Journal articles: 'Optical fibre detectors'

1

Ocampos-Guillén, Alejandro, Natalia Denisenko, and Verónica Fernández-Mármol. "Optimising the interconnection of free-space to fibre quantum networks." EPJ Web of Conferences 198 (2019): 00007. http://dx.doi.org/10.1051/epjconf/201919800007.

Full text

Abstract:

Optimising the interconnection between free-space and fibre links will be necessary for future quantum communication networks. In daylight free-space quantum communication based on direct detection, the required Field Of View (FoV) of the receiver system needs to be minimised to reduce solar background noise coupling into the detectors. Reducing the FoV requires minimising beam wander effects caused by atmospheric turbulence through active optics. We implement a fine tracking system designed to correct tip and tilt wavefront aberrations, using two feedback loops; each of them consisting of a quadrant detector and a fast steering mirror for stabilising the beam in the whole optical axis of the receiver. We test the performance of the tracking system with different optical fibres in order to evaluate the reduction in the quantum bit error rate (QBER) caused by solar background noise. A reduction of 75% for single mode fibre was obtained, and 45% reduction for a 25 µm core diameter fibre, both cases for strong turbulence (Cn2~10-12 – 10-13 m-2/3) and 100 m propagating channel. These results look promising for enabling free-space Quantum Key Distribution (QKD) in wireless networks for realistic/adverse conditions such as daylight and strong turbulent regimes.

APA, Harvard, Vancouver, ISO, and other styles

2

Andres, M. V. "A novel optical fibre technique to calibrate the frequency response of optical detectors." Measurement Science and Technology 3, no. 2 (February 1, 1992): 217–21. http://dx.doi.org/10.1088/0957-0233/3/2/013.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Newman, D. H., and S. Ritchie. "Sources and detectors for optical fibre communications applications: the first 20 years." IEE Proceedings J Optoelectronics 133, no. 3 (1986): 213. http://dx.doi.org/10.1049/ip-j.1986.0036.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Hall, David, Yu-Hsin Liu, and Yu-Hwa Lo. "Single photon avalanche detectors: prospects of new quenching and gain mechanisms." Nanophotonics 4, no. 4 (November 6, 2015): 397–412. http://dx.doi.org/10.1515/nanoph-2015-0021.

Full text

Abstract:

AbstractWhile silicon single-photon avalanche diodes (SPAD) have reached very high detection efficiency and timing resolution, their use in fibre-optic communications, optical free space communications, and infrared sensing and imaging remains limited. III-V compounds including InGaAs and InP are the prevalent materials for 1550 nm light detection. However, even the most sensitive 1550 nm photoreceivers in optical communication have a sensitivity limit of a few hundred photons. Today, the only viable approach to achieve single-photon sensitivity at 1550 nm wavelength from semiconductor devices is to operate the avalanche detectors in Geiger mode, essentially trading dynamic range and speed for sensitivity. As material properties limit the performance of Ge and III-V detectors, new conceptual insight with regard to novel quenching and gain mechanisms could potentially address the performance limitations of III-V SPADs. Novel designs that utilise internal self-quenching and negative feedback can be used to harness the sensitivity of single-photon detectors,while drastically reducing the device complexity and increasing the level of integration. Incorporation of multiple gain mechanisms, together with self-quenching and built-in negative feedback, into a single device also hold promise for a new type of detector with single-photon sensitivity and large dynamic range.

APA, Harvard, Vancouver, ISO, and other styles

5

Rajbenbach, Henri, John Magan, and Werner Steinhoegl. "Photonics: From European support to industrial technology leadership." Photoniques, no. 107 (March 2021): 20–22. http://dx.doi.org/10.1051/photon/202110720.

Full text

Abstract:

Photonics support in the European programmes dates back to the early 90s, though the “Telematics” and “Esprit” initiatives (1983 to 1998) primarily focused on the then emerging field of optical telecommunication, fibre optics, optoelectronic, detectors and III-Vs and semiconductor lasers.

APA, Harvard, Vancouver, ISO, and other styles

6

Faruqi, A. R., and Sriram Subramaniam. "CCD detectors in high-resolution biological electron microscopy." Quarterly Reviews of Biophysics 33, no. 1 (February 2000): 1–27. http://dx.doi.org/10.1017/s0033583500003577.

Full text

Abstract:

1. Introduction 11.1 The ‘band gap’ in silicon 22. Principles of CCD detector operation 32.1 Direct detection 32.2 Electron energy conversion into light 42.3 Optical coupling: lens or fibre optics? 62.4 Readout speed and comparison with film 83. Practical considerations for electron microscopic applications 93.1 Sources of noise 93.1.1 Dark current noise 93.1.2 Readout noise 93.1.3 Spurious events due to X-rays or cosmic rays 103.2 Efficiency of detection 113.3 Spatial resolution and modulation transfer function 123.4 Interface to electron microscope 143.5 Electron diffraction applications 154. Prospects for high-resolution imaging with CCD detectors 185. Alternative technologies for electronic detection 235.1 Image plates 235.2 Hybrid pixel detectors 246. References 26During the past decade charge-coupled device (CCD) detectors have increasingly become the preferred choice of medium for recording data in the electron microscope. The CCD detector itself can be likened to a new type of television camera with superior properties, which makes it an ideal detector for recording very low exposure images. The success of CCD detectors for electron microscopy, however, also relies on a number of other factors, which include its fast response, low noise electronics, the ease of interfacing them to the electron microscope, and the improvements in computing that have made possible the storage and processing of large images.CCD detectors have already begun to be routinely used in a number of important biological applications such as tomography of cellular organelles (reviewed by Baumeister, 1999), where the resolution requirements are relatively modest. However, in most high- resolution microscopic applications, especially where the goal of the microscopy is to obtain structural information at near-atomic resolution, photographic film has continued to remain the medium of choice. With the increasing interest and demand for high-throughput structure determination of important macromolecular assemblies, it is clearly important to have tools for electronic data collection that bypass the slow and tedious process of processing images recorded on photographic film.In this review, we present an analysis of the potential of CCD-based detectors to fully replace photographic film for high-resolution electron crystallographic applications.

APA, Harvard, Vancouver, ISO, and other styles

7

Shikoski, Jovan, Rumen Arnaudov, and Tinko Eftimov. "A study of the frequency characteristics of a photovoltaic convertor РРС-4Е." Photonics Letters of Poland 10, no. 3 (October 1, 2018): 70. http://dx.doi.org/10.4302/plp.v10i3.839.

