nos dias iniciais da movimentação dentária às alterações teciduais observadas microscopicamente e à arquitetura e morfologia do trabeculado e cortical ósseo. Primeiros molares de sessenta e oito ratos machos Wistar foram submetidos à movimentação induzida, divididos em 3 grupos: controle negativo (nenhuma movimentação), não irradiado (movimentação sem irradiação) e laser (movimentação e irradiação com laser de baixa potência de comprimento de onda de 810 nm, potência de 100 mW, área de 0,02cm2 e energia de 1,5 J/ponto) e eutanasiados nos dias 3, 6, 9, 14 e 21. Mensurações da movimentação dentária e análises histomorfométricas foram realizadas em todos os dias estudados. Análise imunoistoquímica dos marcadores RANKL, OPG e TRAP e avaliações por microscopia eletrônica de varredura (MEV) foram feitas nos dias 3, 6 e 9 e o ensaio Western Blotting para proteínas RANKL e SOFAT e imagens de microtomografia computadorizada (MicroCT) nos dias 14 e 21. Os resultados deste estudo mostraram que a movimentação dentária foi significantemente maior no grupo Laser (aumento em média de 40%) em todos os dias avaliados. O lado de compressão mostrou maior expressão de RANKL e osteoclastos TRAP-positivos nos dias 3, 6 e 9 (p<0,05), promovendo significativa redução na área de osso alveolar presente no lado de compressão nos dias 6, 9 e 14 (p<0,05), e alterações microestruturais, como menor fração de volume ósseo/volume total, menor densidade óssea mineral aos 14 dias. A irradiação com laser também aumentou a expressão de RANKL e a citocina SOFAT no dia 14. No lado de tensão, houve maior expressão de OPG especialmente aos 9 dias (p<0,001) e significativo aumento na área de osso alveolar presente nos dias 14 (p<0,01) e 21 (p<0,05) histomorfometricamente e maior densidade óssea mineral e espessura das trabéculas aos 21 dias (p<0,01). Com relação às áreas de hialinização presentes, os resultados mostraram áreas significantemente reduzidas nos dias 3, 6 e 9 nos grupos irradiados, o que explica o menor número de odontoclastos na superfície radicular nestes dias e a redução significante das áreas de reabsorção radicular observadas nas lâminas histológicas nos dias 9, 14 e 21 e nas imagens de MEV nos dias 3 e 9. Os grupos irradiados também mostraram menor volume das lacunas de reabsorção radicular medidas no MicroCT nos dias 14 e 21, especialmente nos lados de compressão. O estudo concluiu que o laser de baixa potência influenciou a remodelação óssea, aumentou a atividade dos osteoclastos no lado da compressão, e estimulou a formação óssea no de tensão, acelerando significativamente o movimento dentário e potencialmente reduzindo as áreas de necrose no ligamento periodontal e, consequentemente, a reabsorção radicular.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Huang, Yi-Zhen, and 黃怡蓁. "Rail Wear Inspection by the Laser Scanning Technique." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r7y6at.
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碩士國立中央大學
土木工程學系
106
The railway transportation system plays a very important role in the developed countries. In recent years, as increase the speed and frequency of trains, the rail system is damaged more quickly. When the damage of the rail head reaches a degree, the contact area between the head of rail and the train will increase. These results carries the passenger comfort ability, noise problems and even lead to traffic accidents. The railway maintenance group must immediately and accurately measure the rail wearing condition to ensure the safety of the rail system operation. Taiwan inspect the wear damage manually have purchase authorities non-contact inspection vehicles from foreign countries .However, the demand on automatic and fast inspection technique is urgent. This study integrates non-contact laser technology, image processing technology and Matlab programming language to develop a rail wear detection system. The experimental measurement of the rail head profile obtained through the image processing and the reference value of the standard rail section is used to calculate the amount of wearing. Using a hand-held rail abrasion instrument for experimental verification to judge errors, This study sought more efficient detection methods and wanted to develop a fast and accurate track damage detection system to enhance the effectiveness of the maintenance work
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Chao, Chun-Wei, and 曹峻瑋. "Application of 3D-Laser Scanning Technique in Tunnel Engineering." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/19596001301890786972.
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碩士國立臺灣大學
土木工程學研究所
94
Traditional tunnel’s profile monitoring usually costs a lot of manpower, finance and time, and it utilizes only few, selected and fixed observation points in a single tunnel’s profile to get the desired information. In the advancement of optics’ technique and of the performance of computer recently, the development of a new monitoring technique, which is easy to operate, rapid and inexpensive, for tunnel engineering might be helpful for us to equally understand the deformation tendency in a tunnel. From this, derived results can serve as a reference for future repairing of the support system, or the parameters of back analyzing about the development of plastic zone considering long-term and/or regular monitoring works, and for developing a more complete three-dimensional (3-D) information about tunnel’s profile. This study was conducted to develop a new non-contact measurement technique which can be applied to tunnel engineering using a two-dimensional laser image and a program to construct the 3-D information in a certain profile. Different from traditional monitoring, this technique can provide a more complete 3-D profile information by first establishing several points whose 3-D information were already known for calibration. In addition to a small simulative tunnel, a bigger one was constructed in the laboratory to simulate the full-scale tunnel in this study. Based from the results in small tunnel, it was observed that the measurement of deformation behavior from the two successive analyses performed is effective. Also, profiling results from this technique and a total-station-based method were compared and showed that RMSE value can be controlled in about 4 mm in this new technique. Moreover, this research uses image processing to construct a 3-D tunnel’s profile information, thus, the influence are mostly from images. Therefore, improvement in the image processing method is advised to achieve a more precise result.
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Chen, Chi-Yuan, and 陳其沅. "Using 3D Laser Scanning Technique in Structure Monitoring and Terrain Modeling." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/92d64z.
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碩士國防大學理工學院
空間科學碩士班
105
ABSTRACT This research integrates ground LiDAR(Light detection and ranging)- 3D scanning technique and point cloud data, selected Daxi Bridge and nearby valley as test areas, attempt to monitoring the bridge deformation in different times, and producing digital elevation model(DEM). The aims of those studies are summarized as follow: (1) Trying to enhance ground LiDAR technique working and point cloud data processing. (2) Replace the traditional surveying with ground LiDAR technique to implement the feasibility of structural monitoring operations. (3) Compared the DEM made in the same area with ground LiDAR and airborne LiDAR. The results show the accuracy of the point cloud data setting approaches 3 mm. Therefore, the deformation of structures monitoring is over 1 cm, it can be depended on ground LiDAR technique. Besides DEM made, e-GNSS positioning is used to fix control points in this case, and the precision of this system can be reached centimeter level. After fix control points fulfilled, all the point cloud data can be transformed to TWD97 coordinate. Finally, compared with the quality of DEMs made, the benefits of ground LiDAR has that higher resolution and lower costs than those of airborne LiDAR. Keywords: Ground LiDAR, Airborne LiDAR, Point Cloud, DEM, e-GNSS
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"Highly Sensitive in-Plane Strain Mapping Using a Laser Scanning Technique." Doctoral diss., 2014. http://hdl.handle.net/2286/R.I.27516.
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abstract: In this work, a highly sensitive strain sensing technique is developed to realize in-plane strain mapping for microelectronic packages or emerging flexible or foldable devices, where mechanical or thermal strain is a major concern that could affect the performance of the working devices or even lead to the failure of the devices. Therefore strain sensing techniques to create a contour of the strain distribution is desired.
The developed highly sensitive micro-strain sensing technique differs from the existing strain mapping techniques, such as digital image correlation (DIC)/micro-Moiré techniques, in terms of working mechanism, by filling a technology gap that requires high spatial resolution while simultaneously maintaining a large field-of-view. The strain sensing mechanism relies on the scanning of a tightly focused laser beam onto the grating that is on the sample surface to detect the change in the diffracted beam angle as a result of the strain. Gratings are fabricated on the target substrates to serve as strain sensors, which carries the strain information in the form of variations in the grating period. The geometric structure of the optical system inherently ensures the high sensitivity for the strain sensing, where the nanoscale change of the grating period is amplified by almost six orders into a diffraction peak shift on the order of several hundred micrometers. It significantly amplifies the small signal measurements so that the desired sensitivity and accuracy can be achieved.