Full text

Abstract:

The paper considers the possibility to use the fiber-compatible photovoltaic converter РРС-4Е simultaneously as a detection photodetector for the combined transmission of photonic power and optical communication signals along a single fiber. We have studied the frequency transfer characteristics of the specialized converter РРС-4Е designed primarily for photovoltaic conversion. Full Text: PDF ReferencesPowering Remote Data Links over Fiber, www.lumentum.com, Lumentum LLC, 2015. DirectLink Basanskaya, A.: Electricity over Glass. Spectrum, IEEE, Vol. 40, No. 10, page 18, 2005. DirectLink Cohen, M.: Power-over-fibre drives remote data exchange. OPTO and Laser Europe, pages 27-29, 2006. DirectLink Yasui, T.; Ohwaki, J.; Mino, M.; Sakai, T.: A Stable 2-W Supply Optical-Powering System. 28th Photovoltaic Specialists Conference, pages 1614-1617, 2000. CrossRef Werthen, J.-G.: Powering Next Generation Networks by Laser Light over Fiber. Optical Fiber communication/National Fiber Optic Engineers Conference, pages 1-3, 2008. DirectLink Iniewski K., Medical Imaging: Principles, Detectors and Electronics, p. 292, New Jersey, 2009. DirectLink Kartalopoulos, S., Optical Bit Error Rate: An Estimation Methodology (2004) Willey- IEEE Press. DirectLink Electronic Devices and Circuits: Discrete and integrated, Chapter 14 Active filters, Denton J. Daily, Prentice Hall, 2001. DirectLink

APA, Harvard, Vancouver, ISO, and other styles

8

Briggs, R., and K. T. V. Grattan. "ICA in the UK Water Industry: Highlights of Recent Developments in the Applications of Optical Techniques." Water Science and Technology 26, no. 5-6 (September 1, 1992): 1305–14. http://dx.doi.org/10.2166/wst.1992.0573.

Full text

Abstract:

The current situation in respect of the impact of recent legislation and funding mechanisms on progress with developments in instrumentation, control and automation (ICA) in the UK Water Industry is discussed, problems with progress identified and potential solutions discussed. Recent developments in applied optical sensing are detailed, particularly those involving the use of Raman Scattering and optical fluorescence utilising non-contact laser probes and detectors and fibre-optic based sensors for use in portable and permanent station monitors.

APA, Harvard, Vancouver, ISO, and other styles

9

Bocciolone, Marco, Giuseppe Bucca, Andrea Collina, and Lorenzo Comolli. "Design and testing of fibre Bragg grating force transducers for the measurement of pantograph–catenary contact force." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 233, no. 4 (August 30, 2018): 396–409. http://dx.doi.org/10.1177/0954409718795762.

Full text

Abstract:

This paper deals with the design, development and testing of a novel force transducer based on fibre-optic technology, for the measurement of contact force between a pantograph and an overhead line. Due to the particular application, in which part of the measurement chain is at high voltage and part is at ground potential, fibre-optic technology has the advantage of making the set-up easier to install and to manage with respect to the adoption of classical electrical-based transducers. Fibre Bragg grating is used as detectors in strain-based force transducers developed for this purpose. Considering that the force transducers become part of the connection between each collector of the pan head and the suspension, a proper design matching many conflicting requirements, such as encumbrance, mass, static and fatigue strength and sensitivity, is necessary. Laboratory tests and in-line tests proved the suitability of the optical force transducers. In particular, tests demonstrated that optical transducers represent an alternative to the classical electrical-based transducers for pantograph–catenary force measurement, reducing the complexity of the complete measurement set-up.

APA, Harvard, Vancouver, ISO, and other styles

10

van der Ziel, J. P., R. M. Mikulyak, and R. A. Logan. "7.5 km bidirectional single-mode optical-fibre link using dual-mode InGaAsP/InP 1.3 μm laser detectors." Electronics Letters 21, no. 11 (May 23, 1985): 511–12. http://dx.doi.org/10.1049/el:19850362.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Wright, P. J. "A superior cathodoluminescence spectral analysis and imaging system for semiconductor characterisation." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 838–39. http://dx.doi.org/10.1017/s0424820100088506.

Full text

Abstract:

Cathodoluminescence is a useful technique in the structural and electro optical characterisation of semiconductors. When performed in a electron microscope, both high spatial resolution images and spectra may be obtained by use of the correct equipment.Many designs for instruments suitable for cathodoluminescence spectral analysis and imaging in electron microscopes have been described in the literature during the past 25 years. These have often exhibited improved performance when compared with commercially available systems. The prime reason for this has been the willingness of the dedicated CL researcher to mount large, heavy monochromators directly to the chamber of their microscope. The result has been a microscope committed to CL analysis. However, many potential CL users have to use shared facilities and may not compromise the performance or appearance of the microscope. Subsequently, many CL systems have had the monochromator decoupled from the CL collection optics by either fibre optic bundles or quartz fibres. This has allowed the monochromator and its associated detectors to be easily decoupled from the SEM when not in use. Considerable transmission losses have been incurred and in many cases, it has been necessary to duplicate detectors to allow both spectral analysis and imaging. This has resulted in instruments which were less than optimum in both efficiency and operation.

APA, Harvard, Vancouver, ISO, and other styles

12

MacDonald, R. I. "Optoelectronic matrix switching." Canadian Journal of Physics 67, no. 4 (April 1, 1989): 389–93. http://dx.doi.org/10.1139/p89-069.

Full text

Abstract:

Because cross talk from electromagnetic coupling increases with frequency, it is difficult to design matrix switches for high-frequency electronic signals. Signals on optical carriers are easier to isolate but more difficult to switch. A hybrid technique exploiting passive optical-signal distribution and switching by optoelectronic effects shows good promise for high isolation matrices to handle signals in the dc to 10 GHz range. The key elements for such optoelectronic switches are optical detectors that have switchable sensitivity.Initial efforts in optoelectronic switching used silicon diode detectors and forward bias to establish the off-state. Recent work has turned primarily to photoconductors fabricated in GaAs or other compound semiconductors. Such photoconductors can have very wide response bandwidths and have the advantage of a zero-bias off-state. Efforts have also been made to develop bipolar detectors that do not need forward bias for the off-state.Experimental work has progressed to the demonstration of complete matrices capable of switching up to eight incoming signals to as many outgoing lines, at bandwidths up to 500 MHz and cross-talk levels below 50 dB. Results for individual switching devices give promise of matrices for many tens of lines and bandwidths to several gigahertz. Monolithic integration of GaAs photoconductor switch arrays has been demonstrated, and work progresses to include integrated control devices and amplifiers.Matrix switches of large dimension and very large bandwidth are expected to have significant applications in areas other than communications switching. In particular, such matrices can be used to set up patterns of delay and signal recombination, using fibre delay lines, to provide rapidly selectable wide-band delay for phasing and other applications, or for wide-band tapped delay-line filters that can be reconfigured rapidly.A review of the current status in optoelectronic matrix switching is given.