The important features, such as strain sensitivity and spatial resolution, for the strain sensing technique are investigated to evaluate the technique. The strain sensitivity has been validated by measurements on homogenous materials with well known reference values of CTE (coefficient of thermal expansion). 10 micro-strain has been successfully resolved from the silicon CTE extraction measurements. Furthermore, the spatial resolution has been studied on predefined grating patterns, which are assembled to mimic the uneven strain distribution across the sample surface. A resolvable feature size of 10 µm has been achieved with an incident laser spot size of 50 µm in diameter.
In addition, the strain sensing technique has been applied to a composite sample made of SU8 and silicon, as well as the microelectronic packages for thermal strain mappings.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2014
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Huang, Nai-Jie, and 黃迺絜. "Analysis of Geological Section for Fault Trenches Using Laser Scanning Technique." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/12578317840577875518.
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碩士國立臺灣大學
土木工程學研究所
104
Excavating fault trenches is one of main method to study paleoseismology. However, the current approach which costs considerable time and manpower only relies on geologists to recognize the multiple faulting events. Therefore, this study constructs an automatic procedure to map geological sections by using terrestrial LiDAR systems integrated with cameras. The experiment results indicated that the proposed approach can provide high-quality images of fault trenches and amount of image deformation can also be simultaneously evaluated. In the supervised classification procedures, the classification accuracies are also encouraging (overall accuracy 81.18% and kappa 0.7646). Furthermore, by using an existing geological section produced in 2002 with the texture analysis and classification from the image, the major categories can be correctly identified. It gives solid evidence that the terrestrial LiDAR techniques can be efficiently extended to the applications in geological studies.
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Chang, Ming-Cheng, and 張明政. "A Study of Using 3D Laser Scanning Technique for Land Parcel Survey－Building Experiment." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/36562905764922151217.
Full textAbstract:
碩士國立中興大學
土木工程學系
92
Cadastral maps and cadastral data can provide an very important basis for the land administration management. The accuracy of cadastral maps is closely related to the rights and interests of citizens. Among cadastral surveys, the land parcel survey undoubtedly plays the most important role. Currently, the land parcel survey is only performed to produce 2-D products. In fact, during building state survey, there are lots of spatial information can be obtained. 2-D cadastral data are not sufficient to meet the needs of modern technology for wide uses in the 3-D field. Therefore, it has been forming an inevitable tendency for the adding of cadastral data into diverse precise 3-D spatial information for more widely uses. Nowadays, the technique of long range 3-D laser scanning has become more matured. So, the join of 3-D Laser Scanning in land parcel survey with its high density and precision scanning will make the traditional cadastral maps to produce a 3-D view and meet the requirement for multifunctional uses. Abundant 3-D point cloud is collected after the use of 3-D scanner over the study area where the technology was introduced to perform land parcel survey. Those points were processed and analyzed to establish buildings model. The coordinate systems at scanning stations were then transformed into currently published cadastral coordinate system to make a simulative cadastre. Once the result after comparison and analysis between the simulative one and the original published cadastral map is corresponding to the regulations, a 3-D cadastre joined with stereo building model can hopefully be set up for browse to public. The 3-D model of cadastral information displayed on monitor not only clearly identifies the boundary situation but also the possible disputes between land owners and the cases of land parcel survey would decrease. From this study, it shows: that (1) the largest error was within 4 centimeter for boundary point, which is allowed by to the Regulation for Cadastral Survey. (2) 3-D cadastre can be browsed by the public for the convenience of reading and to build a clear realization over the land in practical situation.
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Chen, Li-Sheng, and 陳立笙. "Integration of Digital Photogrammetry and Laser Scanning Technique for Generating High-Quality 3D Point Clouds." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/y88x5u.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
105
The Light Detection and Ranging (LiDAR) technique is a popular 3D surveying technique nowadays, which is capable of swiftly and precisely acquiring point cloud data with high density, for various engineering monitoring tasks. However, due to the limitation on the mechanism of the used technique, the point cloud data acquired by the LiDAR system frequently reaches unfavorable results, which have the flaws, such as uneven resolution and missing areas. In order to solve this problem, a combined approach for delivering high quality 3D colored point cloud is developed in this study, making the quality improvement of point cloud can be accomplished by integrating accurate geometric data from the LiDAR point cloud with the auxiliary information from images. The proposed approach, firstly determines the camera exterior orientation parameters by applying a semi-automatic process based on image matching technique. Secondly, for improving the geometric integrity of the raw data, the collinearity condition, as well as the geometry information from edge and planar features, will be used for point cloud reconstruction and densification. Finally, the abundant spectral information from multi-view images will be extracted and assigned to the refined point cloud data for generating high-quality result, which can be serve as a reliable and stable data source for further applications. The experiment result indicated that the proposed approach can adequately utilize the information from image data to increase the geometrical detail of the LiDAR point cloud. In conclusion, the quality improvement can be achieved through the use of data from different sources, which can successively reduces the limitation of current 3D surveying techniques, and also provides much more reliable and stable 3D information for applications.
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Tseng, Hsing-Yu, and 曾欣郁. "The 3D Laser Scanning Technique for Damage Detection of Mortar Wall-Painting in Traditional Buildings." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/m4ce3j.
Full textAbstract:
碩士國立金門大學
土木與工程管理學系碩士班
100
The traditional building walls usually were covered by mortar that become beautifying the space basis. Some paintings of walls are a symbol of cultural heritage and family spirit, at the same time, the wall-painting show increasing living fun and creation, education and art value. For the conservation site, the decorations of historical buildings saved should be regarded as equally important with the building structure. Owing environment factors, the mortar-wall and wall-painting are damaged including humidity variation and water seepage. To the traditional building culture value, the phenomenon is a significant impact. So the investigation and repair for mortar wall-painting is important item for maintenance of historic buildings. The damage detection and investigation of historical buildings is an important reference for restoration and conservation. In recent years, the technology detection system has become the one of essential method in the cultural field. This research is based on the research spirit to use scientific methods to assist professional judgment, trying to capture the space information of point clouds of pre-selected mortar wall-painting using high-precision 3D laser scanning, including 3D coordinates and digital image data. The cases study of the mortar wall-painting is in Tainan area. In the first instance it is using of the handy thermo to obtain the surface temperature of mortar wall-painting for the initial analysis. The result shows that temperature will be lower in the damaged area. Moreover, making 5 types of damage specimen that included powdering, bulging, chapping, flaking and others subsequently obtain the surface data by using 3D laser scanner. Applications on Triangulated irregular networks technology related to the specimen surface changes in the contour maps and detected that the characteristic feature of the different type that coincide the scanning cases. In this study, checking and statistics the success rate of detecting damaged area by infrared temperature sensor and 3D laser scanning technique. Show the reliability of detection technology of this research. So, the research result are joined the existed investigation method and repair damaged mortar wall-painting process to play auxiliary function of science.
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詹金萬. "Laser scanning technique for the detection of minority carrier lifetime inhomogeneities and resistivity inhomogeneities in semiconductor." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/91709420570248232417.
Full text
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DOTTA, GIULIA. "Semi-automatic analysis of landslide spatio-temporal evolution." Doctoral thesis, 2017. http://hdl.handle.net/2158/1076767.
Full textAbstract:
Le tecniche di rilevamento rappresentano un utile strumento per rilevare e caratterizzare i
processi gravitativi di versante, in particolare attraverso l’uso di approcci volti ad individuare
le aree in movimento. Nel dettaglio, tecniche come il laser scanner terrestre e la
fotogrammetria digitale permettono di ottenere rappresentazioni ad alta risoluzione dello
scenario osservato sotto forma di una nuvola di punti (point cloud) in tre dimensioni. Durante
gli ultimi anni, l’uso delle nuvole di punti per investigare i cambiamenti morfologici a scala
temporale e spaziale, è notevolmente aumentato.