APA, Harvard, Vancouver, ISO, and other styles

13

Kitsak, A.I., Ivanov, Y.S., Lushchik, A.P., and Yesipovich, D.L. "The Application of Laser and Fibre-Optic Technologies for the Improvement of the Efficiency of Modern Optical Smoke Detectors." Bezpieczeństwo i Technika Pożarnicza, no. 49 (2018): 86–2. http://dx.doi.org/10.12845/bitp.49.1.2018.8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Maurin, L., P. Ferdinand, V. Bouyer, A. Denoix, G. Jouvin, S. Rougeault, C. Journeau, D. Molina, P. Tena, and Y. Ouerdane. "Remote monitoring of Molten Core-Concrete Interaction experiment with Optical Fibre Sensors & perspectives to improve nuclear safety – DISCOMS project." EPJ Web of Conferences 225 (2020): 08004. http://dx.doi.org/10.1051/epjconf/202022508004.

Full text

Abstract:

The DISCOMS project (Distributed Sensing for Corium Monitoring and Safety) aimed at providing innovative solutions not requiring local electrical power supplies, for remote monitoring of a severe nuclear accident. The solutions are based on both long length SPNDs (Self Powered Neutron Detectors) and on distributed OFSs (Optical Fibre Sensors) capable to detect the onset of a severe accident, the corium pouring on the containment building concrete basemat, and its interaction with the concrete floor under the reactor vessel, until it spreads in the core catcher (EPR case). This paper mainly focuses on these last three detection targets achievable with distributed OFSs. It is based on the results of a Molten Core & Concrete Interaction (MCCI) experiment, namely VULCANO, held in June 2018 with a concrete crucible equipped with overall ~ 180 m long optical fibre sensing cables. This small scale experiment (50 kg of prototypical corium) has demonstrated the ability of distributed OFSs to remotely provide useful data during the MCCI run: i) temperature profiles images up to about 580°C (single wavelength Raman DTS reflectometer) until cooling down to room temperature, ii) high spatial-resolution frequency shifts profiles, due to combined (non-selective) strain and temperature influences (Rayleigh OFDR and Brillouin reflectometers), and iii) cables lengths ablated by the corium on sections weakened by the temperature (Raman DTS, Rayleigh OFDR, telecom and photon counting reflectometers).

APA, Harvard, Vancouver, ISO, and other styles

15

Tauber, J. A., P. H. Nielsen, A. Martín-Polegre, B. Crill, F. Cuttaia, K. Ganga, J. Gudmundsson, et al. "Characterization of the in-flight properties of the Planck telescope." Astronomy & Astrophysics 622 (January 29, 2019): A55. http://dx.doi.org/10.1051/0004-6361/201833150.

Full text

Abstract:

The European Space Agency’s Planck satellite was launched on 14 May 2009, and surveyed the sky stably and continuously between August 2009 and October 2013. The scientific analysis of the Planck data requires understanding the optical response of its detectors, which originates partly from a physical model of the optical system. In this paper, we use in-flight measurements of planets within ∼1° of boresight to estimate the geometrical properties of the telescope and focal plane. First, we use observed grating lobes to measure the amplitude of mechanical dimpling of the reflectors, which is caused by the hexagonal honeycomb structure of the carbon fibre reflectors. We find that the dimpling amplitude on the two reflectors is larger than expected from the ground, by 20% on the secondary and at least a factor of 2 on the primary. Second, we use the main beam shapes of 26 detectors to investigate the alignment of the various elements of the optical system, as well as the large-scale deformations of the reflectors. We develop a metric to guide an iterative fitting scheme, and are able to determine a new geometric model that fits the in-flight measurements better than the pre-flight prediction according to this metric. The new alignment model is within the mechanical tolerances expected from the ground, with some specific but minor exceptions. We find that the reflectors contain large-scale sinusoidal deformations most probably related to the mechanical supports. In spite of the better overall fit, the new model still does not fit the beam measurements at a level compatible with the needs of cosmological analysis. Nonetheless, future analysis of the Planck data would benefit from taking into account some of the features of the new model. The analysis described here exemplifies some of the limitations of in-flight retrieval of the geometry of an optical system similar to that of Planck, and provides useful information for similar efforts in future experiments.

APA, Harvard, Vancouver, ISO, and other styles

16

JANG, KYOUNG WON, DONG HYUN CHO, SANG HUN SHIN, BONGSOO LEE, SOON-CHEOL CHUNG, GYE-RAE TACK, JEONG HAN YI, SIN KIM, and HYOSUNG CHO. "MEASUREMENTS OF HIGH ENERGY X-RAY DOSE DISTRIBUTIONS USING MULTI-DIMENSIONAL FIBER-OPTIC RADIATION DETECTORS." Modern Physics Letters B 22, no. 11 (May 10, 2008): 797–802. http://dx.doi.org/10.1142/s0217984908015401.

Full text

Abstract:

In this study, we have fabricated multi-dimensional fiber-optic radiation detectors with organic scintillators, plastic optical fibers and photo-detectors such as photodiode array and a charge-coupled device. To measure the X-ray dose distributions of the clinical linear accelerator in the tissue-equivalent medium, we have fabricated polymethylmethacrylate phantoms which have one-dimensional and two-dimensional fiber-optic detector arrays inside. The one-dimensional and two-dimensional detector arrays can be used to measure percent depth doses and surface dose distributions of high energy X-ray in the phantom respectively.

APA, Harvard, Vancouver, ISO, and other styles

17

Lee, Ga-Hyeon, Sung-Eun Lee, Si-Kuk Kim, and Seung-Chul Lee. "Study on Smoke Detector Characteristics Using Fire Simulations." Fire Science and Engineering 35, no. 4 (August 31, 2021): 8–14. http://dx.doi.org/10.7731/kifse.f7da19a7.

Full text

Abstract:

To reduce the damage caused by fire detector malfunctions, we investigated the standards and literature pertaining to fire detectors in Korea. The domestic standards cite UL's technical specifications, which provide only the standards and types of combustible materials; however, additional research is needed because no facilities related to the experiments are investigated and no fire experiments have actually been conducted. In this study, we refer to UL 268, which is similar to the domestic standards, as well as detailed experimental conditions and methods to improve smoke detector performances; we also use wood as the combustion material from among the fire sources specified in UL 268. Experiments were conducted to measure the sensitization rates using an optical density meter and repeated to match the wood smoke profile standard provided in UL 268. Furthermore, we compared the smoke concentrations detected by the smoke detectors in the fire experiments with those from fire simulations using FDS software to confirm the detector characteristics. Through these comparisons, we show that this research could be used as preliminary data for performance testing of detectors using UL 268.