In questo contesto è maturato il presente progetto di ricerca, durante il quale, l’efficacia
dell’utilizzo delle nuvole di punti per la caratterizzazione e il monitoraggio di versanti instabili
è stata testata e valutata attraverso lo sviluppo di un tool semi-automatico in linguaggio di
programmazione MATLAB. Lo strumento di analisi proposto consente di investigare le
principali caratteristiche morfologiche dei versanti instabili indagati e di determinare le
variazioni morfologiche e gli spostamenti dalla comparazione di nuvole di punti acquisite in
tempi differenti. In seguito, attraverso una tecnica di clustering, il codice permette di
estrapolare i gruppi le zone interessate da spostamenti significativi e calcolarne l’area.
Il tool introdotto è stato testato su due casi di studio contraddistinti da differenti
caratteristiche geologiche e da diversi fenomeni di instabilità: l’ammasso roccioso di San Leo
(RN) e il versante presso l’abitato di Ricasoli (AR). Per entrambi i casi di studio, sono state
individuate e descritte le aree caratterizzate da deformazione superficiale o accumulo di
materiale e le aree caratterizzate da distacco di materiale. Inoltre, sono stati approfonditi i
fattori che influenzano i risultati della change detection tra nuvole di punti. Remote sensing techniques represent a powerful instrument to detect and characterise
earth’s surface processes, especially using change detection approaches. In particular, TLS
(Terrestrial Laser Scanner) and UAV (Unmanned Aerial Vehicles) photogrammetry technique
allow to obtain high-resolution representations of the observed scenario as a threedimensional
array of points defined by x, y and z coordinates, namely point cloud. During the
last years, the use of 3D point clouds to investigate the morphological changes occurring over
a range of spatial and temporal scales, is considerably increased.
During the three-years PhD research programme, the effectiveness of point cloud exploitation
for slope characterization and monitoring was tested and evaluated by developing and
applying a semi-automatic MATLAB tool. The proposed tool allows to investigate the main
morphological characteristics of unstable slopes by using point clouds and to point out any
spatio-temporal morphological changes, by comparing point clouds acquired at different
times. Once defined a change detection threshold, the routine permits to execute a cluster
analysis and automatically separate zones characterized by significant distances and compute
their area.
The introduced tool was tested on two test sites characterized by different geological setting
and instability phenomena: the San Leo rock cliff (Rimini province, Emilia Romagna region,
northern Italy) and a clayey slope near Ricasoli village (Arezzo province, Tuscany region,
central Italy). For both case of studies, the main displacement or accumulation zones and
detachment zone were mapped and described. Furthermore, the factors influencing the
change detection results are discussed in details.
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CHU, MEI, and 朱梅. "The Design of Imaging Lens for Coaxial Laser Scanning and Visual Inspection Techniques." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/01156864654364687719.
Full textAbstract:
碩士明道大學
光電暨能源工程學系碩士班
98
Owing to the blooming of display industry and the low quality of traditional manufacturing process，the demanding of UV laser manufacture system is increasing. In order to maintain the precision of manufactures, it is necessary to set up the real time monitoring imaging system. The object of this research is to design a coaxial laser scanning and visual inspection imaging lens to monitor the real time image, which is made by the scanning F/ lens for large scale micro lithography. The procedure is to simulate an F/ lens and an imaging lens to meet the initial specification by using Zemax software, and to mock up the image performance with experiment. The initial specification of the coaxial laser scanning and visual inspection imaging lens is listed as follows: ? CCD FOV : 1.6mm * 1.2mm ? CCD Mag : 4X ? Image MTF > =0.3 (@40 lp/mm) (@ 50mm*50mm) The achievements of this research are (1) Design of F-Theta Lens for wavelength 355nm, (2) Design of the coaxial laser scanning and visual inspection imaging lens, (3) Finished the experiment for commercial lens mock-up, and (4) Design of the coaxial laser scanning and visual inspection imaging lens for multi- configuration scanning .
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Komba, J. J. (Julius Joseph). "Analytical and laser scanning techniques to determine shape properties of aggregates used in pavements." Diss., 2013. http://hdl.handle.net/2263/32799.