APA, Harvard, Vancouver, ISO, and other styles

18

Chen, Chong, Yuki Shimizu, Ryo Sato, Hiraku Matsukuma, and Wei Gao. "An Off-Axis Differential Method for Improvement of a Femtosecond Laser Differential Chromatic Confocal Probe." Applied Sciences 10, no. 20 (October 16, 2020): 7235. http://dx.doi.org/10.3390/app10207235.

Full text

Abstract:

This paper presents an off-axis differential method for the improvement of a femtosecond laser differential chromatic confocal probe having a dual-detector configuration. In the proposed off-axis differential method employing a pair of single-mode fiber detectors, a major modification is made to the conventional differential setup in such a way that the fiber detector in the reference detector is located at the focal plane of a collecting lens but with a certain amount of off-axis detector shift, while the fiber detector in the measurement detector is located on the rear focal plane without the off-axis detector shift; this setup is different from the conventional one where the difference between the two confocal detectors is provided by giving a defocus to one of the fiber detectors. The newly proposed off-axis differential method enables the differential chromatic confocal setup to obtain the normalized chromatic confocal output with a better signal-to-noise ratio and approaches a Z-directional measurement range of approximately 46 μm, as well as a measurement resolution of 20 nm, while simplifying the optical alignments in the differential chromatic confocal setup, as well as the signal processing through eliminating the complicated arithmetic operations in the determination of the peak wavelength. Numerical calculations based on a theoretical equation and experiments are carried out to verify the feasibility of the proposed off-axis differential method for the differential chromatic confocal probe with a mode-locked femtosecond laser source.

APA, Harvard, Vancouver, ISO, and other styles

19

Feng, Lin, Jian Wang, and Chao Ding. "A Fire Warning Method Using Tunable Diode Laser Absorption Spectroscopy." Journal of Nanoelectronics and Optoelectronics 16, no. 2 (February 1, 2021): 222–29. http://dx.doi.org/10.1166/jno.2021.2921.

Full text

Abstract:

Tunable diode laser absorption spectroscopy (TDLAS) technology is adopted herein to detect fire gas produced in the early stage of the fire. Based on this technology, a fire warning detection system with multiple lasers and detectors is proposed. Multiple drivers input laser’s temperature and injected current data, making its output wavelength consistent with the measured gas’ absorption peak wavelengths in absorption spectroscopy. Multiple light beams are coupled to the same optical fiber. After the light beams pass through the long optical path absorption cell filled with fire gas, the beams are separated by a converter. The signals are demodulated by different detectors and further analyzed for fire warnings. After the fire warning system’s design, the system’s various hardware modules are designed, including the light source module, TDLAS controller, gas chamber module, photoelectric detector, and data collection. When the temperature remains unchanged, the output wavelength is linearly related to the injected current. When the injected current remains unchanged, the output wavelength is linearly related to the operating temperature. With a semiconductor laser’s injected current of 40 mA, the initial temperature of 38.6 °C, and the output wavelength of 1578.16 nm, the output wavelength increases continuously as the temperature increases. The harmonic signal amplitude after gas absorption is positively correlated with the measured gas concentration, indicating that the second harmonic signals can estimate the fire gas concentration.

APA, Harvard, Vancouver, ISO, and other styles

20

Yahya, Adnan Haj, Nezah Balal, Avi Klein, Jacob Gerasimov, and Aharon Friedman. "Improvement of the Electro-Optical Process in GaAs for Terahertz Single Pulse Detection by Using a Fiber-Coupling System." Applied Sciences 11, no. 15 (July 26, 2021): 6859. http://dx.doi.org/10.3390/app11156859.

Full text

Abstract:

The electro-optical process is a popular method for terahertz radiation detection. Detectors based on the electro-optical process have large bandwidth, and the signal-to-noise ratio (SNR) is relatively high. Further, this detector can be applied to detect high-power signals without using radiation attenuation. This paper presents a method to improve the electro-optic process to THz radiation detection based on GaAs crystals by coupling the optical output signal into fiber. Results demonstrated an improvement in the signal-to-noise ratio that means an increase in the dynamic range of the electro-optical detector.

APA, Harvard, Vancouver, ISO, and other styles

21

Jang, Hyo-Yeon, and Cheol-Hong Hwang. "Obscuration Threshold Database Construction of Smoke Detectors for Various Combustibles." Sensors 20, no. 21 (November 4, 2020): 6272. http://dx.doi.org/10.3390/s20216272.

Full text

Abstract:

The obscuration thresholds for various smoke detectors and combustibles, required as an input parameter in fire simulation, were measured to predict the accurate activation time of detectors. One ionization detector and nine photoelectric detectors were selected. A fire detector evaluator, which can uniformly control the velocity and smoke concentration, was utilized. Filter paper, liquid fuels, and polymer pellets were employed as smoke-generation combustibles. The nominal obscuration thresholds of the considered detectors were 15 %/m, but the ionization detectors activated at approximately 40 %/m and 16 %/m, respectively, on applying filter paper and kerosene. In contrast, the reverse obscuration thresholds were found quantitatively according to the combustibles in the photoelectric detector. This phenomenon was caused by differences in the color of the smoke particles according to the combustibles, which is explained by single-scattering albedo (ratio of light scattering to light extinction). The obscuration thresholds for liquid fuels (kerosene, heptane and toluene) as well as fire types of polymer plastic pellets were also measured for several photoelectric detectors. A database of obscuration thresholds was thereby established according to the detector and combustible types, and it is expected to provide useful information for predicting more accurate detector activation time and required safe egress time (REST).

APA, Harvard, Vancouver, ISO, and other styles

22

Teymurazyan, A., and G. Pang. "Megavoltage X-Ray Imaging Based on Cerenkov Effect: A New Application of Optical Fibres to Radiation Therapy." International Journal of Optics 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/724024.

Full text

Abstract:

A Monte Carlo simulation was used to study imaging and dosimetric characteristics of a novel design of megavoltage (MV) X-ray detectors for radiotherapy applications. The new design uses Cerenkov effect to convert X-ray energy absorbed in optical fibres into light for MV X-ray imaging. The proposed detector consists of a matrix of optical fibres aligned with the incident X rays and coupled to an active matrix flat-panel imager (AMFPI) for image readout. Properties, such as modulation transfer function, detection quantum efficiency (DQE), and energy response of the detector, were investigated. It has been shown that the proposed detector can have a zero-frequency DQE more than an order of magnitude higher than that of current electronic portal imaging device (EPID) systems and yet a spatial resolution comparable to that of video-based EPIDs. The proposed detector is also less sensitive to scattered X rays from patients than current EPIDs.

APA, Harvard, Vancouver, ISO, and other styles

23

Tu, Ran, Yi Zeng, Jun Fang, and Yong-Ming Zhang. "Influence of high altitude on the burning behaviour of typical combustibles and the related responses of smoke detectors in compartments." Royal Society Open Science 5, no. 4 (April 2018): 180188. http://dx.doi.org/10.1098/rsos.180188.