Full textAbstract:
Pavement layers are constructed using a combination of materials, of which rock aggregates constitute a larger proportion. Current understanding is that the performance of pavements is dependent on the aggregate shape properties which include form, angularity and surface texture.
However, direct and accurate measurements of aggregate shape properties remain a challenge.
The current standard test methods used to evaluate aggregate shape properties cannot measure these properties accurately. Among the reasons contributing to the difficulties in the determination of aggregate shape properties is irregular shapes of aggregate particles. Therefore, current research efforts focus on developing accurate, reliable and innovative techniques for evaluation of aggregate shape properties.
The work presented in this dissertation contributes to the current innovative research at the Council for Scientific and Industrial Research (CSIR) in South Africa, to automate the
measurement of aggregate shape properties. The CSIR’s present research is aimed at improving pavement performance through better materials characterisation, using laser scanning and advanced modelling techniques. The objective of this study was to investigate improved techniques for the determination of aggregate shape properties using analytical and laser scanning techniques. A three-dimensional (3-D) laser scanning device was used for scanning six types of aggregate
samples commonly used for construction of pavements in South Africa. The laser scan data
were processed to reconstruct 3-D models of the aggregate particles. The models were further
analysed to determine the shape properties of the aggregates. Two analysis approaches were
used in this study. The first approach used the aggregate’s physical properties (surface area,
volume and orthogonal dimensions) measured by using laser scanning technique to compute
three different indices to describe the form of aggregates. The computed indices were the
sphericity computed by using surface area and volume of an aggregate particle, the sphericity
computed by using orthogonal dimensions of an aggregate particle, and the flat and elongated
ratio computed by using longest and smallest dimensions of an aggregate particle. The second
approach employed a spherical harmonic analysis technique to analyse the aggregate laser scan
data to determine aggregate form, angularity and surface texture indices. A MATLABTM code
was developed for analysis of laser scan data, using the spherical harmonic analysis technique.
The analyses contained in this dissertation indicate that the laser-based aggregate shape indices
were able to describe the shape properties of the aggregates studied. Furthermore, good
correlations were observed between the spherical harmonic form indices and the form indices
determined by using the aggregate’s physical properties. This shows that aggregate laser
scanning is a versatile technique for the determination of various indices to describe aggregate
shape properties.
Further validation of the laser-based technique was achieved by correlating the laser-based
aggregate form indices with the results from two current standard tests; the flakiness index and
the flat and elongated particles ratio tests. The laser-based form indices correlated linearly with
both, the flakiness index and the flat and elongated particles ratio test results. The observed
correlations provide an indication of the validity of laser-based aggregate shape indices. It is
concluded that the laser based scanning technique could be employed for direct and accurate
determination of aggregate shape properties.Dissertation (MEng)--University of Pretoria, 2013.
gm2013
Civil Engineering
Unrestricted
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Baltazar, Luís Filipe Almeida. "Comparing different methods to measure biofilm thickness: the techniques are: optical coherence tomography, confocal laser scanning microscopy and low load compression test." Master's thesis, 2015. http://hdl.handle.net/1822/39586.
Full textAbstract:
Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)Biofilm formation remains a serious concern in industry and in the medical field. They are responsible for huge economical losses in many industrial sectors and for serious infections associated with biomaterial implants and medical devices. These infections are hard to treat because bacteria within the biofilm are more resistant to antibiotics and to the host immune system. Therefore, studying biofilm properties and mechanisms is of utmost relevance to develop efficient approaches to deal with this drawback. Biofilm thickness is an important parameter in biofilm characterization. The main purpose of this thesis was to assess the suitability of Optical Coherence Tomography (OCT) to measure biofilm thickness by comparing the results with the values obtained with the Low Load Compression Test (LLCT) and Confocal Laser Scanning Microscopy (CLSM). OCT is a nondestructive technique, which is increasingly applied on the medical field and allows the acquisition of images in real-time, in situ and with high resolution. Biofilms were grown onto glass slides and the measurements were done in the following order: first OCT, since it is a non-destructive technique, second LLCT and last CLSM. In order to study if slime could influence the measurements, different strains and bacteria exhibiting distinct extracellular polymeric substance (EPS) production capacities were used. Staphylococcus aureus ATCC 12600 is an EPS producer, while Staphylococcus aureus 5298 is not and Streptococcus mutans use extracellular glucans in the presence of sucrose to build its protective matrix, so different treatments with different percentages of sucrose were used in the growth medium during biofilm development. The results obtained proved that OCT is suitable to measure biofilm thicknesses and the presence of slime does not influence the results. In contrast, LLCT measurements showed to be affected by slime and biofilm density. CLSM showed limitations relatively to stain and laser penetration. Additionally, the results obtained emphasize the potential applicability of OCT to investigate the mesoscopic structure of the biofilm.
A formação de biofilmes é um problema sério na industria e na área médica, sendo responsáveis por enormes prejuízos económicos em muitos sectores industriais e por sérias infeções associadas a implantes e dispositivos médicos. Estas infeções são difíceis de tratar, visto que as bactérias quando presentes no biofilme ganham maior resistência a antibióticos e ao sistema imunitário. Por este motivo, estudar as propriedades e mecanismos dos biofilmes é de extrema importância para conseguir desenvolver abordagens eficazes que permitam ultrapassar estes problemas. A espessura dos biofilmes é um parâmetro importante para a sua caracterização. O principal objectivo desta tese foi avaliar a adequação do OCT para medir a espessura dos biofilmes, comparando os resultados com os valores medidos com o LLCT e CLSM. O OCT é uma técnica não destrutiva que tem sido utilizada na área da medicina e permite a aquisição de imagens em tempo real, in-situ e com elevada resolução. Os Biofilmes cresceram em lâminas de vidro e as medições foram feitas na seguinte ordem: primeiro OCT, visto ser uma técnica não destrutiva, seguido do LLCT e por fim o CLSM. Neste trabalho também foi estudado se a presença de EPS pode influenciar as medições em alguma destas técnicas. Para isso foram utilizadas diferentes bactérias e estirpes com capacidades distintas de produção de matrizes extracelulares. A Staphylococcus aureus ATCC 12600 tem capacidade de produzir EPS naturalmente, ao contrário da Staphylococcus aureus 5298. Por outro lado a Streptococcus mutans usa glucanos extracelulares para construir a sua matriz extracelular quando o meio de crescimento possui sacarose. Deste modo foram utilizadas diferentes percentagens deste glícido com o objectivo de obter diferentes tipos de matrizes. Os resultados obtidos provam que o OCT é uma técnica que pode ser usada para medir a espessura de biofilmes. Por outro lado as medições obtidas pelo LLCT são afectadas pela matriz extracelular dos biofilmes e pela sua densidade. O CLSM mostrou limitações relativas a capacidade de penetração do laser e dos corantes. Adicionalmente os resultados obtidos sublinham o potencial do OCT para estudar a estrutura do biofilme ao nível da mesoescala.
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Joshi, Abhishek Shriram. "Image Processing and Super Resolution Methods for a Linear 3D Range Image Scanning Device for Forensic Imaging." 2013. http://hdl.handle.net/1805/3414.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)In the last few decades, forensic science has played a significant role in bringing criminals to justice. Shoe and tire track impressions found at the crime scene are important pieces of evidence since the marks and cracks on them can be uniquely tied to a person or vehicle respectively. We have designed a device that can generate a highly accurate 3-Dimensional (3D) map of an impression without disturbing the evidence. The device uses lasers to detect the changes in depth and hence it is crucial to accurately detect the position of the laser. Typically, the forensic applications require very high resolution images in order to be useful in prosecutions of criminals. Limitations of the hardware technology have led to the use of signal and image processing methods to achieve high resolution images. Super Resolution is the process of generating higher resolution images from multiple low resolution images using knowledge about the motion and the properties of the imaging geometry. This thesis presents methods for developing some of the image processing components of the 3D impression scanning device. In particular, the thesis describes the following two components: (i) methods to detect the laser stripes projected onto the impression surface in order to calculate the deformations of the laser stripes due to 3D surface shape being scanned, and (ii) methods to improve the resolution of the digitized color image of the impression by utilizing multiple overlapping low resolution images captured during the scanning process and super resolution techniques.