Full text

Abstract:

The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n -heptane (TF5). First, the influence of altitude or ambient pressure on mass loss for smouldering combustion (TF2 or TF3) was insignificant, while a significant decrease in the mass burning rate was found for flaming tests (TF4 and TF5) as reported in our previous studies. Second, for photoelectric smoke detectors in flaming fire tests, the effect of altitude was similar to that of the burning rate, whereas for the ionization smoke detectors, the response signal at high altitudes was shown to be ‘enhanced’ by the detection principle of the ionization chamber, leading to an even larger value than at normal altitude for smouldering conditions. Third, to provide a reference for smoke detector design in high-altitude areas, the differences between signal speed in rising and peak values at two locations are discussed. Also, relationship between ion chamber signals and smoke optical densities are presented by utilization of an ionization smoke detector and smoke concentration meter. Moreover, a hierarchical diagram is illustrated to provide a better understanding of the effects of altitude on combustible burning behaviour and the mechanisms of detector response.

APA, Harvard, Vancouver, ISO, and other styles

24

Shangyu Si, Shangyu Si, Liwen Feng Liwen Feng, Yanying Zha Yanying Zha, Gang Zhao Gang Zhao, Fangming Liu Fangming Liu, Senlin Huang Senlin Huang, and Kexin Liu Kexin Liu. "fs-level laser–RF synchronization with a fiber-loop optical-microwave phase detector." Chinese Optics Letters 16, no. 1 (2018): 010607. http://dx.doi.org/10.3788/col201816.010607.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Muslimov, Eduard, Nadezhda Pavlycheva, Emmanuel Hugot, Simona Lombardo, Ilnur Nureev, and Oleg Morozov. "Optical Designs with Curved Detectors for Fiber Bragg Grating Interrogation Monitors." Sensors 21, no. 1 (December 23, 2020): 34. http://dx.doi.org/10.3390/s21010034.

Full text

Abstract:

In this paper, we evaluate the application of curved detectors and freeform optics technologies for fiber Bragg gratings (FBGs) interrogation monitors design. It is shown that, in a high-dispersion spectrograph scheme, the camera part operates in special conditions, which result in a field curvature change. This field curvature can be compensated by the use of a curved detector. When used together with freeform optics, the curved detectors allow for reduction of the number of optical components to two or even one element by merging their functions. Three design examples for the range of 810–860 nm reaching the spectral resolution limit of 89–139 pm at NA=0.14 are presented to demonstrate the achieved performance and the technological trade-offs.

APA, Harvard, Vancouver, ISO, and other styles

26

SCHMIDT, OLIVER, PETER KIESEL, MICHAEL BASSLER, and NOBLE JOHNSON. "CHIP-SIZE WAVELENGTH DETECTORS." International Journal of High Speed Electronics and Systems 17, no. 04 (December 2007): 661–70. http://dx.doi.org/10.1142/s0129156407004862.

Full text

Abstract:

Chip-size wavelength detectors are described that can resolve the spectrum of the incident light with high accuracy over a broad spectral range. The devices can be configured either as compact spectrometers or precise wavelength shift detectors. Applications that are anticipated to benefit from the spectrometers include reagentless optical identification of analytes in fluidic and aerosol samples. The wavelength shift detector is widely applicable as read-out instrument for optical sensors in which a stimulus (e.g., temperature, strain, PH-value, etc.) results in a wavelength shift of an optical output signal, examples include the interrogation system for Fiber Bragg Grating sensors, photonic crystal sensors, Fabry-Perot type sensors, and sensors in which an analyte influences a laser cavity and thereby its emission wavelength.

APA, Harvard, Vancouver, ISO, and other styles

27

Li, Hongqiang, Sai Zhang, Zhen Zhang, Shasha Zuo, Shanshan Zhang, Yaqiang Sun, Ding Zhao, and Zanyun Zhang. "Silicon Waveguide Integrated with Germanium Photodetector for a Photonic-Integrated FBG Interrogator." Nanomaterials 10, no. 9 (August 27, 2020): 1683. http://dx.doi.org/10.3390/nano10091683.

Full text

Abstract:

We report a vertically coupled germanium (Ge) waveguide detector integrated on silicon-on-insulator waveguides and an optimized device structure through the analysis of the optical field distribution and absorption efficiency of the device. The photodetector we designed is manufactured by IMEC, and the tests show that the device has good performance. This study theoretically and experimentally explains the structure of Ge PIN and the effect of the photodetector (PD) waveguide parameters on the performance of the device. Simulation and optimization of waveguide detectors with different structures are carried out. The device’s structure, quantum efficiency, spectral response, response current, changes with incident light strength, and dark current of PIN-type Ge waveguide detector are calculated. The test results show that approximately 90% of the light is absorbed by a Ge waveguide with 20 μm Ge length and 500 nm Ge thickness. The quantum efficiency of the PD can reach 90.63%. Under the reverse bias of 1 V, 2 V and 3 V, the detector’s average responsiveness in C-band reached 1.02 A/W, 1.09 A/W and 1.16 A/W and the response time is 200 ns. The dark current is only 3.7 nA at the reverse bias voltage of −1 V. The proposed silicon-based Ge PIN PD is beneficial to the integration of the detector array for photonic integrated arrayed waveguide grating (AWG)-based fiber Bragg grating (FBG) interrogators.

APA, Harvard, Vancouver, ISO, and other styles

28

Wang, Shu Tao, Peng Wei Zhang, Le Gong, and Xiao Qing Shao. "Novel Optical Fiber Gas Sensing System Based on FBG Filtering." Advanced Materials Research 295-297 (July 2011): 1021–28. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1021.

Full text

Abstract:

Based on law of Beer-Lambert, a novel optical fiber gas sensing system is designed to determine the concentration of gas. The narrow-band filtering characteristic of optical fiber Bragg grating is used by this system to produce the narrow spectrum light signal which is wanted in difference absorption measuring. The system has full optical fiber structure, which is mainly composed by super luminescent emitting diode (SLED), optical fiber of 10km, optical fiber gas detector, optical fiber isolator, optical fiber coupler network, optical fiber detecting grating, photoelectric detector and data processing unit. The aspheric objective optical fiber collimator is adopted by this system to compose optical fiber gas sensing detector, which enhances the optic stability of the detector, diminishes the injection loss and makes the echo signal of the optical fiber detector greatly diminished. Experimental data and results show that this system has its feasibility and it can be used for real time monitoring of gas concentration in the domains of colliery and natural gas station, etc.

APA, Harvard, Vancouver, ISO, and other styles

29

Davis, A. J., P. L. Hink, W. R. Binns, J. W. Epstein, J. J. Connell, M. H. Israel, J. Klarmann, V. Vylet, D. H. Kaplan, and S. Reucroft. "Scintillating optical fiber trajectory detectors." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 276, no. 1-2 (March 1989): 347–58. http://dx.doi.org/10.1016/0168-9002(89)90651-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Jevtic, Radoje, and Milan Blagojevic. "On a linear fire detection using coaxial cables." Thermal Science 18, no. 2 (2014): 603–14. http://dx.doi.org/10.2298/tsci130211102j.

Full text

Abstract:

Alarm systems represent a combination of the various modern engineering solutions (electrical, mechanical, hydraulic, etc.) with the primary goal to protect human lives, living and working environment and material properties. Detectors are basic and common components of these systems. There are many different kinds of detectors which usage depends on system solutions, prices and other technical properties of system application. Different types of non-typical lines can be used as detectors in alarm systems, such as coaxial cables or special constructed electrical lines. The change of some parameters of cables, such as capacity, impedance, resistance or similar, according to temperature, pressure, torsion or other disturbances, can be used for detection of intruder or fire. This work presents experimental results obtained on three different types of coaxial cables: RF 75-3-1, RF 75-4-5 and RF 75-7-9 in order to show changes of capacity as a consequence of heating due to growth of surrounding temperature, and consequently, possible application of cables as fire detector. Before an experiment, a simulation of fire in laboratory 113 in Electrotechnical school Nikola Tesla in Nis was made in FDS (Fire dynamic simulator) software to show the possible spreading of fire, and consequently, to find optimal location for coaxial cables as fire detectors.

APA, Harvard, Vancouver, ISO, and other styles

31

Roby, R. J., A. J. Hamer, E. L. Johnson, S. A. Tilstra, and T. J. Burt. "Improved Method for Flame Detection in Combustion Turbines." Journal of Engineering for Gas Turbines and Power 117, no. 2 (April 1, 1995): 332–40. http://dx.doi.org/10.1115/1.2814099.

Full text

Abstract:

A fast response chemiluminescent flame detection approach is presented along with field test results from a fiber optic based flame detector device. Chemiluminescence, the light given off by molecules formed in their excited states, has long been recognized as a diagnostics method for use in combustion. The recent advent of higher quality optical fibers with improved transmission properties in the UV, as well as UV optical detectors, has made the use of chemiluminescence for gas turbine diagnostics and monitoring practical. Advances in combustor designs on new low-emissions machines as well as reliability issues with some existing machines are creating the need for improved flame dynamics measurements as well as improvements in reliability for existing measurements such as combustor flame detection. This paper discusses the technology, principle of operation, and detectors that operate on the chemiluminescence principle.

APA, Harvard, Vancouver, ISO, and other styles

32

Müller, Kurt, Markus Loepfe, and Dieter Wieser. "Optical simulations for fire detectors." Fire Safety Journal 41, no. 4 (June 2006): 274–78. http://dx.doi.org/10.1016/j.firesaf.2005.09.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Yang, Lei, and Xiao-Fang Zhao. "Intelligent pulse light source in the performance calibration system of two-dimensional neutron detector." Modern Physics Letters B 31, no. 19-21 (July 27, 2017): 1740022. http://dx.doi.org/10.1142/s021798491740022x.

Full text

Abstract:

Chinese Spallation Neutron Source (CSNS) project will use numerous two-dimensional (2D) neutron detectors whose ZnS (Ag) scintillator is doped with 6Li. To ensure the consistency of all neutron detectors, a calibration system for the performance of 2D neutron detectors is designed. For radiation protection, the state control of the radiation source gets more and more strict. It is impossible to directly carry out experiments with massive radioactive particles. Thus, the following scheme has been designed. The controlled pulsed laser light source on a 2D mobile platform is used to replace the neutron bombardment to generate the photon. The pulse signal drives the laser diode to generate pulse light. The pulse light source located on the 2D platform is controlled by the core controller, and goes to the wavelength shift fiber through the optical fiber. The host computer (PC) receives the signal from the electronics system, processes data, and automatically calibrates the performance parameters. As shown by the experimental results, the pulse light source can perfectly meet all requirements of 2D neutron detector calibration system.

APA, Harvard, Vancouver, ISO, and other styles

34

Sun, Yuan Yuan, Qiu Rui Jia, Li Min Song, Zheng Li, and Shi Bo Liu. "Research on the Performance of MSM Gan Ultraviolet Photoelectric Detector." Applied Mechanics and Materials 321-324 (June 2013): 408–11. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.408.

Full text

Abstract:

GaN ultraviolet photoelectric detectorhave advantages of high quantum efficiency, work at room temperature, high-temperature resistance, good corrosion resistance, resistance to radiation ability etc. Therefore, research ofGaN ultraviolet photoelectric detectorhas important application value in the spacecraft, fire monitoring, ultraviolet communication and other fields.MSM Schottky type ultraviolet photoelectric detectorhas been prepared by a metal organic chemical vapor phase epitaxial deposition method in growth of high qualityGaN semiconductor filmon the sapphire substrate. Then optical and electrical properties of device have been studied by analyzing its illumination and light response performance.The detector sample has high pressure resistanceand response degree. After annealed treatment, the ultraviolet detector has response peak for 0.19 A/W and response time for 70ns.

APA, Harvard, Vancouver, ISO, and other styles

35

Araki, Yosuke, Ryutaro Tanaka, Yuto Kojima, Katsuhiko Sekiya, Keiji Yamada, and Shuho Koseki. "Relationship between Cutting Heat and Tool Edge Temperature in End Milling of Titanium Alloy." Key Engineering Materials 749 (August 2017): 15–20. http://dx.doi.org/10.4028/www.scientific.net/kem.749.15.

Full text

Abstract:

In this study, tool edge temperature was measured by a two-color pyrometer with an optional fiber. During one revolution of spindle, the tool edge passes over the fine hole at workpiece after cutting workpiece. An optical fiber inserted into the fine hole transmits infrared ray radiated from tool edge to two detectors with different spectral sensitivities. One peak signal from each detector can be obtained by each spindle revolution. The tool edge temperature can be calculated by taking the ratio of outputs from these two detectors. The relation between cutting heat calculated from cutting force and tool edge temperature was discussed. The tool edge temperature at the same cutting heat could be compared. The wet cutting condition caused lower tool edge temperature than the others at the same cutting heat. MQL and dry showed almost same tool edge temperature. The dispersion of tool edge temperature in wet cutting is wider than that in dry cutting and MQL cutting.

APA, Harvard, Vancouver, ISO, and other styles

36

Taboada, Alvaro. "Preliminary results of the AMIGA engineering array at the Pierre Auger Observatory." EPJ Web of Conferences 210 (2019): 02016. http://dx.doi.org/10.1051/epjconf/201921002016.

Full text

Abstract:

The Auger Muons and Infill for the Ground Array (AMIGA) aims to both extend the detection range of the Pierre Auger Observatory down to energies ~ 1016.5 eV and to measure the muon content of extensive air showers. To accomplish these goals, its detection system is composed of an array of coupled water-Cherenkov and scintillation detectors deployed in a graded triangular grid of 433 and 750 m spacings. At each position, the scintillation detector is buried 2.3 m deep so as to shield it from the air shower electromagnetic component and thus only measure the muon component. These muon detectors have 30 m2 area split into modules, each of them highly segmented in 64 plastic-scintillator strips with an embedded wavelength-shifter optical fiber to transport light to an optical sensor located at the center of the module. During the engineering array phase (finished in November 2017) two module areas (5 m2 and 10 m2) and two optical sensors (photo-multiplier tubes and silicon-photomultipliers) were tested. In this work, we present the final performance of the muon detectors equipped with silicon-photomultipliers which were thereafter selected as the baseline design for the AMIGA production phase. Analyses and results are based both on laboratory and field measurements.

APA, Harvard, Vancouver, ISO, and other styles

37

Zhu, Xingyue, Zhimin Zhao, Kun Qian, Lexin Wang, and Xiufeng Lan. "A rapid method for measuring fat content in milk based on W-type optical fibre sensor system." Transactions of the Institute of Measurement and Control 38, no. 12 (July 22, 2016): 1471–79. http://dx.doi.org/10.1177/0142331215593994.

Full text

Abstract:

A measurement system based on a W-type optical fibre sensor for determining the fat content in milk is investigated in this paper. The system consists of a light source, W-type optical fibre sensor, detector, amplifier, A/D converter, microprocessor and thermoelectric cooler (TEC). According to Mie-scattering theory, the standard models of the system at different temperatures (25°, 30°, 35°, 40° and 45 °C) are obtained. Evaluations of all the models at different temperatures are made, which illustrate that 40 °C is the optimal temperature for fat content in milk. At 40 °C, the linear relationship between the absorbance and the fat content is significant. Furthermore, a prediction experiment has been performed to confirm the validity of the standard model. As a result, the measurement system based on a W-type optical fibre sensor is capable of measuring the fat content in milk effectively and in real time.

APA, Harvard, Vancouver, ISO, and other styles

38

Lauriks, W., C. Desmet, C. Glorieux, and J. Thoen. "Investigation of the thermal anisotropy of unidirectional carbon fiber reinforced composite plates using optically generated thermal waves and a noncontact optical detection technique." Journal of Materials Research 8, no. 12 (December 1993): 3106–10. http://dx.doi.org/10.1557/jmr.1993.3106.

Full text

Abstract:

Optically generated thermal waves have been used to measure the thermal diffusivity of a unidirectional carbon fiber reinforced composite plate (CFRC) both parallel and perpendicular to the fiber direction. The optically generated thermal waves have been used in combination with a noncontact optical detection technique. The diffusivity perpendicular to the fiber direction can also be determined by attaching a pyroelectric detector to the back of the sample. The value obtained this way agrees well with the results from the optical detection technique. An anisotropy factor of about 18 has been measured for a unidirectional CFRC, which agrees well with literature values obtained with completely different techniques.

APA, Harvard, Vancouver, ISO, and other styles

39

Bendali, M., R. Mastrippolito, Y. Charon, M. Leblanc, B. Martin, H. Tricoire, and L. Valentin. "Scintillating optical fiber detectors for DNA sequencing." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 310, no. 1-2 (December 1991): 373–78. http://dx.doi.org/10.1016/0168-9002(91)91063-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

McKinley, B. J., Sang Sheem, John Lutz, and Fred P. Milanovich. "A non-imaging concentrator for fiber optic mediated remote micro-Raman spectroscopy." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 2 (August 1992): 1518–19. http://dx.doi.org/10.1017/s0424820100132224.

Full text

Abstract:

The recent availability of moderate power near-infrared diode lasers (780nm) and near-infrared sensitive ccd detectors have caused a noticeable resurgence in the application of Raman spectroscopy in analytical chemistry. We have long maintained an interest in Raman spectroscopy and have established a micro-Raman facility within the Chemistry Department of our organization. Recently, we have taken advantage of the aforementioned progress in spectroscopic equipment and have upgraded our micro-Raman facility to include a ccd detector and an imaging spectrograph.Since our micro-Raman spectrometer is designed around an ellipsoidal collection mirror, with Raman signal being directed through the illumination sample stage it has application to microscopic or small transparent samples. The improved performance of the device and the availability of highly transmissive optical fibers led one of us (B.J.M.) to propose an apparatus that could replace the existing illuminator with a miniature device that maintains a high collection efficiency and can be used remotely or in-situ by utilizing optical fibers.

APA, Harvard, Vancouver, ISO, and other styles

41

Morshed, Ahmed Hisham. "Intensity-based optical fiber intrusion detector." Optical Engineering 51, no. 3 (March 14, 2012): 034402. http://dx.doi.org/10.1117/1.oe.51.3.034402.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Zhang, Shao Jun, Yue Ming Liu, and Xiao Hong Huangfu. "Mechanism and Simulation of Bi-Layered Micro Optical Fiber Resonator." Applied Mechanics and Materials 241-244 (December 2012): 841–46. http://dx.doi.org/10.4028/www.scientific.net/amm.241-244.841.

Full text

Abstract:

Micro-resonators could be fabricated directly on the optical fiber top by micro mechanical process. The micro optical fiber resonator has more great advantages comparing with the traditional optical excited micro silicon resonators, such as being optically positioned easily between the resonator and the optical fiber end. By this way, the optical excited light through the fiber core is thus put on the micro resonator accurately and then partially reflected by the Fabry-Perot interferometer formed between fiber top and resonator surface. The reflected light from F-P interferometer was sent to the opto-electric detector PIN to demodulate the detected parameter. A matched metal layer can be deposited atop of the resonator in order to increase the optical excitation efficiency. Firstly mechanism analysis of optical excited bi-layered resonator is given by fully considering Longitudinal thermal strain effect and Bi-coating effect, and then the typical theoretical models were setup including the resonating frequency and resonant amplitude, and temperature sensing feature was simulated by computer software. The simulation results indicated that the average frequency sensitivity of temperature sensing is about 29Hz/°C.

APA, Harvard, Vancouver, ISO, and other styles

43

Archibald, D. D., C. E. Miller, L. T. Lin, and D. E. Honigs. "Remote Near-IR Reflectance Measurements with the Use of a Pair of Optical Fibers and a Fourier Transform Spectrometer." Applied Spectroscopy 42, no. 8 (November 1988): 1549–58. http://dx.doi.org/10.1366/0003702884429553.

Full text

Abstract:

A commercial near-infrared (near-IR) Fourier transform (FT) spectrometer was modified to make remote reflectance measurements over a single optical fiber or pair of optical fibers. With the use of two low-hydroxyl fused-silica optical fibers and an InSb detector, the near-IR region from 0.92 to 2.15 μm was measurable. An InGaAs detector was used to obtain reflectance spectra over the region from 0.92 to 1.56 μm. With this detector, single-fiber reflectance and transmission measurements were possible and a variety of dual-fiber probe geometries could be easily employed. Dual-fiber geometries were used to enhance pathlength, to perform depth discrimination, and to make measurements without physical contact between the probe and the specimen. Potential applications and improvements are discussed.

APA, Harvard, Vancouver, ISO, and other styles

44

Kong, Ha-Sung, Jong-Seog Yang, and Kwang-Sun Kang. "Comparative Study of the Conventional and Optical Communication Analog Fire Detector Signal Attenuations with Various Number of Fire Detectors." International Journal of Control and Automation 9, no. 3 (March 31, 2016): 299–308. http://dx.doi.org/10.14257/ijca.2016.9.3.27.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Zheng, Zheng, Dai Hong-gui, Hu Shang-ze, Liu Jian, and Fang Jie. "An optical fibre-type silicate glass thermoluminescent detector." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 301, no. 2 (March 1991): 337–40. http://dx.doi.org/10.1016/0168-9002(91)90476-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Takesue, Hiroki, Shellee D. Dyer, Martin J. Stevens, Varun Verma, Richard P. Mirin, and Sae Woo Nam. "Quantum teleportation over 100 km of fiber using highly efficient superconducting nanowire single-photon detectors." Optica 2, no. 10 (September 23, 2015): 832. http://dx.doi.org/10.1364/optica.2.000832.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Nellen, S., T. Ishibashi, A. Deninger, R. B. Kohlhaas, L. Liebermeister, M. Schell, and B. Globisch. "Experimental Comparison of UTC- and PIN-Photodiodes for Continuous-Wave Terahertz Generation." Journal of Infrared, Millimeter, and Terahertz Waves 41, no. 4 (December 20, 2019): 343–54. http://dx.doi.org/10.1007/s10762-019-00638-5.

Full text

Abstract:

AbstractWe carried out an experimental comparison study of the two most established optoelectronic emitters for continuous-wave (cw) terahertz generation: a uni-traveling-carrier photodiode (UTC-PD) and a pin-photodiode (PIN-PD). Both diodes are commercially available and feature a similar package (fiber-pigtailed housings with a hyper-hemispherical silicon lens). We measured the terahertz output as a function of optical illumination power and bias voltage from 50 GHz up to 1 THz, using a precisely calibrated terahertz power detector. We found that both emitters were comparable in their spectral power under the operating conditions specified by the manufacturers. While the PIN-PD turned out to be more robust against varying operating parameters, the UTC-PD showed no saturation of the emitted terahertz power even for 50 mW optical input power. In addition, we compared the terahertz transmission and infrared (IR) blocking ratio of four different filter materials. These filters are a prerequisite for correct measurements of the absolute terahertz power with thermal detectors.

APA, Harvard, Vancouver, ISO, and other styles

48

Reichl, D., R. Krage, C. Krummel, and G. Gauglitz. "Sensing of Volatile Organic Compounds Using a Simplified Reflectometric Interference Spectroscopy Setup." Applied Spectroscopy 54, no. 4 (April 2000): 583–86. http://dx.doi.org/10.1366/0003702001949762.

Full text

Abstract:

We present a simplified optical sensor system using the principle of reflectometric interference spectroscopy (RIfS) for monitoring organic solvent vapors in air. The shift of the interference pattern caused by a change of the optical thickness of a sensitive layer, due to the influence of analyte, is investigated. The interference pattern is detected by only four wavelengths, in contrast to the system described formerly, which detects the same spectral range with a diode-array spectrometer. With the use of a direct light path between the light-emitting diodes (LEDs), transducer, and detector, no fiber-optic light guides are required. The advantages and requirements of the new optical and electronic setup as well as several applications in gas sensing are discussed with respect to the limits of detection for some analytes.

APA, Harvard, Vancouver, ISO, and other styles

49

Antoshyn, A. A., and V. I. Nikitin. "Technique for Studying of the Dynamics of Changes of a Smoky Environment Parameters during the Transition of Pyrolysis to Flame Combustion." Devices and Methods of Measurements 10, no. 4 (December 12, 2019): 382–90. http://dx.doi.org/10.21122/2220-9506-2019-10-4-382-390.

Full text

Abstract:

The existing methods for monitoring the performance of multi-criteria fire detectors do not provide for verification of their characteristics in the conditions of transition from smoldering to flame burning. The aim of the work is the development of the research methods of the environmental parameters during the transition from smoldering (pyrolysis) to flame combustion for simulation a test fire while checking the quality of multi-criteria fire detectors.A technique to conduct research of environmental parameters under conditions of heating wood samples of different sizes to a temperature of selfignition and burning crumpled and smooth paper has been developed.Changes in the concentration of carbon monoxide, specific optical density, and scattering ability during the transition from smoldering (pyrolysis) to flame burning of prepared wood and crumpled paper were studied for the first time.It is shown that the controlled environmental parameters during the transition from smoldering pyrolysis to flame burning change together. Conclusion: the speed of growth of the scattering ability of smoke decreases by 2.4 times, the speed of increase in the specific optical density and concentration of carbon monoxide increases by 2 and 5.3 times (respec-tively), during the transition from pyrolysis to flame burning of wood.

APA, Harvard, Vancouver, ISO, and other styles

50

Dai, Yun, Zhonghan Zhang, Xibin Wang, Zhuowei Lu, Huamin Kou, Liangbi Su, and Anhua Wu. "Growth and Characterization of Ce-Doped Luag Single Crystal Fibers from Transparent Ceramics by Laser-Heated Pedestal Method." Crystals 11, no. 9 (September 21, 2021): 1149. http://dx.doi.org/10.3390/cryst11091149.

Full text

Abstract:

Scintillation single crystal fibers (SCFs) have great potential applications in the new generation of high-energy ray and particle detectors due to their morphological advantages. In this work; Ce:LuAG SCFs with a diameter of 1 mm were grown along the direction of [111] by laser-heated pedestal growth (LHPG) method using a transparent ceramic as the source rod; and a doping concentration was 0.1 at%, 0.3 at%, 1 at%, respectively. The effects of growth rate and annealing in air on the scintillation and optical properties of SCF are discussed in detail. The results of analyzing the absorption spectra; radioluminescence (RL) spectra; pulse-height spectra and fluorescence lifetime of SCFs show that the SCF maintains excellent scintillation performance while having a fiber structure. Therefore; Ce:LuAG SCF is a potential candidate material for detector.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Optical fibre detectors'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles