Science.gov

Sample records for fibre optic spectroscopy

  1. Dental caries detection by optical spectroscopy: a polarized Raman approach with fibre-optic coupling

    NASA Astrophysics Data System (ADS)

    Ko, A. C.-T.; Choo-Smith, L.-P.; Werner, J.; Hewko, M.; Sowa, M. G.; Dong, C.; Cleghorn, B.

    2006-09-01

    Incipient dental caries lesions appear as white spots on the tooth surface; however, accurate detection of early approximal lesions is difficult due to limited sensitivity of dental radiography and other traditional diagnostic tools. A new fibre-optic coupled spectroscopic method based on polarized Raman spectroscopy (P-RS) with near-IR laser excitation is introduced which provides contrast for detecting and characterizing incipient caries. Changes in polarized Raman spectra are observed in PO 4 3- vibrations arising from hydroxyapatite of mineralized tooth tissue. Demineralization-induced morphological/orientational alteration of enamel crystallites is believed to be responsible for the reduction of Raman polarization anisotropy observed in the polarized Raman spectra of caries lesions. Supporting evidence obtained by polarized Raman spectral imaging is presented. A specially designed fibre-optic coupled setup for simultaneous measurement of parallel- and cross-polarized tooth Raman spectra is demonstrated in this study.

  2. A guiding light: spectroscopy on digital microfluidic devices using in-plane optical fibre waveguides.

    PubMed

    Choi, Kihwan; Mudrik, Jared M; Wheeler, Aaron R

    2015-09-01

    We present a novel method for in-plane digital microfluidic spectroscopy. In this technique, a custom manifold (.stl file available online as ESM) aligns optical fibres with a digital microfluidic device, allowing optical measurements to be made in the plane of the device. Because of the greater width vs thickness of a droplet on-device, the in-plane alignment of this technique allows it to outperform the sensitivity of vertical absorbance measurements on digital microfluidic (DMF) devices by ∼14×. The new system also has greater calibration sensitivity for thymol blue measurements than the popular NanoDrop system by ∼2.5×. The improvements in absorbance sensitivity result from increased path length, as well as from additional effects likely caused by liquid lensing, in which the presence of a water droplet between optical fibres increases fibre-to-fibre transmission of light by ∼2× through refraction and internal reflection. For interrogation of dilute samples, stretching of droplets using digital microfluidic electrodes and adjustment of fibre-to-fibre gap width allows absorbance path length to be changed on-demand. We anticipate this new digital microfluidic optical fibre absorbance and fluorescence measurement system will be useful for a wide variety of analytical applications involving microvolume samples with digital microfluidics. PMID:26232932

  3. Fibre optical spectroscopy and sensing innovation at innoFSPEC Potsdam

    NASA Astrophysics Data System (ADS)

    Haynes, Roger; Reich, Oliver; Rambold, William; Hass, Roland; Janssen, Katja

    2010-07-01

    In October 2009, an interdisciplinary centre for fibre spectroscopy and sensing, innoFSPEC Potsdam, has been established as joint initiative of the Astrophysikalisches Institut Potsdam (AIP) and the Physical Chemistry group of Potsdam University (UPPC), Germany. The centre focuses on fundamental research in the two fields of fibre-coupled multi-channel spectroscopy and optical fibre-based sensing. Thanks to its interdisciplinary approach, the complementary methodologies of astrophysics on the one hand, and physical chemistry on the other hand, are expected to spawn synergies that otherwise would not normally become available in more standard research programmes. innoFSPEC Potsdam targets future innovations for next generation astrophysical instrumentation, environmental analysis, manufacturing control and process analysis, medical diagnostics, non-invasive imaging spectroscopy, biopsy, genomics/proteomics, high throughput screening, and related applications.

  4. High-resolution optical spectroscopy using multimode interference in a compact tapered fibre

    NASA Astrophysics Data System (ADS)

    Wan, Noel H.; Meng, Fan; Schröder, Tim; Shiue, Ren-Jye; Chen, Edward H.; Englund, Dirk

    2015-07-01

    Optical spectroscopy is a fundamental tool in numerous areas of science and technology. Much effort has focused on miniaturizing spectrometers, but thus far at the cost of spectral resolution and broad operating range. Here we describe a compact spectrometer that achieves both high spectral resolution and broad bandwidth. The device relies on imaging multimode interference from leaky modes along a multimode tapered optical fibre, resulting in spectrally distinguishable spatial patterns over a wide range of wavelengths from 500 to 1,600 nm. This tapered fibre multimode interference spectrometer achieves a spectral resolution down to 40 pm in the visible spectrum and 10 pm in the near-infrared spectrum (corresponding to resolving powers of 104-105). Multimode interference spectroscopy is suitable in a variety of device geometries, including planar waveguides in a broad range of transparent materials.

  5. Preliminary research on monitoring the durability of concrete subjected to sulfate attack with optical fibre Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Yue, Yanfei; Bai, Yun; Basheer, P. A. Muhammed; Boland, John J.; Wang, Jing Jing

    2013-04-01

    Formation of ettringite and gypsum from sulfate attack together with carbonation and chloride ingress have been considered as the most serious deterioration mechanisms of concrete structures. Although Electrical Resistance Sensors and Fibre Optic Chemical Sensors could be used to monitoring the latter two mechanisms in situ, currently there is no system for monitoring the deterioration mechanisms of sulfate attack and hence still needs to be developed. In this paper, a preliminary study was carried out to investigate the feasibility of monitoring the sulfate attack with optical fibre Raman spectroscopy through characterizing the ettringite and gypsum formed in deteriorated cementitious materials under an `optical fibre excitation + spectroscopy objective collection' configuration. Bench-mounted Raman spectroscopy analysis was also used to validate the spectrum obtained from the fibre-objective configuration. The results showed that the expected Raman bands of ettringite and gypsum in the sulfate attacked cement paste have been clearly identified by the optical fibre Raman spectroscopy and are in good agreement with those identified from bench-mounted Raman spectroscopy. Therefore, based on these preliminary results, there is a good potential of developing an optical fibre Raman spectroscopy-based system for monitoring the deterioration mechanisms of concrete subjected to the sulfate attack in the future.

  6. Fibre optic fluorescence spectroscopy for monitoring fish freshness

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Wu; Hsiao, Tzu-Chien; Chu, Shou-Chia; Hu, Hung-Hsi; Chen, Jyh-Cheng

    2012-01-01

    In this study, a portable Y-type fibreoptic fluorescence spectroscopy measurement system was used to evaluate the freshness of eight cobias (Rachycentron canadum). The results showed that the ratio of fluorescent intensity, which F480 nm/Fexci+50 nm was belong with the range of collagen type I and type V characteristic spectra, was positive correlated to the frozen time by hours. It was a strong approach to be a potential index for differentiating the fish freshness during delivery process. Besides, the different pattern results of dorsum and abdomen were shown in this study. In further, fibreoptic fluorescence spectroscopy could be a way not only to measure and quantify the freshness of different fish body but also to verify the level of taste.

  7. Optical fibre spectroscopy sensor for the quantitative determination of industrial textile dyes

    NASA Astrophysics Data System (ADS)

    Cubillas, Ana M.; Conde, Olga M.; Anuarbe, Pedro; Gutierrez, Monica; Martinez, Vicente; Lopez-Higuera, Jose M.

    2009-10-01

    In this paper, an extrinsic optical fibre sensor (OFS) for the quantitative determination of dyes used in the textile industry is presented. The system proposed is based on absorption spectroscopy and multivariate calibration methods to infer the concentration of different textile dyes. The performance of the sensor has been successfully assessed using calibrated dyes, with a very good correlation between the multivariate calibration models and the predicted values. The sensor system here demonstrated could be used to predict the colour of dye mixtures during the dyebath and, therefore, reduce the manufacturing costs.

  8. Towards optical fibre based Raman spectroscopy for the detection of surgical site infection

    NASA Astrophysics Data System (ADS)

    Thompson, Alex J.; Koziej, Lukasz; Williams, Huw D.; Elson, Daniel S.; Yang, Guang-Zhong

    2016-03-01

    Surgical site infections (SSIs) are common post-surgical complications that remain significant clinical problems, as they are associated with substantial mortality and morbidity. As such, there is significant interest in the development of minimally invasive techniques that permit early detection of SSIs. To this end, we are applying a compact, clinically deployable Raman spectrometer coupled to an optical fibre probe to the study of bacteria, with the long term goal of using Raman spectroscopy to detect infection in vivo. Our system comprises a 785 nm laser diode for excitation and a commercial (Ocean Optics, Inc.) Raman spectrometer for detection. Here we discuss the design, optimisation and validation of this system, and describe our first experiences interrogating bacterial cells (Escherichia coli) in vitro.

  9. Fibre optics: Forty years later

    SciTech Connect

    Dianov, Evgenii M

    2010-01-31

    This paper presents a brief overview of the state of the art in fibre optics and its main applications: optical fibre communications, fibre lasers and fibre sensors for various physical property measurements. The future of fibre optics and the status of this important area of the modern technology in Russia are discussed. (fiber optics)

  10. Combining scanning haptic microscopy and fibre optic Raman spectroscopy for tissue characterization.

    PubMed

    Candefjord, S; Murayama, Y; Nyberg, M; Hallberg, J; Ramser, K; Ljungberg, B; Bergh, A; Lindahl, O A

    2012-08-01

    The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterization in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental set-up combining micro-scale TRM-scanning haptic microscopy (SHM)-for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 65-81%, and when RS was added it increased to 81-87%. The accuracy for healthy and cancerous human tissue was 67-70% when only SHM was used, and increased to 72-77% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery. PMID:22762445

  11. New generation of optical fibres

    NASA Astrophysics Data System (ADS)

    Dianov, E. M.; Semjonov, S. L.; Bufetov, I. A.

    2016-01-01

    The growing need for information in contemporary society is the motivating force behind the development of fibre optics in general and optical fibre communications in particular. Intensive research effort has been concentrated on designing new types of optical fibres and extending their application field. This paper reviews results of research on new types of optical fibres: bismuthdoped active fibres, multicore fibres and hollow-core fibres, which can be used as key components of systems that ensure further increase in optical information transfer rate.

  12. Detection of premature browning in ground beef with an integrated optical-fibre based sensor using reflection spectroscopy and fibre Bragg grating technology

    NASA Astrophysics Data System (ADS)

    O'Farrell, M.; Sheridan, C.; Lewis, E.; Zhao, W. Z.; Sun, T.; Grattan, K. T. V.; Kerry, J.; Jackman, N.

    2007-07-01

    This paper reports on an optical fibre based sensor system to detect the occurrence of premature browning in ground beef. Premature browning (PMB) occurs when, at a temperature below the pasteurisation temperature of 71°C, there are no traces of pink meat left in the patty. PMB is more frequent if poorer quality beef or beef that has been stored under imperfect conditions. The experimental work pertaining to this paper involved cooking fresh meat and meat that has been stored in a freezer for, 1 week, 1 month and 3 months and recording the reflected spectra and temperature at the core of the product, during the cooking process, in order to develop a classifier based on the spectral response and using a Self-Organising Map (SOM) to classify the patties into one of four categories, based on their colour. Further tests were also carried out on developing an all-optical fibre sensor for measuring both the temperature and colour in a single integrated probe. The integrated probe contains two different sensor concepts, one to monitor temperature, based on Fibre Bragg Grating (FBG) technology and a second for meat quality, based on reflection spectroscopy in the visible wavelength range.

  13. Multi-fibre optical spectroscopy of low-mass stars and brown dwarfs in Upper Scorpius

    NASA Astrophysics Data System (ADS)

    Lodieu, N.; Dobbie, P. D.; Hambly, N. C.

    2011-03-01

    Context. Knowledge of the mass function in open clusters constitutes one way to critically examine the formation mechanisms proposed to explain the existence of low-mass stars and brown dwarfs. Aims: The aim of the project is to determine as accurately as possible the shape of the mass function across the stellar/substellar boundary in the young (5 Myr) and nearby (d = 145 pc) Upper Sco association. Methods: We have obtained multi-fibre intermediate-resolution (R ~ 1100) optical (~5750-8800 Å) spectroscopy of 94 photometric and proper motion selected low-mass star and brown dwarf candidates in Upper Sco with the AAOmega spectrograph on the Anglo-Australian Telescope. Results: We have estimated the spectral types and measured the equivalent widths of youth (Hα) and gravity (Na I and K I) diagnostic features to confirm the spectroscopic membership of about 95% of the photometric and proper motion candidates extracted from 6.5 square degrees surveyed in Upper Sco by the UKIRT Infrared Deep Sky Survey (UKIDSS) Galactic Clusters Survey (GCS). We also detect lithium in the spectra with the highest signal-to-noise, consolidating our conclusions about their youth. Furthermore, we derive an estimate of the efficiency of the photometric and proper motion selections used in our earlier studies using spectroscopic data obtained for a large number of stars falling into the instrument's field-of-view. We have estimated the effective temperatures and masses for each new spectroscopic member using the latest evolutionary models available for low-mass stars and brown dwarfs. Combining the current optical spectroscopy presented here with near-infrared spectroscopy obtained for the faintest photometric candidates, we confirm the shape and slope of our earlier photometric mass function. The luminosity function drawn from the spectroscopic sample of 113 USco members peaks at around M6 and is flat at later spectral type. We may detect the presence of the M7/M8 gap in the luminosity

  14. Fibre-optical microendoscopy.

    PubMed

    Gu, M; Bao, H; Kang, H

    2014-04-01

    Microendoscopy has been an essential tool in exploring micro/nano mechanisms in vivo due to high-quality imaging performance, compact size and flexible movement. The investigations into optical fibres, micro-scanners and miniature lens have boosted efficiencies of remote light delivery to sample site and signal collection. Given the light interaction with materials in the fluorescence imaging regime, this paper reviews two classes of compact microendoscopy based on a single fibre: linear optical microendoscopy and nonlinear optical microendoscopy. Due to the fact that fluorescence occurs only in the focal volume, nonlinear optical microendoscopy can provide stronger optical sectioning ability than linear optical microendoscopy, and is a good candidate for deep tissue imaging. Moreover, one-photon excited fluorescence microendoscopy as the linear optical microendoscopy suffers from severe photobleaching owing to the linear dependence of photobleaching rate on excitation laser power. On the contrary, nonlinear optical microendoscopy, including two-photon excited fluorescence microendoscopy and second harmonic generation microendoscopy, has the capability to minimize or avoid the photobleaching effect at a high excitation power and generate high image contrast. The combination of various nonlinear signals gained by the nonlinear optical microendoscopy provides a comprehensive insight into biophenomena in internal organs. Fibre-optical microendoscopy overcomes physical limitations of traditional microscopy and opens up a new path to achieve early cancer diagnosis and microsurgery in a minimally invasive and localized manner. PMID:24593142

  15. Detection of atmospheric nitrogen dioxide using a miniaturised fibre-optic spectroscopy system and the ambient sunlight.

    PubMed

    Morales, J A; Walsh, J E

    2005-07-01

    A miniaturised fibre-optic spectrometer based system is presented for direct detection of one of the major atmospheric pollutants, nitrogen dioxide, by absorption spectroscopy using the ambient sunlight as light source. The detection system consists of a 10 cm collimator assembly, a fibre-optic cable and a portable diode-array spectrometer. The absorbance spectrum of the open-path is calculated using a reference spectrum recorded when the nitrogen dioxide (NO2) concentration in the atmosphere is low. The relative concentration of the pollutant is calculated normalising the detected spectra and subtracting the background broadband spectrum from the specific NO2 absorbance features, since the broadband spectrum changes according to atmospheric conditions and solar intensity. Wavelengths between 400 and 500 nm are used in order to maximise sensitivity and to avoid interference from other species. Calibration is carried out using Tedlar sample bags of known concentration of the pollutant. A commercial differential optical absorption spectroscopy (DOAS) system is used as a reference standard detection system to compare the results with the new system. Results show that detection of NO2 at typical urban atmospheric levels has been achieved using an inexpensive field based fibre-optic spectrometer and a readily available, easy to align, light source. In addition the new system can be used to get a semi-quantitative estimation of the nitrogen dioxide concentration within errors of 20%. While keeping the typical benefits of open-path techniques, the new system has important advantages over them such as cost, simplicity and portability. PMID:15911394

  16. Simulation of complex phenomena in optical fibres

    NASA Astrophysics Data System (ADS)

    Allington-Smith, Jeremy; Murray, Graham; Lemke, Ulrike

    2012-12-01

    Optical fibres are essential for many types of highly multiplexed and precision spectroscopy. The success of the new generation of multifibre instruments under construction to investigate fundamental problems in cosmology, such as the nature of dark energy, requires accurate modellization of the fibre system to achieve their signal-to-noise ratio (SNR) goals. Despite their simple construction, fibres exhibit unexpected behaviour including non-conservation of etendue (focal ratio degradation, FRD) and modal noise. Furthermore, new fibre geometries (non-circular or tapered) have become available to improve the scrambling properties that, together with modal noise, limit the achievable SNR in precision spectroscopy. These issues have often been addressed by extensive tests on candidate fibres and their terminations, but these are difficult and time-consuming. Modelling by ray tracing and wave analysis is possible with commercial software packages, but these do not address the more complex features, in particular FRD. We use a phase-tracking ray-tracing method to provide a practical description of FRD derived from our previous experimental work on circular fibres and apply it to non-standard fibres. This allows the relationship between scrambling and FRD to be quantified for the first time. We find that scrambling primarily affects the shape of the near-field pattern but has negligible effect on the barycentre. FRD helps to homogenize the near-field pattern but does not make it completely uniform. Fibres with polygonal cross-section improve scrambling without amplifying the FRD. Elliptical fibres, in conjunction with tapering, may offer an efficient means of image slicing to improve the product of resolving power and throughput, but the result is sensitive to the details of illumination. We also investigated the performance of fibres close to the limiting numerical aperture since this may affect the uniformity of the SNR for some prime focus fibre instrumentation.

  17. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Bismuth-ring-doped fibres

    NASA Astrophysics Data System (ADS)

    Zlenko, Aleksandr S.; Akhmetshin, Ural G.; Dvoirin, Vladislav V.; Bogatyrev, Vladimir A.; Firstov, Sergei V.

    2009-11-01

    A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO2 content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications.

  18. Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy

    PubMed Central

    Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

    2016-01-01

    Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident. PMID:27301319

  19. Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

    2016-06-01

    Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident.

  20. Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy.

    PubMed

    Hsieh, Yi-Da; Nakamura, Shota; Abdelsalam, Dahi Ghareab; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Hindle, Francis; Yasui, Takeshi

    2016-01-01

    Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident. PMID:27301319

  1. Speciality optical fibres for astronomy

    NASA Astrophysics Data System (ADS)

    Ellis, S. C.; Bland-Hawthorn, J.

    2015-05-01

    Astrophotonics is a rapidly developing area of research which applies photonic technology to astronomical instrumentation. Such technology has the capability of significantly improving the sensitivity, calibration and stability of astronomical instruments, or indeed providing novel capabilities which are not possible using classical optics. We review the development and application of speciality fibres for astronomy, including multi-mode to single-mode converters, notch filters and frequency combs.In particular we focus on our development of instruments designed to filter atmospheric emission lines to enable much deeper spectroscopic observations in the near-infrared. These instruments employ two novel photonic technologies. First, we have developed complex aperiodic fibre Bragg gratings which filter over 100 irregularly spaced wavelengths in a single device, covering a bandwidth of over 200 nm. However, astronomical instruments require highly multi-mode fibres to enable sufficient coupling into the fibre, since atmospheric turbulence heavily distorts the wavefront. But photonic technologies such as fibre Bragg gratings, require single mode fibres. This problem is solved by the photonic lantern, which enables efficient coupling from a multi-mode fibre to an array of single-mode fibres and vice versa. We present the results of laboratory tests of these technologies and of on-sky experiments made using the first instruments to deploy these technologies on a telescope. These tests show that the fibre Bragg gratings suppress the night sky background by a factor of 9. Current instruments are limited by thermal and detector emission. Planned instruments should improve the background suppression even further, by optimising the design of the spectrograph for the properties of the photonic components. Finally we review ongoing research in astrophotonics, including multi-moded multicore fibre Bragg gratings, which enable multiple gratings to be written into the same device

  2. Portable smartphone optical fibre spectrometer

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas

    2015-09-01

    A low cost, optical fibre based spectrometer has been developed on a smartphone platform for field-portable spectral analysis. Light of visible wavelength is collected using a multimode optical fibre and diffracted by a low cost nanoimprinted diffraction grating. A measurement range over 300 nm span (λ = 400 to 700 nm) is obtained using the smartphone CMOS chip. The spectral resolution is Δλ ~ 0.42 nm/screen pixel. A customized Android application processed the spectra on the same platform and shares with other devices. The results compare well with commercially available spectrometer.

  3. Liquid crystal assisted optical fibres.

    PubMed

    Wahle, M; Kitzerow, H-S

    2014-01-13

    Microstructured fibres which consist of a circular step index core and a liquid crystal inclusion running parallel to this core are investigated. The attenuation and electro-optic effects of light coupled into the core are measured. Coupled mode theory is used to study the interaction of core modes with the liquid crystal inclusion. The experimental and theoretical results show that these fibres can exhibit attenuation below 0.16 dB cm(-1) in off-resonant wavelength regions and still have significant electro-optic effects which can lead to a polarisation extinction of 6 dB cm(-1). PMID:24514987

  4. Highly efficient cladding-pumped fibre laser based on an ytterbium-doped optical fibre and a fibre Bragg grating

    SciTech Connect

    Kurkov, Andrei S; Karpov, V I; Medvedkov, O I; Dianov, Evgenii M; Vasil'ev, Sergei A; Paramonov, Vladimir M; Protopopov, V N; Laptev, A Yu; Gur'yanov, A N; Umnikov, A A; Vechkanov, N I; Artyushenko, V G; Frahm, J

    1999-06-30

    Ytterbium-ion-doped double-clad optical fibres were developed. The differential quantum efficiency of a diode-pumped fibre laser, fabricated on the basis of such optical fibres with a fibre Bragg grating, was 90%. (lasers)

  5. Advanced materials and techniques for fibre-optic sensing

    NASA Astrophysics Data System (ADS)

    Henderson, Philip J.

    2014-06-01

    Fibre-optic monitoring systems came of age in about 1999 upon the emergence of the world's first significant commercialising company - a spin-out from the UK's collaborative MAST project. By using embedded fibre-optic technology, the MAST project successfully measured transient strain within high-performance composite yacht masts. Since then, applications have extended from smart composites into civil engineering, energy, military, aerospace, medicine and other sectors. Fibre-optic sensors come in various forms, and may be subject to embedment, retrofitting, and remote interrogation. The unique challenges presented by each implementation require careful scrutiny before widespread adoption can take place. Accordingly, various aspects of design and reliability are discussed spanning a range of representative technologies that include resonant microsilicon structures, MEMS, Bragg gratings, advanced forms of spectroscopy, and modern trends in nanotechnology. Keywords: Fibre-optic sensors, fibre Bragg gratings, MEMS, MOEMS, nanotechnology, plasmon.

  6. Optical Fibre Current Measurement

    NASA Astrophysics Data System (ADS)

    Rogers, A. J.

    1983-08-01

    Passive optical devices offer valuable technical and economic advantages for power-system current and voltage measurement. Such devices can also be used to measure a variety of other power-system parameters (e.g. temperature, pressure, strain, etc.). The main advantages of all such devices may be summarized as follows: (i) No powering is required at high voltage points. (ii) There is freedom from saturation effects. (iii) They have large measurement bandwith. (iv) The measurement sensitivity is high. (v) The costs are low and are not strongly dependent on system voltages. (vi) They are readily interfaced with interference-immune communications links.

  7. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Polarisation reflectometry of anisotropic optical fibres

    NASA Astrophysics Data System (ADS)

    Konstantinov, Yurii A.; Kryukov, Igor'I.; Pervadchuk, Vladimir P.; Toroshin, Andrei Yu

    2009-11-01

    Anisotropic, polarisation-maintaining fibres have been studied using a reflectometer and integrated optic polariser. Linearly polarised pulses were launched into the fibre under test at different angles between their plane of polarisation and the main optical axis of the fibre. A special procedure for the correlation analysis of these reflectograms is developed to enhance the reliability of the information about the longitudinal optical uniformity ofanisotropic fibres.

  8. Fibre optic systems for gas detection principals, progress and prospects

    NASA Astrophysics Data System (ADS)

    Culshaw, Brian

    2010-11-01

    Gas sensing is evolving into an important application contributing particularly to environmental and safety monitoring. Fibre optic sensing will have an important role to play as the need for gas measurements increase. This paper seeks to overview of the optical techniques which are compatible with fibre optic technology and present a limited snapshot of the applications. Fibre optic techniques offer intrinsic safety, reliability and very long interrogation distances over the fibre link together with prospects for highly multiplexed and distributed systems. There are two basic approaches for fibre sensing targeted at gas measurements. The first involves some intermediate compound in contact with the end of the fibre (or deposited along the fibre) whose optical properties change with the presence of the gas of interest, usually measured spectroscopically. The second involves direct absorption spectroscopy typically in the near infrared. Former techniques are invariably responsive to a number of gas species and are usually difficult to calibrate accurately. The latter techniques are highly gas specific and can be accurately calibrated. However both approaches have their application sectors depending upon particular measurement requirements. The paper presents a brief overview of the principles of both these techniques and analyses some of their applications.

  9. Lead silicate microstructured optical fibres for electro-optical applications.

    PubMed

    Zhang, Wen Qi; Manning, Sean; Ebendorff-Heidepriem, Heike; Monro, Tanya M

    2013-12-16

    We report progress towards the realization of optical modulators based on electro-optic effects in soft glass fibres. A hybrid fabrication procedure was developed for producing microstructured lead silicate glass fibres with internal electrodes. Electro-optical characterization confirms experimentally that the enhanced nonlinear properties and superior isolation between the optical field and the electrodes make these fibres an ideal candidate platform for efficient electro-optical devices. PMID:24514705

  10. A compact polymer optical fibre ultrasound detector

    NASA Astrophysics Data System (ADS)

    Broadway, Christian; Gallego, Daniel; Pospori, Andreas; Zubel, Michal; Webb, David J.; Sugden, Kate; Carpintero, Guillermo; Lamela, Horacio

    2016-03-01

    Polymer optical fibre (POF) is a relatively new and novel technology that presents an innovative approach for ultrasonic endoscopic applications. Currently, piezo electric transducers are the typical detectors of choice, albeit possessing a limited bandwidth due to their resonant nature and a sensitivity that decreases proportionally to their size. Optical fibres provide immunity from electromagnetic interference and POF in particular boasts more suitable physical characteristics than silica optical fibre. The most important of these are lower acoustic impedance, a reduced Young's Modulus and a higher acoustic sensitivity than single-mode silica fibre at both 1 MHz and 10 MHz. POF therefore offers an interesting alternative to existing technology. Intrinsic fibre structures such as Bragg gratings and Fabry-Perot cavities may be inscribed into the fibre core using UV lasers. These gratings are a modulation of the refractive index of the fibre core and provide the advantages of high reflectivity, customisable bandwidth and point detection. We present a compact in fibre ultrasonic point detector based upon a POF Bragg grating (POFBG) sensor. We demonstrate that the detector is capable of leaving a laboratory environment by using connectorised fibre sensors and make a case for endoscopic ultrasonic detection through use of a mounting structure that better mimics the environment of an endoscopic probe. We measure the effects of water immersion upon POFBGs and analyse the ultrasonic response for 1, 5 and 10 MHz.

  11. Optical Fibre Pressure Sensors in Medical Applications

    PubMed Central

    Poeggel, Sven; Tosi, Daniele; Duraibabu, DineshBabu; Leen, Gabriel; McGrath, Deirdre; Lewis, Elfed

    2015-01-01

    This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas. PMID:26184228

  12. Fibre-optic sensors in health care

    NASA Astrophysics Data System (ADS)

    Grazia Mignani, Anna; Baldini, Francesco

    1997-05-01

    Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are able to offer in different application fields such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology and dentistry.

  13. Progress in reliability of silica optical fibres

    NASA Astrophysics Data System (ADS)

    Severin, Irina; Poulain, M.; El Abdi, R.

    2008-04-01

    Silica optical fibres that were developed for telecommunication networks extend their use for sensors and smart structures. Their reliability and expected lifetime has appeared as a major concern. Series of experiments were implemented in order to assess fibre behaviour in different environmental conditions, including chemical corrosion and mechanical stress. Optical fibres were aged in water under controlled stress overlapping microwave energy for different durations. Fibre samples were wound on different diameter mandrels applying consequently a non-uniform tensile, respectively compression stress in function of the fibre's section. Different experimental combinations were implemented in order to separate aging factor effects. Then, these aged / stretched fibres were dynamic tensile tested at different strain rates and results were statistically treated using Weibull theory. In certain cases and testing conditions, comparison with as received fibres has revealed strength increase with a generally mono-modal defect distribution on the fibre surface. Base on previous and current results, the structural relaxation phenomenon at the silica cladding - polymer coating interface might be evidenced.

  14. Chalcogenide-tellurite composite microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Kohoutek, T.; Duan, Z.; Kawashima, H.; Yan, X.; Suzuki, T.; Matsumoto, M.; Misumi, Takashi; Ohishi, Y.

    2012-02-01

    We report on fabrication a composite microstructured optical fibre composed of highly nonlinear chalcogenide Ge-Ga- Sb-S glass core and tellurite TeO2-ZnO-Li20-Bi2O3 glass clad. We aimed at obtaining more flattened chromatic dispersion for pumping chalcogenide glass based optical fibre by a pulse laser at current telecommunication wavelengths, i.e. λ = 1.35 - 1.7 μm, which is difficult to achieve by using a single material chalcogenide fibers due to their high refractive index (n > 2.1). A fibre design exploiting a composite of two glasses and one ring of the air holes brings similar options for tuning the fibre dispersion such as use of complex multi rings of air-holes approach. A good choice of glasses, allows for fabricating a composite chalcogenide-tellurite optical fibre benefiting from high nonlinearity of chalcogenide core glass but exploiting a tellurite glass technology and fibre drawing. In the paper, we discuss some aspects of CMOF design concerning current chalcogenide and tellurite glass choice. Also, we show the supercontinuum spectra recorded from current chalcogenide-tellurite CMOF pumped with a custom made femtosecond fibre laser at λ = 1.55 μm with the pulse duration of 400 fs.

  15. Erbium-doped aluminophosphosilicate optical fibres

    SciTech Connect

    Likhachev, M E; Bubnov, M M; Zotov, K V; Medvedkov, O I; Lipatov, D S; Yashkov, M V; Gur'yanov, Aleksei N

    2010-09-10

    We have studied the active properties of erbium-doped aluminophosphosilicate (APS) core fibres in wide ranges of erbia, alumina and phosphorus pentoxide concentrations. The absorption and luminescence spectra of the P{sub 2}O{sub 5}- or Al{sub 2}O{sub 3}-enriched erbium-doped APS fibres are shown to be similar to those of the erbium-doped fibres singly doped with phosphorus pentoxide or alumina, respectively. The formation of AlPO{sub 4} in APS fibres leads not only to a reduction in the refractive index of the glass but also to a marked increase in Er{sub 2}O{sub 3} solubility in silica. (optical fibres)

  16. A high-energy fibre-to-fibre connection for direct optical initiation systems

    NASA Astrophysics Data System (ADS)

    Bowden, M. D.; Knowles, S. L.

    2012-11-01

    Direct Optical Initiation (DOI), uses a moderate energy laser to shock initiate secondary explosives, via either a flyer plate or exploding metal foil. DOI offers significant performance and safety advantages over conventional electrical initiation. Optical fibres are used to transport the optical energy from the laser to the explosive device. A DOI system comprises of a laser, one or more optical fibres, and one or more laser detonators. Realisation of a DOI system is greatly eased by the use of fibre-to-fibre connections, allowing for easy integration into bulkheads or other interfaces, such as firing tanks and environmental test chambers. Fibres to fibre connectors capable of transmitting the required energy densities are not commercially available. Energy densities in the region of 35 J cm-2 are required for initiation, above the damage threshold of typical optical fibres. Laser-induced damage is typically caused by laser absorption at the input face due to imperfections in the surface polishing. To successfully transmit energy densities for DOI, a high quality fibre end face finish is required. A fibre-to-fibre connection utilizing micro-lens array injection into a large-core, tapered optical fibre, a hermetic fibre bulkhead feedthrough, and a disposable test fibre has been developed. This permits easy connection of test detonators or components, with the complex free-space to fibre injection simplified to a single operation. The damage threshold and transmission losses of the fibre-to-fibre connection have been established for each interface.

  17. Vortex shedding fluid flowmeter using optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Lyle, J. H.; Pitt, C. W.

    1981-03-01

    An optical fibre flowmeter is described which uses a single fibre mounted transversely to the fluid flow within the pipe. The fibre is vibrated by the natural phenomenon of vortex shedding, causing phase modulation of the optical carrier within. The modulation is detected at the fibre exit by the fibredyne technique, and the flow rate determined from the vibration frequency.

  18. EDITORIAL: Optical Fibre Sensors 17 (OFS-17)

    NASA Astrophysics Data System (ADS)

    Tatam, Ralph P.; Jones, Julian D. C.

    2006-05-01

    This special issue of Measurement Science and Technology provides an overview of current developments in the field of optical fibre sensors. The papers presented here are more detailed versions of those presented at the 17th Optical Fibre Sensors conference (OFS-17) held at the Oud St-Jan Art and Congress Centre in Bruges, Belgium, from 23 27 May 2005. The first OFS conference was held in London in 1983 and the conference series is now held in international locations every 18 months and is the recognized venue for presentations of papers describing recent developments in the field of fibre optic sensing. The conference in Bruges was the largest to date of the OFS series with approximately 450 attendees and consisted of a plenary talk, describing photonic crystal gas sensors, ten invited contributions, 51 oral presentations and 197 posters. A third of the papers in this special issue are concerned with fibre Bragg and long period gratings, reflecting the widespread interest in this technology. Papers describe new laser based fabrication and processing techniques, signal processing methods, and applications to the measurement of physical parameters such as radiation detection, hydrogen sensing, load monitoring in wind turbines and stress measurement for geotechnical applications. Other non-grating sensing methodologies are presented for the measurement of gases, refractive index, colour and electric field/voltage. In addition to the descriptions of optical fibres sensors and signal processing schemes there are a number of contributions describing developments in enabling technologies such as sources for use with fibre sensors including, for example, quantum dots for temperature sensing. Developments in emerging technologies such as nanostructured fibres for sensing and investigating the sensing properties of carbon nanotubes using fibre sensor techniques are described along with the use of coherent imaging fibre bundles for flow measurement applications. We hope that

  19. Complex geometrical optics of nonlinear inhomogeneous fibres

    NASA Astrophysics Data System (ADS)

    Berczynski, Pawel

    2011-03-01

    This paper analyses the Gaussian beam (GB) evolution in nonlinear fibres with special attention given to the influence of the initial curvature of the wavefront and to the fibres' permittivity profile. The analysis is performed in the framework of paraxial complex geometrical optics (PCGO). This method reduces the problem of GB evolution in nonlinear and inhomogeneous media to the solution of ordinary differential equations, which can be easily solved either analytically or numerically. It is shown that the PCGO approach radically simplifies modelling of nonlinear phenomena in fibres as compared with standard methods of nonlinear optics such as the variational method approach and the method of moments. It is shown that the PCGO method readily supplies the solution of the nonlinear Schrödinger equation (NLS) for a self-focusing fibre with a focusing permittivity profile and provides a number of new results. The discussion on the interplay between the nonlinear (self-focusing and self-defocusing) and linear (focusing and defocusing) components of the total permittivity demonstrates the new possibilities to limit the collapse phenomenon in nonlinear fibres of Kerr type taking into account the effect of initial beam divergence.

  20. Fibre optic grating sensors for biofuels

    NASA Astrophysics Data System (ADS)

    Muller, M.; Fabris, J. L.; Kalinowski, H. J.

    2010-09-01

    Biofuels will have more intense impact on the energetic grid of the planet, because known fossil fuels reserves are being exhausted. The biofuel production relies on the transformation process of some organic material in the desired hydrocarbon product. Because of the natural characteristics of the related processes, fibre optic sensors appear to be adequate candidates to be used.

  1. EDITORIAL: Optical Fibre Sensors 18 (OFS-18)

    NASA Astrophysics Data System (ADS)

    Jones, Julian D. C.; Tatam, Ralph P.

    2007-10-01

    The International Conference on Optical Fibre Sensors (OFS-18) was held in October 2006 in Cancún, Mexico, under the general chairmanship of Dr Alexis Mendez (MCH Engineering LLC, USA) and Dr Fernando Mendoza (Centro de Investigaciones en Optica, Mexico). 'OFS', as it has become known, is firmly established as the leading international conference for the optical fibre sensor community. Since its inception, in London in 1983, and under the leadership of an international steering committee independent of any learned society or professional institution, it has been held approximately every eighteen months. The venue nominally rotates from Europe, to the Americas, and thence to Asia and the Pacific. OFS-18 demonstrated the continuing vigour of the community, with some 250 papers presented, plus two workshops, with attendance as international as ever. In recent years, it has become a tradition to publish a post-conference special issue in the journal Measurement Science and Technology, and these special issues offer a representative sample of the current status of the field. In the nearly 25 years since OFS began, many of the early ideas and laboratory-based proof-of-principle experiments have led to highly developed instrumentation systems, and to successful commercial products. Perhaps the most mature of all of these technologies is the optical fibre gyroscope, with the fibre hydrophone a close second—originally developed for defence applications for which it is now established, but with increasing relevance to the oil and gas industry; electromagnetic sensors based on the Faraday and electro-optic effects are of growing significance in the power generation and distribution industry; whilst in-fibre grating-based sensors occupy an expanding niche in structural monitoring, especially in civil engineering. It is therefore appropriate that the first day of OFS was devoted to workshops on structural health monitoring, and to commemorate the 30th anniversary of the

  2. Spun microstructured optical fibres for Faraday effect current sensors

    SciTech Connect

    Chamorovsky, Yury K; Starostin, Nikolay I; Morshnev, Sergey K; Gubin, Vladimir P; Ryabko, Maksim V; Sazonov, Aleksandr I; Vorob'ev, Igor' L

    2009-11-30

    We report a simple design of spun holey fibres and the first experimental study of the magneto-optical response of spun microstructured fibres with high built-in birefringence. Such fibres enable the Faraday-effect-induced phase shift to effectively accumulate in a magnetic field even at very small coiling diameters. For example, the magneto-optical sensitivity of a 5-mm-diameter fibre coil consisting of 100 turns is {approx}70% that of an ideal fibre, in good agreement with theoretical predictions. (optical fibres and fibreoptic sensors)

  3. Fibre optic distributed differential displacement sensor

    NASA Astrophysics Data System (ADS)

    Wylie, Michael T. V.; Brown, Anthony W.; Colpitts, Bruce G.

    2011-05-01

    A Fibre Optic Distributed Differential Displacement Sensor is modelled and experimentally verified to determine shape. Created using a steel tape, 9/125 μm single mode fibre, and adhesive, the FODDDS can be used to determine shape or displacement of any object to which it is bonded. A circular shape is examined, and a radius of curvature comparison yields an error of 2%. The sensitivity of the FODDDS, for the substrate thickness used in this experiment, is shown to be 1.27 mm between adjacent data points, which corresponds to a radius of curvature of 103 m.

  4. Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

    NASA Astrophysics Data System (ADS)

    Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'Skii, Valery; Nori, Franco; Katori, Hidetoshi

    2014-06-01

    Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom-atom and atom-wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom-atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0-3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time.

  5. Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

    PubMed Central

    Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'skii, Valery; Nori, Franco; Katori, Hidetoshi

    2014-01-01

    Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom–atom and atom–wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom–atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0−3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time. PMID:24934478

  6. Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre.

    PubMed

    Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'skii, Valery; Nori, Franco; Katori, Hidetoshi

    2014-01-01

    Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom-atom and atom-wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom-atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the (1)S0-(3)P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time. PMID:24934478

  7. Photosensitivity of optical fibres doped with different impurities

    SciTech Connect

    Larionov, Yu V; Rybaltovsky, A A; Semenov, S L; Vartapetov, Sergei K; Kurzanov, M A; Obidin, Aleksei Z

    2004-02-28

    Photosensitivities of hydrogen-loaded silica fibres doped with germanium, phosphorus, antimony, and aluminium are estimated and compared. It is shown that although all the fibres can be pre-exposed, the degree of this effect is noticeably different for different fibres because the induction of the refractive index is determined by a combined contribution from a one-step photochemical reaction and a two-step reaction responsible for pre-exposure. One-step reactions dominate in more photosensitive optical fibres, while two-step reactions dominate in less photosensitive fibres. (optical fibres)

  8. Novel ultrahigh resolution optical fibre temperature sensor

    NASA Astrophysics Data System (ADS)

    Poeggel, Sven; Duraibabu, Dineshbabu; Dooly, Gerard; Lewis, Elfed; Leen, Gabriel

    2016-05-01

    In this paper a novel patent pending high resolution optical fibre temperature sensor, based on an optical fibre pressure and temperature sensor (OFTPS), which is surrounded by an oil filled chamber, is presented. The OFPTS is based on a Fabry Perot interferometer (FPI) which has an embedded fibre Bragg grating (FBG). The high ratio between the volume of the oil filled outer cavity and the FPIs air filled cavity, results in a highly sensitive temperature sensor. The FBG element of the device can be used for wide range temperature measurements, and combining this capability with the high resolution capability of the FPI/oil cavity results in a wide range and high resolution temperature sensing device. The outer diameter of the sensor is less than 1mm in diameter and can be designed to be even smaller. The sensors temperature response was measured in a range of ΔT = 7K and resulted in a shift in the optical spectrum of ΔλF = 61.42nm. Therefore the Q-point of the reflected optical FPI spectrum is shifting with a sensitivity of sot = 8.77 nm/K . The sensitivity can easily be further increased by changing the oil/air volumetric ratio and therefore adapt the sensor to a wide variety of applications.

  9. Fibre Optic Sensors for Selected Wastewater Characteristics

    PubMed Central

    Chong, Su Sin; Abdul Aziz, A. R.; Harun, Sulaiman W.

    2013-01-01

    Demand for online and real-time measurements techniques to meet environmental regulation and treatment compliance are increasing. However the conventional techniques, which involve scheduled sampling and chemical analysis can be expensive and time consuming. Therefore cheaper and faster alternatives to monitor wastewater characteristics are required as alternatives to conventional methods. This paper reviews existing conventional techniques and optical and fibre optic sensors to determine selected wastewater characteristics which are colour, Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). The review confirms that with appropriate configuration, calibration and fibre features the parameters can be determined with accuracy comparable to conventional method. With more research in this area, the potential for using FOS for online and real-time measurement of more wastewater parameters for various types of industrial effluent are promising. PMID:23881131

  10. Generation of optical frequency combs in fibres: an optical pulse analysis

    NASA Astrophysics Data System (ADS)

    Zajnulina, Marina; Böhm, Michael; Blow, Keith; Chavez Boggio, José M.; Rieznik, Andres A.; Haynes, Roger; Roth, Martin M.

    2014-07-01

    The innovation of optical frequency combs (OFCs) generated in passive mode-locked lasers has provided astronomy with unprecedented accuracy for wavelength calibration in high-resolution spectroscopy in research areas such as the discovery of exoplanets or the measurement of fundamental constants. The unique properties of OCFs, namely a highly dense spectrum of uniformly spaced emission lines of nearly equal intensity over the nominal wavelength range, is not only beneficial for high-resolution spectroscopy. Also in the low- to medium-resolution domain, the OFCs hold the promise to revolutionise the calibration techniques. Here, we present a novel method for generation of OFCs. As opposed to the mode-locked laser-based approach that can be complex, costly, and difficult to stabilise, we propose an all optical fibre-based system that is simple, compact, stable, and low-cost. Our system consists of three optical fibres where the first one is a conventional single-mode fibre, the second one is an erbium-doped fibre and the third one is a highly nonlinear low-dispersion fibre. The system is pumped by two equally intense continuous-wave (CW) lasers. To be able to control the quality and the bandwidth of the OFCs, it is crucial to understand how optical solitons arise out of the initial modulated CW field in the first fibre. Here, we numerically investigate the pulse evolution in the first fibre using the technique of the solitons radiation beat analysis. Having applied this technique, we realised that formation of higherorder solitons is supported in the low-energy region, whereas, in the high-energy region, Kuznetsov-Ma solitons appear.

  11. Fibre optic sensors for mine hazard detection

    NASA Astrophysics Data System (ADS)

    Liu, T.; Wang, C.; Wei, Y.; Zhao, Y.; Huo, D.; Shang, Y.; Wang, Z.; Ning, Y.

    2009-07-01

    We report the development of a comprehensive safety monitoring solution for coal mines. A number of fibre optic sensors have been developed and deployed for safety monitoring of mine roof integrity and hazardous gases. The FOS-based mine hazard detection system offers unique advantages of intrinsic safety, multi-location and multi-parameter monitoring. They can be potentially used to build expert systems for mine hazard early detection and prevention.

  12. The Applications Of Fibre Optics In Gas Turbine Engine Instrumentation

    NASA Astrophysics Data System (ADS)

    Davinson, Ian

    1984-08-01

    Instrumentation in Gas Turbines must operate in extremely harsh environments. Electro-optical methods are being increasingly used to measure such variables as displacement, temperature and gas flow and fibre optics are often required to enable sensitive electronic components to be placed remote from the hostile region. This paper reviews applications of fibre optics in Rolls-Royce up to the present. In addition the case for using fibre optic sensors for the measurement of other parameters in future will be presented, along with a discussion of the prospects for fibre optic data transmission on the next generation of digitally controlled engines.

  13. A Fibre Optic Sensor Of Physiological Parameters

    NASA Astrophysics Data System (ADS)

    Legendre, J. P.; Forester, G. V.

    1986-11-01

    This paper presents an ultraminiature fibre optic probe capable of physiological monitoring in situ. The system has been described previously where a fibre optic reflectometer was configured as a temperature sensor and as a refractometer. For the present experiments a bare fibre tip was used as sensing element. We show that we have been able to monitor cyclic physiological parameters such as heart and respiratory rates in various animal preparations. The probe has been used to obtain signals from the oesophagus, the lower gastro-intestinal tract, the abdominal cavity and from blood vessels (arteries and veins). The probe has also measured phasic activity coincident with mechanical activity of isolated heart muscle. The small physical size of the sensor (125 µm diameter), its flexibility and the fact that it is biologically inert are all very important characteristics for medical and biological considerations. Most recently, the probe has been used to monitor cardiac and respiratory rates while obtaining NMR spectra assessing metabolic activity. This was possible only because the probe is magnetically transparent.

  14. Fibre Optic Temperature Sensors Using Fluorescent Phenomena.

    NASA Astrophysics Data System (ADS)

    Selli, Raman Kumar

    Available from UMI in association with The British Library. A number of fibre optic sensors based on fluorescent phenomena using low cost electronic and optical filtering techniques, for temperature sensing applications are described and discussed. The initial device developed uses the absorption edge change of an optical glass to monitor changes in temperature with a second wavelength reference channel being generated from a fluorescent material, neodymium doped in glass. This device demonstrates the working of the self-referencing principle in a practical device tested over the temperature range of -60^circ C to 200^circC. This initial device was improved by incorporating a microprocessor and by modifying the processing electronic circuitry. An alternative probe was constructed which used a second fibre placed along-side the addressing fibre in contrast to the original device where the fibre is placed at the opposite end of the addressing fibre. A device based on the same principle but with different absorption glasses and a different fluorescent medium, crystalline ruby, was also examined. This device operated at a lower wavelength region compared to the infra -red working region of the first device. This work illustrated the need to make an appropriate choice of sensor absorption glass so that the cheaper indicator type LEDs, which operated at lower wavelengths, may be used. Ruby is a fluorescent material which is characterized by each emission wavelength having its own temperature characteristics. The integrated energy output over the complete emission spectrum is independent of temperature. This provided a means of generating a reference from the complete spectrum while a small frequency band gave a temperature dependent output. This characteristic of ruby was used to develop a temperature measuring device. A final system which utilises the temperature dependent decay-time emission properties of crystalline ruby was developed. In this case the ruby was

  15. Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres

    NASA Astrophysics Data System (ADS)

    Jülich, Florian; Aulbach, Laura; Wilfert, Andre; Kratzer, Peter; Kuttler, Rolf; Roths, Johannes

    2013-09-01

    Gauge factors of fibre Bragg grating (FBG)-based strain sensors that had been inscribed into three different types of optical fibres, which differ in core diameters and doping concentrations, were determined at room temperature with high accuracy. Repeated measurements were carried out with several samples of each type of fibre to allow statistical evaluations. For each type, the gauge factors were measured in two configurations: when the bare fibres were glued on a specimen at the location of the FBG and when they were vertically suspended and not bonded to any structure at the location of the FBG. By combining the results of both configurations, the strain transfer ratio of the gluing process and the strain-optic coefficient, peff, of the different types of fibres were determined. The strain-optic coefficient was found to vary up to 1.5% for the different types of optical fibres. The strain transfer ratio was obtained to be close to unity (>99%), showing the high quality of the gluing technique employed. The investigations demonstrate that highly accurate strain sensing is possible with fibre-optic strain sensors. The results are important for the development of accurate and reliable attaching techniques for coated sensor fibres and fibre-optic sensor patches.

  16. Measurement of dispersion in optical fibres with a microstructure cladding

    SciTech Connect

    Levchenko, A E; Kurkov, Andrei S; Semenov, S L

    2005-09-30

    Based on the interferometric technique, a setup is built for measuring the spectral dependence of chromatic dispersion in fibres with a microstructure cladding. The setup provides measurements in a broad spectral range from 670 to 1550 nm taking birefringence in the fibre into account. The results of measurements of dispersion in a standard fibre with this setup and a commercial device are in good agreement. (optical fibres)

  17. Spider silk: a novel optical fibre for biochemical sensing

    NASA Astrophysics Data System (ADS)

    Hey Tow, Kenny; Chow, Desmond M.; Vollrath, Fritz; Dicaire, Isabelle; Gheysens, Tom; Thévenaz, Luc

    2015-09-01

    Whilst being thoroughly used in the textile industry and biomedical sector, silk has not yet been exploited for fibre optics-based sensing although silk fibres directly obtained from spiders can guide light and have shown early promises to being sensitive to some solvents. In this communication, a pioneering optical fibre sensor based on spider silk is reported, demonstrating for the first time the use of spider silk as an optical fibre sensor to detect polar solvents such as water, ammonia and acetic acid.

  18. Nonlinear Optics and Solitons in Photonic Crystal Fibres

    NASA Astrophysics Data System (ADS)

    Skryabin, Dmitry V.; Wadsworth, William J.

    The fibre optics revolution in communication technologies followed the 1950's demonstration of the glass fibres with dielectric cladding [1]. Transmission applications of fibre optics have become a dominant modern day technology not least because nonlinearities present in - or introduced into - glass and enhanced by the tight focusing of the fibre modes allow for numerous light processing techniques, such as amplification, frequency conversion, pulse shaping, and many others. For these reasons, and because of the rich fundamental physics behind it, nonlinear fibre optics has become a blossoming discipline in its own right [1]. The 1990's witnessed another important development in fibre optics. Once again it came from a new approach to the fibre cladding, comprising a periodic pattern of air holes separated by glass membranes forming a photonic crystal structure [2, 3]. This prompted the name Photonic Crystal Fibres (PCFs). The fascinating story behind the invention of PCF and research into various fibre designs can be found, e.g., in [4]. Our aim here is to review the role played by PCFs in nonlinear and quantum optics, which is becoming the mainstream of the PCF related research and applications. Our focus will be on the areas where PCFs have brought to life effects and applications which were previously difficult, impossible to observe or simply not thought about.

  19. Optical fibre-based detection of DNA hybridization.

    PubMed

    Hine, Anna V; Chen, Xianfeng; Hughes, Marcus D; Zhou, Kaiming; Davies, Edward; Sugden, Kate; Bennion, Ian; Zhang, Lin

    2009-04-01

    A dual-peak LPFG (long-period fibre grating), inscribed in an optical fibre, has been employed to sense DNA hybridization in real time, over a 1 h period. One strand of the DNA was immobilized on the fibre, while the other was free in solution. After hybridization, the fibre was stripped and repeated detection of hybridization was achieved, so demonstrating reusability of the device. Neither strand of DNA was fluorescently or otherwise labelled. The present paper will provide an overview of our early-stage experimental data and methodology, examine the potential of fibre gratings for use as biosensors to monitor both nucleic acid and other biomolecular interactions and then give a summary of the theory and fabrication of fibre gratings from a biological standpoint. Finally, the potential of improving signal strength and possible future directions of fibre grating biosensors will be addressed. PMID:19290879

  20. Quantum cryptography on multiuser optical fibre networks

    NASA Astrophysics Data System (ADS)

    Townsend, Paul D.

    1997-01-01

    To establish a secure communication channel, it is necessary to distribute between two users a key which allows safe encryption and decryption of messages. But because decryption is a simple task for any key holder, it is crucial that the key remains secret during distribution. Secrecy cannot be guaranteed if distribution occurs on the basis of classical physical mechanisms, as it is impossible to know whether the key has been intercepted during transmission. Quantum cryptography1-3 provides a fundamental solution to this problem. When quantum-mechanical processes are used to establish the key, any eavesdropping during transmission leads to an unavoidable and detectable disturbance in the received key information. Quantum cryptography has been demonstrated using standard telecommunication fibres linking single pairs of users4-8, but practical implementations will require communication networks with many users9. Here I introduce a practical scheme for multi-user quantum cryptography, and demonstrate its operation on an optical fibre network. The scheme enables a single controller on the network to establish, and regularly update, a distinct secret key with each network user. These keys can then be used to securely encrypt conventional data transmissions that are broadcast on the network.

  1. Rare-earth doped fibre optic devices and asymmetric fibre couplers

    NASA Astrophysics Data System (ADS)

    Sanaei, Farin

    The objective of the work reported in this thesis was to improve the quality and range of rare-earth doped fibre optic devices and asymmetric fibre couplers which can be fabricated for all-optical systems. This objective has been realised by improvements to the existing fibre fabrication processes and fused tapered coupler machine and by the generation of new fabrication techniques. An improved Flash-Condensation technique for the deposition of multi-layer highly-doped cladding fibre has been developed and tested. As a result a highly Yb-doped cladding fibre has been fabricated and characterised. It has been shown that up to 7wt% phosphorous pentoxide together with up to 1.4wt% lanthanide oxide can be doped into a multi-layer cladding fibre successfully. As far as it is known, no previous work on doping a thick cladding with Yb 3+ ions has been reported. We have shown experimentally that a 94% efficient superfluorescent fibre source in the 950-1150nm range using a highly doped cladding fibre can be designed and fabricated. This is the highest superfluorescent efficiency ever reported in the literature. By taking advantage of the superfluorescence of a large Yb-cladding doped fibre, we have demonstrated a singlemode fibre laser with a linewidth of 0.3nm and a slope efficiency of 79%. This means that by using a high pump power we can achieve many watts of laser power in the fibre very easily. Again, this is the highest slope efficiency ever reported. For the purpose of making application specific couplers, we have designed and improved the equipment control system for the fabrication of fused tapered fibre devices, and have developed various procedures for making better couplers. We have also successfully fabricated and analysed asymmetric fused fibre couplers, with the highest reported asymmetric coupling of 24:1. Using eight of these low loss asymmetric couplers, a prototype passive all-optical fibre data bus was constructed and analysed. Such data buses are very

  2. Flat Ge-doped optical fibres for food irradiation dosimetry

    SciTech Connect

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-04-24

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  3. Flat Ge-doped optical fibres for food irradiation dosimetry

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-04-01

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  4. Modelling the extrusion of preforms for microstructured optical fibres

    NASA Astrophysics Data System (ADS)

    Tronnolone, Hayden; Stokes, Yvonne; Crowdy, Darren

    2013-11-01

    Owing to a novel design, microstructured optical fibres (MOFs) promise the realisation of fibres with effectively any desired optical properties. MOFs are typically constructed from glass and employ a series of air channels aligned along the fibre axis to form a waveguide. The construction of MOFs by first extruding a preform and then drawing this into the final fibre has the potential to produce fibres on an industrial scale; however, this is hindered by a limited understanding of the fluid flow that arises during this process. We focus on the extrusion stage of fabrication and discuss a model of the fibre evolution based upon complex-variable techniques. The relative influence of the various physical processes involved is discussed, along with limitations of the model.

  5. A novel wireless mobile platform integrated with optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Bochao; Yang, Shuo; Sun, Tong; Grattan, Kenneth T. V.

    2014-05-01

    This paper presents a novel design of wireless mobile platform which enables effective integration of a number of optical fibre sensors with an advanced mobile wireless sensor network (WSN) and allows for potential applications such as monitoring in remote and harsh environments and tracking, exploiting fully the advantages offered both by mobile WSN and by advanced optical fibre sensing technologies. The platform which was designed and implemented consists of an optical fibre sensor module and a smart mobile WSN module, which shows important advantages for mobile sensing and tracking and mesh networking. In this study, a fibre Bragg grating (FBG)-based temperature sensor was specially designed and integrated successfully into the optical fibre sensor module as an exemplar to investigate the performance of the integrated system based on the mobile WSN platform. The positive experimental results obtained have confirmed the functionality of the platform designed and demonstrated its capacity for real-time optical fibre sensor data monitoring, processing and wireless transmission. The successful creation of this type of wireless mobile platform with optical fibre sensors would be expected to make an important impact on many sectors, where either conventional optical sensor designs or WSNs alone cannot meet the systems requirements.

  6. Measurement of magnetic field using Rayleigh backscattering in optical fibres

    SciTech Connect

    Wuilpart, M.; Caucheteur, C.; Goussarov, A.; Aerssens, M.; Massaut, V.; Megret, P.

    2011-07-01

    In this paper, we investigate the use of optical reflectometry in optical fibres for the measurement of magnetic field. The dedicated application concerns the measurement of plasma current in the fusion reactor. The measurement is based on the rotation of the polarization state of the Rayleigh backscattered signal when an optical pulse is launched in the fibre. Particular care has been undertaken to evaluate the impact of linear birefringence on the measurement performance. (authors)

  7. REVIEW ARTICLE Blue extension of optical fibre supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Travers, J. C.

    2010-11-01

    Supercontinuum generation in optical fibres pumped with high power pulse sources in the modulation instability regime is reviewed. The physical mechanisms and supercontinuum dynamics are described in detail. Routes to optimized output in terms of spectral flatness and particularly blue and ultraviolet spectral extent are presented, including the use of cascaded and tapered photonic crystal fibres.

  8. Fibre-Bragg-grating writing in single-mode optical fibres by UV femtosecond pulses

    SciTech Connect

    Zagorul'ko, K A; Kryukov, P G; Dianov, Evgenii M; Dragomir, A; Nikogosyan, D N

    2003-08-31

    Fibre-Bragg-grating writing in single-mode optical fibres by the phase-mask method using 220-fs, 264-nm UV pulses of intensity 31 - 77 GW cm{sup -2} is reported for the first time. The achieved degree of modulation of the photoinduced refractive index was 1.9 x 10{sup -3} in an H{sub 2}-loaded SMF-28 telecommunication fibre and 1.1 x 10{sup -3} in a H{sub 2}-free Nufern GF1 fibre. The dependence of the induced refractive index on the intensity for the same irradiation fluences in the case of the H{sub 2}-loaded SMF-28 fibre shows that the refractive index is induced due to nonlinear absorption. (letters)

  9. Negative curvature fibres: exploiting the potential for novel optical sensors

    NASA Astrophysics Data System (ADS)

    Novo, C. C.; Urich, A.; Choudhury, D.; Carter, R.; Hand, D. P.; Thomson, R. R.; Yu, F.; Knight, J. C.; Brooks, S.; Mcculloch, S.; Shephard, J. D.

    2015-09-01

    One of the main challenges for fibre optic based sensing is robust operation in the mid-infrared (mid-IR) region. This is of major interest because this wavelength region is where the characteristic absorption spectra for a wide range of molecules lie. However, due to the high absorption of silica (above 2 μm), mid-IR sensors based on solid core silica fibres are not practical. Of the many alternatives to solid silica fibres, hollow core microstrutured optical fibres are being explored and show great promise. One relatively new fibre, the hollow core negative curvature fibre (NCF) is promising for novel optical devices due to the simple structure (in comparison to other microstructured fibres) in combination with a hollow core which enables low loss mid-IR infrared guidance in a silica based fibre. In this paper, an all silica NCF that is post-processed with a fs laser, in order to increase access to the hollow core, is presented with acceptable loss and significant potential for mid-IR gas sensing.

  10. Applications of optical fibres at Lublin University of Technology

    NASA Astrophysics Data System (ADS)

    Kacejko, Piotr; Wójcik, Waldemar

    2015-12-01

    The article contains a brief history and present days of research and education in application of optical fibres at Lublin University of Technology. It also presents the potential of research groups working at the University.

  11. Fibre-Optic Endoscopy In Clinical Practice

    NASA Astrophysics Data System (ADS)

    Jourdan, Martin H.

    1985-08-01

    Man's curiosity has led him to seek methods of investigating the inner workings of the human body, but it is only recently that it has become possible to properly visualise the inner cavities of the human frame. Physiologists such as William Beaumont have occasionally had the opportunity to see the function of the gastrointestinal tract, in this case the gastric fistula of Alexis St Martin who was injured following an accidental firearm explosion. Rigid instruments, down which lights are shone, can be used to visualise the respiratory passages, the gullet, the rectum, and the bladder, and in the past artists were employed to record what was seen. Such instruments are still in use, although light from a powerful source is now conducted down the instrument using a fibreoptic bundle. The first semi-flexible instrument which could be inserted into the stomach and used to visualise its walls was developed by Schindler and Wolf in Germany in 1932. The optics consisted of a series of convex-lenses, transmitting an image back to the eye, but again the view obtained was limited and since its optics were side viewing, the gullet could not be viewed. The advent of fibre-optics revolutionised the situation, and the first fibrescope conducting the image up a fibreoptic bundle was a side-viewing instrument, developed by Hirschowitz, Curtiss, Peters and Pollard by 1958, and used for viewing the stomach. Since those pioneering days, the development of fibrescopes for viewing every potential cavity in the human body has proceeded in leaps and bounds.

  12. Novel shape memory alloy optical fibre connection method

    NASA Astrophysics Data System (ADS)

    Trouillard, G.; Zivojinovic, P.; Cerutti, R.; Godmaire, X. Pruneau; Weynant, E.

    2010-02-01

    In this paper, the capacity and quality of a shape memory alloy device is demonstrated for installation and connection of 125-μm to 1000-μm optical fibres. The new mechanical splice has the particularity of using a very simple tool for aligning and holding the cladding of fibres itself without the need of glue. Optimend main characteristics are its small dimensions (few millimetres), reusability, glueless, ruggedness, low temperature variation, heat dissipation and ease of use. These properties are very suitable for many optical fibre applications where both quick and reliable connections are desirable.

  13. Smart Structures with Fibre-Optic Technologies

    SciTech Connect

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-08

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  14. Smart Structures with Fibre-Optic Technologies

    NASA Astrophysics Data System (ADS)

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-01

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  15. Fibre optics improving deepwater rov pipeline inspection

    SciTech Connect

    McGregor, D.

    1983-09-01

    Pipeline inspection is a complex test requiring a variety of sensors. The trend in recent times has been to fit, simultaneously, all of the above sensors to a vehicle in order to maximise data collection from the pipeline in a single pass. This data is then processed in real time as the ROV travels the pipeline. Thus, a chart representing all the available data can be made available shortly after completion of a dive. The current generation of ROVs uses umbilicals containing various combinations of power conductors, co-axia and twisted pairs to carry the sensor data. These umbilicals, however, have inherent disadvantages which become apparent as sensor data increase in quantity and complexity. This disadvantage is the incompatibility of required high quality-data being transmitted to the surface and the large amounts of electrical energy demanded by the vehicle. Another disadvantage is the incompatibility between sensor signals in terms of frequency and power. However, to eliminate these problems, and to provide for future developments in ROV technology, the new generation of ROVs utilise fibre-optic conductors, the advantages being that they are immune from electro-magnetic interference, they offer wider band-widths with lower power losses (typically 5 dB or less per km) than conventional copper conductors, and are easier to handle as umbilicals lengthen due to demand for vehicles to reach greater depths. Typically, these new umbilicals will be 1.5 km in length.

  16. Steady-state heating of active fibres under optical pumping

    SciTech Connect

    Gainov, V V; Shaidullin, R I; Ryabushkin, Oleg A

    2011-07-31

    We have measured the temperature in the core of rare-earth-doped optical fibres under lasing conditions at high optical pump powers using a fibre Mach - Zehnder interferometer and probe light of wavelength far away from the absorption bands of the active ions. From the observed heating kinetics of the active medium, the heat transfer coefficient on the polymer cladding - air interface has been estimated. The temperature of the active medium is shown to depend on the thermal and optical properties of the polymer cladding. (fiber and integrated optics)

  17. Use of Spun optical fibres in current sensors

    SciTech Connect

    Gubin, Vladimir P; Isaev, Victor A; Morshnev, Sergey K; Sazonov, Aleksandr I; Starostin, Nikolay I; Chamorovsky, Yury K; Oussov, Aleksey I

    2006-03-31

    The polarisation properties of a Spun optical fibre are studied in connection with their applications in fibreoptic current sensors based on the Faraday effect. A model of this fibre is proposed which represents it as an anisotropic medium with the spiral structure of the fast and slow birefringence axes. A sensor is developed based on an all-fibre low-coherence linear interferometer with a threshold sensitivity of 70 mA Hz{sup -1/2}, a maximum measured current of 3000 A, and a scale-factor reproducibility of {+-}0.6%. It is found that for a given diameter of the fibre contour, the normalised sensitivity is independent of the fibre length. The experimental results confirm the theory. (laser applications and other topics in quantum electronics)

  18. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Spun microstructured optical fibresfor Faraday effect current sensors

    NASA Astrophysics Data System (ADS)

    Chamorovsky, Yury K.; Starostin, Nikolay I.; Morshnev, Sergey K.; Gubin, Vladimir P.; Ryabko, Maksim V.; Sazonov, Aleksandr I.; Vorob'ev, Igor'L.

    2009-11-01

    We report a simple design of spun holey fibres and the first experimental study of the magneto-optical response of spun microstructured fibres with high built-in birefringence. Such fibres enable the Faraday-effect-induced phase shift to effectively accumulate in a magnetic field even at very small coiling diameters. For example, the magneto-optical sensitivity of a 5-mm-diameter fibre coil consisting of 100 turns is ~70% that of an ideal fibre, in good agreement with theoretical predictions.

  19. Recent progress in polymer optical fibre gratings

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Carroll, K.; Webb, D. J.; Bennion, I.; Kalli, K.; Emiliyanov, G.; Bang, O.; Kjær, E.; Peng, G. D.

    2008-04-01

    We describe our recent progress in polymer fibre Bragg grating technology, including the writing of the first FBGs in TOPAS cyclic olefin copolymer, enhancements to photosensitivity brought about by dopants and studies on grating annealing.

  20. Development of fibre optic broadband sources at 1 μm region for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Trifanov, Irina; Berendt, Martin O.; Salcedo, José R.; Podoleanu, Adrian G.; Lobo Ribeiro, António B.

    2008-09-01

    Recent developments on broadband optical sources emitting at 1050 nm wavelength for medical applications, in particular optical coherence tomography (OCT), have revealed enhanced depth penetration into the choroid, reduced scattering losses and improved image performances in eyes with turbid media, when compared to the most commercial used semiconductor optical source technology at 820 nm. In this paper, we present our study of fibre optic broadband sources (BBS) at 1 micron region, based on the amplified spontaneous emission (ASE) from rare-earth doped silica fibres for the integration into OCT systems. The target specifications for this type of sources are: 1050 nm central emission wavelength, with spectral width of ~70 nm, tens of miliwatts of output power and smoothly shaped output spectra. Several combinations of rare-earth doped optical fibres integrated into different fibre optic configurations have been tested. Optical bandwidth optimization and spectral shaping using different fibre optic techniques are presented and their autocorrelation function compared.

  1. Highly birefringent low-mode-asymmetry microstructured optical fibres

    SciTech Connect

    Denisov, A N; Levchenko, A E; Semenov, S L; Dianov, Evgenii M

    2011-03-31

    A novel birefringent microstructured fibre (BMF) design is proposed, and its birefringence and dispersion characteristics are analysed using the finite element method. The results indicate that the proposed BMF design ensures high birefringence ({approx}5x10{sup -3}) at a low mode asymmetry. At a certain core ellipticity, the BMF configurations considered may have equal mode field sizes along two orthogonal axes. (fibre optics)

  2. Optical properties of active bismuth centres in silica fibres containing no other dopants

    SciTech Connect

    Bufetov, Igor' A; Semenov, S L; Vel'miskin, V V; Firstov, Sergei V; Dianov, Evgenii M; Bufetova, G A

    2010-09-10

    Optical fibre preforms and fibres with a bismuth-doped silica core containing no other dopants have been fabricated by the powder-in-tube technique. The optical loss has been measured for the first time in such fibres in a wide spectral range, from 190 to 1700 nm. We have studied the luminescence of active bismuth centres and the luminescence lifetime for some of their bands in both the preforms and the fibres drawn out from them. (optical fibres)

  3. Near infrared spectroscopy for fibre based gas detection

    NASA Astrophysics Data System (ADS)

    Stewart, George; Johnstone, Walter; Thursby, Graham; Culshaw, Brian

    2010-04-01

    Gas sensing systems based on fibre optic linked near infra red absorption cells are potentially a flexible and effective tool for monitoring accumulations of hazardous and noxious gases in enclosed areas such as tunnels and mines. Additionally the same baseline technology is readily modified to measure concentrations of hydrocarbon fuels - notably but not exclusively methane, and monitoring emissions of greenhouse gases. Furthermore the system can be readily implemented to provide intrinsically safe monitoring over extensive areas at up to ~250 points from a single interrogation unit. In this paper we review our work on fibre coupled gas sensing systems. We outline the basic principles through which repeatable and accurate self calibrating gas measurements may be realised, including the recover of detailed line shapes for non contact temperature and / or pressure measurements in addition to concentration assessments in harsh environments. We also outline our experience in using these systems in extensive networks operating under inhospitable conditions over extended periods extending to several years.

  4. REVIEW ARTICLE Fibre optic devices produced by arc discharges

    NASA Astrophysics Data System (ADS)

    Rego, G.

    2010-11-01

    We present an overview of the applications of the electric arc technique related to optical fibre technology. The use of arc discharges ranges from the well-known fibre splicing, going through the fabrication of basic devices such as fibre tapers and microspheres, to tailoring the spectra of UV-induced gratings such as in the apodization of fibre Bragg gratings and also in the fabrication of phase-shifted and sampled fibre Bragg gratings. However, in the past decade a topic more intensively investigated was probably long-period fibre gratings. Therefore, some devices based on arc-induced gratings, namely, phase-shifted and step-changed gratings and bandpass filters are discussed. We also present an electrically insulated thermocouple assembled in situ using arc discharges. This sensor is very useful in the determination of the temperature attained by the fibre during an arc discharge, this property being fundamental for the discussion of the mechanisms of formation and for the understanding of the thermal properties of arc-induced devices.

  5. Optical harmonic generation in hollow-core photonic-crystal fibres: analysis of optical losses and phase-matching conditions

    SciTech Connect

    Naumov, A N; Zheltikov, Aleksei M

    2002-02-28

    We consider hollow-core fibres with a microstructure photonic-crystal cladding, which open a unique opportunity of implementing nonlinear-optical interactions of waveguide modes with transverse sizes on the order of several microns in the gas phase. Phase-matching conditions for optical harmonic generation can be improved in higher waveguide modes of hollow-core photonic-crystal fibres by optimising parameters of the gas medium filling the fibre and characteristics of the fibre. (optical fibres)

  6. Experimental qualification by extensive evaluation of fibre optic strain sensors

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Kusche, Nadine; Schukar, Vivien G.; Münzenberger, Sven; Habel, Wolfgang R.

    2013-09-01

    Fibre optic strain sensors used in practical applications have to provide reliable measurements. Therefore, the applied sensor and the sensor systems must be validated experimentally. This can be achieved with facilities which use physically independent measurement systems in order to avoid the influences caused by the application of a reference sensor. This paper describes the testing methods of the specially developed validation facility KALFOS for the qualification and evaluation of surface-applied strain sensors. For reliable sensor results, the performance of fibre optic strain patches with and without FBG under combined thermal and mechanical loading was investigated. Additionally, the strain gauge factor of the fibre optic strain patches with FBG was determined experimentally and compared to the specified strain gauge factor. These results will be the basis for the development of guidelines and standards concerning the application of the sensors.

  7. Bismuth-doped optical fibres: A new breakthrough in near-IR lasing media

    SciTech Connect

    Dianov, Evgenii M

    2012-09-30

    Recent results demonstrate that bismuth-doped optical fibres have considerable potential as near-IR active lasing media. This paper examines bismuth-doped fibres intended for the fabrication of fibre lasers and optical amplifiers and reviews recent results on the luminescence properties of various types of bismuth-doped fibres and the performance of bismuth-doped fibre lasers and optical amplifiers for the spectral range 1150 - 1550 nm. Problems are discussed that have yet to be solved in order to improve the efficiency of the bismuth lasers and optical amplifiers. (optical fibres, lasers and amplifiers. properties and applications)

  8. A fibre optic chemical sensor for the detection of cocaine

    NASA Astrophysics Data System (ADS)

    Nguyen, T. Hien; Sun, Tong; Grattan, Kenneth T. V.; Hardwick, S. A.

    2010-09-01

    A fibre-optic chemical sensor for the detection of cocaine has been developed, based on a molecularly imprinted polymer (MIP) containing a fluorescein moiety as the signalling group. The fluorescent MIP was formed and covalently attached to the distal end of an optical fibre. The sensor exhibited an increase in fluorescence intensity in response to cocaine in the concentration range of 0 - 500 μM in aqueous acetonitrile mixtures with good reproducibility over 24 h. Selectivity for cocaine over others drugs has also been demonstrated.

  9. Luminescent properties of bismuth centres in aluminosilicate optical fibres

    SciTech Connect

    Bulatov, Lenar I; Mashinskii, Valerii M; Dvoirin, Vladislav V; Dianov, Evgenii M; Kustov, Evgenii F

    2010-02-28

    The shape and spectral position of the luminescence bands of bismuth-doped aluminosilicate glass fibres are shown to depend on excitation power and wavelength. This indicates that the red and IR luminescence bands are composed of several components. The absorption and radiative transitions involved are identified, and a diagram of energy levels and transitions is obtained for four modifications of a bismuth centre in different environments in the aluminosilicate glass network. The effect of local environment on the optical properties of the bismuth centres is examined. (optical fibres and waveguides)

  10. Polymer optical fibre sensors for endoscopic optoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Broadway, Christian; Gallego, Daniel; Woyessa, Getinet; Pospori, Andreas; Bang, Ole; Webb, David J.; Carpintero, Guillermo; Lamela, Horacio

    2015-07-01

    Opto-acoustic imaging (OAI) shows particular promise for in-vivo biomedical diagnostics. Its applications include cardiovascular, gastrointestinal and urogenital systems imaging. Opto-acoustic endoscopy (OAE) allows the imaging of body parts through cavities permitting entry. The critical parameter is the physical size of the device, allowing compatibility with current technology, while governing flexibility of the distal end of the endoscope based on the needs of the sensor. Polymer optical fibre (POF) presents a novel approach for endoscopic applications and has been positively discussed and compared in existing publications. A great advantage can be obtained for endoscopy due to a small size and array potential to provide discrete imaging speed improvements. Optical fibre exhibits numerous advantages over conventional piezo-electric transducers, such as immunity from electromagnetic interference and a higher resolution at small sizes. Furthermore, micro structured polymer optical fibres offer over 12 times the sensitivity of silica fibre. We present a polymer fibre Bragg grating ultrasound detector with a core diameter of 125 microns. We discuss the ultrasonic signals received and draw conclusions on the opportunities and challenges of applying this technology in biomedical applications.

  11. Photonic bandgap single-mode optical fibre with ytterbium-doped silica glass core

    SciTech Connect

    Egorova, O N; Semenov, S L; Vel'miskin, V V; Dianov, Evgenii M; Salganskii, M Yu; Yashkov, M V; Gur'yanov, Aleksei N

    2011-01-24

    A photonic bandgap fibre with an ytterbium-doped silica glass core is fabricated and investigated. The possibility of implementing single-mode operation of such fibres in a wide spectral range at a large (above 20 {mu}m) mode field diameter makes them promising for fibre lasers and amplifiers. To ensure a high quality of the beam emerging from the fibre, particular attention is paid to increasing the optical homogeneity of the ytterbium-doped core glass. (optical fibres)

  12. Novel technique for solar power illumination using plastic optical fibres

    NASA Astrophysics Data System (ADS)

    Munisami, J.; Kalymnios, D.

    2008-09-01

    Plastic Optical Fibres (POF) were developed almost 3 decades ago. They are mainly used for short haul data communications (up to 1 km with data rates up to 1 Gbps). Over the years, POF has found applications in many other areas including solar energy transport for illumination. In such an application, light is collected from the sun and is directed into a space which needs to be illuminated. The use of fibres and more specifically POF, in daylighting systems, started only a few years ago. Several approaches have been investigated and we have seen the development of a few commercial products. The market however, has not really taken off for these technologies simply because of their enormous price tags. It is important to note that the use of POF in these designs has been limited to the function of POF as the transmission medium only. We propose a novel solar illumination technique using POF as both the light collecting/concentrating mechanism and the transmission medium. By modifying the structure of the fibre, solar light can be directed into the fibre by using an analogous process to fibre side emission but, in the reverse. We shall report on the solar light capturing efficiency of POF as modified by several types of external imperfections introduced onto the fibre. One major advantage of our proposed approach lies in the fact that we aim to eliminate at least one of the two axes of sun tracking that is currently used in existing solar illumination systems.

  13. New optical fibres for high-capacity optical communications

    PubMed Central

    Richardson, D. J.

    2016-01-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing. PMID:26809569

  14. New optical fibres for high-capacity optical communications.

    PubMed

    Richardson, D J

    2016-03-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing. PMID:26809569

  15. Determining crystal growth kinetic parameters using optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Boerkamp, M.; Lamb, D. W.; Lye, P. G.

    2012-12-01

    The capability of an 'intrinsic exposed core optical fibre sensor' (IECOFS) as a monitoring device of scale formation has been evaluated. The IECOFS has been used to measure kinetics parameters of calcium carbonate heterogeneous crystal growth such as the activation energy, the crystal growth rate and the induction time. The IECOFS was able to evaluate crystal growth inhibition through the use of chemical inhibitors.

  16. Fibre Optics In A Multi-Star Wideband Local Network

    NASA Astrophysics Data System (ADS)

    Fox, J. R.

    1983-08-01

    Early experience has been gained with the switched-star type of network in the Fibrevision cable TV trial at Milton Keynes, and British Telecom are progressing towards a full-scale multi-star wideband local network. This paper discusses both the present and future use of fibre optics in this type of network.

  17. Pyridine Vapors Detection by an Optical Fibre Sensor

    PubMed Central

    Elosua, Cesar; Bariain, Candido; Matias, Ignacio R.; Rodriguez, Antonio; Colacio, Enriquie; Salinas-Castillo, Alfonso; Segura-Carretero, Antonio; Fernandez-Gutiérrez, Alberto

    2008-01-01

    An optical fibre sensor has been implemented towards pyridine vapors detection; to achieve this, a novel vapochromic material has been used, which, in solid state, suffers a change in colour from blue to pink-white in presence of pyridine vapours. This complex is added to a solution of PVC (Poly Vinyl Chloride), TBP (Tributylphosphate) and tetrahydrofuran (THF), forming a plasticized matrix; by dip coating technique, the sensing material is fixed onto a cleaved ended optical fibre. The fabrication process was optimized in terms of number of dips and dipping speed, evaluating the final devices by dynamic range. Employing a reflection set up, the absorbance spectra and changes in the reflected optical power of the sensors were registered to determine their response. A linear relation between optical power versus vapor concentration was obtained, with a detection limit of 1 ppm (v/v).

  18. Distributed fibre optic strain measurements on a driven pile

    NASA Astrophysics Data System (ADS)

    Woschitz, Helmut; Monsberger, Christoph; Hayden, Martin

    2016-05-01

    In civil engineering pile systems are used in unstable areas as a foundation of buildings or other structures. Among other parameters, the load capacity of the piles depends on their length. A better understanding of the mechanism of load-transfer to the soil would allow selective optimisation of the system. Thereby, the strain variations along the loaded pile are of major interest. In this paper, we report about a field trial using an optical backscatter reflectometer for distributed fibre-optic strain measurements along a driven pile. The most significant results gathered in a field trial with artificial pile loadings are presented. Calibration results show the performance of the fibre-optic system with variations in the strain-optic coefficient.

  19. Slow light with electromagnetically induced transparency in optical fibre

    NASA Astrophysics Data System (ADS)

    Muhamad Hatta, Agus; Kamli, Ali A.; Al-Hagan, Ola A.; Moiseev, Sergey A.

    2015-08-01

    Slow light with electromagnetically induced transparency (EIT) in the core of optical fibre containing three-level atoms is investigated. The guided modes are treated in the weakly guiding approximation which renders the analysis into a manageable form. The transparency window and permittivity profile of the core due to the strong pump field in the EIT scheme is calculated. For a specific permittivity profile of the core due to EIT, the propagation constant of the weak signal field and spatial shape of fundamental guided mode are calculated by solving the vector wave equation using the finite difference method. It is found that the transparency window and slow light field can be controlled via the optical fibre parameters. The reduced group velocity of slow light in this configuration is useful for many technological applications such as optical memories, effective control of single photon fields, optical buffers and delay lines.

  20. Investigation of sensing properties of microstructured polymer optical fibres

    NASA Astrophysics Data System (ADS)

    Witt, J.; Steffen, M.; Schukar, M.; Krebber, K.

    2010-04-01

    We investigated sensing properties of single mode poly methyl methacrylate (PMMA) microstructured polymer optical fibres (MPOF) with mechanically imprinted long period gratings (LPG). After preparation of the MPOF end-faces the samples were elongated with silica fibres. These samples were used to measure the influence of strain to the LPG wavelength which showed the viscoelastic nature of PMMA. We also measured the influence of temperature and humidity. The results show that MPOF LPGs are well suited for strain sensing. One MPOF LPG was stitched to a textile. Using this textile we measured a simulated respiratory motion.

  1. A suite of optical fibre sensors for structural condition monitoring

    NASA Astrophysics Data System (ADS)

    Sun, T.; Grattan, K. T. V.; Carlton, J.

    2015-05-01

    This paper is to review the research activities at City University London in the development of a range of fibre Bragg grating (FBG)-based sensors, including strain, temperature, relative humidity, vibration and acoustic sensors, with an aim to meet the increasing demands from industry for structural condition monitoring. As a result, arrays of optical fibre sensors have been instrumented into various types of structures, including concrete, limestone, marine propellers, pantograph and electrical motors, allowing for both static and dynamic monitoring and thus enhanced structural reliability and integrity.

  2. Optical turbulence and spectral condensate in long fibre lasers

    PubMed Central

    Turitsyna, E. G.; Falkovich, Gregory; El-Taher, Atalla; Shu, Xuewen; Harper, Paul; Turitsyn, Sergei K.

    2012-01-01

    We study numerically optical turbulence using the particular example of a recently created, ultra-long fibre laser. For normal fibre dispersion, we observed an intermediate state with an extremely narrow spectrum (condensate), which experiences instability and a sharp transition to a fluctuating regime with a wider spectrum. We demonstrate that the number of modes has an impact on the condensate's lifetime. The smaller the number of modes, the more resistant is the condensate to perturbations. Experimental results show a good agreement with numerical simulations. PMID:22870062

  3. Numerical modelling of multimode fibre-optic communication lines

    NASA Astrophysics Data System (ADS)

    Sidelnikov, O. S.; Sygletos, S.; Ferreira, F.; Fedoruk, M. P.

    2016-01-01

    The results of numerical modelling of nonlinear propagation of an optical signal in multimode fibres with a small differential group delay are presented. It is found that the dependence of the error vector magnitude (EVM) on the differential group delay can be reduced by increasing the number of ADC samples per symbol in the numerical implementation of the differential group delay compensation algorithm in the receiver. The possibility of using multimode fibres with a small differential group delay for data transmission in modern digital communication systems is demonstrated. It is shown that with increasing number of modes the strong coupling regime provides a lower EVM level than the weak coupling one.

  4. Effect of embedded optical fibres on the mechanical properties of cochlear electrode arrays.

    PubMed

    Carland, Emma M; Stoddart, Paul R; Cadusch, Peter J; Fallon, James B; Wade, Scott A

    2016-02-01

    Incorporating optical fibres in cochlear electrode arrays has been proposed to provide sensors to help minimise insertion trauma and also for the delivery of light in optical nerve stimulation applications. However, embedding an optical fibre into an electrode array may change its stiffness properties, which can affect the level of trauma during insertion. This report uses measurements of buckling and deflection force to compare the stiffness properties of a range of cochlear electrode arrays (Nucleus straight array, rat array, cat array and guinea pig array) with custom arrays containing an embedded optical fibre. The cladding diameters of the optical fibres tested were 125 µm, 80 µm and 50 µm. The results show that the stiffness of the optical-fibre-embedded arrays is related to the diameter of the optical fibre. Comparison with wired arrays suggests optical fibres with a diameter of 50 µm could be embedded into an electrode array without significantly changing the stiffness properties of the array. PMID:26776375

  5. Programmable logic controller optical fibre sensor interface module

    NASA Astrophysics Data System (ADS)

    Allwood, Gary; Wild, Graham; Hinckley, Steven

    2011-12-01

    Most automated industrial processes use Distributed Control Systems (DCSs) or Programmable Logic Controllers (PLCs) for automated control. PLCs tend to be more common as they have much of the functionality of DCSs, although they are generally cheaper to install and maintain. PLCs in conjunction with a human machine interface form the basis of Supervisory Control And Data Acquisition (SCADA) systems, combined with communication infrastructure and Remote Terminal Units (RTUs). RTU's basically convert different sensor measurands in to digital data that is sent back to the PLC or supervisory system. Optical fibre sensors are becoming more common in industrial processes because of their many advantageous properties. Being small, lightweight, highly sensitive, and immune to electromagnetic interference, means they are an ideal solution for a variety of diverse sensing applications. Here, we have developed a PLC Optical Fibre Sensor Interface Module (OFSIM), in which an optical fibre is connected directly to the OFSIM located next to the PLC. The embedded fibre Bragg grating sensors, are highly sensitive and can detect a number of different measurands such as temperature, pressure and strain without the need for a power supply.

  6. FRD in optical fibres at low temperatures: investigations for Gemini's Wide-field Fibre Multi-Object Spectrograph

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. C.; de Oliveira, L. S.; Dos Santos, J. B.; Arruda, M. V.; Dos Santos, L. G. C.; Rodrigues, F.; de Castro, F. L. F.

    2011-06-01

    While there is no direct evidence for the deterioration in Focal Ratio Degradation (FRD) of optical fibres in severe temperature gradients, the fibre ends inserted into metallic containment devices such as steel ferrules can be a source of stress, and hence increased FRD at low temperatures. In such conditions, instruments using optical fibres may suffer some increase in FRD and consequent loss of system throughput when they are working in environments with significant thermal gradients, a common characteristic of ground-based observatories. In this paper we present results of experiments with optical fibres inserted in different materials as a part of our prototyping study for Gemini's Wide-field Multi-Object Spectrograph (WFMOS) project. Thermal effects and the use of new holding techniques will be discussed in the context of Integral Field Units and multi-fibres systems. In this work, we have used careful methodologies that give absolute measurements of FRD to quantify the advantages of using epoxy-based composites rather than metals as support structures for the fibre ends. This is shown to be especially important in minimizing thermally induced stresses in the fibre terminations. Not only is this important for optimizing fibre spectrograph performance but the benefits of using such materials are demonstrated in the minimization of positional variations and the avoidance of metal-to-glass delamination. Furthermore, by impregnating the composites with small zirconium oxide particles the composite materials supply their own fine polishing grit which aids significantly to the optical quality of the finished product.

  7. Monitoring of harmful gaseous emissions from land transport vehicles using a mid-infrared optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Mulrooney, Jim; Clifford, John; Fitzpatrick, Colin; Lewis, Elfed

    2006-04-01

    This paper discusses the development of an optical fibre sensor suitable for the detection of gas emissions from motor vehicles based on mid-infrared spectroscopy. Initial measurements are presented for carbon dioxide emissions from a petrol engine using low-cost mid-infrared components, and a practical detection system, which could be fitted to a vehicle, is outlined.

  8. Chirality measurements using optical fibre long period gratings fabricated in high birefringent fibre

    NASA Astrophysics Data System (ADS)

    Korposh, S.; Tatam, R. P.; James, S. W.; Lee, S.-W.

    2015-07-01

    A Long period grating (LPG) with a period of 111 μm was fabricated in the highly birefringent (Hi-Bi) optical fibre with the aim of developing a sensor for chirality measurements. The LPG sensor was exposed to different concentrations of glucose D(+) and fructose D(-) in water, which have similar structures but exhibit opposite optical rotations, i.e. chirality. The behaviour of the resonance bands of the submodes corresponding to the two orthogonal polarization states was different depending on the chirality of the compound, thus allowing discrimination between two compounds.

  9. Propagation of an optical discharge through optical fibres upon interference of modes

    SciTech Connect

    Bufetov, I A; Frolov, A A; Shubin, A V; Likhachev, M E; Lavrishchev, S V; Dianov, E M

    2008-05-31

    The propagation of an optical discharge (OD) through optical fibres upon interference of LP{sub 01} and LP{sub 02} modes is studied. Under these conditions after the OD propagation through the fibre, the formation of an axially-symmetric group sequence of voids with a spatial period equal to that of mode interference (200-500 {mu}m depending on the parameters of the fibre) is observed. The groups of voids are formed near the sections of the fibre with a minimal diameter of the intensity distribution of laser radiation. Large spaces between voids in the fibre have allowed us to measure accurately the difference {Delta}n of refractive indices of the fibre core and cladding and distribution of dopants in different cross sections of the fibre after the OD propagation. A substantial increase in {Delta}n (up to ten times) is observed. Approximately half this increase is caused by compression and densification of the fibre material after the propagation of the optical discharge. (interaction of laser radiation with matter. laser plasma)

  10. Special optical fibres and sensors for aeronautics

    NASA Astrophysics Data System (ADS)

    Lepesant, Jean-Pierre; Turpin, Marc

    1990-09-01

    The primary motivations for using fiber optics for onboard communications, flight, and engine control in aircrafts, are immunity from electromagnetic interference and lightnings, lighter weight, smaller size, and a high degree of data formatting flexibility. The present status of the optical fiber fabrication technologies is presented along with some of the applications currently accessible for optical fibers in terms of inflight communications, navigation, and physical data collection and optical power transmission. Typical values are given of the characteristics made achievable by the evolution of the technologies.

  11. Interrogation of fibre Bragg gratings through a fibre optic rotary joint on a geotechnical centrifuge

    NASA Astrophysics Data System (ADS)

    Correia, Ricardo; James, Stephen W.; Marshall, Alec; Heron, Charles; Korposh, Sergiy

    2016-05-01

    The monitoring of an array of fibre Bragg gratings (FBGs) strain sensors was performed through a single channel, single mode fibre optic rotary joint (FORJ) mounted on a geotechnical centrifuge. The array of three FBGs was attached to an aluminum plate that was anchored at the ends and placed on the model platform of the centrifuge. Acceleration forces of up to 50g were applied and the reflection signal of the monitored FBGs recorded dynamically using a 2.5kHz FBG interrogator placed outside the centrifuge. The use of a FORJ allowed the monitoring of the FBGs without submitting the FBG interrogator to the high g-forces experienced in the centrifuge.

  12. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    NASA Astrophysics Data System (ADS)

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-10-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay.

  13. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    PubMed Central

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-01-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay. PMID:26490424

  14. Fabricating optical fibre-top cantilevers for temperature sensing

    NASA Astrophysics Data System (ADS)

    Li, J.; Albri, F.; Sun, J. N.; Miliar, M. M.; Maier, R. R. J.; Hand, D. P.; MacPherson, W. N.

    2014-03-01

    In this paper, we propose techniques to fabricate micro-cantilevers onto the end of standard single mode optical fibres using a combination of picosecond laser machining and focused ion beam milling techniques and demonstrate their use as temperature sensors. Using this approach the cantilever can be pre-aligned with the core of the fibre during fabrication, therefore offering a stable and straightforward means of optically addressing the cantilever. The cantilever is designed to measure deflection over a range of 10 µm using a simple readout technique. A phase recovery algorithm is employed to reduce the interrogation error to around 2-3 nm. Finally, a temperature cycling experiment demonstrates that the cantilever could be used as a temperature sensor from room temperature to 500 °C with an average rms temperature error from 20 °C to 500 °C of ˜±1.4 °C.

  15. An Optical Fibre-Based Sensor for Respiratory Monitoring

    PubMed Central

    Krehel, Marek; Schmid, Michel; Rossi, René M.; Boesel, Luciano F.; Bona, Gian-Luca; Scherer, Lukas J.

    2014-01-01

    In this paper, a textile-based respiratory sensing system is presented. Highly flexible polymeric optical fibres (POFs) that react to applied pressure were integrated into a carrier fabric to form a wearable sensing system. After the evaluation of different optical fibres, different setups were compared. To demonstrate the feasibility of such a wearable sensor, the setup featuring the best performance was placed on the human torso, and thus it was possible to measure the respiratory rate. Furthermore, we show that such a wearable system enables to keep track of the way of breathing (diaphragmatic, upper costal and mixed) when the sensor is placed at different positions of the torso. A comparison of the results with the output of some commercial respiratory measurements devices confirmed the utility of such a monitoring device. PMID:25051033

  16. Flow-cell fibre-optic enzyme sensor for phenols

    SciTech Connect

    Papkovsky, D.B.; Ghindilis, A.L.; Kurochkin, I.N. )

    1993-07-01

    A solid-state fibre-optic luminescent oxygen sensor was used for flow-through measurements. It acts as a transducer in a new flow-cell enzyme sensor arrangement. This arrangement comprises a flow path, sample injector, microcolumn with the immobilized enzyme, oxygen membrane and fibre-optic connector joined together to form an integral unit. Laccase enzyme was used as a recognition system which provided specific oxidation of the substrates with the dissolved oxygen being monitored. The assay procedure was optimized and performance of the new system studied. The sensor was applied to the determination polyphenol content in tea, brandy, etc. (quality control test). The sensitivity to some important phenolic compounds was tested with the view of industrial wastewater control applications. 5 refs., 6 figs., 1 tab.

  17. Passive Tamper Indicating Enclosures Incorporating Embedded Optical Fibre

    SciTech Connect

    Wynn, Paul; White, Helen; Allen, Keir; Simmons, Kevin L.; Sliva, Paul; Benz, Jacob M.; Tanner, Jennifer E.

    2011-08-14

    AWE and PNNL are engaged in a technical collaboration investigating techniques to enhance continuity of knowledge over Accountable Items within a verified nuclear weapons dismantlement process. Tamper Indicating Enclosures (TIE) will likely be deployed as part of a chain of custody regime to indicate an unauthorised attempt to access an Accountable Item. This paper looks at the use of passive TIEs incorporating embedded optical fibre; concepts relating to deployment, tamper indication and unique identification will be discussed.

  18. Hazard monitoring in mines using fibre optic sensors

    NASA Astrophysics Data System (ADS)

    Liu, T.; Wang, C.; Wei, Y.; Zhao, Y.; Huo, D.; Shang, Y.; Wang, Z.; Ning, Y.

    2009-10-01

    We report the development of a comprehensive safety monitoring solution for coal mines. A number of fibre optic sensors have been developed and deployed for safety monitoring of mine roof integrity and hazardous gases. The FOS-based mine hazard detection system offers unique advantages of intrinsic safety, multi-location and multi-parameter monitoring. They can be potentially used to build expert systems for mine hazard early detection and prevention.

  19. The proposition of reflectometric fibre optic load sensor

    NASA Astrophysics Data System (ADS)

    Borecki, Michał; Bebłowska, Maria; Wrzosek, Paweł

    2006-10-01

    Fibre optic load sensor are gaining attention because of their immunity to electromagnetic and radio frequency interference, suitability for use at elevated temperatures, and intrinsically safe nature. Construction of load sensor for application in safety systems has been presented. The device consists of sensor's head and source and detector units. Designed sensor could be mounted in monitored place (e.g. under a floor) and controlled by PC unit or could be used as a portable device for a valuable object protection.

  20. Precision 3-D microscopy with intensity modulated fibre optic scanners

    NASA Astrophysics Data System (ADS)

    Olmos, P.

    2016-01-01

    Optical 3-D imagers constitute a family of precision and useful instruments, easily available on the market in a wide variety of configurations and performances. However, besides their cost they usually provide an image of the object (i.e. a more or less faithful representation of the reality) instead of a truly object's reconstruction. Depending on the detailed working principles of the equipment, this reconstruction may become a challenging task. Here a very simple yet reliable device is described; it is able to form images of opaque objects by illuminating them with an optical fibre and collecting the reflected light with another fibre. Its 3-D capability comes from the spatial filtering imposed by the fibres together with their movement (scanning) along the three directions: transversal (surface) and vertical. This unsophisticated approach allows one to model accurately the entire optical process and to perform the desired reconstruction, finding that information about the surface which is of interest: its profile and its reflectance, ultimately related to the type of material.

  1. Distributed acoustic fibre optic sensors for condition monitoring of pipelines

    NASA Astrophysics Data System (ADS)

    Hussels, Maria-Teresa; Chruscicki, Sebastian; Habib, Abdelkarim; Krebber, Katerina

    2016-05-01

    Industrial piping systems are particularly relevant to public safety and the continuous availability of infrastructure. However, condition monitoring systems based on many discrete sensors are generally not well-suited for widespread piping systems due to considerable installation effort, while use of distributed fibre-optic sensors would reduce this effort to a minimum. Specifically distributed acoustic sensing (DAS) is employed for detection of third-party threats and leaks in oil and gas pipelines in recent years and can in principle also be applied to industrial plants. Further possible detection routes amenable by DAS that could identify damage prior to emission of medium are subject of a current project at BAM, which aims at qualifying distributed fibre optic methods such as DAS as a means for spatially continuous monitoring of industrial piping systems. Here, first tests on a short pipe are presented, where optical fibres were applied directly to the surface. An artificial signal was used to define suitable parameters of the measurement system and compare different ways of applying the sensor.

  2. Modified sensing element of a fibre-optic current sensor based on a low-eigenellipticity spun fibre

    SciTech Connect

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P

    2014-10-31

    We have proposed and investigated a modified sensing element of a spun fibre current sensor for the case when the beat length of the built-in linear birefringence of the fibre is equal to or less than the spin pitch of its helical structure. The proposed configuration makes it possible to restore the interferometer contrast reduced because of the decrease in the ellipticity of the wavelength-averaged polarisation state of radiation propagating in such spun fibre. The modified sensing element contains two polarisation state converters: one, located at the spun fibre input, produces polarisation with ellipticity equal to the eigenellipticity of the fibre, and the other ensures conversion of the elliptical polarisation to an orthogonal one through mirror reflection at the fibre output. We have also demonstrated that the magneto-optical sensitivity decreases slightly for the analysed spectrum-averaged parameters of the polarisation state of radiation in the spun fibre. Experimental data lend support to the theoretical predictions. (fibre-optic sensors)

  3. Laser-generated ultrasound with optical fibres using functionalised carbon nanotube composite coatings

    NASA Astrophysics Data System (ADS)

    Colchester, Richard J.; Mosse, Charles A.; Bhachu, Davinder S.; Bear, Joseph C.; Carmalt, Claire J.; Parkin, Ivan P.; Treeby, Bradley E.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2014-04-01

    Optical ultrasound transducers were created by coating optical fibres with a composite of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). Dissolution of CNTs in PDMS to create the composite was facilitated by functionalisation with oleylamine. Composite surfaces were applied to optical fibres using dip coating. Under pulsed laser excitation, ultrasound pressures of 3.6 MPa and 4.5 MPa at the coated end faces were achieved with optical fibre core diameters of 105 and 200 μm, respectively. The results indicate that CNT-PDMS composite coatings on optical fibres could be viable alternatives to electrical ultrasound transducers in miniature ultrasound imaging probes.

  4. Plastic optical fibre sensor for quality control in food industry

    NASA Astrophysics Data System (ADS)

    Novo, C.; Bilro, L.; Ferreira, R.; Alberto, N.; Antunes, P.; Leitão, C.; Nogueira, R.; Pinto, J. L.

    2013-05-01

    The present work addresses the need for new devices felt in the context of quality control, especially in the food industry. Due to the spectral dependence of the attenuation coefficient, a novel dual-parameter sensor for colour and refractive index was developed and tested. The sensor employs plastic optical fibres to measure the transmitted optical power in three measurement cells each with a different incident wavelength. The performance of the sensor was tested using several dyes at different concentrations and aqueous solutions of glycerine and ethanol. Results show that this technique allows the monitoring of refractive index and colour without cross-sensitivity.

  5. Fibre optic system for biochemical and microbiological sensing

    NASA Astrophysics Data System (ADS)

    Penwill, L. A.; Slater, J. H.; Hayes, N. W.; Tremlett, C. J.

    2007-07-01

    This poster will discuss state-of-the-art fibre optic sensors based on evanescent wave technology emphasising chemophotonic sensors for biochemical reactions and microbe detection. Devices based on antibody specificity and unique DNA sequences will be described. The development of simple sensor devices with disposable single use sensor probes will be illustrated with a view to providing cost effective field based or point of care analysis of major themes such as hospital acquired infections or bioterrorism events. This presentation will discuss the nature and detection thresholds required, the optical detection techniques investigated, results of sensor trials and the potential for wider commercial application.

  6. Manufacturing implications of fibre optic systems

    NASA Astrophysics Data System (ADS)

    Roy, S. D.; Gardiner, P. T.

    1982-08-01

    It is pointed out that fiber optic data transmission offers powerful advantages over conventional copper based links. These advantages are related to increased bandwidth, smaller diameter, lower weight, elimination of crosstalk, and complete immunity to electromagnetic interference. A major difficulty concerning the introduction of fiber optic systems has been related to the lack of properly developed manufacturing and repair techniques to produce systems which have an adequate performance compatible with operation in the airborne environment. An experimental manufacturing program was, therefore, initiated to assess the performance of operation, tooling systems, and airborne system performance. On the basis of the results of the investigations, it is concluded that a complete set of components exist, albeit in the prototype state to enable a range of applications. The system performance obtainable is adequate for many interconnection applications.

  7. Gaseous hydrogen leakage optical fibre detection system

    NASA Astrophysics Data System (ADS)

    Trouillet, Alain; Veillas, Colette; Sigronde, E.; Gagnaire, Henri; Clement, Michel

    2004-06-01

    Liquid hydrogen has been intensively used in aerospace applications during the past forty years and is of great interest for fuel cells technologies and future automotive applications. Following upon major explosive risks due to the use of hydrogen in air, previous studies were carried out in our laboratory in order to develop optical fiber sensors for the detection of hydrogen leakage. This communication is aimed towards a prototype optical fiber system designed for the detection of gaseous hydrogen leakage near the conecting flanges of the liquid hydrogen pipes on the test bench of the engine Vulcain of the rocket ARIANE V. Depending on the configuration, the prototype sensor provides a two-level alarm signal and the detection of gaseous hydrogen leakage is possible for concentrations lower than the lower explosive limit in air (between 0.1 and 4%) with alarm response times lower than 10 seconds in a wide range of temperatures between -35°C and 300°C. The sensing principle based on palladium-hydrogen interaction is presented as well as the detection system composed of an optical fiber probe and an optoelectronic device.

  8. The polymer converter for effectively connecting polymer with silica optical fibres

    NASA Astrophysics Data System (ADS)

    Pura-Pawlikowska, P.; Dudek, M.; Wonko, R.; Marć, P.; Kujawińska, M.; Jaroszewicz, L. R.

    2016-09-01

    We present a micrometer-size polymer converter (microbridge) for connecting polymer optical fibres with silica fibres. The procedure of preparing such microstructure is based on a process of photopolymerization. A polymer converter grows as an extension of the fibres' cores due to a self-guiding effect of the light beam in a photopolymerizable medium. Since the polymer microbridge has refractive index greater inside than outside, such a structure works as a waveguide leading the light beam between connected optical fibres. By selection of time of light exposition to the mixture and optical power of the incident light beam, it is possible to obtain a polymer converter with very good optical and mechanical characteristics. Possibility of using polymer microbridges grown directly from the fibres' core as coupling elements between silica and polymer fibres is a good alternative for obtaining permanent coupling of such fibres.

  9. Optical frequency comb spectroscopy.

    PubMed

    Foltynowicz, A; Masłowski, P; Ban, T; Adler, F; Cossel, K C; Briles, T C; Ye, J

    2011-01-01

    Optical frequency combs offer enormous potential in the detection and control of atoms and molecules by combining their vast spectral coverage with the extremely high spectral resolution of each individual comb component. Sensitive and multiplexed trace gas detection via cavity-enhanced direct frequency comb spectroscopy has been demonstrated for various molecules and applications; however, previous demonstrations have been confined to the visible and near-infrared wavelength range. Future spectroscopic capabilities are created by developing comb sources and spectrometers for the deep ultraviolet and mid-infrared spectral regions. Here we present a broadband high resolution mid-infrared frequency comb-based Fourier transform spectrometer operating in the important molecular fingerprint spectral region of 2100-3600 cm(-1) (2.8-4.8 microm). The spectrometer, employing a multipass cell, allows simultaneous acquisition of broadband, high resolution spectra (down to 0.0035 cm(-1) of many molecular species at concentrations in the part-per-billion range in less than 1 min acquisition time. The system enables precise measurements of concentration even in gas mixtures that exhibit continuous absorption bands. The current sensitivity, 2 x 10(-8) cm(-1) Hz-1/2 per spectral element, is expected to improve by two orders of magnitude with an external enhancement cavity. We have demonstrated this sensitivity increase by combining cavity-enhanced frequency comb spectroscopy with a scanning Fourier transform spectrometer in the near-infrared region and achieving a sensitivity of 4.7 x 10(-10) cm(-1) Hz(-1/2). A cavity-enhanced mid-infrared comb spectrometer will provide a near real-time, high sensitivity, high resolution, precisely frequency calibrated, broad bandwidth system for many applications. PMID:22457942

  10. Raman fibre optic approach to artwork dating

    NASA Astrophysics Data System (ADS)

    Castro, K.; Pérez-Alonso, M.; Rodríguez-Laso, M. D.; Madariaga, J. M.

    2004-10-01

    Raman micro-probe spectroscopy has been applied to the analysis of a non catalogued hand-crafted wallpaper during its restoration process. The analysis has been totally non-destructive without the necessity of taking any sample. The artwork showed a great chromatic palette having been detected the presence of calcium carbonate, Prussian blue, ultramarine blue, gypsum (CaSO 4·2H 2O), minium (Pb 3O 4), vermilion (HgS), chrome orange (CaCO 3), chrome yellow (PbCrO 4), barium sulphate and carbon black (C). From the spectroscopic analysis the date of its manufacturing has been set between 1828 and 1830, introduction of chrome yellow and orange, as well as artificial ultramarine blue, and 1840, when continuous industrial wallpapers were extensively manufactured in Europe.

  11. Optical isolators for 2-micron fibre lasers

    NASA Astrophysics Data System (ADS)

    Stevens, Gary; Legg, Thomas H.; Shardlow, Peter

    2015-02-01

    We report on the development and testing of optical isolators for use in 2-micron fiber laser systems. A variety of potential Faraday rotator materials were characterised to identify the most suitable materials for use in the 1700-2100nm wavelength range. Isolators based on the three best performing materials were then developed and packaged as fiber-in, fiber-out and fiber-in, beam-out devices. The isolators were then tested in CW, pulsed and ultrafast laser systems. The three different designs produced different performance characteristics, but all designs demonstrated isolation >25dB and insertion losses of <1.2 dB.

  12. Optical fibres based on natural biological minerals - sea sponge spicules

    SciTech Connect

    Kulchin, Yu N; Voznesenskii, S S; Galkina, A N; Mal'tseva, T L; Nagornyi, I G; Bukin, O A; Gnedenkov, S V; Kuryavyi, V G; Sinebryukhov, S L; Cherednichenko, A I; Drozdov, A L

    2008-01-31

    A complex study of spicules of glass sponges Hyalonema sieboldi and Pheronema sp. is performed. It is shown that skeletal spicules represent a bundle of composite fibres cemented with silicon dioxide, which imparts a high mechanical strength to spicules. The presence of a layered organosilicon structure at the nanometre scale in the spicule cross section gives rise to a periodic spatial modulation of the permittivity of the spicule material, which allows one to treat spicules as one-dimensional photonic crystals. Upon excitation of basal spicules by second-harmonic pulses from a Nd:YAG laser, we observed a considerable increase in the fluorescence intensity in the long-wavelength region with a maximum at 770 nm, saturation and anomalously large fluorescence lifetimes. (fibre optics)

  13. Characterization of Fibre Channel over Highly Turbulent Optical Wireless Links

    SciTech Connect

    Johnson, G W; Henderer, B D; Wilburn, J W; Ruggiero, A J

    2003-07-28

    We report on the performance characterization and issues associated with using Fibre Channel (FC) over a highly turbulent free-space optical (FSO) link. Fibre Channel is a storage area network standard that provides high throughput with low overhead. Extending FC to FSO links would simplify data transfer from existing high-bandwidth sensors such as synthetic aperture radars and hyperspectral imagers. We measured the behavior of FC protocol at 1 Gbps in the presence of synthetic link dropouts that are typical of turbulent FSO links. Results show that an average bit error rate of less than 2 x 10{sup -8} is mandatory for adequate throughput. More importantly, 10 ns dropouts at a 2 Hz rate were sufficient to cause long (25 s) timeouts in the data transfer. Although no data was lost, this behavior is likely to be objectionable for most applications. Prospects for improvements in hardware and software will be discussed.

  14. HIV detection by optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Joshi, Narahari V.; Doria, M.; Medina, Honorio

    2001-10-01

    Reliable and economical Human Immnodeficiency Virus (HIV) testing was achieved by optical absorption spectroscopy of the core of the hair in the range of 400 nm to 800 nm. In HIV+ patients, extra optical active material is deposited in the core and optical absorption spectra, recorded in polarized radiation reveal special features, which can be used for guidance, detection, monitoring and control.

  15. Nonlinear Dynamics of Stimulated Brillouin Scattering in Optical Fibres

    NASA Astrophysics Data System (ADS)

    Johnstone, Alan

    1992-09-01

    Available from UMI in association with The British Library. This thesis presents an experimental investigation of the dynamical and steady-state behaviour of stimulated Brillouin scattering (SBS) under cw pump conditions in single-mode optical fibres. Both SBS generated from the amplification of spontaneous Brillouin scattering, an SBS generator, and from the amplification of a probe signal, an SBS amplifier, were studied. For the generator without feedback, both the scattered wave and the transmitted pump were found to exhibit aperiodic behaviour under all operating conditions, fibres lengths between 25 m and 300 m were studied using a maximum pump power of 4 W, with the SBS showing approximately 100% modulation. The bandwidth of the chaotic SBS signal was found to be independent of the single-pass gain. The addition of feedback leads to the SBS and transmitted pump signals showing sustained or random bursts of quasi-periodic oscillations. The effects of varying the cavity reflectivity and also the pump power are shown. These were the first experimental reports of such behaviour (HAR90,JOH91) and were found to be in good agreement with the theoretical work carried out by Lu and Harrison (LU91a,LU91b). The output of an SBS amplifier was found to dynamically follow the applied probe signal except in some cases of high pump and very low probe values. Also investigated was the creation of phase singularities in the wavefronts of optical fibres. Only first-order screw dislocations were observed and their dependence on the number of fibre modes present was examined.

  16. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors

    PubMed Central

    Krishnamurthy, Sriram; Badcock, Rodney A.; Machavaram, Venkata R.; Fernando, Gerard F.

    2016-01-01

    Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from −600 µε (conventional processing without pre-stress) to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to “neutralising” the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E-glass composites. PMID

  17. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors.

    PubMed

    Krishnamurthy, Sriram; Badcock, Rodney A; Machavaram, Venkata R; Fernando, Gerard F

    2016-01-01

    Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from -600 µε (conventional processing without pre-stress) to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to "neutralising" the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E-glass composites. PMID

  18. Optimisation of an acoustically antiguiding structure for raising the stimulated Brillouin scattering threshold in optical fibres

    NASA Astrophysics Data System (ADS)

    Khudyakov, M. M.; Likhachev, M. E.; Bubnov, M. M.; Lipatov, D. S.; Gur'yanov, A. N.; Temyanko, V.; Nagel, J.; Peyghambarian, N.

    2016-05-01

    Optical fibres having a radially nonuniform acoustically antiguiding structure produced by codoping their core with alumina and germania have been fabricated and investigated. The influence of the shape of the antiguiding acoustic refractive index profile and fibre core diameter on the stimulated Brillouin scattering (SBS) threshold and spectrum in the fibres has been assessed. An increase in SBS threshold by 4.4 dB with respect to a germanosilicate fibre having the same mode field diameter has been demonstrated.

  19. Temperature-Insensitive Fibre-Optic Acceleration Sensor Based on Intensity-Referenced Fibre Bragg Gratings

    NASA Astrophysics Data System (ADS)

    Sun, Li-Qun; Dong, Bo; Wang, Yong-Xin; Evan, LALLY; Wang, An-Bo

    2008-10-01

    A temperature-insensitive acceleration sensor using two fibre Bragg gratings (FBGs), based on reflection spectrum intensity modulation and optical power detection, is proposed and demonstrated. A cantilever beam is used to generate acceleration-induced axial strain along two sensing gratings, which are glued on the two opposite surfaces of the beam. Because the two gratings operate within the linear spectral range of a light source, formed by a thermally-tunable extrinsic Fabry-Perot optical filter, the intensity difference of the two reflections from the gratings is proportional to the acceleration applied. This eliminates the need for sophisticated wavelength interrogation of the gratings, and it also endows the sensor with immunity to temperature variation. Compared with a commercial micromachined accelerometer, the sensor is proven to be capable of accurately detecting acceleration.

  20. Feasibility of constructing a UV fibre laser based on a nitrogen-doped silica optical fibre

    SciTech Connect

    Bufetov, Igor' A; Grekov, M V; Golant, K M; Dianov, Evgenii M; Khrapko, R R

    1998-04-30

    Nonlinear frequency conversion of neodymium laser ({lambda}= 1.06 {mu}m) radiation was observed when this radiation was injected into the core of a single-mode optical fibre made of nitrogen-doped silica. This resulted in generation of visible violet and near-ultraviolet radiation (355 - 430 nm). The conversion efficiency was up to 2 x 10{sup -4}. The observed UV radiation was the result of the following processes: generation of the third harmonic of the fundamental pump frequency, stimulated Raman scattering of the third harmonic, and generation of the third harmonics of the Raman-scattered components of the pump radiation. Lasing was also observed in the 380-430 nm wavelength range at colour centres associated with the presence of nitrogen in the silica core. (nonlinear optical phenomena and devices)

  1. Examination of cellulose textile fibres in historical objects by micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kavkler, Katja; Demšar, Andrej

    2011-02-01

    The investigation and characterisation of historical objects can be an exacting piece of work because of the small quantity of material that can be investigated and the degradation of the material and its value, which sometimes demands only non-destructive methods. In this study, as one such method, Raman spectroscopy was used to investigate the cellulose fibres of painting canvases and linings. Historical samples of fabrics were taken from different paintings and their linings from different locations in Slovenia. Raman spectra were recorded on the fibres of these historical samples. Additionally, a database of the Raman spectra of modern cellulose fibres was created and compared with the literature data. Differences in the Raman spectra of different cellulose fibres were observed, and on this basis fibres of different types were discriminated. The recorded Raman spectra of historical samples were compared with the database spectra of modern cellulose fibres. Strong luminescence effects because of the changes caused by ageing, degradation products and surface contamination caused difficulties in interpreting the Raman spectra of historical fibres. The luminescence effects were partly overcome by prolonged exposition times and previous "signal quenching" with the laser. The Raman spectra of historical cotton showed no luminescence effects, and only slight differences to the reference spectra of modern cotton fibres appeared, whereas the Raman spectra of historical flax fibres were overwhelmed with luminescence and showed changes in spectra through degradation. The research showed that by using Raman spectroscopy the identification and differentiation of different cellulose fibres and materials that accompany cellulose in the fibres are possible and that degraded and aged material can be differentiated.

  2. Modern fibre-optic coherent lidars for remote sensing

    NASA Astrophysics Data System (ADS)

    Hill, Chris

    2015-10-01

    This paper surveys some growth areas in optical sensing that exploit near-IR coherent laser sources and fibreoptic hardware from the telecoms industry. Advances in component availability and performance are promising benefits in several military and commercial applications. Previous work has emphasised Doppler wind speed measurements and wind / turbulence profiling for air safety, with recent sharp increases in numbers of lidar units sold and installed, and with wider recognition that different lidar / radar wavebands can and should complement each other. These advances are also enabling fields such as microDoppler measurement of sub-wavelength vibrations and acoustic waves, including non-lineof- sight acoustic sensing in challenging environments. To shed light on these different applications we review some fundamentals of coherent detection, measurement probe volume, and parameter estimation - starting with familiar similarities and differences between "radar" and "laser radar". The consequences of changing the operating wavelength by three or four orders of magnitude - from millimetric or centimetric radar to a typical fibre-optic lidar working near 1.5 μm - need regular review, partly because of continuing advances in telecoms technology and computing. Modern fibre-optic lidars tend to be less complicated, more reliable, and cheaper than their predecessors; and they more closely obey the textbook principles of easily adjusted and aligned Gaussian beams. The behaviours of noises and signals, and the appropriate processing strategies, are as expected different for the different wavelengths and applications. For example, the effective probe volumes are easily varied (e.g. by translating a fibre facet) through six or eight orders of magnitude; as the average number of contributing scatterers varies, from <<1 through ~1 to >>1, we should review any assumptions about "many" scatterers and Gaussian statistics. Finally, some much older but still relevant scientific

  3. Optical fibre monitoring of Madeira wine estufagem process

    NASA Astrophysics Data System (ADS)

    Novo, C.; Bilro, L.; Ferreira, R.; Alberto, N.; Antunes, P.; Nogueira, R.; Pinto, J. L.

    2013-11-01

    In this work, the study of a particular step of Madeira's winemaking process called estufagem with a plastic optical fibre sensor is presented. Madeira wine is a type of fortified wine produced in the Madeira island of Portugal. The characteristic aroma and exceptional stability of these wines result from the singular used winemaking method that consists in the estufagem where the wine is heated up to 55 °C for at least 3 months, among other steps. This heating based process can produce significant changes in wine colour, aroma and taste. By measuring the transmitted optical power through the wine in three different cells at three different wavelengths it is possible to monitor wine colour evolution during the estufagem. The plastic optical fibres offer easy non-skilled handling, ruggedness and low cost, overcoming the difficulties of the electronic and conventional systems and improving the time of the laboratory offline methods. Results show that it is possible to distinguish the different Madeira wines (from sweet to dry wines) obtained based on different wine grapes as well as the colour evolution during the diverse months of the estufagem.

  4. Pipeline leakage detection using distributed fibre optical temperature sensing

    NASA Astrophysics Data System (ADS)

    Grosswig, S.; Hurtig, E.; Luebbecke, S.; Vogel, B.

    2005-05-01

    The leakage detection system based on the distributed fibre optical temperature measurement method is an analysing method for continuous detection and localization of leakages at pipelines in the steady and unsteady operation states according to the German rules for pipelines TRbF 301/TRFL which is valid in Germany since April 2003. The leakage detection system is useable under the precondition that there is a sufficient large temperature gradient between the leakage area and the unaffected environment. This can be caused by the medium itself or through a physical effect due to the leakage, e.g. gas expansion, evaporation. It's a very sensitive method, so also creeping leakages can be detected.

  5. Optical properties of IR-emitting centres in Pb-doped silica fibres

    SciTech Connect

    Zlenko, Alexander S; Firstov, Sergei V; Ryumkin, K E; Khopin, V F; Iskhakova, L D; Semenov, S L; Bufetov, Igor' A; Dianov, Evgenii M

    2012-04-30

    The first fibre preforms with a Pb-doped silica core, free of other dopants, have been produced using chemical vapour deposition. The preforms have been used to fabricate holey optical fibres. The spectroscopic properties of the fibres have been studied in detail in the range 400 - 1700 nm: we have measured the optical loss, constructed a three-dimensional luminescence excitation - emission graph and determined the decay time for the major luminescence peaks.

  6. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors

    PubMed Central

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-01-01

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry–Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2–10 nmkPa and a resolution of better than ΔP = 10 Pa (0.1 cm H2O). A static pressure test in 38 cmH2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k=10.7 pmK, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes. PMID:26184331

  7. Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors.

    PubMed

    Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

    2015-01-01

    This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry-Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2-10 nm/kPa and a resolution of better than ΔP = 10 Pa protect (0.1 cm H2O). A static pressure test in 38 cm H2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k = 10.7 pm/K, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes. PMID:26184331

  8. Contributed Review: Distributed optical fibre dynamic strain sensing

    NASA Astrophysics Data System (ADS)

    Masoudi, Ali; Newson, Trevor P.

    2016-01-01

    Extensive research on Brillouin- and Raman-based distributed optical fibre sensors over the past two decades has resulted in the commercialization of distributed sensors capable of measuring static and quasi-static phenomena such as temperature and strain. Recently, the focus has been shifted towards developing distributed sensors for measurement of dynamic phenomena such as dynamic strain and sound waves. This article reviews the current state of the art distributed optical fibre sensors capable of quantifying dynamic vibrations. The most important aspect of Rayleigh and Brillouin scattering processes which have been used for distributed dynamic measurement are studied. The principle of the sensing techniques used to measure dynamic perturbations are analyzed followed by a case study of the most recent advances in this field. It is shown that the Rayleigh-based sensors have longer sensing range and higher frequency range, but their spatial resolution is limited to 1 m. On the other hand, the Brillouin-based sensors have shown a higher spatial resolution, but relatively lower frequency and sensing ranges.

  9. Contributed Review: Distributed optical fibre dynamic strain sensing.

    PubMed

    Masoudi, Ali; Newson, Trevor P

    2016-01-01

    Extensive research on Brillouin- and Raman-based distributed optical fibre sensors over the past two decades has resulted in the commercialization of distributed sensors capable of measuring static and quasi-static phenomena such as temperature and strain. Recently, the focus has been shifted towards developing distributed sensors for measurement of dynamic phenomena such as dynamic strain and sound waves. This article reviews the current state of the art distributed optical fibre sensors capable of quantifying dynamic vibrations. The most important aspect of Rayleigh and Brillouin scattering processes which have been used for distributed dynamic measurement are studied. The principle of the sensing techniques used to measure dynamic perturbations are analyzed followed by a case study of the most recent advances in this field. It is shown that the Rayleigh-based sensors have longer sensing range and higher frequency range, but their spatial resolution is limited to 1 m. On the other hand, the Brillouin-based sensors have shown a higher spatial resolution, but relatively lower frequency and sensing ranges. PMID:26827302

  10. Birefringence in anisotropic optical fibres studied by polarised light Brillouin reflectometry

    SciTech Connect

    Smirnov, A S; Burdin, V V; Konstantinov, Yu A; Petukhov, A S; Drozdov, I R; Kuz'minykh, Ya S; Besprozvannykh, V G

    2015-01-31

    Modal birefringence (the difference between the effective refractive indices of orthogonal polarisation modes) is one of the key parameters of anisotropic single-mode fibres, characterising their ability to preserve a linearly polarised state of input light. This parameter is commonly measured using short pieces of fibre, but such procedures are destructive and allow the birefringence to be determined only at the ends of long fibres. In this study, polarised light Brillouin reflectometry is used to assess birefringence uniformity throughout the length of an anisotropic fibre. (optical fibres)

  11. Observation of Kuznetsov-Ma soliton dynamics in optical fibre

    PubMed Central

    Kibler, B.; Fatome, J.; Finot, C.; Millot, G.; Genty, G.; Wetzel, B.; Akhmediev, N.; Dias, F.; Dudley, J. M.

    2012-01-01

    The nonlinear Schrödinger equation (NLSE) is a central model of nonlinear science, applying to hydrodynamics, plasma physics, molecular biology and optics. The NLSE admits only few elementary analytic solutions, but one in particular describing a localized soliton on a finite background is of intense current interest in the context of understanding the physics of extreme waves. However, although the first solution of this type was the Kuznetzov-Ma (KM) soliton derived in 1977, there have in fact been no quantitative experiments confirming its validity. We report here novel experiments in optical fibre that confirm the KM soliton theory, completing an important series of experiments that have now observed a complete family of soliton on background solutions to the NLSE. Our results also show that KM dynamics appear more universally than for the specific conditions originally considered, and can be interpreted as an analytic description of Fermi-Pasta-Ulam recurrence in NLSE propagation. PMID:22712052

  12. Six-channel adaptive fibre-optic interferometer

    SciTech Connect

    Romashko, R V; Bezruk, M N; Kamshilin, A A; Kulchin, Yurii N

    2012-06-30

    We have proposed and analysed a scheme for the multiplexing of orthogonal dynamic holograms in photorefractive crystals which ensures almost zero cross talk between the holographic channels upon phase demodulation. A six-channel adaptive fibre-optic interferometer was built, and the detection limit for small phase fluctuations in the channels of the interferometer was determined to be 2.1 Multiplication-Sign 10{sup -8} rad W{sup 1/2} Hz{sup -1/2}. The channel multiplexing capacity of the interferometer was estimated. The formation of 70 channels such that their optical fields completely overlap in the crystal reduces the relative detection limit in the working channel by just 10 %. We found conditions under which the maximum cross talk between the channels was within the intrinsic noise level in the channels (-47 dB).

  13. Micro-size optical fibre strain interrogation system

    NASA Astrophysics Data System (ADS)

    Mrad, Nezih; Xiao, Gaozhi; Guo, Honglei

    2008-03-01

    Within several countries, the military is undergoing significant economic pressure to extend the use of its air fleet beyond its established design life. The availability of low weight, small size, reliable and cost-effective technologies to detect and monitor incipient damage and to alert prior to catastrophic failures is critical to sustain operational effectiveness. To enable the implementation of distributed and highly multiplexed optical fiber sensors networks to aerospace platforms, the data acquisition (interrogation) system has to meet small size and low weight requirements. This paper reports on our current development of micro-sized Echelle Diffractive Gratings (EDG) based interrogation system for strain monitoring of serially multiplexed fibre Bragg grating sensors. The operation principle of the interrogator and its suitability for strain measurements is demonstrated. Static load measurements obtained using this system are compared to those acquired using a optical multi-wavelength meter and are found to have strong correlation.

  14. FIBRE OPTICS: Optical fibres based on natural biological minerals — sea sponge spicules

    NASA Astrophysics Data System (ADS)

    Kulchin, Yu N.; Bukin, O. A.; Voznesenskii, S. S.; Galkina, A. N.; Gnedenkov, S. V.; Drozdov, A. L.; Kuryavyi, V. G.; Mal'tseva, T. L.; Nagornyi, I. G.; Sinebryukhov, S. L.; Cherednichenko, A. I.

    2008-01-01

    A complex study of spicules of glass sponges Hyalonema sieboldi and Pheronema sp. is performed. It is shown that skeletal spicules represent a bundle of composite fibres cemented with silicon dioxide, which imparts a high mechanical strength to spicules. The presence of a layered organosilicon structure at the nanometre scale in the spicule cross section gives rise to a periodic spatial modulation of the permittivity of the spicule material, which allows one to treat spicules as one-dimensional photonic crystals. Upon excitation of basal spicules by second-harmonic pulses from a Nd:YAG laser, we observed a considerable increase in the fluorescence intensity in the long-wavelength region with a maximum at 770 nm, saturation and anomalously large fluorescence lifetimes.

  15. Electron irradiation response on Ge and Al-doped SiO 2 optical fibres

    NASA Astrophysics Data System (ADS)

    Yaakob, N. H.; Wagiran, H.; Hossain, I.; Ramli, A. T.; Bradley, D. A.; Hashim, S.; Ali, H.

    2011-05-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  16. Acid-etched Fabry-Perot micro-cavities in optical fibres

    NASA Astrophysics Data System (ADS)

    Machavaram, V. R.; Badcock, R. A.; Fernando, G. F.

    2007-07-01

    Significant progress has been made in recent years on the design and fabrication of optical fibre-based sensor systems for applications in structural health monitoring. Two sensor designs have tended to dominate namely, fibre Bragg gratings and extrinsic fibre Fabry-Perot sensors. However, the cost and time associated with these sensors is relatively high and as a consequence, the current paper describes a simple procedure to fabricate intrinsic fibre Fabry-Perot interferometric strain sensors. The technique involves the use of hydrofluoric acid to etch a cavity in a cleaved optical fibre. Two such etched cavities were fusion spliced to create an intrinsic fibre Fabry-Perot cavity. The feasibility of using this device for strain monitoring was demonstrated. Excellent correlation was obtained between the optical and surface-mounted electrical resistance strain gauge.

  17. Optical fibre techniques for use within tamper indicating enclosures designed for arms control verification purposes

    NASA Astrophysics Data System (ADS)

    Dyer, Thomas C.; Thompson, Alexander W. J.; Wynn, Paul; White, Helen

    2014-10-01

    Ensuring that a future nuclear arms control agreement can be verified is a complex technical challenge. Tamper Indicating Enclosures (TIEs) are likely to be deployed as part of a chain of custody regime, providing an indication of an unauthorised attempt to access an item within the agreement. This paper focuses on the assessment of optical fibre techniques for ensuring boundary control as part of a TIE design. The results of optical fibre damage, subsequent repair attempts, enclosure construction considerations and unique identification features have been evaluated for a selection of fused-silica optical fibres. This paper focuses on detecting a fibre repair attempt, presents a method for increasing repair resistance and a method for uniquely identifying an enclosure using the optical signature from the embedded optical fibre.

  18. Positioning of Embedded Optical Fibres Sensors for the Monitoring of Buckling in Stiffened Composite Panels

    NASA Astrophysics Data System (ADS)

    Riccio, A.; Di Caprio, F.; Camerlingo, F.; Scaramuzzino, F.; Gambino, B.

    2013-02-01

    A numerical/experimental study on the monitoring of the skin buckling phenomenon in stiffened composite panels by embedding optical fibres is presented in this paper. A numerical procedure has been introduced able to provide the most efficient embedded optical fibre path (with minimum length) fulfilling the grating sensors locations and directions requirements whilst satisfying specific embedding/integrity constraints for the optical fibre. The developed numerical procedure has been applied to a stiffened composite panel under compression load. The best location and direction of the grating sensors and the optimal optical fibre path for the monitoring of the skin buckling phenomenon have been found by performing respectively non-linear FEM analyses and optimization analyses. The procedure has been validated by means of an experimental testing activity on a stiffened panel instrumented with embedded optical fibres and back-to-back strain gauges which have been positioned according to the numerically estimated grating sensors locations and directions.

  19. Transmission spectra and optical losses of infiltration-modified hollow photonic-crystal fibres

    SciTech Connect

    Konorov, Stanislav O; Serebryannikov, E E; Zheltikova, D A; Mitrokhin, V P; Sidorov-Biryukov, D A; Fedotov, Andrei B; Zheltikov, Aleksei M; Kilin, Sergei Ya

    2005-09-30

    Transmission spectra and optical losses of hollow photonic-crystal fibres (PCFs) filled with liquid-phase materials are studied. For hollow PCFs with a cladding period of about 5 {mu}m and a core diameter of about 50 {mu}m, infiltration with water increases optical losses by approximately two orders of magnitude relative to the optical losses of the same PCF before infiltration. (optical fibres)

  20. Spun optical fibres: A helical structure of linear birefringence or circular birefringence?

    SciTech Connect

    Morshnev, Sergey K; Gubin, Vladimir P; Vorob'ev, I P; Starostin, I I; Sazonov, Aleksandr I; Chamorovsky, Yury K; Korotkov, N M

    2009-03-31

    An experiment has been proposed, theoretically substantiated and accomplished which has provided conclusive evidence in favour of one of two models for the behaviour of polarised light in optical fibres fabricated by spinning preforms with a high built-in linear birefringence (spun fibres): a helical structure of the built-in linear birefringence axes and circular birefringence. The experiment, carried out with a reflective fibreoptic dual-polarisation interferometer, has shown that the behaviour of polarisation states in spun fibres can be understood in terms of a helical structure of the built-in linear birefringence axes. (optical fibres)

  1. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography.

    PubMed

    Lu, Zenghai; Kasaragod, Deepa K; Matcher, Stephen J

    2011-02-21

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincaré sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP. PMID:21263175

  2. SOLITONS AND OPTICAL FIBERS: Multiwavelength pulse transmission in an optical fibre — amplifier system

    NASA Astrophysics Data System (ADS)

    Panoiu, N.-C.; Mel'nikov, I. V.; Mihalache, D.; Etrich, C.; Lederer, F.

    2002-11-01

    The structure and dynamics of solitary waves created in the interaction of multiwavelength pulses in a single-mode optical fibre with amplification, filtering, and amplitude modulation is analysed. It is shown that there is a critical wavelength separation between channels above which wavelength-division multiplexing with solitons is feasible and that this separation increases with the number of channels.

  3. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

    2011-02-01

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincaré sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  4. A novel optical fibre doped with the nano-material as InP

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Lee, Ly Guat; Zhang, Ru

    2007-11-01

    As the key of these optical devices which are widely used in the communication system, high nonlinear optical fibre will play an important role in the future optical fibre communication. With recent growth of nano-technology, researchers are hoping to obtain some kinds of optical fibre by combining the optical fibre with the nanotechnology. According to this current situation, the optical fibre doped with nano-material as InP (indium phosphide) is manufactured by using the MCVD (modified chemical vapor deposition) technology after our comprehensive consideration of many relative factors. Proved by experiments, this novel optical fibre has an excellent waveguide characteristic. After a consideration of the model of this novel optical fibre, its propagation constant β has been simulated by using the FEM (finite element method), and the graphs of presentation of magnetic field of the core are also obtained. In accordance with the results, the effective refractive index n eff = 1.401 has be calculated. Both the calculated result and the simulated graphs are matching well with the test, and this result is a step-stone bridge for future research of nonlinear parameter on this novel optical fiber.

  5. Real-time locating and speed measurement of fibre fuse using optical frequency-domain reflectometry.

    PubMed

    Jiang, Shoulin; Ma, Lin; Fan, Xinyu; Wang, Bin; He, Zuyuan

    2016-01-01

    We propose and experimentally demonstrate real-time locating and speed measurement of fibre fuse by analysing the Doppler shift of reflected light using optical frequency-domain reflectometry (OFDR). Our method can detect the start of a fibre fuse within 200 ms which is equivalent to a propagation distance of about 10 cm in standard single-mode fibre. We successfully measured instantaneous speed of propagating fibre fuses and observed their subtle fluctuation owing to the laser power instability. The resolution achieved for speed measurement in our demonstration is 1 × 10(-3) m/s. We studied the fibre fuse propagation speed dependence on the launched power in different fibres. Our method is promising for both real time fibre fuse monitoring and future studies on its propagation and termination. PMID:27146550

  6. Real-time locating and speed measurement of fibre fuse using optical frequency-domain reflectometry

    NASA Astrophysics Data System (ADS)

    Jiang, Shoulin; Ma, Lin; Fan, Xinyu; Wang, Bin; He, Zuyuan

    2016-05-01

    We propose and experimentally demonstrate real-time locating and speed measurement of fibre fuse by analysing the Doppler shift of reflected light using optical frequency-domain reflectometry (OFDR). Our method can detect the start of a fibre fuse within 200 ms which is equivalent to a propagation distance of about 10 cm in standard single-mode fibre. We successfully measured instantaneous speed of propagating fibre fuses and observed their subtle fluctuation owing to the laser power instability. The resolution achieved for speed measurement in our demonstration is 1 × 10‑3 m/s. We studied the fibre fuse propagation speed dependence on the launched power in different fibres. Our method is promising for both real time fibre fuse monitoring and future studies on its propagation and termination.

  7. Real-time locating and speed measurement of fibre fuse using optical frequency-domain reflectometry

    PubMed Central

    Jiang, Shoulin; Ma, Lin; Fan, Xinyu; Wang, Bin; He, Zuyuan

    2016-01-01

    We propose and experimentally demonstrate real-time locating and speed measurement of fibre fuse by analysing the Doppler shift of reflected light using optical frequency-domain reflectometry (OFDR). Our method can detect the start of a fibre fuse within 200 ms which is equivalent to a propagation distance of about 10 cm in standard single-mode fibre. We successfully measured instantaneous speed of propagating fibre fuses and observed their subtle fluctuation owing to the laser power instability. The resolution achieved for speed measurement in our demonstration is 1 × 10−3 m/s. We studied the fibre fuse propagation speed dependence on the launched power in different fibres. Our method is promising for both real time fibre fuse monitoring and future studies on its propagation and termination. PMID:27146550

  8. An Eight Channel Fibre Optical Spectrophotometer For Industrial Applications

    NASA Astrophysics Data System (ADS)

    Kopola, H.; Kaijansaari, R.; Myllyla, R.

    1986-08-01

    Traditional instruments for spectral reflectance measurements consist of a broadband light source, a monochromator, a photodetector, a mechanical chopper, an analysing unit and a display. This equipment enables us to perform continuous reflectance spectrum measurements of an object. In many appearance measurement applications the reflectance at particular discrete wavelengths give adequate spectral information. Then the broadband light source and the monochromator can be replaced by narrow band light sources (e.g. a LED or a laser diode), which in industrial measurements have significant advantages: the possibility of electronic chopping, electrical and mechanical reliability and efficient connectability to optical fibres. With a view to the reguirements of industrial enviroments an eight channel spectrophotometer has been constructed. The equipment is composed of eight electronically chopped LED's, two photodiode detectors, a temperature controller, a fibre optic probe, a signal conditioning electronics, a microprocessor based controlling and analysing unit, a display and a plotter interface. The wavelengths of the semiconductor sources can be chosen from a commercial selection between 480 nm ... 1500 nm. The chopping of the channels is time multiplexed and the duration of one sampling sequence is 640 μs. Samples are taken syn-chronously from the emitted light pulses with the reference detector and from the light modulated by the object under test with the measurement detector. Before every light pulse, a "dark" sample is taken from the background irradiance to be reduced from the measurement signal. The microprocessor takes care of further signal processing, computation of the parameters and displaying of the results on the 8 x 4 digit display or on plotter curve. The influence of intensity variation of the emitters is eliminated by relative measurement and the consequences of temperature changes are minimized by stabilizing the temperature of the transmitters

  9. Development of a prototype compact fibre frequency synthesiser for mobile femtosecond optical clocks

    SciTech Connect

    Pivtsov, V S; Korel', I I; Koliada, N A; Farnosov, S A; Denisov, V I; Nyushkov, B N

    2014-06-30

    A prototype compact fibre frequency synthesiser based on a femtosecond erbium fibre laser and an original hybrid highly nonlinear fibre is developed and preliminarily studied. This synthesiser will ensure an extremely low relative instability of synthesised frequencies (down to 10{sup -17}) with the use of a corresponding optical standard and will be used in mobile optical clocks. The realised frequency stabilisation principle makes the synthesiser universal and allows it to transfer the frequency stability of various types of optical standards to the synthesised radio- and optical frequencies. (extreme light fields and their applications)

  10. A distributed optical fibre dynamic strain sensor based on phase-OTDR

    NASA Astrophysics Data System (ADS)

    Masoudi, A.; Belal, M.; Newson, T. P.

    2013-08-01

    A distributed optical fibre sensor is introduced which is capable of quantifying multiple dynamic strain perturbations along 1 km of a sensing fibre simultaneously using a standard telecommunication single-mode optical fibre. The technique is based on measuring the phase between the Rayleigh scattered light from two sections of the fibre which define the gauge length. The phase is spatially determined along the entire length of the fibre with a single pulse. This allows multiple moving strain perturbation to be tracked and quantified along the entire length of the fibre. The demonstrated setup has a spatial resolution of 2 m with a frequency range of 500-5000 Hz. The minimum detectable strain perturbation of the sensor was measured to be 80 nɛ.

  11. Optical spectroscopy of novel materials

    NASA Astrophysics Data System (ADS)

    Reijnders, Anjan A.

    Optical Spectroscopy is a well-established experimental technique for the study of solids, gasses, and liquids. This thesis focuses on two broad topics related to optical spectroscopy; experimental instrumentation, and its application to novel materials. The first half of the thesis discusses the design and construction of a novel, multifunctional magneto-optical spectroscopy apparatus with exceptional repeatability. Included are the operating principles of FTIR reflectance and transmittance spectroscopy, and the optical ray-tracing design, physical design, and characterization of a custom built magneto-optical spectroscopy apparatus. The second half of the thesis discusses the experimental results of a comprehensive spectroscopic study of Topological Insulators and thermoelectric Pb0.77Sn0.23Se. Topological Insulators (TIs) are a recently discovered phase of matter in which highly conductive free carriers are found on the surface of small band-gap insulators. A challenge in TI research is the experimental isolation of conductive surface states from the bulk states, which are frequently plagued by residual conductivity due to impurities. In this work, optical spectroscopy is used to simultaneously probe the bulk and surface states to study their individual optical properties, in addition to their coupling. Using variable temperature, crystal orientation, and a broad frequency range, we identify compounds with the most resistive bulk states, and provide new insights into carrier dynamics, surface state conductance suppression as a function of temperature, and practical material optimization guidelines for application purposes. A comprehensive optical investigation of Pb0.77Sn0.23Se is also discussed. This is a promising thermoelectric, which exhibits a temperature dependent band inversion, associated with a topological phase transition. We find clear evidence for this band inversion, and find a bulk carrier lifetime dominated by electron-acoustic phonon scattering

  12. Optical spectroscopy and tooth decay

    NASA Astrophysics Data System (ADS)

    Misra, P.; De, T.; Singh, R.

    2005-11-01

    Optical spectroscopy in the ultraviolet, visible and mid-infrared spectral regions has been used to discriminate between healthy and diseased teeth of patients in the age range 15-75 years. Spectral scans of absorbance versus wavenumber and fluorescence intensity versus wavelength have been recorded and investigated for caries and periodontal disease. Such optical diagnostics can prove very useful in the early detection and treatment of tooth decay.

  13. Photothermal determination of optical coefficients of tissue phantoms using an optical fibre probe.

    PubMed

    Laufer, J G; Beard, P C; Walker, S P; Mills, T N

    2001-10-01

    The absorption and reduced scattering coefficients of turbid tissue phantoms have been determined from photothermal measurements made using an optical fibre probe. The thermal sensor was a thin polymer film positioned at the end of a multimode optical fibre. The film was illuminated by the output of a continuous-wave diode laser and formed the cavity of a low-finesse Fabry-Perot interferometer. Low energy laser pulses, launched into the fibre and passed through the film, produced an abrupt temperature rise in the target tissue, which was placed in contact with the film. The subsequent conduction of heat into the film caused a change in its optical thickness and hence the reflected intensity. The absorption and reduced scattering coefficients of gelatine tissue phantoms of known optical properties were determined from the measurements using a numerical model of photothermal signal generation and maximum a posteriori estimation. The determined optical coefficients were in good agreement with the known values. The results showed that the probe can be used for the determination of optical coefficients provided the thermal coefficients of the target tissue are known with low uncertainty. PMID:11686272

  14. Capillary optical fibre with Sm3+ doped ribbon core

    NASA Astrophysics Data System (ADS)

    Baranowska, Agata; Miluski, Piotr; Kochanowicz, Marcin; Zmojda, Jacek; Dorosz, Dominik

    2015-09-01

    The paper presents new construction of luminescent photonic sensor based on an optical fiber capillary with a side ribbon doped with Sm3+ ions. Samarium ions ensure efficient excitation at the wavelength of 405 nm and multi colour luminescence in visible spectrum (550-720 nm). This phenomenon was proposed to increase sensor accuracy by using measurements of certain wavelength. The luminescence and angular characteristics of developed optrode were characterized at the lateral and face excitation of special capillary fibre construction. Rhodamine B (RhB) was used as a test solution in designed optrode. The nearly linear characteristic of RhB concentration was obtained for up to 0.15 % (w/w). The results indicate that the designed optrode can be used for construction of compact luminescent sensor for measuring selected properties of the solutions.

  15. Photon Irradiation Response on Ge and Al-Doped SiO{sub 2} Optical Fibres

    SciTech Connect

    Yaakob, Nor Haliza; Wagiran, Husin; Ramli, Ahmad Termizi; Asni, Hazila; Ali, Hassan

    2010-07-07

    Recently, research groups have reported a number of radiation effects on the applications of SiO{sub 2} optical fibres with possible use as dosimeter material because these optical fibre provide a good basis for medical radiation dosimetry. The objective of this study is to investigate the thermoluminescence response and fading characteristic for germanium and aluminium doped SiO{sub 2} optical fibres with photon irradiation. These optical fibres are placed in solid phantom and irradiated to 6 and 10 MV photon beam at dose ranging from 0.06 Gy to 0.24 Gy using Primus MLC 3339 linear accelerator at Hospital Sultan Ismail, Johor Bahru. In fading studies, the TL measurements were continued up to 14 days period. The optical fibres will produce glow curves whereby the information is then analyzed. Al and Ge-doped optical fibres have a linear dose-TL signal relationship that is proportionality between the TL signal and the doses. Comparison for TL response between different linear accelerator showed a good agreement because these optical fibres also have a linear dose-TL signal relationship even using different equipments.

  16. Photon Irradiation Response on Ge and Al-Doped SiO2 Optical Fibres

    NASA Astrophysics Data System (ADS)

    Yaakob, Nor Haliza; Wagiran, Husin; Ramli, Ahmad Termizi; Ali, Hassan; Asni, Hazila

    2010-07-01

    Recently, research groups have reported a number of radiation effects on the applications of SiO2 optical fibres with possible use as dosimeter material because these optical fibre provide a good basis for medical radiation dosimetry. The objective of this study is to investigate the thermoluminescence response and fading characteristic for germanium and aluminium doped SiO2 optical fibres with photon irradiation. These optical fibres are placed in solid phantom and irradiated to 6 and 10 MV photon beam at dose ranging from 0.06 Gy to 0.24 Gy using Primus MLC 3339 linear accelerator at Hospital Sultan Ismail, Johor Bahru. In fading studies, the TL measurements were continued up to 14 days period. The optical fibres will produce glow curves whereby the information is then analyzed. Al and Ge-doped optical fibres have a linear dose-TL signal relationship that is proportionality between the TL signal and the doses. Comparison for TL response between different linear accelerator showed a good agreement because these optical fibres also have a linear dose-TL signal relationship even using different equipments.

  17. EDITORIAL: The 20th International Conference on Optical Fibre Sensors, OFS-20 The 20th International Conference on Optical Fibre Sensors, OFS-20

    NASA Astrophysics Data System (ADS)

    Culshaw, Brian; Ecke, Wolfgang; Jones, Julian; Tatam, Ralph; Willsch, Reinhardt

    2010-09-01

    Welcome to our special issue on fibre optic sensors. Fibre optic sensors were first suggested in the patent literature in the mid 1960s as an innovative means for making measurements. This proposed a surface finish measurement tool with high precision and resulted in an instrument that remains available today. Much has happened since, with significant innovation in the techniques through which light propagating whilst guided in a fibre can be unambiguously, repeatedly and predictably modulated in response to an external phenomenon. The technique offers not only the precision mentioned earlier but also inherent electromagnetic immunity, the capability to sense at long distances, light weight, small size and a multiplicity of network architectures, all of which can be interrogated from a single point. Even so, fibre sensors is a niche technology, attractive only when its very special features offer substantial user benefit. There are, however, many such niches exemplified in the electrical power supply industry, in gyroscopes for navigational instruments, in hydrophones and geophones. Then there are the distributed sensing architectures that enable useful measurements of pressure, strain and temperature fields affecting the optical properties of the fibre itself to map these parameter fields as a function of position along lengths of fibre to many tens of kilometres. The fibre sensing concept spawned its own research community, and the international conference on Optical Fibre Sensors first appeared in 1983 in London then emerged into a series travelling from Europe to the Americas and into the Asia-Pacific region. The 20th in the series took place in Edinburgh at the end of 2009 and this special issue of Measurement Science and Technology presents extended versions of some of the papers that first appeared at the conference. The science and technology of fibre sensing have evolved significantly over the history of the conference, drawing on developments in optical

  18. Ultra-sensitive all-fibre photothermal spectroscopy with large dynamic range.

    PubMed

    Jin, Wei; Cao, Yingchun; Yang, Fan; Ho, Hoi Lut

    2015-01-01

    Photothermal interferometry is an ultra-sensitive spectroscopic means for trace chemical detection in gas- and liquid-phase materials. Previous photothermal interferometry systems used free-space optics and have limitations in efficiency of light-matter interaction, size and optical alignment, and integration into photonic circuits. Here we exploit photothermal-induced phase change in a gas-filled hollow-core photonic bandgap fibre, and demonstrate an all-fibre acetylene gas sensor with a noise equivalent concentration of 2 p.p.b. (2.3 × 10(-9) cm(-1) in absorption coefficient) and an unprecedented dynamic range of nearly six orders of magnitude. The realization of photothermal interferometry with low-cost near infrared semiconductor lasers and fibre-based technology allows a class of optical sensors with compact size, ultra sensitivity and selectivity, applicability to harsh environment, and capability for remote and multiplexed multi-point detection and distributed sensing. PMID:25866015

  19. Ultra-sensitive all-fibre photothermal spectroscopy with large dynamic range

    PubMed Central

    Jin, Wei; Cao, Yingchun; Yang, Fan; Ho, Hoi Lut

    2015-01-01

    Photothermal interferometry is an ultra-sensitive spectroscopic means for trace chemical detection in gas- and liquid-phase materials. Previous photothermal interferometry systems used free-space optics and have limitations in efficiency of light–matter interaction, size and optical alignment, and integration into photonic circuits. Here we exploit photothermal-induced phase change in a gas-filled hollow-core photonic bandgap fibre, and demonstrate an all-fibre acetylene gas sensor with a noise equivalent concentration of 2 p.p.b. (2.3 × 10−9 cm−1 in absorption coefficient) and an unprecedented dynamic range of nearly six orders of magnitude. The realization of photothermal interferometry with low-cost near infrared semiconductor lasers and fibre-based technology allows a class of optical sensors with compact size, ultra sensitivity and selectivity, applicability to harsh environment, and capability for remote and multiplexed multi-point detection and distributed sensing. PMID:25866015

  20. Optical Fiber Spectroscopy

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.

    1999-01-01

    This is the final report of work done on NASA Grant NAG-1-443. The work covers the period from July 1, 1992 to December 1, 1998. During this period several distinct but related research studies and work tasks were undertaken. These different subjects are enumerated below with a description of the work done on each of them. The focus of the research was the development of optical fibers for use as distributed temperature and stress sensors. The initial concept was to utilize the utilize the temperature and stress dependence of emission from rare earth and transition metal ions substitutionally doped into crystalline or glass fibers. During the course of investigating this it became clear that fiber Bragg gratings provided a alternative for making the desired measurements and there was a shift of research focus on to include the photo-refractive properties of germano-silicate glasses used for most gratings and to the possibility of developing fiber laser sources for an integrated optical sensor in the research effort. During the course of this work several students from Christopher Newport University and other universities participated in this effort. Their names are listed below. Their participation was an important part of their education.

  1. Evaluating distributed fibre optic sensors integrated into thermoplastic composites for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Schukar, Marcus; Steffen, Milan; Krebber, Katerina

    2014-05-01

    Strain sensors used for structural health monitoring (SHM) must provide reliable measurement data during their entire service lifetime. To achieve this for fibre optic sensors integrated into composites, the integration of the sensor has to be adapted according to the process conditions. This paper describes the fabrication of thermoplastic composite samples with integrated distributed fibre optic sensors (DFOS) based on copper-nickel and polyimide coated silica optical fibres. The performance of these DFOS as SHM sensors is evaluated in terms of reliability by measurements derived from comparative measurements with resistance strain gauges and from fatigue tests with 10 million load cycles.

  2. Fibre-optic biosensor based on luminescence and immobilized enzymes: microdetermination of sorbitol, ethanol and oxaloacetate.

    PubMed

    Gautier, S M; Blum, L J; Coulet, P R

    1990-01-01

    We have investigated highly selective and ultrasensitive biosensors based on luminescent enzyme systems linked to optical transducers. A fibre-optic sensor with immobilized enzymes was designed; the solid-phase bioreagent was maintained in close contact contact with the tip of a glass fibre bundle connected to the photomultiplier tube of a luminometer. A bacterial luminescence fibre-optic sensor was used for the microdetermination of NADH. Various NAD(P)-dependent enzymes, sorbitol dehydrogenase, alcohol dehydrogenase and malate dehydrogenase, were co-immobilized on preactivated polyamide membranes with the bacterial system and used for the microdetermination of sorbitol, ethanol and oxaloacetate at the nanomolar level with a good precision. PMID:2316395

  3. New sensor based on fibre optics for measurement of heart movement.

    PubMed

    Hoeland, K; Kloppe, A; Hexamer, M; Nowack, G; Werner, J

    2002-09-01

    Innovative fibre-optic sensor technology for measuring the movement of the myocardial walls, and from this the heart chamber volumes, was developed. An optical fibre, with a mirror at its end, is inserted into a catheter located in the heart. An opto-electrical control unit positioned outside the heart contains both the light source and the signal receiver. It generates and couples the light into the fibre and transforms and analyses the reflected signal. With such a system, the movement of the cardiac wall can be continuously measured during each cycle, because the fibre moves synchronously with the heart, and this movement bends the fibre, changing the optical attenuation. Experiments where the fibres were wound around metal cylinders of different diameters revealed a maximum sensitivity of 4% mm(-1), diameter. The noise signal corresponded to about 1% of the diameter. First tests in a working pig heart showed a high correspondence of the fibre signal with cardiac parameters. Although these tests are promising, further long-term, extensive experiments in preclinical test devices, and later in clinical tests, must be carried out before the new sensor is used in clinical practice. The fibre-optic technique could be used in monitoring devices, assist devices, pacemaker systems or cardioverter defibrillators. PMID:12452419

  4. Weaving the invisible thread: design of an optically invisible metamaterial fibre.

    PubMed

    Tuniz, Alessandro; Kuhlmey, Boris T; Chen, Parry Y; Fleming, Simon C

    2010-08-16

    We present the design of an invisible metamaterial fibre operating at optical frequencies, which could be fabricated by adapting existing fibre drawing techniques. The invisibility is realised by matching the refractive index of the metamaterial fibre with the surroundings. We present a general recipe for the fabrication of such fibres, and numerically characterise a specific example using hexagonally arranged silver nanowires in a silica background. We find that invisibility is highly sensitive to details of the metamaterial boundary, a problem that is likely to affect most invisibility and cloaking schemes. PMID:20721197

  5. Characterisation of an electrical heating method for metallic-coated optical fibres for distributed sensing applications

    NASA Astrophysics Data System (ADS)

    Lu, Xin; Soto, Marcelo A.; Thévenaz, Luc

    2016-05-01

    In several applications a temperature contrast between the sensing fibre and the environment is required to detect changes in the environmental heat capacity. For this purpose the process of electrical heating in metallic-coated fibres is theoretically analysed and modelled in steady-state conditions based on the thermal energy generated by resistive heating and the losses induced by convection and radiation. The impact of ambient temperature and pressure is investigated. The proposed model for the thermal exchange is experimentally validated using a high-resolution Brillouin distributed fibre sensor, which is used to measure the longitudinal profile of the temperature reached by electrical heating along an Alcoated optical fibre.

  6. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Fibreoptic distributed temperature sensor with spectral filtration by directional fibre couplers

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. G.; Babin, Sergei A.; Shelemba, Ivan S.

    2009-11-01

    We demonstrate a Raman-based all-fibre temperature sensor utilising a pulsed erbium fibre laser. The sensor is made of a standard single-mode telecom fibre, SMF-28, and includes a number of directional couplers as band-pass filters. The temperature profile along a 7-km fibreoptic line is measured with an accuracy of 2oC and a spatial resolution of 10 m. In data processing, we take into account the difference in attenuation between the spectral components of the backscatter signal.

  7. Miniature fibre optic probe for minimally invasive photoacoustic sensing

    NASA Astrophysics Data System (ADS)

    Mathews, Sunish J.; Zhang, Edward Z.; Desjardins, Adrien E.; Beard, Paul C.

    2016-03-01

    A miniature (175 μm) all-optical photoacoustic probe has been developed for minimally invasive sensing and imaging applications. The probe comprises a single optical fibre which delivers the excitation light and a broadband 50 MHz Fabry-Pérot (F-P) ultrasound sensor at the distal end for detecting the photoacoustic waves. A graded index lens proximal to the F-P sensor is used to reduce beam walk-off and thus increase sensitivity as well as confine the excitation beam in order to increase lateral spatial resolution. The probe was evaluated in non-scattering media and found to provide lateral and axial resolutions of < 100 μm and < 150 μm respectively for distances up to 1 cm from the tip of the probe. The ability of the probe to detect a blood vessel mimicking phantom at distances up to 7 mm from the tip was demonstrated in order to illustrate its potential suitability for needle guidance applications.

  8. Influence of pump wavelength and core size on stimulated Brillouin scattering spectra of acoustically antiguiding optical fibres

    SciTech Connect

    Likhachev, M E; Alekseev, V V; Bubnov, M M; Yashkov, M V; Vechkanov, N N; Gur'yanov, A N; Peyhambarian, N; Temyanko, V; Nagel, J

    2014-11-30

    Optical fibres having an acoustically antiguiding structure produced by alumina doping of their core have been fabricated and investigated. The stimulated Brillouin scattering (SBS) spectra of the fibres have been measured and calculated theoretically. The results demonstrate that the shape of the SBS spectrum of the acoustically antiguiding fibres strongly depends on the pump wavelength, core size and dopant profile across the fibre. A considerable broadening of the SBS gain spectrum is only possible at certain guidance parameters of the fibre and a fixed operating wavelength. (fibre and integrated-optical structures)

  9. Fabrication and characterisation of FBG sensors in low loss polymer optical fibre

    NASA Astrophysics Data System (ADS)

    Lacraz, Amédée.; Theodosiou, Andreas; Polis, Michalis; Kalli, Kyriacos

    2016-05-01

    In this paper, we report on an effective way to locally alter the refractive index of a low-loss polymer optical fibre (POF), in order to fabricate novel fibre optical sensors. Such refractive index modifications, if reproduced periodically, create fibre Bragg gratings (FBGs) that find diverse applications in telecommunications and sensing. With a femtosecond laser set-up, we were able to inscribe refractive index changes in the core of the fibre on an area as small as a μm2. This technique can be effectively used to produce FBGs with a tailored length and strength and, so, with desired optical properties. The fibre used was a large core, graded index, multimode perfluorinated fibre. FBGs resonate at different wavelengths depending on the mode distribution in multimode fibres, because the effective refractive index depends on the spatial distribution of the light inside the core. Therefore, the reflection spectrum from the grating degenerates into multiple resonances, each associated with a different mode. The detection of the reflected modes was performed with a custom made software that was able to track a specific reflected mode even when the FBG underwent perturbation, such as temperature or strain changes. Moreover, a key advantage of low-loss fibre is the possibility to use long lengths of fibre and to be able to inscribe several FBGs in a single piece of fibre. With our detection system, we managed to track the perturbation of individual FBGs in a fibre array of multiple gratings. The combination of our femtosecond inscription setup and a mode detection system is encouraging for the development of low loss POF sensing devices.

  10. Design and performance characterization of a fibre optical sensor for liquid level monitoring

    NASA Astrophysics Data System (ADS)

    Gao, J. Z.; Zhao, Y. L.; Jiang, Z. D.

    2005-01-01

    In order to continuously monitor liquid level in petroleum and chemical industries, a fibre optical sensor based on a microbend effect was designed and manufactured. The sensor is composed of a sensing diaphragm with a hard center, a microbend modulator (a pair of tooth plates), sensing and reference fibres, adjusting bolts, a stainless steel housing, emitting/detecting devices and signal processing circuits. To reduce the effect of temperature, the diaphragm is directly machined instead of welded onto the housing. To eliminate the fluctuation of light source, a reference fibre configured in parallel with the sensing fibre is introduced. Also, the cost was lowered by using standard communication optical fibres. Test results show that this sensor is suited for applications of liquid level measurement especially in fields where electrical isolation and/or electro magnetic interference (EMI) resistance are strictly required.

  11. Nuisance alarm suppression techniques for fibre-optic intrusion detection systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Seedahmed S.; Visagathilagar, Yuvaraja; Katsifolis, Jim

    2012-02-01

    The suppression of nuisance alarms without degrading sensitivity in fibre-optic intrusion detection systems is important for maintaining acceptable performance. Signal processing algorithms that maintain the POD and minimize nuisance alarms are crucial for achieving this. A level crossings algorithm is presented for suppressing torrential rain-induced nuisance alarms in a fibre-optic fence-based perimeter intrusion detection system. Results show that rain-induced nuisance alarms can be suppressed for rainfall rates in excess of 100 mm/hr, and intrusion events can be detected simultaneously during rain periods. The use of a level crossing based detection and novel classification algorithm is also presented demonstrating the suppression of nuisance events and discrimination of nuisance and intrusion events in a buried pipeline fibre-optic intrusion detection system. The sensor employed for both types of systems is a distributed bidirectional fibre-optic Mach Zehnder interferometer.

  12. Bragg grating inscription in CYTOP polymer optical fibre using a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Lacraz, A.; Polis, M.; Theodosiou, A.; Koutsides, C.; Kalli, K.

    2015-05-01

    We report on the inscription of fibre Bragg gratings (FBGs) in CYTOP (cyclic transparent optical polymer) optical fibres. A femtosecond laser beam, operating in the visible wavelength range, is focussed into the core of the fibre for direct inscription of FBGs. The fibre is moved under the focussed beam by a nanometre-resolution air-bearing stage for maximal inscription precision. The grating plane dimensions (measured with bright field microscopy) are typically 30μm × 30μm × 1μm (line by line grating) or 10μm×1μm×1μm (point by point grating) and centred in the core of the fibre for optimal grating efficiency. The FBGs have a typical reflectivity of 70%, a bandwidth of 0.25nm and an index change of ~10-4. The FBG operate in the C-band, where CYTOP offers key advantages over poly (methyl methacrylate) optical fibres, having a significantly lower optical loss in the important near infra-red (NIR) optical communications window, with a theoretical loss of ~0.3dB/km at 1550nm. Additionally, CYTOP has a far lower affinity for water absorption and a core mode refractive index that coincides with the aqueous index regime. These properties offer several unique opportunities for polymer optical fibre sensing at NIR wavelengths, such as compatibility with existing optical networks, the potential for optical fibre sensor multiplexing and suitability for bio-sensing. We have investigated the temperature response of the grating: a linear positive shift of ~ +40pm/K has been measured with little difference between the heating and cooling response. The strain response of the FBG has also been studied with a linear shift of ~ +1.3pm/μɛ measured over a few hundreds of μɛ. We also demonstrated compatibility with a commercial Bragg grating demodulator.

  13. Air-structured optical fibre drawn from a 3D-printed preform

    NASA Astrophysics Data System (ADS)

    Cook, Kevin; Leon-Saval, Sergio; Canning, John; Reid, Zane; Hossain, Md. Arafat; Peng, Gang-Ding

    2015-09-01

    We report the first optical fibre drawn from a 3D-printed preform. An air-structured polymer preform is printed using a modified butadiene plastic called Bendlay as opposed to the more-common Acrylonitrile Butadiene Styrene (ABS). The preform is subsequently drawn to fibre form at a relatively low temperature of 160 °C and maintains its air-structured cladding holes. Such ability to freely-design and 3D-print complex preform structures, such as photonic bandgap and photonic crystal structures, opens up an exciting new front in optical fibre fabrication.

  14. Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

    NASA Astrophysics Data System (ADS)

    Woulfe, P.; Sullivan, F. J.; O'Keeffe, S.

    2016-05-01

    An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is presented, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 250μm of a 500μm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for brachytherapy, in prostate cancer treatment, providing oncologists with real-time information of the radiation dose to the target area and/or nearby critical structures. The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to Iodine-125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

  15. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    PubMed Central

    Czegledi, Cristian B.; Karlsson, Magnus; Agrell, Erik; Johannisson, Pontus

    2016-01-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincaré sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue. PMID:26905596

  16. Raman-Enhanced Phase-Sensitive Fibre Optical Parametric Amplifier

    NASA Astrophysics Data System (ADS)

    Fu, Xuelei; Guo, Xiaojie; Shu, Chester

    2016-02-01

    Phase-sensitive amplification is of great research interest owing to its potential in noiseless amplification. One key feature in a phase-sensitive amplifier is the gain extinction ratio defined as the ratio of the maximum to the minimum gains. It quantifies the capability of the amplifier in performing low-noise amplification for high phase-sensitive gain. Considering a phase-sensitive fibre optical parametric amplifier for linear amplification, the gain extinction ratio increases with the phase-insensitive parametric gain achieved from the same pump. In this work, we use backward Raman amplification to increase the phase-insensitive parametric gain, which in turn improves the phase-sensitive operation. Using a 955 mW Raman pump, the gain extinction ratio is increased by 9.2 dB. The improvement in the maximum phase-sensitive gain is 18.7 dB. This scheme can significantly boost the performance of phase-sensitive amplification in a spectral range where the parametric pump is not sufficiently strong but broadband Raman amplification is available.

  17. Polarization Drift Channel Model for Coherent Fibre-Optic Systems.

    PubMed

    Czegledi, Cristian B; Karlsson, Magnus; Agrell, Erik; Johannisson, Pontus

    2016-01-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincaré sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue. PMID:26905596

  18. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    NASA Astrophysics Data System (ADS)

    Czegledi, Cristian B.; Karlsson, Magnus; Agrell, Erik; Johannisson, Pontus

    2016-02-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincaré sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.

  19. Fibre Optic System for Monitoring Rotational Seismic Phenomena

    PubMed Central

    Kurzych, Anna; Jaroszewicz, Leszek R.; Krajewski, Zbigniew; Teisseyre, Krzysztof P.; Kowalski, Jerzy K.

    2014-01-01

    We outline the development and the application in a field test of the Autonomous Fibre-Optic Rotational Seismograph (AFORS), which utilizes the Sagnac effect for a direct measurement of the seismic-origin rotations of the ground. The main advantage of AFORS is its complete insensitivity to linear motions, as well as a direct measurement of rotational components emitted during seismic events. The presented system contains a special autonomous signal processing unit which optimizes its operation for the measurement of rotation motions, whereas the applied telemetric system based on the Internet allows for an AFORS remote control. The laboratory investigation of such two devices indicated that they keep an accuracy of no less than 5.1 × 10−9 to 5.5 × 10−8 rad/s in the detection frequency band from 0.83∼106.15 Hz and protect linear changes of sensitivity in the above bandpass. Some experimental results of an AFORS-1 application for a continuous monitoring of the rotational events in the Książ (Poland) seismological observatory are also presented. PMID:24651723

  20. Fibre optic system for monitoring rotational seismic phenomena.

    PubMed

    Kurzych, Anna; Jaroszewicz, Leszek R; Krajewski, Zbigniew; Teisseyre, Krzysztof P; Kowalski, Jerzy K

    2014-01-01

    We outline the development and the application in a field test of the Autonomous Fibre-Optic Rotational Seismograph (AFORS), which utilizes the Sagnac effect for a direct measurement of the seismic-origin rotations of the ground. The main advantage of AFORS is its complete insensitivity to linear motions, as well as a direct measurement of rotational components emitted during seismic events. The presented system contains a special autonomous signal processing unit which optimizes its operation for the measurement of rotation motions, whereas the applied telemetric system based on the Internet allows for an AFORS remote control. The laboratory investigation of such two devices indicated that they keep an accuracy of no less than 5.1 × 10(-9) to 5.5 × 10(-8) rad/s in the detection frequency band from 0.83~106.15 Hz and protect linear changes of sensitivity in the above bandpass. Some experimental results of an AFORS-1 application for a continuous monitoring of the rotational events in the Książ (Poland) seismological observatory are also presented. PMID:24651723

  1. Raman-Enhanced Phase-Sensitive Fibre Optical Parametric Amplifier

    PubMed Central

    Fu, Xuelei; Guo, Xiaojie; Shu, Chester

    2016-01-01

    Phase-sensitive amplification is of great research interest owing to its potential in noiseless amplification. One key feature in a phase-sensitive amplifier is the gain extinction ratio defined as the ratio of the maximum to the minimum gains. It quantifies the capability of the amplifier in performing low-noise amplification for high phase-sensitive gain. Considering a phase-sensitive fibre optical parametric amplifier for linear amplification, the gain extinction ratio increases with the phase-insensitive parametric gain achieved from the same pump. In this work, we use backward Raman amplification to increase the phase-insensitive parametric gain, which in turn improves the phase-sensitive operation. Using a 955 mW Raman pump, the gain extinction ratio is increased by 9.2 dB. The improvement in the maximum phase-sensitive gain is 18.7 dB. This scheme can significantly boost the performance of phase-sensitive amplification in a spectral range where the parametric pump is not sufficiently strong but broadband Raman amplification is available. PMID:26830136

  2. Study of a fibre optics current sensor for the measurement of plasma current in ITER

    NASA Astrophysics Data System (ADS)

    Wuilpart, Marc; Vanus, Benoit; Andrasan, Alina; Gusarov, Andrei; Moreau, Philippe; Mégret, Patrice

    2016-05-01

    In this article, we study the feasibility of using a fibre-optics current sensor (FOCS) for the measurement of plasma current in the future fusion reactor ITER. The sensor is based on a classical FOCS interrogator involving the measurement of the state of polarization rotation undergone by the light in presence of a magnetic field (Faraday effect) in an optical fibre surrounding the current and terminated by a Faraday mirror. We considered a uniformly spun optical fibre as the sensing element and we used the Stokes formalism to simulate the sensor. The objective of the simulations is to quantify the ratio LB/SP (beat length over the spun period of the spun fibre) enabling a measurement error in agreement with the ITER specifications. The simulator takes into account the temperature variations undergone by the measurement system under ITER operation. The simulation work showed that a LB/SP ratio of 19.2 is adequate.

  3. Simultaneous temperature and humidity measurements in a mechanical ventilator using an optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Hernandez, F. U.; Correia, R.; Morgan, S. P.; Hayes-Gill, B.; Evans, D.; Sinha, R.; Norris, A.; Harvey, D.; Hardman, J. G.; Korposh, S.

    2016-05-01

    An optical fibre sensor for simultaneous temperature and humidity measurements consisting of one fibre Bragg grating (FBG) to measure temperature and a mesoporous film of bilayers of Poly(allylamine hydrochloride)(PAH) and silica (SiO2) nanoparticles deposited onto the tip of the same fibre to measure humidity is reported. The hygroscopic film was created using the layer-by-layer (LbL) method and the optical reflection spectra were measured up to a maximum of 23 bilayers. The temperature sensitivity of the FBG was 10 pm/°C while the sensitivity to humidity was (-1.4x10-12 W / %RH) using 23 bilayers. The developed sensor was tested in the mechanical ventilator and temperature and humidity of the delivered artificial air was simultaneously measured. Once calibrated, the optical fibre sensor has the potential to control the absolute humidity as an essential part of critical respiratory care.

  4. High power optical fibre delivery system for the laser generation of ultrasound.

    PubMed

    Dewhurst, R J; Nurse, A G; Palmer, S B

    1988-11-01

    A plastic-clad optical fibre system has been examined as a delivery system of pulsed laser energy for the generation of ultrasound. The onset of significant optical damage caused by the laser has been investigated. By using multimode fibres of approximately 1 m length with 600 micron core size, it was found that laser power densities from the fibre were sufficient to produce ultrasonic waveforms corresponding to both the thermoelastic and plasma generation regimes. Out-of-plane acoustic displacements of greater than 250 pm can be achieved through 2.5 cm thick aluminium test samples, showing that fibre optical delivery systems may be considered in systems using laser-generated ultrasound for non-destructive testing applications. PMID:3188281

  5. Optical Spectroscopy at the Nanoscale

    NASA Astrophysics Data System (ADS)

    Hong, Xiaoping

    Recent advances in material science and fabrication techniques enabled development of nanoscale applications and devices with superior performances and high degree of integration. Exotic physics also emerges at nanoscale where confinement of electrons and phonons leads to drastically different behavior from those in the bulk materials. It is therefore rewarding and interesting to investigate and understand material properties at the nanoscale. Optical spectroscopy, one of the most versatile techniques for studying material properties and light-matter interactions, can provide new insights into the nanomaterials. In this thesis, I explore advanced laser spectroscopic techniques to probe a variety of different nanoscale phenomena. A powerful tool in nanoscience and engineering is scanning tunneling microscopy (STM). Its capability in atomic resolution imaging and spectroscopy unveiled the mystical quantum world of atoms and molecules. However identification of molecular species under investigation is one of the limiting functionalities of the STM. To address this need, we take advantage of the molecular `fingerprints' - vibrational spectroscopy, by combining an infrared light sources with scanning tunneling microscopy. In order to map out sharp molecular resonances, an infrared continuous wave broadly tunable optical parametric oscillator was developed with mode-hop free fine tuning capabilities. We then combine this laser with STM by shooting the beam onto the STM substrate with sub-monolayer diamondoids deposition. Thermal expansion of the substrate is detected by the ultrasensitive tunneling current when infrared frequency is tuned across the molecular vibrational range. Molecular vibrational spectroscopy could be obtained by recording the thermal expansion as a function of the excitation wavelength. Another interesting field of the nanoscience is carbon nanotube, an ideal model of one dimensional physics and applications. Due to the small light absorption with

  6. Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre

    NASA Astrophysics Data System (ADS)

    Saglamyurek, Erhan; Jin, Jeongwan; Verma, Varun B.; Shaw, Matthew D.; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

    2015-02-01

    The realization of a future quantum Internet requires the processing and storage of quantum information at local nodes and interconnecting distant nodes using free-space and fibre-optic links. Quantum memories for light are key elements of such quantum networks. However, to date, neither an atomic quantum memory for non-classical states of light operating at a wavelength compatible with standard telecom fibre infrastructure, nor a fibre-based implementation of a quantum memory, has been reported. Here, we demonstrate the storage and faithful recall of the state of a 1,532 nm wavelength photon entangled with a 795 nm photon, in an ensemble of cryogenically cooled erbium ions doped into a 20-m-long silica fibre, using a photon-echo quantum memory protocol. Despite its currently limited efficiency and storage time, our broadband light-matter interface brings fibre-based quantum networks one step closer to reality.

  7. Nanostructured optical fibre arrays for high-density biochemical sensing and remote imaging.

    PubMed

    Deiss, F; Sojic, N; White, D J; Stoddart, P R

    2010-01-01

    Optical fibre bundles usually comprise a few thousand to tens of thousands of individually clad glass optical fibres. The ordered arrangement of the fibres enables coherent transmission of an image through the bundle and therefore enables analysis and viewing in remote locations. In fused bundles, this architecture has also been used to fabricate arrays of various micro to nano-scale surface structures (micro/nanowells, nanotips, triangles, etc.) over relatively large areas. These surface structures have been used to obtain new optical and analytical capabilities. Indeed, the imaging bundle can be thought of as a "starting material" that can be sculpted by a combination of fibre drawing and selective wet-chemical etching processes. A large variety of bioanalytical applications have thus been developed, ranging from nano-optics to DNA nanoarrays. For instance, nanostructured optical surfaces with intrinsic light-guiding properties have been exploited as surface-enhanced Raman scattering (SERS) platforms and as near-field probe arrays. They have also been productively associated with electrochemistry to fabricate arrays of transparent nanoelectrodes with electrochemiluminescent imaging properties. The confined geometry of the wells has been loaded with biosensing materials and used as femtolitre-sized vessels to detect single molecules. This review describes the fabrication of high-density nanostructured optical fibre arrays and summarizes the large range of optical and bioanalytical applications that have been developed, reflecting the versatility of this ordered light-guiding platform. PMID:19916005

  8. Prediction of alpaca fibre quality by near-infrared reflectance spectroscopy.

    PubMed

    Canaza-Cayo, A W; Alomar, D; Quispe, E

    2013-07-01

    Rapid and efficient methods to evaluate variables associated with fibre quality are essential in animal breeding programs and fibre trade. Near-infrared reflectance spectroscopy (NIRS) combined with multivariate analysis was evaluated to predict textile quality attributes of alpaca fibre. Raw samples of fibres taken from male and female Huacaya alpacas (n = 291) of different ages and colours were scanned and their visible-near-infrared (NIR; 400 to 2500 nm) reflectance spectra were collected and analysed. Reference analysis of the samples included mean fibre diameter (MFD), standard deviation of fibre diameter (SDFD), coefficient of variation of fibre diameter (CVFD), mean fibre curvature (MFC), standard deviation of fibre curvature (SDFC), comfort factor (CF), spinning fineness (SF) and staple length (SL). Patterns of spectral variation (loadings) were explored by principal component analysis (PCA), where the first four PC's explained 99.97% and the first PC alone 95.58% of spectral variability. Calibration models were developed by modified partial least squares regression, testing different mathematical treatments (derivative order, subtraction gap, smoothing segment) of the spectra, with or without applying spectral correction algorithms (standard normal variate and detrend). Equations were selected through one-out cross-validation according to the proportion of explained variance (R 2CV), root mean square error in cross-validation (RMSECV) and the residual predictive deviation (RPD), which relates the standard deviation of the reference data to RMSECV. The best calibration models were accomplished when using the NIR region (1100 to 2500 nm) for the prediction of MFD and SF, with R 2CV = 0.90 and 0.87; RMSECV = 1.01 and 1.08 μm and RPD = 3.13 and 2.73, respectively. Models for SDFD, CVFD, MFC, SDFC, CF and SL had lower predictive quality with R 2CV < 0.65 and RPD < 1.5. External validation performed for MFD and SF on 91 samples was slightly poorer than cross

  9. Assessment of Ge-doped optical fibres subjected to x-ray irradiation

    NASA Astrophysics Data System (ADS)

    Ibrahim, S. A.; Che Omar, S. S.; Hashim, S.; Mahdiraji, G. A.; Bradley, D. A.; Kadir, A. B.; Isa, N. M.

    2014-11-01

    We have reported the thermoluminescence (TL) response of five different diameters ~120, 241, 362, 483, and 604 μm of 6 mol percent Ge-doped optical fibres. The perfomance of the Ge-doped optical fibre are compared with commercially available TLD-100 chips (LiF:Mg,Ti) in terms of their sensitivity and minimum detectable dose (MDD). The irradiation was performed using X-ray machine (Model ISO 'Narrow Spectrum Series') provided by the Malaysian Nuclear Agency (MNA) at 60 kV X-ray irradiation in low doses ranging from 1-10 mGy. The results show the linear TL dose response from the fibres up to 10 mGy. The smallest diameter of 120 pm optical fibre shows the highest TL dose response compared to above mentioned fibres. The minimum detectable dose (MDD) is 0.82, 0.20, 0.14, 0.08, and 0.13 mGy for Ge-doped with diameters of 120, 241, 362, 483 and 604 μm. All TL materials show the MDD value within the delivered dose 0.01-1.00 mGy subjected to x-ray irradiation. The Ge-doped fibre with diameter of 483 pm was matched the MDD value of TLD-100 chips that equivalent to 0.08 mGy at the same irradiation. We have observed that among the five different diameters of optical fibre, 120 μm shows the best results and its better response than TLD-100 chips (by a factor of 5). The linear response at low dose levels makes this optical fibre most suitable for medical application.

  10. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications

    NASA Astrophysics Data System (ADS)

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M.

    2016-02-01

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure.

  11. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications

    PubMed Central

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M.

    2016-01-01

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure. PMID:26899468

  12. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications.

    PubMed

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M

    2016-01-01

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure. PMID:26899468

  13. Optical Spectroscopy of New Materials

    NASA Technical Reports Server (NTRS)

    White, Susan M.; Arnold, James O. (Technical Monitor)

    1993-01-01

    Composites are currently used for a rapidly expanding number of applications including aircraft structures, rocket nozzles, thermal protection of spacecraft, high performance ablative surfaces, sports equipment including skis, tennis rackets and bicycles, lightweight automobile components, cutting tools, and optical-grade mirrors. Composites are formed from two or more insoluble materials to produce a material with superior properties to either component. Composites range from dispersion-hardened alloys to advanced fiber-reinforced composites. UV/VIS and FTIR spectroscopy currently is used to evaluate the bonding between the matrix and the fibers, monitor the curing process of a polymer, measure surface contamination, characterize the interphase material, monitor anion transport in polymer phases, characterize the void formation (voids must be minimized because, like cracks in a bulk material, they lead to failure), characterize the surface of the fiber component, and measure the overall optical properties for energy balances.

  14. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    SciTech Connect

    Chamorovskiy, A Yu; Okhotnikov, Oleg G

    2012-11-30

    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  15. TAIPAN: optical spectroscopy with StarBugs

    NASA Astrophysics Data System (ADS)

    Kuehn, Kyler; Lawrence, Jon; Brown, David M.; Case, Scott; Colless, Matthew; Content, Robert; Gers, Luke; Gilbert, James; Goodwin, Michael; Hopkins, Andrew M.; Ireland, Michael; Lorente, Nuria P. F.; Muller, Rolf; Nichani, Vijay; Rakman, Azizi; Richards, Samuel N.; Saunders, Will; Staszak, Nick F.; Tims, Julia; Waller, Lewis G.

    2014-07-01

    TAIPAN is a spectroscopic instrument designed for the UK Schmidt Telescope at the Australian Astronomical Observatory. In addition to undertaking the TAIPAN survey, it will serve as a prototype for the MANIFEST fibre positioner system for the future Giant Magellan Telescope. The design for TAIPAN incorporates up to 300 optical fibres situated within independently-controlled robotic positioners known as Starbugs, allowing precise parallel positioning of every fibre, thus significantly reducing instrument configuration time and increasing observing time. We describe the design of the TAIPAN instrument system, as well as the science that will be accomplished by the TAIPAN survey. We also highlight results from the on-sky tests performed in May 2014 with Starbugs on the UK Schmidt Telescope and briefly introduce the role that Starbugs will play in MANIFEST.

  16. Palladium coated ball lens for optical fibre refractometry based hydrogen sensing

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sahar A.; Correia, Ricardo; Francis, Daniel; Brooks, Simon J.; Jones, Ben J. S.; Thompson, Alexander W. J.; Hodgkinson, Jane; Tatam, Ralph P.

    2014-05-01

    An optical fibre refractometer using a ball lens as a sensor head has been developed and characterised. Light from a superluminescent diode is directed to an optical fibre sensor head and the intensity of the returned beam gives a measure of the refractive index of the medium at the ball lens fibre tip. A second beam is used to reference the intensity measurements. The system is capable of detecting changes in refractive index with a resolution of 0.003 RIU. The ball lenses have been coated with an 80nm thick layer of palladium and the potential use of this system as a micromirror hydrogen sensor is demonstrated. This technique offers a simple sensor head arrangement, with a large signal sampling area compared with that of a bare fibre.

  17. High-throughput imaging of self-luminous objects through a single optical fibre

    NASA Astrophysics Data System (ADS)

    Barankov, Roman; Mertz, Jerome

    2014-11-01

    Imaging through a single optical fibre offers attractive possibilities in many applications such as micro-endoscopy or remote sensing. However, the direct transmission of an image through an optical fibre is difficult because spatial information is scrambled upon propagation. We demonstrate an image transmission strategy where spatial information is first converted to spectral information. Our strategy is based on a principle of spread-spectrum encoding, borrowed from wireless communications, wherein object pixels are converted into distinct spectral codes that span the full bandwidth of the object spectrum. Image recovery is performed by numerical inversion of the detected spectrum at the fibre output. We provide a simple demonstration of spread-spectrum encoding using Fabry-Perot etalons. Our technique enables the two-dimensional imaging of self-luminous (that is, incoherent) objects with high throughput in principle independent of pixel number. Moreover, it is insensitive to fibre bending, contains no moving parts and opens the possibility of extreme miniaturization.

  18. Measuring the dispersion curve of a PMMA-fibre optic cable using a dye laser

    NASA Astrophysics Data System (ADS)

    Zorba, Serkan; Farah, Constantine; Pant, Ravi

    2010-11-01

    An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and the other coupled to the optical fibre cable at the end of which there is another photodetector. The difference in time of arrival at the detectors is used to compute the speed of light in the fibre for a given colour. In addition to a pedagogically simple and intuitive demonstration of the measurement of index of refraction, the use of a long fibre eliminates the need to direct the dangerous UV/visible laser pulse beam across a classroom, as is usually done in similar experiments. Ways to avoid systematic errors and other technical pitfalls—such as ringing oscillations—are presented.

  19. Cardiac induced localised motion of the human torso detected by a long period grating fibre optic sensing scheme

    NASA Astrophysics Data System (ADS)

    Allsop, T.; Lloyd, G.; Bhamber, R. S.; Hadzievski, L.; Halliday, M.; Webb, D. J.

    2014-05-01

    Cardiovascular health of the human population is a major concern for medical clinicians, with cardiovascular diseases responsible for 48% of all deaths worldwide, according to the World Health Organisation. Therefore the development of new practicable and economical diagnostic tools to scrutinise the cardiovascular health of humans is a major driver for clinicians. We offer a new technique to obtain seismocardiographic signals covering both ballistocardiography (below 20Hz) and audible heart sounds (20Hz upwards). The detection scheme is based upon an array of curvature/displacement sensors using fibre optic long period gratings interrogated using a variation of the derivative spectroscopy interrogation technique.

  20. Mechanisms of optical losses in fibres with a high concentration of germanium dioxide

    SciTech Connect

    Likhachev, M E; Bubnov, M M; Semenov, S L; Shvetsov, V V; Dianov, Evgenii M; Khopin, V F; Gur'yanov, A N

    2003-07-31

    The mechanisms of optical losses determining the scattering of light in single-mode fibres with a high germanium-dioxide content in a core are investigated. The coefficients of the Rayleigh scattering in fibres with a high level of doping (a molar concentration of GeO{sub 2} of up to 30 %) are measured for the first time. The investigations of the angular distribution of the intensity of light scattered from the fibre have revealed the presence of an additional, anomalous scattering of light besides the Rayleigh scattering. The nature of this phenomenon is discussed. (special issue devoted to the memory of academician a m prokhorov)

  1. Fibres reinforced dentures investigated with en-face optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Negrutiu, Meda L.; Sinescu, Cosmin; Hughes, Michael; Bradu, Adrian; Goguta, Luciana; Rominu, Mihai; Negru, Radu; Podoleanu, Adrian Gh.

    2008-04-01

    The complete dentures are currently made using different technologies. In order to avoid deficiencies of the prostheses made using the classical technique, several alternative procedures have been devised. In order to enhance the mechanical strength, complete denture bases are reinforced with fibres. Their material and structure vary wildly, which makes the investigation difficult. In this study, optical coherence tomography (OCT) is evaluated as a possible non-invasive technique to assess the biomechanical behaviour of the reinforcing fibres. OCT images demonstrate structural defects between fibres and the acrylic material in all dentures bases investigated. We conclude that OCT can successfully be used as a noninvasive analysis method.

  2. Real-time gamma dosimetry using PMMA optical fibres for applications in the sterilization industry

    NASA Astrophysics Data System (ADS)

    O'Keeffe, S.; Fernandez Fernandez, A.; Fitzpatrick, C.; Brichard, B.; Lewis, E.

    2007-10-01

    The use of polymethylmethacrylate (PMMA)-based plastic optical fibre as an intrinsic real-time gamma dosimeter is investigated. The radiation-induced attenuation of the fibres is monitored in situ during the course of irradiation. The PMMA fibre exhibited a linear radiation- induced attenuation response at various wavelengths for a dose range of 50 Gy to 50 kGy. The sensitivity, ranging from 0.4 dBm-1 kGy-1 to 0.03 dBm-1 kGy-1, is wavelength dependent, with high sensitivity at the lower wavelengths.

  3. Light propagation mechanism switching in a liquid crystal infiltrated microstructured polymer optical fibre

    NASA Astrophysics Data System (ADS)

    Rutkowska, K. A.; Milenko, K.; Chojnowska, O.; Dąbrowski, R.; Woliński, T. R.

    2015-12-01

    In this work studies on propagation properties of a microstructured polymer optical fibre infiltrated with a nematic liquid crystal are presented. Specifically, the influence of an infiltration method on the LC molecular alignment inside fibre air-channels and, thus, on light guidance is discussed. Switching between propagation mechanisms, namely the transition from modified total internal reflection (mTIR) to the photonic bandgap effect obtained by varying external temperature is also demonstrated.

  4. Optical fibre with a germanate glass core for lasing near 2 {mu}m

    SciTech Connect

    Dvoirin, Vladislav V; Mashinskii, Valerii M; Iskhakova, L D; Dianov, Evgenii M; Yashkov, M V; Khopin, V F; Gur'yanov, Aleksei N

    2011-01-24

    An optical fibre with a core based on thulium-doped germanate glass (45SiO{sub 2} - 55GeO{sub 2}) and a quartz glass cladding is developed for the first time. Lasing on Tm{sup 3+} ions ({lambda} =1.862 {mu}m) with an output power up to 70 mW at a differential efficiency of 37% is obtained in a laser based on this fibre. (letters)

  5. Fibre-optic photochemical stroke: generating and measuring photochemical changes inside the brain

    NASA Astrophysics Data System (ADS)

    Tsiminis, G.; Klarić, T. S.; Schartner, E. P.; Warren-Smith, S. C.; Lewis, M. D.; Koblar, S. A.; Monro, T. M.

    2014-05-01

    We report here on the development of a method to induce a stroke in a specific location within a mouse brain through the use of an optical fibre. By capturing the emitted fluorescence signal generated using the same fibre it is then possible to monitor photochemical changes within the brain in real-time, potentially reducing the requirement for post-operative histology to determine if a stroke has successfully been induced within the animal.

  6. EDITORIAL: The 19th International Conference on Optical Fibre Sensors, OFS-19 The 19th International Conference on Optical Fibre Sensors, OFS-19

    NASA Astrophysics Data System (ADS)

    Sampson, David D.; Jones, Julian D. C.; Tatam, Ralph P.

    2009-03-01

    OFS-19 was held in April 2008 in Perth, Australia, with Professor David Sampson (University of Western Australia) as General Chair assisted by Technical Programme Co-Chairs Professor Stephen Collins (Victoria University, Australia), Professor Kyunghwan Oh (Yonsei University, Korea) and Dr Ryozo Yamauchi (Fujikura Ltd, Japan). 'OFS-19' has once again affirmed the OFS series as the leading international conference for the optical fibre sensor community. Since its inception, in London in 1983, and under the leadership of an international steering committee independent of any learned society or professional institution, it has been held approximately every eighteen months. The venue nominally rotates from Europe, to the Americas, and thence to Asia and the Pacific. OFS-19 demonstrated the continuing vigour of the community, with some 240 papers presented, plus 8 tutorials; submissions and attendance were from 29 countries, with a little over half coming from the Asia-Pacific Region. In recent years, it has become a tradition to publish a post-conference special issue in Measurement Science and Technology, and these special issues offer a representative sample of the current status of the field. In the 25 years since OFS began, many of the early ideas and laboratory-based proof-of-principle experiments have successfully evolved into highly developed instrumentation systems and commercial products. One of the greatest success stories has been the optical fibre Bragg grating. Its exquisite intrinsic sensitivity to temperature and strain has led to an expanding niche in structural monitoring, especially in civil engineering. It has formed the 'beach-head' for penetration of optical fibre sensors into the oil and gas industry, initially in the harsh environment of down-hole monitoring. Latterly, it has paved the way for new applications of one of the earliest fibre optic sensors, the fibre hydrophone, which is now making its mark in sub-sea seismic surveying. Additionally

  7. Inverse four-wave-mixing and self-parametric amplification effect in optical fibre

    PubMed Central

    Turitsyn, Sergei K.; Bednyakova, Anastasia E.; Fedoruk, Mikhail P.; Papernyi, Serguei B.; Clements, Wallace R.L.

    2015-01-01

    An important group of nonlinear processes in optical fibre involves the mixing of four waves due to the intensity dependence of the refractive index. It is customary to distinguish between nonlinear effects that require external/pumping waves (cross-phase modulation and parametric processes such as four-wave mixing) and self-action of the propagating optical field (self-phase modulation and modulation instability). Here, we present a new nonlinear self-action effect, self-parametric amplification (SPA), which manifests itself as optical spectrum narrowing in normal dispersion fibre, leading to very stable propagation with a distinctive spectral distribution. The narrowing results from an inverse four-wave mixing, resembling an effective parametric amplification of the central part of the spectrum by energy transfer from the spectral tails. SPA and the observed stable nonlinear spectral propagation with random temporal waveform can find applications in optical communications and high power fibre lasers with nonlinear intra-cavity dynamics. PMID:26345290

  8. Brillouin light scattering from surface acoustic waves in a subwavelength-diameter optical fibre.

    PubMed

    Beugnot, Jean-Charles; Lebrun, Sylvie; Pauliat, Gilles; Maillotte, Hervé; Laude, Vincent; Sylvestre, Thibaut

    2014-01-01

    Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward-guided acoustic wave Brillouin scattering and backward-stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of Brillouin light scattering from surface acoustic waves. These Rayleigh-type surface waves travel the wire surface at a specific velocity of 3,400 m s(-1) and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics. PMID:25341638

  9. Fibre optical measuring network based on quasi-distributed amplitude sensors for detecting deformation loads

    SciTech Connect

    Kul'chin, Yurii N; Kolchinskiy, V A; Kamenev, O T; Petrov, Yu S

    2013-02-28

    A new design of a sensitive element for a fibre optical sensor of deformation loads is proposed. A distributed fibre optical measuring network, aimed at determining both the load application point and the load mass, has been developed based on these elements. It is shown that neural network methods of data processing make it possible to combine quasi-distributed amplitude sensors of different types into a unified network. The results of the experimental study of a breadboard of a fibre optical measuring network are reported, which demonstrate successful reconstruction of the trajectory of a moving object (load) with a spatial resolution of 8 cm, as well as the load mass in the range of 1 - 10 kg with a sensitivity of 0.043 kg{sup -1}. (laser optics 2012)

  10. Modified femtosecond laser inscription method for tailored grating sensors in encapsulated silica and low-loss polymer optical fibres

    NASA Astrophysics Data System (ADS)

    Kalli, Kyriacos; Lacraz, Amedee; Theodosiou, Andreas; Kofinas, Marios

    2016-05-01

    There is great interest in the development of flexible wavelength filters and optical fibre sensors, such as Bragg and superstructure gratings, grating arrays and chirped gratings in glass and polymer optical fibres. A major hurdle is the development of an inscription method that should offer flexibility and reliability and be generally applicable to all optical fibre types. With this in mind we have developed a novel femtosecond laser inscription method; plane-by-plane inscription, whereby a 3D-index change of controlled length across the fibre core, width along the fibre axis and depth is written into the optical fibre. We apply this method for the inscription of various grating types in coated silica and low- loss CYTOP polymer optical fibres. The plane-by-plane method allows for multiple and overlapping gratings in the fibre core. Moreover, we demonstrate that this novel fibre Bragg grating inscription technique can be used to modify and add versatility to an existing, encapsulated optical fibre pressure sensor. The femtosecond laser is operated in the green or the near infra-red, based on the material properties under laser modification.

  11. Hybrid optical spectral and time division multiplexing for passive interferometric fibre optic sensor networks

    NASA Astrophysics Data System (ADS)

    Al-Raweshidy, H. S.; Edwards, D. J.

    1993-01-01

    A new technique called hybrid optical spectral and time division multiplexing for passive interferometric fibre optic sensor networks has been developed. The idea of this technique is initially to modulate the optical spectrum with different sub-carrier frequencies at different time interval lasting for a period T. A proper selection for the sub-carrier values could minimise the crosstalk between sensors. The use of a synchronised gating signal at the detector output enables the simultaneous interrogation of signals from different sensors. A two-interferometric sensor network has been demonstrated and a 42 dB crosstalk has been achieved. The salient features of this technique are the simplicity, low crosstalk and high number of permissible sensors.

  12. Shape memory polymeric composites sensing by optic fibre Bragg gratings: A very first approach

    NASA Astrophysics Data System (ADS)

    Quadrini, Fabrizio; Santo, Loredana; Ciminello, Monica; Concilio, Antonio; Volponi, Ruggero; Spena, Paola

    2016-05-01

    Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, spanning from self-repairing of structures to self-deploying of antennas, solar sails, or functional devices (e.g. for grabbing small space debris). In all these cases, it may be essential to have information about their configuration at different stages of shape recovery. In this study, the strain history of a prepreg carbon fibre system, cured with a shape memory polymer (SMP) interlayer, is monitored through a Fibre Bragg Grating (FBG), a fibre optic sensor device. SMPC has been manufactured by using traditional technologies for aerospace. After manufacturing cylindrical shape samples, an external fibre optic system is added to the composite structure; this system is especially suited for high temperatures which are necessary for SMP recovery and composite softening. Sensor functionality is checked before and after each strain history path. Optic fibre arrangement is optimized to avoid unwanted breakings whereas strains are limited by fibre collapsing, i.e. within nominal 2% of deformation. Dynamic information about shape recovery gives fundamental insights about strain evolution during time as well as its spatial distribution.

  13. A mobile wireless sensor network platform for use with optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Bochao; Yang, Shuo; Sun, Tong; Grattan, Kenneth T. V.

    2013-05-01

    This paper presents a novel design of a system for using smart mobile robots to deploy a Wireless Sensor Network (WSN) for different optical fibre sensors, allowing for potential applications where there is a remote and harsh monitoring environment and allowing for the advantages of the optical fibre technology for the sensor itself to be used. The platform which was designed is comprised of a smart mobile robot, an optical fibre sensor module and a WSN module integrated with a localization component based on Received Signal Strength Indicator (RSSI), which has important advantages for mobile sensing and tracking, flexible deployment and mesh networking. The design principle and implementation-related issues for the platform have been discussed in this study. To investigate the performance of the mobile WSN platform, an experiment simulating measurement in a real environment has been performed. With the positive experimental data obtained, the functionalities of the platform are successfully demonstrated, which enables the real-time monitoring and transmission of sensor data and in addition estimated positional information. The exploitation of this kind of mobile WSN platform with fibre optic sensors is expected to make an impact on many applications, including those where advanced optical fibre sensing is particularly advantageous, yet where conventional WSNs cannot meet the requirements of the total sensing system.

  14. Remote distributed optical fibre dose measuring of high gamma-irradiation with highly sensitive Al- and P-doped fibres

    NASA Astrophysics Data System (ADS)

    Faustov, A. V.; Gusarov, A.; Wuilpart, M.; Fotiadi, A.; Liokumivich, L. B.; Zolotovskiy, I. O.; Tomashuk, A. L.; de Schoutheete, T.; Mégret, P.

    2013-05-01

    We present our results on measuring distributed Radiation-Induced Absorption (RIA) by means of a commercially available Optical Frequency Domain Reflectometry (OFDR) system. We also compare distributed OFDR RIA measurements with spatially integrated spectral transmission detection using an Optical Spectra Analyser (OSA). We have chosen four different highly gamma-radiation sensitive fibres, two of which were doped with Al and two with P. The dose rate during irradiations was about 590 Gy/h. The irradiations were conducted at temperatures of 30°C and 80°C. Different temperatures were needed for studying the temperature dependence of the annealing speed of RIA. All four fibres demonstrated a strong saturation-like increase of RIA with the dose accumulation up to several tens of dB/m as detected by the OSA. In case of the OFDR measurements the change of the absorption in an optical fibre resulted in a clear change of the slope of the corresponding Rayleigh backscattering trace. The RIA dependences measured with the OFDR were in a reasonable agreement with the measurements obtained with the OSA. This allows us to use the RIA dependences on absorption dose obtained by means of OSA for the distributed dose reconstruction based on the OFDR technique. We also irradiated different lengths of one of the P-doped fibers to see if it influences accuracy of the distributed dose detection and to find out the minimal possible length of the probe. The results of the presented experiments provide a basis for a dose estimation model based on RIA in which temperature oscillations are taken into account.

  15. The 22nd International Conference on Optical Fibre Sensors, OFS-22

    NASA Astrophysics Data System (ADS)

    Liao, Yianbiao; Jin, Wei; Jones, Julian; Tatam, Ralph

    2013-09-01

    In October 2013, the 22nd International Conference on Optical Fibre Sensors was held in Beijing, attracting about 500 participants with 417 presentations. The conference began in 1983 in London, and in the subsequent 30 years has defined the subject. The conference is held approximately every 18 months, and rotates between three world regions: Asia/Pacific, Europe and the Americas. The conference is not 'owned' by any learned society or professional institution, but is organized by a self-sustaining international steering committee. This special feature represents the sixth occasion on which Measurement Science and Technology has published papers based on a development of a cross-section of work presented at the conference. The subject of optical fibre sensors has its beginnings in the enabling technologies of the optical fibre itself and the development of laser technologies suitable for practical use in demanding real-world applications. But the real driver for the subject in its early years was in the development of systems for defence applications, most notably for strategic-grade sea-bed hydrophone arrays for submarine detection, and the optical fibre gyroscope (the community has recently celebrated the 35th anniversary of its earliest publication) for aerospace navigation. Both applications continue to be important, but now with extensive civil applications: hydrophones for oil exploration and reservoir monitoring and management, and fibre gyroscopes for applications ranging from those requiring low cost and mass production (such as industrial robots and in agricultural machinery) to the most exotic and highest performance for space applications. The articles in this special feature exemplify the principal themes of the subject: enabling technologies, application-specific developments and systems considerations. In recent years, perhaps the most important—indeed, dominant—enabling technologies have been based on structuring of fibres: longitudinally, as

  16. Electromagnetic waves in optical fibres in a magnetic field

    NASA Astrophysics Data System (ADS)

    Gorelik, V. S.; Burdanova, M. G.

    2016-03-01

    A new method is reported of recording the secondary radiation of luminescent substances based on the use of capillary fibres of great length. Theoretical analysis of the dispersion curves of electromagnetic radiation in capillary fibres doped with erbium ions Er3+ has been established. The Lorentz model is used for describing the dispersion properties of electromagnetic waves in a homogeneous medium doped with rare-earth ions. The dispersion dependencies of polariton and axion-polariton waves in erbium nitrate hydrate are determined on the basis of the model of the interaction between electromagnetic waves and the resonance electronic states of erbium ions in the absence and presence of a magnetic field.

  17. Measurements of growth and decay of radiation induced attenuation during the irradiation and recovery of plastic optical fibres

    NASA Astrophysics Data System (ADS)

    Kovačević, M. S.; Savović, S.; Djordjevich, A.; Bajić, J.; Stupar, D.; Kovačević, M.; Simić, S.

    2013-04-01

    In this work, we present the experimental study of the radiation-induced attenuation in step-index polymethyl-methacrylate based plastic optical fibre by exposure to low dose rate ionizing radiation. The low dose exposure has been found to induce significant permanent attenuation in plastic optical fibres. Based on the experimental results, the formula between radiation-induced attenuation and radiation dose is obtained accordingly. The recovery properties of plastic optical fibre also were investigated. The fibre begins to recover immediately after irradiation, but it does not fully recover, i.e. the irradiation leads to permanent damage of polymer.

  18. A Dual Sensor for pH and Hydrogen Peroxide Using Polymer-Coated Optical Fibre Tips

    PubMed Central

    Purdey, Malcolm S.; Thompson, Jeremy G.; Monro, Tanya M.; Abell, Andrew D.; Schartner, Erik P.

    2015-01-01

    This paper demonstrates the first single optical fibre tip probe for concurrent detection of both hydrogen peroxide (H2O2) concentration and pH of a solution. The sensor is constructed by embedding two fluorophores: carboxyperoxyfluor-1 (CPF1) and seminaphtharhodafluor-2 (SNARF2) within a polymer matrix located on the tip of the optical fibre. The functionalised fibre probe reproducibly measures pH, and is able to accurately detect H2O2 over a biologically relevant concentration range. This sensor offers potential for non-invasive detection of pH and H2O2 in biological environments using a single optical fibre. PMID:26694413

  19. Enhanced all-optical modulation in a graphene-coated fibre with low insertion loss

    NASA Astrophysics Data System (ADS)

    Zhang, Haojie; Healy, Noel; Shen, Li; Huang, Chung Che; Hewak, Daniel W.; Peacock, Anna C.

    2016-03-01

    Graphene is a highly versatile two-dimensional material platform that offers exceptional optical and electrical properties. Of these, its dynamic conductivity and low effective carrier mass are of particular interest for optoelectronic applications as they underpin the material’s broadband nonlinear optical absorption and ultra-fast carrier mobility, respectively. In this paper, we utilize these phenomena to demonstrate a high-speed, in-fibre optical modulator developed on a side-polished optical fibre platform. An especially low insertion loss (<1 dB) was achieved by polishing the fibre to a near atomically smooth surface (<1 nm RMS), which minimized scattering and ensured excellent contact between the graphene film and the fibre. In order to enhance the light-matter interaction, the graphene film is coated with a high index polyvinyl butyral layer, which has the added advantage of acting as a barrier to the surrounding environment. Using this innovative approach, we have fabricated a robust and stable all-fibre device with an extinction ratio as high as 9 dB and operation bandwidth of 0.5 THz. These results represent a key step towards the integration of low-dimensional materials within standard telecoms networks.

  20. Optical-fibre backscatter polarimetry for the distributed measurement of full strain fields

    NASA Astrophysics Data System (ADS)

    Rogers, A. J.; Shatalin, S. V.; Kannellopoulos, S. E.

    2005-11-01

    Fully-distributed optical-fibre sensing (FDOFS) systems are developing rapidly and are offering significant advantages for measurement functions in a variety of structural applications, especially in the oil industry, the power supply industry, the aerospace industries and civil engineering construction. Polarization techniques are well established in FDOFS, and in the analysis of polarization-mode dispersion (PMD) for optical-fibre telecommunications. However, a major problem has been that of determining, from one end of the fibre, the distribution of the full polarization properties of a monomode optical fibre, along its length, with some specific spatial resolution. This paper will present a new technique for providing this full information, and thus for measuring the distribution of any parameter, external to the fibre, which can modify its polarization behaviour. As a result, for example, it becomes possible to measure simultaneously the distribution of a strain field comprising the longitudinal and the two transverse components of direct strain, plus the transverse shear strain. The technique comprises an extension of polarization-optical time domain reflectometry (POTDR) [16], and necessitates on-line processing. Details of the physical principles, the algorithms and the polarimetry will be presented, together with some early results illustrating the measurement accuracies which can be achieved.

  1. Enhanced all-optical modulation in a graphene-coated fibre with low insertion loss

    PubMed Central

    Zhang, Haojie; Healy, Noel; Shen, Li; Huang, Chung Che; Hewak, Daniel W.; Peacock, Anna C.

    2016-01-01

    Graphene is a highly versatile two-dimensional material platform that offers exceptional optical and electrical properties. Of these, its dynamic conductivity and low effective carrier mass are of particular interest for optoelectronic applications as they underpin the material’s broadband nonlinear optical absorption and ultra-fast carrier mobility, respectively. In this paper, we utilize these phenomena to demonstrate a high-speed, in-fibre optical modulator developed on a side-polished optical fibre platform. An especially low insertion loss (<1 dB) was achieved by polishing the fibre to a near atomically smooth surface (<1 nm RMS), which minimized scattering and ensured excellent contact between the graphene film and the fibre. In order to enhance the light-matter interaction, the graphene film is coated with a high index polyvinyl butyral layer, which has the added advantage of acting as a barrier to the surrounding environment. Using this innovative approach, we have fabricated a robust and stable all-fibre device with an extinction ratio as high as 9 dB and operation bandwidth of 0.5 THz. These results represent a key step towards the integration of low-dimensional materials within standard telecoms networks. PMID:27001353

  2. Development of Landslide Early Warning System Using Macro-bending Loss Based Optical Fibre Sensor

    NASA Astrophysics Data System (ADS)

    Marzuki, Ahmad; Heriyanto, Muhammad; Dedy Setiyadi, Ika; Koesuma, Sorja

    2015-06-01

    This paper presents the design of a simple and cheap landslide early warning system which mainly consists of a displacement fibre sensor, mechanical displacement converter, and Short Messaging Service (SMS) gateway equipped with a siren. Displacement fibre optic sensors were made by wrapping a polymer optical fibre (POF) around a holey elastic cylinder connected to a mechanical displacement converter that converts a real land displacement in centimetres order of magnitude into millimetres order that fibre optic sensor can detect. From the experimental results we suggest an optical fibre sensor that has ability to monitor land displacement in the range of 40 cm, sensitivity of (5.9 ± 0.2) dB/cm and linearity 99.5% as well as the way of improving sensor performance to meet the real need. A whole system has been tested making use of a slider attached to the mechanical displacement converter. Once a nonzero continuous displacement for 5 seconds or a downward land displacement of 10.0 cm occurs, the system will activate the siren and spread an alert via SMS automatically.

  3. 6df: An Automated Multi-Object Fibre Spectroscopy System for the UKST

    NASA Astrophysics Data System (ADS)

    Parker, Q. A.; Miziarski, S.; Watson, F. G.

    Apart from carrying out wide-field photographic imaging the U.K. Schmidt Telescope of the Anglo-Australian Observatory also operates the FLAIR multi-fibre spectroscopy system (e.g. Parker and Watson 1995). In the five years in which FLAIR has operated as a common-user facility, over 22 000 object spectra have been obtained. However, a major drawback of the current system is that the fibre positioning is only semi-automated and can take four to six hours to affix the 100 fibres over the UKST field. With a thinned CCD being commissioned in 1995 typical observations of sufficient S/N now take much less than this (e.g. about an hour for galaxy redshifts to B 17). Clearly FLAIR is operating far short of its potential. Consequently a fully-automated, off telescope, pick-place fibre-positioning system known as 6dF has been proposed to address this bottle-neck. The aim is to provide a system capable of configuring 150 fibres in under an hour across a 6-degree circular field. Three field plates are also planned allowing rapid field interchange (10-15 minute field plate changeover expected) to keep up with the observations. A factor 10 improvement in observing efficiency is promised. For the first time, an effective means of tackling major, full hemisphere, spectroscopic surveys will be available at the UKST. An all southern sky near-infrared selected galaxy redshift survey is a specific high-priority example. We have just completed a phase-A design study where many of the concepts have been successfully tested. The estimated cost of 6dF is $A450k with some funding already in place. The instrument will be built over a timescale of 2 years with expected commissioning in early 2000.

  4. Optical Coherence Tomography Assisted Retinal Nerve Fibre Layer Thickness Profile in High Myopia

    PubMed Central

    Malakar, Mousumi; Askari, Syed Nasir; Ashraf, Humayun; Ahuja, Anupam; Asghar, Adil

    2015-01-01

    Introduction: To evaluate the association of high myopia with retinal nerve fibre layer (RNFL) thickness by Fourier domain optical coherence tomography (FD OCT). Materials and Methods: Fifty highly myopic eyes (25 patients) and forty emmetropic eyes (20 Normal subject) were randomly selected after excluding concomitant ophthalmic disorder and RNFL thickness measured using the Fourier domain optical coherence tomography (FD OCT). Results: The overall mean RNFL thickness in the myopic groups and control were 87.89 μm and 111.64 μm respectively. The mean retinal nerve fibre thickness was significantly less in myopic eyes as compared to control group (p =0.0001). Retinal nerve fibre layer thickness shows topographic double hump pattern in both the groups (myopes and emmetropes). Conclusion: Retinal nerve fibre thickness was significantly less in myopic eyes as compared to emmetropic eyes. The retinal nerve fibre layer thinning in high myopes may be confused with open angle glaucoma, a disease also prevalent in high myopes. There is therefore a need to have retinal nerve fibre layer thickness normogram for high myopes of a given population group to avoid wrong interpretation. PMID:25859476

  5. New concept of low-intrusion quasi-distributed optical fibre extensometer

    NASA Astrophysics Data System (ADS)

    Courteville, Alain; Delaveau, Marie; Delepine-Lesoille, Sylvie; Quétel, Lionel; Gautier, Yves; Dubroca, Stéphane; Dumoulin, John

    2006-04-01

    We present a novel concept of quasi-distributed optical fibre extensometers for embedment into concrete, with optimized, continuous transfer of the strain field to the fibre, and fully corrected from thermal variations. These sensors have been developed for structural health monitoring applications. They are composed of a combination of optical cavities and Bragg gratings cascaded along a single fibre. The cavities, which are the parts sensitive to the concrete strain, are formed by partially reflecting elements inserted into the fibre. Their length, which is also the measurement basis, can range from 10 cm to several metres. Several cavities can be cascaded along a single fibre, allowing quasi-distributed strains measurements. Bragg Gratings are inserted along the same fibre, close to the cavities, and are used to measure the temperature locally. Both types of sensors are read by a fibre optic low coherence interferometer featuring a temporal delay line. The interferometer is used in an original way to measure simultaneously the length variations of the cavities and the wavelength shifts of the Bragg gratings. In this paper we present the design of the sensor, and in particular the study of the composite packaging whose shape and mechanical properties have been optimized by finite elements modelling to minimize the intrusion effect and ensure a continuous transfer of the strain field when embedded into concrete. We develop the optical reading method, presenting the theory of the sensor interrogation, or how to get the strain and temperature information. We describe also the instrumentation. Finally we present some laboratory experiments that show very good agreement between standard sensors and OFS, and an example of implementation into a bridge near Angouleme, France.

  6. Humidity insensitive step-index polymer optical fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Woyessa, G.; Fasano, A.; Stefani, A.; Markos, C.; Nielsen, K.; Rasmussen, H. K.; Bang, O.

    2015-09-01

    We have fabricated and characterised a humidity insensitive step index(SI) polymer optical fibre(POF) Bragg grating sensors. The fibre was made based on the injection molding technique, which is an efficient method for fast, flexible and cost effective preparation of the fibre preform. The fabricated SIPOF has a core made from TOPAS with a glass transition temperature of 134°C and a cladding from ZEONEX with a glass transition temperature of 138°C. The main advantages of the proposed SIPOF are the low water absorption and good chemical resistance compared to the conventional poly-methyl-methacrylate (PMMA) based SIPOFs. The fibre has a minimum loss of ~6dB/m at 770nm.

  7. Reflective variable optical attenuators and fibre ring lasers for wavelength-division multiplexing systems

    NASA Astrophysics Data System (ADS)

    Liu, He Liang

    Wavelength division multiplexing (WDM) optical fibre system is an important enabling technology to fulfill the demands for bandwidth in the modern information age. The main objective of this project is to study novel devices with the potential to enhance the performance of WDM systems. In particular, a novel reflective variable optical attenuator (RVOA) used for dynamic gain equalization (DGE) and fibre lasers based on an entirely new type of erbium-doped fibres with ultrawide tuning range were investigated theoretically and experimentally. We proposed a new type of RVOA device which could be potentially integrated with arrayed waveguide grating (AWG) to reduce the cost of DGE substantially. Initially, fibre-based RVOAs, fabricated with optical fibre components such as fibre coupler and Faraday rotator mirror, were investigated theoretically and experimentally. Larger attenuation range up to 22 dB was realized for fibre coupler-based ROVA with a Faraday rotator mirror and its polarization-dependent loss is about 0.5 dB. Then polymeric waveguide-based RVOAs were investigated theoretically and experimentally. Using an epoxy Novolak resin as core material and an UV-cured resin (Norland's NOA61) as cladding material, a polymeric waveguide RVOA was successfully fabricated. The dynamic 15 dB attenuation range was achieved and the PDL was less than 0.2 dB. The measured insertion loss of the polymeric waveguide RVOA was too large (about 18 dB) and was mainly induced by coupling loss, material loss and poor alignment. In the second part of the study, fibre ring lasers with continuous wavelength tuning over wide wavelength range and fibre ring lasers with discrete wavelength tuning were investigated. Tunable lasers are important devices in WDM systems because they could be employed as reserved sources and therefore avoiding the need to stock large inventory of lasers to cover the ITU-wavelength grid. In this project, erbium ions doped bismuth oxide glass fibres instead of

  8. Optical properties of bismuth-doped silica fibres in the temperature range 300 - 1500 K

    SciTech Connect

    Dvoretskii, D A; Bufetov, Igor' A; Vel'miskin, V V; Zlenko, Alexander S; Khopin, V F; Semjonov, S L; Guryanov, Aleksei N; Denisov, L K; Dianov, Evgenii M

    2012-09-30

    The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi{sup 3+} profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect. (optical fibres, lasers and amplifiers. properties and applications)

  9. Spectrally encoded optical fibre sensor systems and their application in process control, environmental and structural monitoring

    NASA Astrophysics Data System (ADS)

    Willsch, Reinhardt; Ecke, Wolfgang; Schwotzer, Gunter

    2005-09-01

    Different types of advanced optical fibre sensor systems using similar spectral interrogation principles and potential low-cost polychromator optoelectronic signal processing instrumentation will be presented, and examples of their industrial application are demonstrated. These are such sensors as multimode fibre based humidity, temperature, and pressure sensors with extrinsic microoptical Fabry-Perot transducers for process control in gas industry, UV absorption evanescent field sensors for organic pollution monitoring in groundwater, and single mode fibre Bragg grating (FBG) multiplexed strain & vibration and temperature sensor networks for structural health monitoring applications in electric power facilities, aerospace, railways, geotechnical and civil engineering. Recent results of current investigations applying FBGs and microstructured fibres for chemical sensing will be discussed.

  10. Generation of an astronomical optical frequency comb in three fibre-based nonlinear stages

    NASA Astrophysics Data System (ADS)

    Chavez Boggio, J. M.; Rieznik, A. A.; Zajnulina, M.; Böhm, M.; Bodenmüller, D.; Wysmolek, M.; Sayinc, H.; Neumann, Jörg; Kracht, Dietmar; Haynes, R.; Roth, M. M.

    2012-06-01

    The generation of a broadband optical frequency comb with 80 GHz spacing by propagation of a sinusoidal wave through three dispersion-optimized nonlinear stages is numerically investigated. The input power, the dispersion, the nonlinear coefficient, and lengths are optimized for the first two stages for the generation of low-noise ultra-short pulses. The final stage is a low-dispersion highly-nonlinear fibre where the ultra-short pulses undergo self-phase modulation for strong spectral broadening. The modeling is performed using a Generalized Nonlinear Schrodinger Equation incorporating Kerr and Raman nonlinearities, self-steepening, high-order dispersion and gain. In the proposed approach the sinusoidal input field is pre-compressed in the first fibre section. This is shown to be necessary to keep the soliton order below ten to minimize the noise build-up during adiabatic pulse compression, when the pulses are subsequently amplified in the next fibre section (rare-earth-doped-fibre with anomalous dispersion). We demonstrate that there is an optimum balance between dispersion, input power and nonlinearities, in order to have adiabatic pulse compression. It is shown that the intensity noise grows exponentially as the pulses start to be compressed in the amplifying fibre. Eventually, the noise decreases and reaches a minimum when the pulses are maximally compressed. A train of 70 fs pulses with up to 3.45 kW peak power and negligible noise is generated in our simulations, which can be spectrally broadened in a highly-nonlinear fibre. The main drawback of this compression technique is the small fibre length tolerance where noise is negligible (smaller than 10 cm for erbium-doped fibre length of 15 m). We finally investigate how the frequency comb characteristics are modified by incorporating an optical feedback. We show that frequency combs appropriate for calibration of astronomical spectrographs can be improved by using this technique.

  11. Addressing the needs of the telecoms industry for optical fibre communication in Africa

    NASA Astrophysics Data System (ADS)

    Leitch, Andrew W. R.; Conibear, Ann B.

    2005-10-01

    We report on a successful partnership between the Department of Physics at the Nelson Mandela Metropolitan University (NMMU) and Telkom, South Africa's national telecommunications company, to train physics students in the important fields related to optical fibre technology. The partnership, which began in 2001 and forms part of Telkom's Centre of Excellence program in South Africa, is currently being extended to other countries in Africa. The training being conducted in the Physics Department has as one of its main goals an increased understanding of polarisation mode dispersion (PMD), an effect that will ultimately limit the transmission speeds through optical fibre.

  12. Design of a fibre-optic disc accelerometer: theory and experiment

    NASA Astrophysics Data System (ADS)

    Wang, Yongjie; Xiao, Hao; Zhang, Songwei; Li, Fang; Liu, Yuliang

    2007-06-01

    Mechanical principles of fibre-optic disc accelerometers (FODA) different from those assumed in previous calculation methods are presented. An FODA with a high sensitivity of 82 rad/g and a resonance frequency of 360 Hz is designed and tested. In this system, the minimum measurable demodulation phase of the phase-generated carrier (PGC) is 10-5 rad, and the minimum acceleration reaches 120 ng theoretically. This kind of FODA, with its high responsivity, all-optic-fibre configuration, small size, light weight and stiff shell housing, ensures effective performance in practice.

  13. Non-disturbing optical power monitor for links in the visible spectrum using a polymer optical fibre

    NASA Astrophysics Data System (ADS)

    Ribeiro, Ricardo M.; Freitas, Taiane A. M. G.; Barbero, Andrés P. L.; Silva, Vinicius N. H.

    2015-08-01

    We describe a simple and inexpensive inline optical power monitor (OPMo) for polymer optical fibre (POF) links that are transmitting visible light carriers. The OPMo is non-invasive in the sense that it does not tap any guided light from the fibre core; rather, it collects and detects the spontaneous side-scattered light. Indeed, the OPMo indicates whether a POF transmission link has dark or live status and measures the average optical power level of the propagating signals without disconnecting the fibre link. This paper demonstrates the proof-of-principle of the device for one wavelength at a time, selected from a set of previously calibrated wavelength channels which have been found in the 45 dB dynamic range, with 50 dBm sensitivity or insensitivity by the use or non-use of a mode scrambler. Our findings are very promising milestones for further OPMo development towards the marketplace.

  14. Fibre optic sensor for the detection of adulterant traces in coconut oil

    NASA Astrophysics Data System (ADS)

    Sheeba, M.; Rajesh, M.; Vallabhan, C. P. G.; Nampoori, V. P. N.; Radhakrishnan, P.

    2005-11-01

    The design and development of a fibre optic evanescent wave refractometer for the detection of trace amounts of paraffin oil and palm oil in coconut oil is presented. This sensor is based on a side-polished plastic optical fibre. At the sensing region, the cladding and a small portion of the core are removed and the fibre nicely polished. The sensing region is fabricated in such a manner that it sits perfectly within a bent mould. This bending of the sensing region enhances its sensitivity. The oil mixture of different mix ratios is introduced into the sensing region and we observed a sharp decrease in the output intensity. The observed variation in the intensity is found to be linear and the detection limit is 2% (by volume) paraffin oil/palm oil in coconut oil. The resolution of this refractometric sensor is of the order of 10-3. Since coconut oil is consumed in large volumes as edible oil in south India, this fibre optic sensor finds great relevance for the detection of adulterants such as paraffin oil or palm oil which are readily miscible in coconut oil. The advantage of this type of sensor is that it is inexpensive and easy to set up. Another attraction of the side-polished fibre is that only a very small amount of analyte is needed and its response time is only 7 s.

  15. A fibre-optic mode-filtered light sensor for general and fast chemical assay

    NASA Astrophysics Data System (ADS)

    Zhou, Leiji; Wang, Kemin; Choi, Martin M. F.; Xiao, Dan; Yang, Xiaohai; Chen, Rui; Tan, Weihong

    2004-01-01

    A simple and fast-response fibre-optic chemical sensor based on mode-filtered light detection (MFLD) has been successfully developed. The sensor was constructed by inserting an unmodified fibre core into a silica capillary tubing; a charge-coupled device which acted as a multi-channel detector was positioned alongside the capillary to detect the emanated mode-filtered light. An interesting finding was observed: there was an increase in the signal upon the decrease in the sample refractive index when an unclad optical fibre was employed, which was different from the results of a polymer-clad fibre reported previously. This phenomenon of opposite signal trend can clearly be interpreted by applying a mathematical derivation based on light propagation in the optical fibre. The derived mathematical model correlates well with the experimental results. It also provides a good theoretical foundation for the future development of MFLD-based analyser in conjunction with liquid chromatographic separation and assay. The proposed MFLD sensor was successfully applied to determine acetic acid with a linear response in the range 0-90 v/v % and a correlation coefficient of 0.9959. The sensor has the advantages of high S/N ratio and very fast response time. It offers the potential for use as a general sensor in food and chemical industries.

  16. An 8-mm diameter fibre robot positioner for massive spectroscopy surveys

    NASA Astrophysics Data System (ADS)

    Fahim, N.; Prada, F.; Kneib, J. P.; Glez-de-Rivera, G.; Hörler, P.; Sánchez, J.; Azzaro, M.; Becerril, S.; Bleuler, H.; Bouri, M.; Castaño, J.; Garrido, J.; Gillet, D.; Gómez, C.; Gómez, M. A.; González-Arroyo, A.; Jenni, L.; Makarem, L.; Yepes, G.; Arrillaga, X.; Carrera, M. A.; Diego, R.; Charif, M.; Hug, M.; Lachat, C.

    2015-06-01

    Massive spectroscopic survey are becoming trendy in astrophysics and cosmology, as they can address new fundamental knowledge such as understanding the formation of the Milky Way and probing the nature of the mysterious dark energy. To enable massive spectroscopic surveys, new technology has been developed to place thousands of optical fibres at a given position on a focal plane. This technology needs to be: (1) accurate, with micrometer positional accuracy; (2) fast to minimize overhead; (3) robust to minimize failure; and (4) low cost. In this paper, we present the development, properties, and performance of a new single 8-mm in diameter fibre positioner robot, using two 4-mm DC-brushless gearmotors, that allows us to achieve accuracies up to 0.07 arcsec (5 μm). This device has been developed in the context of the Dark Energy Spectroscopic Instrument.1

  17. Luminescence and photoinduced absorption in ytterbium-doped optical fibres

    SciTech Connect

    Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E; Bubnov, M M; Umnikov, A A; Yashkov, M V; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-12-31

    Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role in photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.

  18. Optofluidic realization and retaining of cell–cell contact using an abrupt tapered optical fibre

    PubMed Central

    Xin, Hongbao; Zhang, Yao; Lei, Hongxiang; Li, Yayi; Zhang, Huixian; Li, Baojun

    2013-01-01

    Studies reveal that there exists much interaction and communication between bacterial cells, with parts of these social behaviors depending on cell–cell contacts. The cell–cell contact has proved to be crucial for determining various biochemical processes. However, for cell culture with relatively low cell concentration, it is difficult to precisely control and retain the contact of a small group of cells. Particularly, the retaining of cell–cell contact is difficult when flows occur in the medium. Here, we report an optofluidic method for realization and retaining of Escherichia coli cell–cell contact in a microfluidic channel using an abrupt tapered optical fibre. The contact process is based on launching a 980-nm wavelength laser into the fibre, E. coli cells were trapped onto the fibre tip one after another, retaining cell–cell contact and forming a highly organized cell chain. The formed chains further show the ability as bio-optical waveguides. PMID:23771190

  19. Fibre optic sensor for non-invasive monitoring of blood pressure during MRI scanning.

    PubMed

    Myllylä, Teemu S; Elseoud, Ahmed Abou; Sorvoja, Hannu S S; Myllylä, Risto A; Harja, Juha M; Nikkinen, Juha; Tervonen, Osmo; Kiviniemi, Vesa

    2011-01-01

    This report focuses on designing and implementing a non-invasive blood pressure (NIBP) measuring device capable of being used during magnetic resonance imaging (MRI). Based on measuring pulse wave velocity in arterial blood, the device uses the obtained result to estimate diastolic blood pressure. Pulse transit times are measured by two fibre optical accelerometers placed over the chest and carotid artery. The fabricated accelerometer contains two static fibres and a cantilever beam, whose free end is angled at 90 degrees to act as a reflecting surface. Optical fibres are used for both illuminating the surface and receiving the reflected light. When acceleration is applied to the sensor, it causes a deflection in the beam, thereby changing the amount of reflected light. The sensor's output voltage is proportional to the intensity of the reflected light. Tests conducted on the electronics and sensors inside an MRI room during scanning proved that the device is MR- compatible. No artifacts or distortions were detected. PMID:20401906

  20. Optofluidic realization and retaining of cell-cell contact using an abrupt tapered optical fibre

    NASA Astrophysics Data System (ADS)

    Xin, Hongbao; Zhang, Yao; Lei, Hongxiang; Li, Yayi; Zhang, Huixian; Li, Baojun

    2013-06-01

    Studies reveal that there exists much interaction and communication between bacterial cells, with parts of these social behaviors depending on cell-cell contacts. The cell-cell contact has proved to be crucial for determining various biochemical processes. However, for cell culture with relatively low cell concentration, it is difficult to precisely control and retain the contact of a small group of cells. Particularly, the retaining of cell-cell contact is difficult when flows occur in the medium. Here, we report an optofluidic method for realization and retaining of Escherichia coli cell-cell contact in a microfluidic channel using an abrupt tapered optical fibre. The contact process is based on launching a 980-nm wavelength laser into the fibre, E. coli cells were trapped onto the fibre tip one after another, retaining cell-cell contact and forming a highly organized cell chain. The formed chains further show the ability as bio-optical waveguides.

  1. Fibre-optic coupling to high-resolution CCD and CMOS image sensors

    NASA Astrophysics Data System (ADS)

    van Silfhout, R. G.; Kachatkou, A. S.

    2008-12-01

    We describe a simple method of gluing fibre-optic faceplates to complementary metal oxide semiconductor (CMOS) active pixel and charge coupled device (CCD) image sensors and report on their performance. Cross-sectional cuts reveal that the bonding layer has a thickness close to the diameter of the individual fibres and is uniform over the whole sensor area. Our method requires no special tools or alignment equipment and gives reproducible and high-quality results. The method maintains a uniform bond layer thickness even if sensor dies are mounted at slight angles with their package. These fibre-coupled sensors are of particular interest to X-ray imaging applications but also provide a solution for compact optical imaging systems.

  2. Microfluidic flow and heat transfer and their influence upon optical modes in microstructure fibres

    NASA Astrophysics Data System (ADS)

    Davies, E.; Christodoulides, P.; Florides, G.; Kalli, K.

    2015-05-01

    Using finite element analysis (FEA), a model has been constructed to predict the thermo-fluidic and optical properties of a microstructure optical fibre (MOF). The properties under study include external temperature, input water velocity and optical fibre geometry. Under laminar flow the steady-state temperature is dependent on the water channel radius while independent of the input velocity. A critical channel radius is observed below which the steady-state temperature of the water channel is constant, while above, the temperature decreases. The MOF has been found capable of supporting multiple modes whose response to temperature was dominated by the thermo-optic coefficient of glass, despite the larger thermo-optic coefficient of water. This is attributed to the majority of the light being confined within the glass, which increased with increasing external temperature due to a larger difference in the refractive index between the glass core and the water channel.

  3. CONFERENCE NOTE: CETO—Centro de Ciências e Tecnologias Opticas, Trends in Optical Fibre Metrology and Standards

    NASA Astrophysics Data System (ADS)

    1994-01-01

    Summer School, 27 June to 8 July 1994, Viana do Castelo, Hotel do Parque, Portugal Optical fibres, with their extremely low transmission loss, untapped bandwidth and controllable dispersion, dominate a broad range of technologies in which applications must respond to the increasing constraints of today's specifications as well as envisage future requirements. Optical fibres dominate communications systems. In the area of sensors, fibre optics will be fully exploited for their immunity to EMI, their high sensitivity and their large dynamic range. The maturity of single mode optical technology has led to intensive R&D of a range of components based on the advantages of transmission characteristics and signal processing. Specifications and intercompatibility requests for the new generation of both analogue and digital fibre optical components and systems has created a demand for sophisticated measuring techniques based on unique and complex instruments. In recent years there has been a signification evolution in response to the explosion of applications and the tightening of specifications. These developments justify a concerted effort to focus on trends in optical fibre metrology and standards. Objective The objective of this school is to provide a progressive and comprehensive presentation of current issues concerning passive and active optical fibre characterization and measurement techniques. Passive fibre components support a variety of developments in optical fibre systems and will be discussed in terms of relevance and standards. Particular attention will be paid to devices for metrological purposes such as reference fibres and calibration artefacts. The characterization and testing of optical fibre amplifiers, which have great potential in telecommunications, data distribution networks and as a system part in instrumentation, will be covered. Methods of measurement and means of calibration with traceability will be discussed, together with the characterization

  4. Dense central office solution for point-to-point fibre access including a novel compact dual bi-directional fibre optical transceiver

    NASA Astrophysics Data System (ADS)

    Arvidsson, Gunnar; Junique, Stéphane; Persson, Karl-Åke; Sundberg, Erland

    2006-07-01

    The centralized Point-to-Point fibre access approach with a dedicated single mode optical fibre link connecting each customer to a Central Office (CO) has advantages regarding future-proofness, security, and simple and low-cost optical links and transceivers. The potential bottleneck in handling the large number of optical fibres that need to be terminated in the CO, and combined with optoelectronic components, has been studied within the IST 6th Framework Programme integrated project MUSE. The key parts in the CO are the passive cabinet where customer fibres are accessible through fibre connectors in the Optical Distribution Frame (ODF), and the active cabinet with switching equipment and optical transceivers. For the passive cabinet we conclude, that the most efficient solution is that each connection from the active cabinet to a customer passes only one ODF, and that small form factor connectors are used. For the active cabinet we have demonstrated the feasibility of an SFF-size module containing two bi-directional transceiver units by building and successfully testing a prototype, increasing the customer port density by a factor of two compared to commercial transceivers. The power consumption, which impacts power supply, cooling and cost, has been analyzed, and we propose measures to significantly decrease the power consumption.

  5. Acousto-optic devices for operation with 2μm fibre lasers

    NASA Astrophysics Data System (ADS)

    Ward, J. D.; Stevens, G.; Shardlow, P. C.

    2016-03-01

    Fibre lasers operating in the 2μm region are of increasing interest for a range of applications, including laser machining and biomedical systems. The large mode area compared to 1μm fibre lasers combined with operation in an "eye-safe" region of the spectrum makes them particularly attractive. When developing fibre lasers at 1μm and 1·5μm manufacturers were able to call upon enabling technologies used by the telecoms industry, but at longer wavelengths, including 2μm, many such components are either unavailable or immature. We report on recent developments of Acousto-Optic Modulators and Tunable Filters that are specifically optimised for use with fibre systems operating at or around 2μm. AO devices are interesting due to their ability to conserve spatial-coherence, making them appropriate for use with single-mode optical fibres. We describe how the choice of interaction medium is an important consideration, particularly affecting the drive power and the polarisation behaviour of the device - the latter being an important parameter when used in a fibre system. We also describe two designs of AO Tunable Filter intended for laser tuning. Both designs have been demonstrated intracavity in 2μm fibre lasers. The first gives exceptionally narrow resolution (δλ/λ<0·1%). The second design is of a novel type of AOTF where a matched pair of AOTFs is configured to give a substantially net zero frequency-shift with little or no loss of pointing stability, any minor deviations in manufacture being self-compensated. Furthermore, small controlled frequency-shifts (up to about 10kHz) may be introduced with little or no detriment to the alignment of the system.

  6. Deformation Measurement of a Driven Pile Using Distributed Fibre-optic Sensing

    NASA Astrophysics Data System (ADS)

    Monsberger, Christoph; Woschitz, Helmut; Hayden, Martin

    2016-03-01

    New developments in distributed fibre-optic sensing allow the measurement of strain with a very high precision of about 1 µm / m and a spatial resolution of 10 millimetres or even better. Thus, novel applications in several scientific fields may be realised, e. g. in structural monitoring or soil and rock mechanics. Especially due to the embedding capability of fibre-optic sensors, fibre-optic systems provide a valuable extension to classical geodetic measurement methods, which are limited to the surface in most cases. In this paper, we report about the application of an optical backscatter reflectometer for deformation measurements along a driven pile. In general, pile systems are used in civil engineering as an efficient and economic foundation of buildings and other structures. Especially the length of the piles is crucial for the final loading capacity. For optimization purposes, the interaction between the driven pile and the subsurface material is investigated using pile testing methods. In a field trial, we used a distributed fibre-optic sensing system for measuring the strain below the surface of an excavation pit in order to derive completely new information. Prior to the field trial, the fibre-optic sensor was investigated in the laboratory. In addition to the results of these lab studies, we briefly describe the critical process of field installation and show the most significant results from the field trial, where the pile was artificially loaded up to 800 kN. As far as we know, this is the first time that the strain is monitored along a driven pile with such a high spatial resolution.

  7. Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures

    NASA Astrophysics Data System (ADS)

    Perry, M.; Saafi, M.; Fusiek, G.; Niewczas, P.

    2015-04-01

    In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mɛ of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mɛ compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10-2 and -2 × 10-4 respectively. The typical strain resolution in the uniaxial sensor was 100 μ \\varepsilon . The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mɛ of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10-2 and 4 × 10-5 respectively. The biaxial sensor’s strain resolution was approximately 10 μ \\varepsilon in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.

  8. A review of recent advances in optical fibre sensors for in vivo dosimetry during radiotherapy

    PubMed Central

    O'Keeffe, S; McCarthy, D; Woulfe, P; Grattan, M W D; Hounsell, A R; Sporea, D; Mihai, L; Vata, I; Leen, G

    2015-01-01

    This article presents an overview of the recent developments and requirements in radiotherapy dosimetry, with particular emphasis on the development of optical fibre dosemeters for radiotherapy applications, focusing particularly on in vivo applications. Optical fibres offer considerable advantages over conventional techniques for radiotherapy dosimetry, owing to their small size, immunity to electromagnetic interferences, and suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based dosemeters, together with being lightweight and flexible, mean that they are minimally invasive and thus particularly suited to in vivo dosimetry. This means that the sensor can be placed directly inside a patient, for example, for brachytherapy treatments, the optical fibres could be placed in the tumour itself or into nearby critical tissues requiring monitoring, via the same applicators or needles used for the treatment delivery thereby providing real-time dosimetric information. The article outlines the principal sensor design systems along with some of the main strengths and weaknesses associated with the development of these techniques. The successful demonstration of these sensors in a range of different clinical environments is also presented. PMID:25761212

  9. Validation of an Endoscopic Fibre-Optic Pressure Sensor for Noninvasive Measurement of Variceal Pressure

    PubMed Central

    Sun, Bin; Kong, De-Run; Li, Su-Wen; Yu, Dong-Feng; Wang, Ging-Jing; Yu, Fang-Fang; Wu, Qiong; Xu, Jian-Ming

    2016-01-01

    In this study, the authors have developed endoscopic fibre-optic pressure sensor to detect variceal pressure and presented the validation of in vivo and in vitro studies, because the HVPG requires catheterization of hepatic veins, which is invasive and inconvenient. Compared with HVPG, it is better to measure directly the variceal pressure without puncturing the varices in a noninvasive way. PMID:27314010

  10. Measuring the Dispersion Curve of a PMMA-Fibre Optic Cable Using a Dye Laser

    ERIC Educational Resources Information Center

    Zorba, Serkan; Farah, Constantine; Pant, Ravi

    2010-01-01

    An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

  11. Surface plasmon resonance based fibre optic chemical sensor for the detection of cocaine

    NASA Astrophysics Data System (ADS)

    Nguyen, T. Hien; Sun, Tong; Grattan, Kenneth T. V.

    2016-05-01

    A surface plasmon based fibre-optic chemical sensor for the detection of cocaine has been developed using a molecularly imprinted polymer (MIP) film with embedded gold nanoparticles as the recognition element. The MIP was formed on the layer of gold thin film which was deposited on the surface of a fibre core. The sensing was based on swelling of the MIP film induced by analyte binding that shifted the resonance spectrum toward a shorter wavelength. The sensor exhibited a response to cocaine in the concentration range of 0 - 400 μM in aqueous acetonitrile mixtures. Selectivity for cocaine over other drugs has also been demonstrated.

  12. Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

    NASA Astrophysics Data System (ADS)

    Bogdanowicz, R.; Śmietana, M.; Gnyba, M.; Gołunski, Ł.; Ryl, J.; Gardas, M.

    2014-09-01

    In this paper, the growth of polycrystalline chemical vapour deposition (CVD) diamond thin films on fused silica optical fibres has been investigated. The research results show that the effective substrate seeding process can lower defect nucleation, and it simultaneously increases surface encapsulation. However, the growth process on glass requires high seeding density. The effects of suspension type and ultrasonic power were the specific objects of investigation. In order to increase the diamond density, glass substrates were seeded using a high-power sonication process. The highest applied power of sonotrode reached 72 W during the performed experiments. The two, most common diamond seeding suspensions were used, i.e. detonation nanodiamond dispersed in (a) dimethyl sulfoxide and (b) deionised water. The CVD diamond nucleation and growth processes were performed using microwave plasma assisted chemical vapour deposition system. Next, the seeding efficiency was determined and compared using the numerical analysis of scanning electron microscopy images. The molecular composition of nucleated diamond was examined with micro-Raman spectroscopy. The sp3/sp2 band ratio was calculated using Raman spectra deconvolution method. Thickness, roughness, and optical properties of the nanodiamond films in UV-vis wavelength range were investigated by means of spectroscopic ellipsometry. It has been demonstrated that the high-power sonication process can improve the seeding efficiency on glass substrates. However, it can also cause significant erosion defects at the fibre surface. We believe that the proposed growth method can be effectively applied to manufacture the novel optical fibre sensors. Due to high chemical and mechanical resistance of CVD diamond films, deposition of such films on the sensors is highly desirable. This method enables omitting the deposition of an additional adhesion interlayer at the glass-nanocrystalline interface, and thus potentially increases

  13. An investigation into the use of micro-Raman spectroscopy for the analysis of car paints and single textile fibres

    NASA Astrophysics Data System (ADS)

    Zięba-Palus, Janina; Wąs-Gubała, Jolanta

    2011-05-01

    Micro-Raman spectroscopy was applied to identification and differentiation between criminalistic traces such as micropaint chips and single fibres. The aim was to determine the degree of discrimination between fibres coloured by defined chemical dye classes and to differentiate between paint samples on the basis of pigment/dye content. Samples of coloured cotton fibres and samples of green car paints were examined. It was found that the majority of the obtained Raman spectra provided information about the main dyes present in the sample. However, in some cases fluorescence of the samples made dye identification impossible. Spectral libraries for examined paint samples and single fibres were created in order to facilitate quick recognition of similar forensic traces using this analytical method.

  14. Validation and qualification of surface-applied fibre optic strain sensors using application-independent optical techniques

    NASA Astrophysics Data System (ADS)

    Schukar, Vivien G.; Kadoke, Daniel; Kusche, Nadine; Münzenberger, Sven; Gründer, Klaus-Peter; Habel, Wolfgang R.

    2012-08-01

    Surface-applied fibre optic strain sensors were investigated using a unique validation facility equipped with application-independent optical reference systems. First, different adhesives for the sensor's application were analysed regarding their material properties. Measurements resulting from conventional measurement techniques, such as thermo-mechanical analysis and dynamic mechanical analysis, were compared with measurements resulting from digital image correlation, which has the advantage of being a non-contact technique. Second, fibre optic strain sensors were applied to test specimens with the selected adhesives. Their strain-transfer mechanism was analysed in comparison with conventional strain gauges. Relative movements between the applied sensor and the test specimen were visualized easily using optical reference methods, digital image correlation and electronic speckle pattern interferometry. Conventional strain gauges showed limited opportunities for an objective strain-transfer analysis because they are also affected by application conditions.

  15. Intensifying the response of distributed optical fibre sensors using 2D and 3D image restoration

    NASA Astrophysics Data System (ADS)

    Soto, Marcelo A.; Ramírez, Jaime A.; Thévenaz, Luc

    2016-03-01

    Distributed optical fibre sensors possess the unique capability of measuring the spatial and temporal map of environmental quantities that can be of great interest for several field applications. Although existing methods for performance enhancement have enabled important progresses in the field, they do not take full advantage of all information present in the measured data, still giving room for substantial improvement over the state-of-the-art. Here we propose and experimentally demonstrate an approach for performance enhancement that exploits the high level of similitude and redundancy contained on the multidimensional information measured by distributed fibre sensors. Exploiting conventional image and video processing, an unprecedented boost in signal-to-noise ratio and measurement contrast is experimentally demonstrated. The method can be applied to any white-noise-limited distributed fibre sensor and can remarkably provide a 100-fold improvement in the sensor performance with no hardware modification.

  16. Temperature sensitivity of Bragg gratings in PMMA and TOPAS microstructured polymer optical fibres

    NASA Astrophysics Data System (ADS)

    Webb, David J.; Kalli, Kyriacos; Zhang, Chi; Komodromos, Michael; Argyros, Alexander; Large, Maryanne; Emiliyanov, Grigoriy; Bang, Ole; Kjaer, Erik

    2008-04-01

    We report on the temperature response of FBGs recorded in pure PMMA and TOPAS holey fibres. The gratings are fabricated for operational use at near IR wavelengths, using a phase mask and a CW He-Cd laser operating at 325nm. The room temperature grating response is non-linear and characterized by quadratic behaviour for temperatures from room temperature to the glass transition temperature, and this permanent change is affected by the thermal history of the gratings. We also report the first FBG inscription in microstructured polymer optical fibres fabricated from TOPAS. This material is fully polymerized and has very low moisture absorption, leading to very good fibre drawing properties. Furthermore, although TOPAS is chemically inert and bio-molecules do not readily bind to its surface, treatment with Antraquinon and subsequent UV activation allows sensing molecules to be deposited in well defined spatial locations. When combined with grating technology this provides considerable potential for label-free bio-sensing.

  17. Intensifying the response of distributed optical fibre sensors using 2D and 3D image restoration

    PubMed Central

    Soto, Marcelo A.; Ramírez, Jaime A.; Thévenaz, Luc

    2016-01-01

    Distributed optical fibre sensors possess the unique capability of measuring the spatial and temporal map of environmental quantities that can be of great interest for several field applications. Although existing methods for performance enhancement have enabled important progresses in the field, they do not take full advantage of all information present in the measured data, still giving room for substantial improvement over the state-of-the-art. Here we propose and experimentally demonstrate an approach for performance enhancement that exploits the high level of similitude and redundancy contained on the multidimensional information measured by distributed fibre sensors. Exploiting conventional image and video processing, an unprecedented boost in signal-to-noise ratio and measurement contrast is experimentally demonstrated. The method can be applied to any white-noise-limited distributed fibre sensor and can remarkably provide a 100-fold improvement in the sensor performance with no hardware modification. PMID:26927698

  18. A Micro-Computed Tomography Technique to Study the Quality of Fibre Optics Embedded in Composite Materials

    PubMed Central

    Chiesura, Gabriele; Luyckx, Geert; Voet, Eli; Lammens, Nicolas; Van Paepegem, Wim; Degrieck, Joris; Dierick, Manuel; Van Hoorebeke, Luc; Vanderniepen, Pieter; Sulejmani, Sanne; Sonnenfeld, Camille; Geernaert, Thomas; Berghmans, Francis

    2015-01-01

    Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven. PMID:25961383

  19. A high-resolution integrated optical spectrometer with applications to fibre sensor signal processing

    NASA Astrophysics Data System (ADS)

    Varasi, M.; Signorazzi, M.; Vannucci, A.; Dunphy, Jim

    1996-02-01

    An integrated optical device has been developed to realize the instrumentation for the processing of the optical signal such as those from fibre optic Bragg grating sensors (FBG) embedded in composite materials. The optical circuit integrates on X-cut 0957-0233/7/2/009/img7 an acousto-optical TE - TM converter included between two crossed polarizers, in order to realize a tunable high-resolution optical filter. The design and fabrication process parameters and solutions adopted with the aim of obtaining very-high-resolution filters ( FWHM < 0.45 nm at 1300 nm) are discussed. The device has been demonstrated to allow the polarization-independent spectrum analysis of in-fibre optical radiation, exploiting the heterodyne detection of the optical signals from the output of the acousto-optical tunable filter. The application as instrumentation for the processing of optical signals from such sensors is described and the experimental results are presented for the monitoring of static and dynamic deformations of composite material structures such as those in which the FBG sensors have been embedded.

  20. Coherent tunnelling adiabatic passage in optical fibres using superimposed long-period fiber gratings

    NASA Astrophysics Data System (ADS)

    Thyagarajan, K.; Gupta, Ruchi

    2016-08-01

    In this paper, we present the optical analogue of stimulated Raman adiabatic passage (STIRAP) technique for three level atomic system in optical fibre geometry. Considering linearly polarized modes of an optical fibre, it is shown that using a pair of superimposed long-period gratings with peak refractive index perturbation varying spatially along the propagation axis, light can be transferred adiabatically from one core mode to another core mode via an intermediate cladding mode which itself does not get appreciably excited; thus acting like a dark mode. We compare the transmission spectrum of superimposed long-period gratings involved in adiabatic transfer with the transmission spectrum of conventional long-period grating. The analogue output is further analysed for its tolerance to the changes in the ambient refractive index, temperature and other fabrication parameters.

  1. Temporal spying and concealing process in fibre-optic data transmission systems through polarization bypass

    PubMed Central

    Bony, P.Y.; Guasoni, M.; Morin, P.; Sugny, D.; Picozzi, A.; Jauslin, H.R.; Pitois, S.; Fatome, J.

    2014-01-01

    Recent research has been focused on the ability to manipulate a light beam in such a way to hide, namely to cloak, an event over a finite time or localization in space. The main idea is to create a hole or a gap in the spatial or time domain so as to allow for an object or data to be kept hidden for a while and then to be restored. By enlarging the field of applications of this concept to telecommunications, researchers have recently reported the possibility to hide transmitted data in an optical fibre. Here we report the first experimental demonstration of perpetual temporal spying and blinding process of optical data in fibre-optic transmission line based on polarization bypass. We successfully characterize the performance of our system by alternatively copying and then concealing 100% of a 10-Gb s−1 transmitted signal. PMID:25135759

  2. Modulation instabilities in birefringent two-core optical fibres

    NASA Astrophysics Data System (ADS)

    Li, J. H.; Chiang, K. S.; Malomed, B. A.; Chow, K. W.

    2012-08-01

    Previous studies of the modulation instability (MI) of continuous waves (CWs) in a two-core fibre (TCF) did not consider effects caused by co-propagation of the two polarized modes in a TCF that possesses birefringence, such as cross-phase modulation (XPM), polarization-mode dispersion (PMD) and polarization-dependent coupling (PDC) between the cores. This paper reports an analysis of these effects on the MI by considering a linear-birefringence TCF and a circular-birefringence TCF, which feature different XPM coefficients. The analysis focuses on the MI of the asymmetric CW states in the TCFs, which have no counterparts in single-core fibres. We find that the asymmetric CW state exists when its total power exceeds a threshold (minimum) value, which is sensitive to the value of the XPM coefficient. We consider, in particular, a class of asymmetric CW states that admit analytical solutions. In the anomalous dispersion regime, without taking the PMD and PDC into account, the MI gain spectra of the birefringent TCF, if scaled by the threshold power, are almost identical to those of the zero-birefringence TCF. However, in the normal dispersion regime, the power-scaled MI gain spectra of the birefringent TCFs are distinctly different from their zero-birefringence counterparts, and the difference is particularly significant for the circular-birefringence TCF, which takes a larger XPM coefficient. On the other hand, the PMD and PDC only exert weak effects on the MI gain spectra. We also simulate the nonlinear evolution of the MI of the CW inputs in the TCFs and obtain good agreement with the analytical solutions.

  3. Dynamic operation of optical fibres beyond the single-mode regime facilitates the orientation of biological cells

    PubMed Central

    Kreysing, Moritz; Ott, Dino; Schmidberger, Michael J.; Otto, Oliver; Schürmann, Mirjam; Martín-Badosa, Estela; Whyte, Graeme; Guck, Jochen

    2014-01-01

    The classical purpose of optical fibres is delivery of either optical power, as for welding, or temporal information, as for telecommunication. Maximum performance in both cases is provided by the use of single-mode optical fibres. However, transmitting spatial information, which necessitates higher-order modes, is difficult because their dispersion relation leads to dephasing and a deterioration of the intensity distribution with propagation distance. Here we consciously exploit the fundamental cause of the beam deterioration—the dispersion relation of the underlying vectorial electromagnetic modes—by their selective excitation using adaptive optics. This allows us to produce output beams of high modal purity, which are well defined in three dimensions. The output beam distribution is even robust against significant bending of the fibre. The utility of this approach is exemplified by the controlled rotational manipulation of live cells in a dual-beam fibre-optical trap integrated into a modular lab-on-chip system. PMID:25410595

  4. Dynamic operation of optical fibres beyond the single-mode regime facilitates the orientation of biological cells

    NASA Astrophysics Data System (ADS)

    Kreysing, Moritz; Ott, Dino; Schmidberger, Michael J.; Otto, Oliver; Schürmann, Mirjam; Martín-Badosa, Estela; Whyte, Graeme; Guck, Jochen

    2014-11-01

    The classical purpose of optical fibres is delivery of either optical power, as for welding, or temporal information, as for telecommunication. Maximum performance in both cases is provided by the use of single-mode optical fibres. However, transmitting spatial information, which necessitates higher-order modes, is difficult because their dispersion relation leads to dephasing and a deterioration of the intensity distribution with propagation distance. Here we consciously exploit the fundamental cause of the beam deterioration—the dispersion relation of the underlying vectorial electromagnetic modes—by their selective excitation using adaptive optics. This allows us to produce output beams of high modal purity, which are well defined in three dimensions. The output beam distribution is even robust against significant bending of the fibre. The utility of this approach is exemplified by the controlled rotational manipulation of live cells in a dual-beam fibre-optical trap integrated into a modular lab-on-chip system.

  5. Large-field-of-view laser-scanning OR-PAM using a fibre optic sensor

    NASA Astrophysics Data System (ADS)

    Allen, T. J.; Zhang, E.; Beard, P. C.

    2015-03-01

    Laser-Scanning-Optical-Resolution Photoacoustic Microscopy (LSOR-PAM) requires an ultrasound detector with a low noise equivalent pressure (NEP) and a large angular detection aperture in order to image a large field of view (FOV). It is however challenging to meet these requirements when using piezoelectric receivers since using a small sensing element size (<100μm) in order to achieve a large angular detection aperture will inevitability reduce the sensitivity of the detector as it scales with decreasing element size. Fibre optic ultrasound sensors based on a Fabry Perot cavity do not suffer from this limitation and can provide high detection sensitivity (NEP<0.1kPa over a 20 MHz measurement bandwidth) with a large angular detection aperture due to their small active element size (~10μm). A LSOR-PAM system was developed and combined with this type of fibre optic ultrasound sensor. A set of phantom studies were undertaken. The first study demonstrated that a high resolution image over a large field of view (Ø11mm) could be obtained with a sampledetector separation of only 1.6mm. In the second study, a 12μm diameter tube filled with methylene blue whose absorption coefficient was similar to that of blood was visualised demonstrating that the fibre optic sensor could provide sufficient SNR for in-vivo microvascular OR-PAM imaging. These preliminary results suggest that the fibre optic sensor has the potential to outperform piezoelectric detectors for Laser-Scanning Optical Resolution Photoacoustic Microscopy (LSOR-PAM).

  6. Optical spectroscopy for food and beverages control

    NASA Astrophysics Data System (ADS)

    Mignani, Anna Grazia; Ciaccheri, Leonardo; Mencaglia, Andrea Azelio

    2011-08-01

    A selection of spectroscopy-based, fiber optic and micro-optic devices is presented. They have been designed and tested for monitoring the quality and safety of typical foodstuffs. The VIS-NIR spectra, considered as product fingerprints, allowed to discriminating the geographic region of production and to detecting nutritional and nutraceutic indicators.

  7. Optical spectroscopy for food and beverages control

    NASA Astrophysics Data System (ADS)

    Mignani, Anna Grazia; Ciaccheri, Leonardo; Mencaglia, Andrea Azelio

    2010-12-01

    A selection of spectroscopy-based, fiber optic and micro-optic devices is presented. They have been designed and tested for monitoring the quality and safety of typical foodstuffs. The VIS-NIR spectra, considered as product fingerprints, allowed to discriminating the geographic region of production and to detecting nutritional and nutraceutic indicators.

  8. Noise spectroscopy of an optical microresonator

    SciTech Connect

    Kozlov, G. G.

    2013-05-15

    The noise spectrum is calculated for the intensity of light transmitted through an optical microresonator whose thickness experiences thermal oscillations. The noise spectrum reveals a maximum at the frequency of an acoustic mode localized in the optical microresonator and depends on the size of the illuminated region. The noise intensity estimates show that it can be detected by the modern noise spectroscopy technique.

  9. The applications of fibre optics in gas turbine engine instrumentation

    NASA Astrophysics Data System (ADS)

    Davidson, I.

    1984-05-01

    Fiber optic instrumentation in aircraft engines is reviewed. Data transmission, endoscopy, flame detection, radiation pyrometry, laser anemometry, blade tip clearance sensors, and pinhole cameras are described.

  10. Suppression of side lobes in a spectrum of fibre Bragg gratings due to the transverse displacement of phase mask with respect to the optical fibre

    SciTech Connect

    Abdullina, S R; Nemov, I N; Babin, Sergei A

    2012-09-30

    The possibility of apodisation of fibre Bragg gratings (FBGs) recorded in the interference region of two Gaussian beams in the phase-mask scheme is considered. The FBG reflection spectra are numerically simulated for different values of recordingbeam parameters and the distance between the axes of interfering beams diffracted into different orders, which is varied by transverse displacement of the phase mask with respect to the optical fibre. Suppression of side lobes and smoothing out of the FBG spectrum with an increase in the transverse displacement of the phase mask is experimentally demonstrated. It is shown that this effect is caused by the equalisation of the mean induced refractive index in the FBG region. (optical fibres, lasers and amplifiers. properties and applications)

  11. Characteristics of optimized fibre-optic ultrasound receivers for minimally invasive photoacoustic detection

    NASA Astrophysics Data System (ADS)

    Zhang, Edward Z.; Beard, Paul C.

    2015-03-01

    A range of miniature (125μm o.d.) fibre optic ultrasound sensors based on the use of interferometric polymer optical cavities has been developed for minimally invasive photoacoustic imaging and sensing applications. It was observed that by careful selection of both the fibre tip and cavity geometry it is possible to achieve exceptional acoustic performance. Specifically, rounding the tip of the fibre to remove the presence of sharp diffractive boundaries enables a well behaved frequency response along with a near omnidirectional response at frequencies in the tens of MHz range to be achieved. The use of a plano-convex rather than a planar cavity provides high finesse and therefore detection sensitivity. Thus, by using a plano-convex cavity formed at the tip of radiused single mode fibre it was possible to realise a miniature ultrasound detector with a bandwidth of 80MHz, a noise-equivalent pressure of 40Pa (over a 20MHz measurement bandwidth) and a near omnidirectional response at frequencies as high as 30MHz. These characteristics suggest this type of sensor could find applications in interventional medicine for guiding needles or catheters, as mechanically scanned photoacoustic imaging probes or in laser scanning OR-PAM.

  12. Optical fibre Fabry–Perot relative humidity sensor based on HCPCF and chitosan film

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohui; Jiang, Mingshun; Sui, Qingmei; Geng, Xiangyi

    2016-09-01

    An optical fibre Fabry-Perot interferometer (FPI) sensor for relative humidity (RH) measurement is proposed. The FPI is formed by splicing a short section of hollow-core photonic crystal fibre(HCPCF) to single mode fibre and covering a chitosan film at the end of HCPCF. The refractive index of chitosan and film thickness will change with ambient RH, leading to the change in the reflected interference spectrum of FPI. RH response of the FPI sensor is analysed theoretically and demonstrated experimentally. It shows nonlinear response to RH values from 35 to 95%RH. The interference fringe shifts to shorter wavelength as RH increases with a maximum sensitivity of 0.28 nm/%RH at high RH level. And the fringe contrast also decreases as RH increases with an available maximum sensitivity of 0.5 dB/%RH. The sensor shows good stability and fast response time less than 1 min. With its advantages of compact structure, good performance, simple and safe fabrication, the proposed optical fibre FPI sensor has great potential for RH sensing.

  13. Cavitation Detection Using a Fibre-Optic Hydrophone: A Pilot Study

    NASA Astrophysics Data System (ADS)

    Bull, V.; Civale, J.; Rivens, I.; ter Haar, G. R.

    2011-09-01

    A fibre-optic hydrophone has been used to detect broadband acoustic emissions associated with inertial cavitation activity. Its potential for this application has been investigated in tap water and in agar gels, and compared with signals from a passive cavitation detector (PCD) and a microphone detecting audible frequency emissions. Processing of the fibre-optic hydrophone data to find the total RMS voltage over an integrated frequency range of 15-20 MHz gives a high signal to noise ratio, comparable with that of the PCD. The sensitivity and effective field of view of the fibre tip appear sufficient for detecting even low level cavitation activity, however the precise directional response has yet to be assessed. Emissions from acoustic cavitation in tap water and agar gel from peak negative pressures reaching 5.8 and 3.5 MPa respectively were detectable when the fibre was up to 20 mm and 2 mm respectively from the acoustic axis, whilst retaining a high signal to noise ratio.

  14. High-throughput imaging of self-luminous objects through a single optical fibre.

    PubMed

    Barankov, Roman; Mertz, Jerome

    2014-01-01

    Imaging through a single optical fibre offers attractive possibilities in many applications such as micro-endoscopy or remote sensing. However, the direct transmission of an image through an optical fibre is difficult because spatial information is scrambled upon propagation. We demonstrate an image transmission strategy where spatial information is first converted to spectral information. Our strategy is based on a principle of spread-spectrum encoding, borrowed from wireless communications, wherein object pixels are converted into distinct spectral codes that span the full bandwidth of the object spectrum. Image recovery is performed by numerical inversion of the detected spectrum at the fibre output. We provide a simple demonstration of spread-spectrum encoding using Fabry-Perot etalons. Our technique enables the two-dimensional imaging of self-luminous (that is, incoherent) objects with high throughput in principle independent of pixel number. Moreover, it is insensitive to fibre bending, contains no moving parts and opens the possibility of extreme miniaturization. PMID:25410902

  15. Optically stimulated differential impedance spectroscopy

    DOEpatents

    Maxey, Lonnie C; Parks, II, James E; Lewis, Sr., Samuel A; Partridge, Jr., William P

    2014-02-18

    Methods and apparatuses for evaluating a material are described. Embodiments typically involve use of an impedance measurement sensor to measure the impedance of a sample of the material under at least two different states of illumination. The states of illumination may include (a) substantially no optical stimulation, (b) substantial optical stimulation, (c) optical stimulation at a first wavelength of light, (d) optical stimulation at a second wavelength of light, (e) a first level of light intensity, and (f) a second level of light intensity. Typically a difference in impedance between the impedance of the sample at the two states of illumination is measured to determine a characteristic of the material.

  16. A Fibre-Optic Communications Network for Teaching Clinical Medicine.

    ERIC Educational Resources Information Center

    Williams, Robin

    1985-01-01

    Describes an interactive television system based on fiber-optic communications technology which is used to facilitate participation by University of London medical students in lecture/tutorials by teachers in different hospital locations. Highlights include advantages of fiber-optics, cable manufacture and installation, opto-electronic interface,…

  17. Direct single-mode fibre-coupled miniature White cell for laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Kühnreich, Benjamin; Höh, Matthias; Wagner, Steven; Ebert, Volker

    2016-02-01

    We present the design, setup, and characterization of a new lens-free fibre-coupled miniature White cell for extractive gas analysis using direct tunable diode laser absorption spectroscopy (dTDLAS). The construction of this cell is based on a modified White cell design and allows for an easy variation of the absorption length in the range from 29 cm to 146 cm. The design avoids parasitic absorption paths outside the cell by using direct, lensless fibre coupling and allows small physical cell dimensions and cell volumes. To characterize the cell performance, different H2O and CH4 concentration levels were measured using dTDLAS. Detection limits of 2.5 ppm ṡ m for CH4 (at 1.65 μm) and 1.3 ppm ṡ m for H2O (at 1.37 μm) were achieved. In addition, the gas exchange time and its flow-rate dependence were determined for both species and found to be less than 15 s for CH4 and up to a factor of thirteen longer for H2O.

  18. Optics and Spectroscopy at Surfaces and Interfaces

    NASA Astrophysics Data System (ADS)

    Bordo, Vladimir G.; Rubahn, Horst-Günter

    2005-10-01

    This book covers linear and nonlinear optics as well as optical spectroscopy at solid surfaces and at interfaces between a solid and a liquid or gas. The authors give a concise introduction to the physics of surfaces and interfaces. They discuss in detail physical properties of solid surfaces and of their interfaces to liquids and gases and provide the theoretical background for understanding various optical techniques. The major part of the book is dedicated to a broad review on optical techniques and topical applications such as infrared and optical spectroscopy or optical microscopy. Discussions of nonlinear optics, but also nano-optics and local spectroscopy complement this self-contained work. Helpful features include about 50 problems with solutions, a glossary and a thoroughly elaborated list of topical references. The book is suited as a text for graduate students but also for scientists working in physics, chemistry, materials or life sciences who look for an expert introduction to surface optical aspects of their studies.

  19. Optical fibre-based goniometer for sensing patient position and movement within a magnetic resonance scanner using chromatic modulation.

    PubMed

    Scully, P J; Holmes, R; Jones, G R

    1993-01-01

    An optical fibre-based goniometer is described. This instrument was designed to measure the angular position of patients' limbs within the core of a magnetic resonance body scanner, via a 40 m remote fibre-optic link. The sensor exploits the advantages of optical fibre-based sensing, which include immunity to electromagnetic interference, intrinsic safety and chemical immunity. The detection electronics and signal processing are based on the principles of chromatic modulation, an inexpensive, intensity-independent technique in which a change in the spectral power distribution is measured over a broad bandwidth, by photodetectors with differing spectral responses. The optical fibre goniometer has an angular range of 90 degrees, with an average resolution of 2'. The long-term accuracy is within +/- 1 degree, the specified accuracy for the physiological application. PMID:8326506

  20. Research of dispersion slope parameters of single-mode optical fibres depending on radius of a fibre and height of refractive index profile

    NASA Astrophysics Data System (ADS)

    Andreev, Roman V.; Praporshchikov, Denis E.

    2005-06-01

    At the solution of a problem of synthesis of refractive index profile of optical fibres with the set dispersive characteristics by optimization methods it is important at formation of initial conditions with the maximal accuracy to come nearer to a global minimum. It demands preliminary research of dependences of chromatic dispersion slopes from parameters of refractive index profile ofan optical fibre. In the given job results of theoretical researches of chromatic dispersion slopes, its parameters (wavelength of zero dispersion, an inclination of the spectral characteristic) are submitted depending on core radius and profile height. For calculations of dispersion the known analytical expressions received on the basis of the modified Gaussian approximation method were used. Calculations have been executed for single-mode optical fibres with a step, triangular and parabolic refractive index profile in a working range of wavelengths of CWDM systems. The received results allow to predict tendencies of chromatic dispersion changes, give quantitative ratings of its spectral characteristics changes depending on the form and parameters ofrefractive index profile of an optical fibre.

  1. A highly versatile optical fibre vacuum feed-through

    NASA Astrophysics Data System (ADS)

    Davidson, Ian A.; Azzouz, Hatim; Hueck, Klaus; Bourennane, Mohamed

    2016-05-01

    Coupling light into a vacuum system is a non-trivial problem, requiring the use of a specialized feed-through. This feed-through must be both leak tight and offer a low optical loss if it is to be suitable for general use. In this paper, we report on the development of an extremely simple yet versatile, low cost, demountable optical fiber vacuum feed-through based on the modification of a standard optical fiber bulkhead connector. The modified connector was found to have a leak rate of 6.6 ± 2.1 × 10-6 mbar l/s and an optical loss of -0.41 ± 0.28 dB, making it suitable for use in high vacuum applications.

  2. Novel fibre-optic-based ionization radiation probes

    NASA Astrophysics Data System (ADS)

    Jackson, David A.

    2004-06-01

    CsI ionization radiation probes interrogated via a fiber optic transceiver link for monitoring medical procedures such as Intensity Modulated Radiotherapy, Brachytherapy and Nuclear Medicine are presented together with potential industrial, environmental and military applications.

  3. Direct optical activation of skeletal muscle fibres efficiently controls muscle contraction and attenuates denervation atrophy

    PubMed Central

    Magown, Philippe; Shettar, Basavaraj; Zhang, Ying; Rafuse, Victor F.

    2015-01-01

    Neural prostheses can restore meaningful function to paralysed muscles by electrically stimulating innervating motor axons, but fail when muscles are completely denervated, as seen in amyotrophic lateral sclerosis, or after a peripheral nerve or spinal cord injury. Here we show that channelrhodopsin-2 is expressed within the sarcolemma and T-tubules of skeletal muscle fibres in transgenic mice. This expression pattern allows for optical control of muscle contraction with comparable forces to nerve stimulation. Force can be controlled by varying light pulse intensity, duration or frequency. Light-stimulated muscle fibres depolarize proportionally to light intensity and duration. Denervated triceps surae muscles transcutaneously stimulated optically on a daily basis for 10 days show a significant attenuation in atrophy resulting in significantly greater contractile forces compared with chronically denervated muscles. Together, this study shows that channelrhodopsin-2/H134R can be used to restore function to permanently denervated muscles and reduce pathophysiological changes associated with denervation pathologies. PMID:26460719

  4. Plastic optical fibre sensor for in-vivo radiation monitoring during brachytherapy

    NASA Astrophysics Data System (ADS)

    Woulfe, P.; Sullivan, F. J.; Lewis, E.; O'Keeffe, S.

    2015-09-01

    An optical fibre sensor is presented for applications in real-time in-vivo monitoring of the radiation dose a cancer patient receives during seed implantation in Brachytherapy. The sensor is based on radioluminescence whereby radiation sensitive scintillation material is embedded in the core of a 1mm plastic optical fibre. Three scintillation materials are investigated: thallium-doped caesium iodide (CsI:Tl), terbium-doped gadolinium oxysulphide (Gd2O2S:Tb) and europium-doped lanthanum oxysulphide (La2O2S:Eu). Terbium-doped gadolinium oxysulphide was identified as being the most suitable scintillator and further testing demonstrates its measureable response to different activities of Iodine-125, the radio-active source commonly used in Brachytherapy for treating prostate cancer.

  5. Applications Of A Fibre Optic TV Holography System To The Study Of Large Automotive Structures.

    NASA Astrophysics Data System (ADS)

    Davies, Jeremy C.; Buckberry, Clive H.

    1990-04-01

    Mono-mode fibre optic components, including directional couplers and piezo-electric phase control elements, have been used to construct a TV holography system. The instrument has advantages of simplicity and ruggedness of construction and, with a 40m fibre optic link to a 600m argon ion laser, has proved to be an ideal tool for studying the structural behaviour of automotive assemblies. The TV holography system is described and two examples presented of its use: analysis of the deformation of a petrol engine cylinder bore due to head bolt forces, and the vibration study of a vehicle bodyshell subjected to wheel induced inputs. Limitations in the application of the technique are identified and future work to address these shortcomings outlined.

  6. GENERAL: Experimental Investigation on a Fibre-Optic Hydrophone with a Cylindrical Helmholtz Resonator

    NASA Astrophysics Data System (ADS)

    Wang, Ze-Feng; Hung, Yong-Ming; Meng, Zhou; Ni, Ming

    2008-05-01

    A novel mechanical anti-aliasing filtering fibre-optic hydrophone with a cylindrical Helmholtz resonator is constructed and tested. The experimental results show that the hydrophone has a function of low-pass filtering. The low frequency acoustic sensitivity is about -160 dB (1 rad/μPa), and the response curve has a resonance determined by the Helmholtz resonator. Theoretical and experimental results both show that the resonant frequency moves towards high frequency with the increasing orifice diameters. The sensitivity attenuation of high frequency is larger than 10 dB. This new fibre-optic hydrophone is a prototype device for a class of sensors used to eliminate the aliasing in future sonar systems.

  7. Study on the Sensing Coating of the Optical Fibre CO2 Sensor

    PubMed Central

    Wysokiński, Karol; Napierała, Marek; Stańczyk, Tomasz; Lipiński, Stanisław; Nasiłowski, Tomasz

    2015-01-01

    Optical fibre carbon dioxide (CO2) sensors are reported in this article. The principle of operation of the sensors relies on the absorption of light transmitted through the fibre by a silica gel coating containing active dyes, including methyl red, thymol blue and phenol red. Stability of the sensor has been investigated for the first time for an absorption based CO2 optical fiber sensor. Influence of the silica gel coating thickness on the sensitivity and response time has also been studied. The impact of temperature and humidity on the sensor performance has been examined too. Response times of reported sensors are very short and reach 2–3 s, whereas the sensitivity of the sensor ranges from 3 to 10 for different coating thicknesses. Reported parameters make the sensor suitable for indoor and industrial use. PMID:26694412

  8. Continuous-wave parametric oscillation in polarisation-maintaining optical fibre

    SciTech Connect

    Zlobina, E A; Kablukov, S I; Babin, Sergei A

    2011-09-30

    Continuous-wave parametric oscillation in a polarisation-maintaining optical fibre has been achieved for the first time using polarisation phase matching. Up-conversion with a frequency shift of {approx}8.6 THz has been demonstrated experimentally. The single-pass optical power generated at 1017 nm in a 85-m-long Nufern PM980-XP fibre exceeded 40 mW. The conversion efficiency was 3.3%, which is an order of magnitude higher than that reported previously for cw parametric up-conversion in the 1-{mu}m spectral region. We compare theoretical predictions with experimental data and analyse factors that may influence output power saturation with increasing signal and pump powers.

  9. Distributed optical fibre temperature measurements in a low dose rate radiation environment based on Rayleigh backscattering

    NASA Astrophysics Data System (ADS)

    Faustov, A.; Gussarov, A.; Wuilpart, M.; Fotiadi, A. A.; Liokumovich, L. B.; Kotov, O. I.; Zolotovskiy, I. O.; Tomashuk, A. L.; Deschoutheete, T.; Mégret, P.

    2012-04-01

    On-line monitoring of environmental conditions in nuclear facilities is becoming a more and more important problem. Standard electronic sensors are not the ideal solution due to radiation sensitivity and difficulties in installation of multiple sensors. In contrast, radiation-hard optical fibres can sustain very high radiation doses and also naturally offer multi-point or distributed monitoring of external perturbations. Multiple local electro-mechanical sensors can be replaced by just one measuring fibre. At present, there are over four hundred operational nuclear power plants (NPPs) in the world 1. Operating experience has shown that ineffective control of the ageing degradation of major NPP components can threaten plant safety and also plant life. Among those elements, cables are vital components of I&C systems in NPPs. To ensure their safe operation and predict remaining life, environmental monitoring is necessary. In particular, temperature and radiation dose are considered to be the two most important parameters. The aim of this paper is to assess experimentally the feasibility of optical fibre temperature measurements in a low doserate radiation environment, using a commercially available reflectometer based on Rayleigh backscattering. Four different fibres were installed in the Sub-Pile Room of the BR2 Material testing nuclear reactor in Mol, Belgium. This place is man-accessible during the reactor shut-down, allowing easy fibre installation. When the reactor operates, the dose-rates in the room are in a range 0.005-5 Gy/h with temperatures of 40-60 °C, depending on the location. Such a surrounding is not much different to some "hot" environments in NPPs, where I&C cables are located.

  10. Photoinduced and thermal reactions involving hydrogen in high-germania-core optical fibres

    SciTech Connect

    Rybaltovskii, A O; Koltashev, V V; Medvedkov, O I; Rybaltovsky, A A; Sokolov, V O; Plotnichenko, V G; Dianov, Evgenii M; Klyamkin, Semen N

    2008-12-31

    We report a Raman scattering study of photoinduced and thermal reactions between H{sub 2} and germanosilicate optical fibres with 22 mol % and 97 mol % GeO{sub 2} in the core (F1 and F2, respectively) after H{sub 2} loading at 150 MPa (1500 atm). The mechanisms of photoreactions are investigated in a wide range of incident laser wavelengths (244, 333, 354, 361 and 514 nm). Thermal reactions are studied at 500 {sup 0}C. The results indicate that the main mechanism behind the formation of hydrogen-containing defects with Raman bands at 700, 750, 2190, 3600 and 3680 cm{sup -1} involves {identical_to}Ge-O-Ge{identical_to} or {identical_to}Ge-O-Si{identical_to} bond breaking and formation of hydride and hydroxyl species: =GeH{sub 2} (700, 750 cm{sup -1}), {identical_to}Ge-H (2190 cm{sup -1}), {identical_to}GeO-H (3600 cm{sup -1}) and {identical_to}SiO-H (3680 cm{sup -1}). The key features of the reactions in the F1 and F2 fibres are analysed. In particular, photoinduced reactions give {identical_to}Si-OH groups only in the F1 fibres, whereas the formation of germanium nanoclusters at a relatively low temperature ({approx}500 {sup 0}C) or {identical_to}GeO-H and {identical_to}Ge-H defects under 514-nm irradiation has only been observed in the F2 fibres. (optical fibres)

  11. The radiation tolerance of MTP and LC optical fibre connectors to 500 kGy(Si) of gamma radiation

    NASA Astrophysics Data System (ADS)

    Hall, D. C.; Hamilton, P.; Huffman, B. T.; Teng, P. K.; Weidberg, A. R.

    2012-04-01

    The LHC luminosity upgrade, known as the High Luminosity LHC (HL-LHC), will require high-speed optical links to read out data from the detectors. The optical fibre connectors contained within such a link must have a small form factor and be capable of operating in the harsh radiation environment at the HL-LHC. MTP ribbon fibre connectors and LC single fibre connectors were exposed to 500 kGy(Si) of gamma radiation and their radiation hardness was investigated. Neither type of connector exhibited evidence for any significant radiation damage and both connectors could be qualified for use at HL-LHC detectors.

  12. Dissolved oxygen sensing using an optical fibre long period grating coated with hemoglobin

    NASA Astrophysics Data System (ADS)

    Partridge, M.; James, S. W.; Tatam, R. P.

    2015-09-01

    A method for the preparation of a sensor consisting of an optical fibre long period grating coated with human hemoglobin is described. The utility of this sensor in detecting dissolved oxygen in phosphate buffered saline solution, by the conversion of the coated hemoglobin from deoxyhemoglobin to oxyhemoglobin, is described. The sensor shows good repeatability with a %CV of less than 1% for oxygenated and deoxygenated states and no drift or hysteresis with repeated cycling.

  13. A Novel Approach to the Sensing of Liquid Density Using a Plastic Optical Fibre Cantilever Beam

    ERIC Educational Resources Information Center

    Kulkarni, Atul; Kim, Youngjin; Kim, Taesung

    2009-01-01

    This article reports for the first time the use of a plastic optical fibre (POF) cantilever beam to measure the density of a liquid. The sensor is based on the Archimedes buoyancy principle. The sensor consists of a POF bonded on the surface of a metal beam in the form of a cantilever configuration, and at the free end of the beam a displacer is…

  14. Minimizing inter-channel cross-phase modulation with optical phase conjugation in asymmetric fibre links.

    PubMed

    Hesketh, Graham D; Petropoulos, Periklis

    2016-09-01

    Using analytic and numerical modelling of fibre transmission systems that employ optical phase conjugation (OPC), we show inter-channel cross-phase modulation depends on the integrated square error between nonlinear profiles before and after OPC and that arranging amplifiers and tuning power levels is crucial to minimizing noise. We derive modulation transparent formulas for phase noise and optimal power settings. Examples are shown for 16 and 64 quadrature amplitude modulation. PMID:27607633

  15. 3D printed sensing patches with embedded polymer optical fibre Bragg gratings

    NASA Astrophysics Data System (ADS)

    Zubel, Michal G.; Sugden, Kate; Saez-Rodriguez, D.; Nielsen, K.; Bang, O.

    2016-05-01

    The first demonstration of a polymer optical fibre Bragg grating (POFBG) embedded in a 3-D printed structure is reported. Its cyclic strain performance and temperature characteristics are examined and discussed. The sensing patch has a repeatable strain sensitivity of 0.38 pm/μepsilon. Its temperature behaviour is unstable, with temperature sensitivity values varying between 30-40 pm/°C.

  16. Nonlinear dynamics of optical pulses in fibres with a travelling refractive-index-change wave

    SciTech Connect

    Adamova, M S; Zolotovskii, Igor' O; Sementsov, Dmitrii I

    2009-03-31

    Dynamics of soliton-like wave packets in fibres with a travelling refractive-index-change wave is studied. It is shown that both a soliton-like propagation regime of a pulse and a self-compression regime in the region of normal group velocity dispersion are possible. It is also shown that in the case of a copropagating or counterpropagating pulse and optically inhomogeneous wave nonreciprocal effects appear. (solitons)

  17. SOLITONS: Nonlinear dynamics of optical pulses in fibres with a travelling refractive-index-change wave

    NASA Astrophysics Data System (ADS)

    Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.

    2009-03-01

    Dynamics of soliton-like wave packets in fibres with a travelling refractive-index-change wave is studied. It is shown that both a soliton-like propagation regime of a pulse and a self-compression regime in the region of normal group velocity dispersion are possible. It is also shown that in the case of a copropagating or counterpropagating pulse and optically inhomogeneous wave nonreciprocal effects appear.

  18. Railway track component condition monitoring using optical fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Buggy, S. J.; James, S. W.; Staines, S.; Carroll, R.; Kitson, P.; Farrington, D.; Drewett, L.; Jaiswal, J.; Tatam, R. P.

    2016-05-01

    The use of optical fibre Bragg grating (FBG) strain sensors to monitor the condition of safety critical rail components is investigated. Fishplates, switchblades and stretcher bars on the Stagecoach Supertram tramway in Sheffield in the UK have been instrumented with arrays of FBG sensors. The dynamic strain signatures induced by the passage of a tram over the instrumented components have been analysed to identify features indicative of changes in the condition of the components.

  19. Evaluation of the optical switching characteristics of erbium-doped fibres for the development of a fibre Bragg grating sensor interrogator

    NASA Astrophysics Data System (ADS)

    Rigas, Evangelos; Correia, R.; Stathopoulos, N. A.; Savaidis, S. P.; James, S. W.; Bhattacharyya, D.; Kirby, P. B.; Tatam, R. P.

    2014-05-01

    A polling topology that employs optical switching based on the properties of erbium-doped fibres (EDFs) is used to interrogate an array of FBGs. The properties of the EDF are investigated in its pumped and un-pumped states and the EDFs' switching properties are evaluated by comparing them with a high performance electronically controlled MEM optical switch. Potential advantages of the proposed technique are discussed.

  20. Adaptive spatial carrier frequency method for fast monitoring optical properties of fibres

    NASA Astrophysics Data System (ADS)

    Sokkar, T. Z. N.; El-Farahaty, K. A.; El-Bakary, M. A.; Omar, E. Z.; Agour, M.; Hamza, A. A.

    2016-05-01

    We present an extension of the adaptive spatial carrier frequency method which is proposed for fast measuring optical properties of fibrous materials. The method can be considered as a two complementary steps. In the first step, the support of the adaptive filter shall be defined. In the second step, the angle between the sample under test and the interference fringe system generated by the utilized interferometer has to be determined. Thus, the support of the optical filter associated with the implementation of the adaptive spatial carrier frequency method is accordingly rotated. This method is experimentally verified by measuring optical properties of polypropylene (PP) fibre with the help of a Mach-Zehnder interferometer. The results show that errors resulting from rotating the fibre with respect to the interference fringes of the interferometer are reduced compared with the traditional band pass filter method. This conclusion was driven by comparing results of the mean refractive index of drown PP fibre at parallel polarization direction obtained from the new and adaptive spatial carrier frequency method.

  1. Sensitivity enhancement using annealed polymer optical-fibre-based sensors for pressure sensing applications

    NASA Astrophysics Data System (ADS)

    Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

    2016-05-01

    Thermal annealing can be used to induce a permanent negative Bragg wavelength shift for polymer fibre grating sensors and it was originally used for multiplexing purposes. Recently, researchers showed that annealing can also provide additional benefits, such as strain and humidity sensitivity enhancement and augmented temperature operational range. The annealing process can change both the optical and mechanical properties of the fibre. In this paper, the annealing effects on the stress and force sensitivities of PMMA fibre Bragg grating sensors are investigated. The incentive for that investigation was an unexpected behaviour observed in an array of sensors which were used for liquid level monitoring. One sensor exhibited much lower pressure sensitivity and that was the only one that was not annealed. To further investigate the phenomenon, additional sensors were photo-inscribed and characterised with regard their stress and force sensitivities. Then, the fibres were annealed by placing them in hot water, controlling with that way the humidity factor. After annealing, stress and force sensitivities were measured again. The results show that the annealing can improve the stress and force sensitivity of the devices. This can provide better performing sensors for use in stress, force and pressure sensing applications.

  2. Investigation of focal ratio degradation in optical fibres for astronomical instrumentation

    NASA Astrophysics Data System (ADS)

    Crause, Lisa; Bershady, Matthew; Buckley, David

    2008-07-01

    A differential method was used to investigate the focal ratio degradation (FRD) exhibited by, and throughput of, a selection of current-generation optical fibres. These fibres were tested to establish which would be best suited to feed the High Resolution Spectrograph being built for the Southern African Large Telescope (SALT), as well as for future instruments on WIYN and SALT. The double re-imaging system of Bershady et al. (2004) was substantially modified to improve image quality and measurement efficiency, and to permit a direct FRD-measurement in the far-field. The re-imaging method compares the beam profile produced by light which passes through a fibre to that which does not. Broad and intermediate band-pass filters were used between 400-800 nm to test for wavelength dependence in the observed FRD over a wide range in beam-speeds. Our results continue to be at odds with a mico-bend model for FRD. We conclude that the new Polymicro FBP fibre is the most suitable product for broadband applications.

  3. Fibre Optic Connections And Method For Using Same

    DOEpatents

    Chan, Benson; Cohen, Mitchell S.; Fortier, Paul F.; Freitag, Ladd W.; Hall, Richard R.; Johnson, Glen W.; Lin, How Tzu; Sherman, John H.

    2004-03-30

    A package is described that couples a twelve channel wide fiber optic cable to a twelve channel Vertical Cavity Surface Emitting Laser (VCSEL) transmitter and a multiple channel Perpendicularly Aligned Integrated Die (PAID) receiver. The package allows for reduction in the height of the assembly package by vertically orienting certain dies parallel to the fiber optic cable and horizontally orienting certain other dies. The assembly allows the vertically oriented optoelectronic dies to be perpendicularly attached to the horizontally oriented laminate via a flexible circuit.

  4. Fibre-optic thermometer using semiconductor-etalon sensor

    NASA Technical Reports Server (NTRS)

    Beheim, G.

    1986-01-01

    A fiber-optic thermometer is described which uses a thick-film SiC sensing etalon. The etalon's temperature-dependent phase shift is determined by analyzing its spectral reflectance, using an LED and a tunable Michelson interferometer. Temperatures from 20 to 1000 C are measured with better than 0.5 deg C resolution.

  5. High-Speed Optical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Marsh, T. R.

    The large surveys and sensitive instruments of modern astronomy are turning ever more examples of variable objects, many of which are extending the parameter space to testing theories of stellar evolution and accretion. Future projects such as the Laser Interferometer Space Antenna (LISA) and the Large Synoptic Survey Telescope (LSST) will only add more challenging candidates to this list. Understanding such objects often requires fast spectroscopy, but the trend for ever larger detectors makes this difficult. In this contribution I outline the science made possible by high-speed spectroscopy, and consider how a combination of the well-known progress in computer technology combined with recent advances in CCD detectors may finally enable it to become a standard tool of astrophysics.

  6. Fibre segment interferometry using code-division multiplexed optical signal processing for strain sensing applications

    NASA Astrophysics Data System (ADS)

    Kissinger, Thomas; Charrett, Thomas O. H.; Tatam, Ralph P.

    2013-09-01

    A novel optical signal processing scheme for multiplexing fibre segment interferometers is proposed. The continuous-wave, homodyne technique combines code-division multiplexing with single-sideband modulation. It uses only one electro-optic phase modulator to achieve both range separation and quadrature interferometric phase measurement. This scheme is applied to fibre segment interferometry, where a number of long-gauge length interferometric fibre sensors are formed by subtracting pairs of signals from equidistantly placed, weak back reflectors. In this work we give a detailed account of the signal processing involved and, in particular, explore aspects such as electronic bandwidth requirements, noise, crosstalk and linearity, which are important design considerations. A signal bandwidth of ±20 kHz permits the resolution of phase change rates of 2.5 × 104 rad s-1 for each of the four 16.5 m long segments in our setup. We show that dynamic strain resolutions below 0.2 nanostrain Hz-0.5 at 2 m sensor gauge length are achievable, even with an inexpensive diode laser. When used in applications that require only relative strain change measurements, this scheme compares well to more established techniques and can provide high-fidelity yet cost-effective measurements.

  7. Ge-doped optical fibres as thermoluminescence dosimeters for kilovoltage X-ray therapy irradiations

    NASA Astrophysics Data System (ADS)

    Issa, Fatma; Latip, Nur Atiqah Abd; Bradley, David A.; Nisbet, Andrew

    2011-10-01

    We investigate key dosimetric parameters for the thermoluminescence (TL) of Ge-doped silica optical fibres irradiated by X-rays generated at 90 and 300 kVp. The parameters include dose response, reproducibility and fading. Relative dose measurements were performed, obtaining central axis percentage depth dose (PDD) values, use being made of doped fibres irradiated in water and solid water phantoms. TL yields were compared with published data and ionisation chamber measurements. Linearity to dose was demonstrated over the investigated range (0.1-6 Gy), with reproducibility to within±2%. TL fading was found to be minimal, at <1.5% over a 12 h period. The RMI 457 solid water phantom correction factor was found to be 1.155±0.152 and 0.955±0.221 at 90 and 300 kVp, respectively. The maximum discrepancy between PDD values obtained using optical fibres and ionisation chamber measurements was 2.1% at 90 kVp, while the maximum discrepancy between tabulated data and measurements was 1.1% at 300 kVp.

  8. Characterization of Ge-doped optical fibres for MV radiotherapy dosimetry

    NASA Astrophysics Data System (ADS)

    Noor, Noramaliza M.; Hussein, M.; Kadni, T.; Bradley, D. A.; Nisbet, A.

    2014-05-01

    Ge-doped optical fibres offer promising thermoluminescence (TL) properties together with small physical size and modest cost. Their use as dosimeters for postal radiotherapy dose audits of megavoltage photon beams has been investigated. Key dosimetric characteristics including reproducibility, linearity, dose rate, temperature and angular dependence have been established. A methodology of measuring absorbed dose under reference conditions was developed. The Ge-doped optical fibres offer linearity between TL yield and dose, with a reproducibility of better than 5%, following repeated measurements (n=5) for doses from 5 cGy to 1000 cGy. The fibres also offer dose rate, angular and temperature independence, while an energy-dependent response of 7% was found over the energy range 6 MV to 15 MV (TPR20,10 of 0.660, 0.723 and 0.774 for 6, 10 and 15 MV respectively). The audit methodology has been developed with an expanded uncertainty of 4.22% at 95% confidence interval for the photon beams studied.

  9. Characterization of chemically and enzymatically treated hemp fibres using atomic force microscopy and spectroscopy

    NASA Astrophysics Data System (ADS)

    George, Michael; Mussone, Paolo G.; Abboud, Zeinab; Bressler, David C.

    2014-09-01

    The mechanical and moisture resistance properties of natural fibre reinforced composites are dependent on the adhesion between the matrix of choice and the fibre. The main goal of this study was to investigate the effect of NaOH swelling of hemp fibres prior to enzymatic treatment and a novel chemical sulfonic acid method on the physical properties of hemp fibres. The colloidal properties of treated hemp fibres were studied exclusively using an atomic force microscope. AFM imaging in tapping mode revealed that each treatment rendered the surface topography of the hemp fibres clean and exposed the individual fibre bundles. Hemp fibres treated with laccase had no effect on the surface adhesion forces measured. Interestingly, mercerization prior to xylanase + cellulase and laccase treatments resulted in greater enzyme access evident in the increased adhesion force measurements. Hemp fibres treated with sulfonic acid showed an increase in surface de-fibrillation and smoothness. A decrease in adhesion forces for 4-aminotoulene-3-sulfonic acid (AT3S) treated fibres suggested a reduction in surface polarity. This work demonstrated that AFM can be used as a tool to estimate the surface forces and roughness for modified fibres and that enzymatic coupled with chemical methods can be used to improve the surface properties of natural fibres for composite applications. Further, this work is one of the first that offers some insight into the effect of mercerization prior to enzymes and the effect on the surface topography. AFM will be used to selectively screen treated fibres for composite applications based on the adhesion forces associated with the colloidal interface between the AFM tip and the fibre surfaces.

  10. Characterization of alkali treated flax fibres by means of FT Raman spectroscopy and environmental scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Jähn, A.; Schröder, M. W.; Füting, M.; Schenzel, K.; Diepenbrock, W.

    2002-08-01

    Flax fibres grown under well managed conditions were submitted to NaOH chemical treatments, so called Mercerization. The extent of the polymorphic transformation of cellulose I into cellulose II taking place within the crystalline domains of the fibre cellulose was dependent on the alkali concentration. FT Raman spectroscopy turned out to represent an ideal tool for detecting the polymorphic transformation of the cellulosic fine structure of the flax fibres in vivo. In addition to the differences of the FT Raman spectra in the frequency range below 1500 cm -1, second derivatives of the spectra in the range of the CH stretching vibrations could also be used to distinguish the two polymorphic modifications. The intensity ratio R of the stretching modes νsCOC and νasCOC represents a spectral parameter characterising the molecular structure of the flax fibres. As a supplementary tool, Environmental scanning electron microscopy (ESEM) was used to visualize the microstructural fibre properties dependent on the alkali concentrations during the Mercerization.

  11. Few-cycle dissipative solitons in active nonlinear optical fibres

    SciTech Connect

    Rosanov, N N; Semenov, V E; Vysotina, N V

    2008-02-28

    The propagation of self-induced transparency video pulses is studied in a waveguide containing two-level atoms of two types, which can either amplify or absorb pulses. It is shown that the amplified pulse can be compressed down to the duration comparable with the inverse frequency of the atomic transition (a few femtoseconds) along with the increase in the peak amplitude. The mechanisms restricting the compression of amplified self-induced transparency pulses are analysed (the introduction of the third atomic level and the use of the Bragg grating of the waveguide refractive index). (nonlinear optical phenomena)

  12. Surface-bonded optical fibre sensors for the inspection of CFRP plates using ultrasonic Lamb waves

    NASA Astrophysics Data System (ADS)

    Pierce, S. G.; Philp, W. R.; Culshaw, B.; Gachagan, A.; McNab, A.; Hayward, G.; Lecuyer, F.

    1996-12-01

    Surface-bonded single-mode optical fibre sensors have been used to monitor the interaction of ultrasonic 0964-1726/5/6/007/img9 Lamb waves with defects in carbon fibre composite plates. Lamb waves were initiated using Perspex-coupled piezoelectric transducers. The defects investigated comprised holes, regions of impact damage and delaminations. Holes could be identified by analysing direct 0964-1726/5/6/007/img9 reflections and impact damage by 0964-1726/5/6/007/img9 back-wall echo amplitude. Large delaminations gave a poor direct 0964-1726/5/6/007/img9 reflection. Evidence was found for mode conversion at centre plane delaminations.

  13. Measurement of the thermal expansion of melt-textured YBCO using optical fibre grating sensors

    NASA Astrophysics Data System (ADS)

    Zeisberger, M.; Latka, I.; Ecke, W.; Habisreuther, T.; Litzkendorf, D.; Gawalek, W.

    2005-02-01

    In this paper we present measurements of the thermal expansion of melt-textured YBaCuO in the temperature range 30-300 K by means of optical fibre sensors. The sample, which had a size of 38 × 38 × 18 mm3, was prepared by our standard melt-texturing process using SmBaCuO seeds. One fibre containing three Bragg gratings which act as strain sensors was glued to the sample surface with two sensors parallel to the ab-plane and one sensor parallel to the c-axis. The sample was cooled down to a minimum temperature of 30 K in a vacuum chamber using a closed cycle refrigerator. In the temperature range we used, the thermal expansion coefficients are in the range of (3-9) × 10-6 K-1 (ab-direction) and (5-13) × 10-6 K-1 (c-direction).

  14. Review of optical breast imaging and spectroscopy.

    PubMed

    Grosenick, Dirk; Rinneberg, Herbert; Cubeddu, Rinaldo; Taroni, Paola

    2016-09-01

    Diffuse optical imaging and spectroscopy of the female breast is an area of active research. We review the present status of this field and discuss the broad range of methodologies and applications. Starting with a brief overview on breast physiology, the remodeling of vasculature and extracellular matrix caused by solid tumors is highlighted that is relevant for contrast in optical imaging. Then, the various instrumental techniques and the related methods of data analysis and image generation are described and compared including multimodality instrumentation, fluorescence mammography, broadband spectroscopy, and diffuse correlation spectroscopy. We review the clinical results on functional properties of malignant and benign breast lesions compared to host tissue and discuss the various methods to improve contrast between healthy and diseased tissue, such as enhanced spectroscopic information, dynamic variations of functional properties, pharmacokinetics of extrinsic contrast agents, including the enhanced permeability and retention effect. We discuss research on monitoring neoadjuvant chemotherapy and on breast cancer risk assessment as potential clinical applications of optical breast imaging and spectroscopy. Moreover, we consider new experimental approaches, such as photoacoustic imaging and long-wavelength tissue spectroscopy. PMID:27403837

  15. Astronomical optical frequency comb generation in nonlinear fibres and ring resonators: optimization studies

    NASA Astrophysics Data System (ADS)

    Chavez Boggio, J. M.; Fremberg, T.; Bodenmüller, D.; Wysmolek, M.; Sanyic, H.; Fernando, H.; Neumann, J.; Kracht, D.; Haynes, R.; Roth, M. M.

    2012-09-01

    We here discuss recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam. Two different platforms (and approaches) are numerically and experimentally investigated targeting medium and low resolution spectrographs at astronomical facilities in which innoFSPEC is currently involved. In the first approach, a frequency comb is generated by propagating two lasers through three nonlinear stages - the first two stages serve for the generation of low-noise ultra-short pulses, while the final stage is a low-dispersion highly-nonlinear fibre where the pulses undergo strong spectral broadening. In our approach, the wavelength of one of the lasers can be tuned allowing the comb line spacing being continuously varied during the calibration procedure - this tuning capability is expected to improve the calibration accuracy since the CCD detector response can be fully scanned. The input power, the dispersion, the nonlinear coefficient, and fibre lengths in the nonlinear stages are defined and optimized by solving the Generalized Nonlinear Schrodinger Equation. Experimentally, we generate the 250GHz line-spacing frequency comb using two narrow linewidth lasers that are adiabatically compressed in a standard fibre first and then in a double-clad Er/Yb doped fibre. The spectral broadening finally takes place in a highly nonlinear fibre resulting in an astro-comb with 250 calibration lines (covering a bandwidth of 500 nm) with good spectral equalization. In the second approach, we aim to generate optical frequency combs in dispersion-optimized silicon nitride ring resonators. A technique for lowering and flattening the chromatic dispersion in silicon nitride waveguides with silica cladding is proposed and demonstrated. By minimizing the waveguide dispersion in the resonator two goals are targeted: enhancing the phase matching for non-linear interactions and producing equally spaced resonances. For this purpose, instead of one cladding layer our design

  16. Ultra-deep Optical Spectroscopy with PMAS

    NASA Astrophysics Data System (ADS)

    Roth, M. M.; Fechner, T.; Wolter, D.; Kelz, A.; Becker, T.

    PMAS, the Potsdam Multi-Aperture Spectrophotometer, is a new integral field spectrograph in the optical, which is optimized for good transmission and high image quality from 350 nm to 1 mm. We present our plan to implement a CCD charge-shuffle mode to allow for beam switching with a very high degree of sky subtraction accuracy for faint object 3-D spectroscopy.

  17. Demonstration of Berry Phase in Optical Spectroscopy

    NASA Technical Reports Server (NTRS)

    Xia, Hui-Rong; Zhang, Yong; Jiang, Hong-Ji; Ding, Liang-En

    1996-01-01

    In this paper we demonstrate that the observed phase shift of the RF signal and its intensity dependence under extreme low pump and probe laser field conditions are dominated by Berry phase effect in optical spectroscopy with good adiabatic approximation, which provides all features' agreements between the theoretical and the experimental results.

  18. Improved multipass optics for diode laser spectroscopy

    SciTech Connect

    Hu, T.A.; Chappell, E.L.; Munley, J.T.; Sharpe, S.W. )

    1993-12-01

    Feedback between optical elements can be a major source of noise when trying to attain high sensitivity in infrared absorption experiments. We find that a conventional White-cell optical arrangement introduces etaloning fringes that modulate the peak-to-peak amplitude of our signals by 1 part in 16 666, a fractional change of 6[times]10[sup [minus]5]. Although relatively small, this noise'' is systematic and adds coherently with averaging, obscuring interesting absorption features. An easily constructed multipass optical system suited for performing high-resolution infrared spectroscopy in molecular beams is described. The design is based on a variation of the White cell and has been optimized for use with lead salt diode lasers. One of the key components in the improved design is the addition of an oscillating mirror for spoiling optical feedback generated by laser scatter and/or poor mode coupling of the laser to the multipass optics.

  19. Optical fibre multi-parameter sensing with secure cloud based signal capture and processing

    NASA Astrophysics Data System (ADS)

    Newe, Thomas; O'Connell, Eoin; Meere, Damien; Yuan, Hongwei; Leen, Gabriel; O'Keeffe, Sinead; Lewis, Elfed

    2016-05-01

    Recent advancements in cloud computing technologies in the context of optical and optical fibre based systems are reported. The proliferation of real time and multi-channel based sensor systems represents significant growth in data volume. This coupled with a growing need for security presents many challenges and presents a huge opportunity for an evolutionary step in the widespread application of these sensing technologies. A tiered infrastructural system approach is adopted that is designed to facilitate the delivery of Optical Fibre-based "SENsing as a Service- SENaaS". Within this infrastructure, novel optical sensing platforms, deployed within different environments, are interfaced with a Cloud-based backbone infrastructure which facilitates the secure collection, storage and analysis of real-time data. Feedback systems, which harness this data to affect a change within the monitored location/environment/condition, are also discussed. The cloud based system presented here can also be used with chemical and physical sensors that require real-time data analysis, processing and feedback.

  20. Guidelines for the characterization and use of fibre optic sensors: basic definitions and a proposed standard for FBG-based strain sensors

    NASA Astrophysics Data System (ADS)

    Habel, Wolfgang R.; Baumann, Ingolf; Berghmans, Francis; Borzycki, Krzysztof; Chojetzki, Christoph; Haase, Karl-Heinz; Jaroszewicz, Leszek R.; Kleckers, Thomas; Niklès, Marc; Rothhardt, Manfred; Schlüter, Vivien; Thévenaz, Luc; Tur, Moshe; Wuilpart, Marc

    2009-10-01

    This paper describes the outcome of two groups which are involved in the specification of guidelines for fibre optic sensors performance and testing. The "Guideline for use of fibre optic sensors" from the COST-299 guideline group, and the "Optical Strain Sensor based on Fibre Bragg Grating" from the GESA guideline group of the VDI - "The Association of German Engineers". Through appropriate specifications and definitions, both guidelines aim at enabling better understanding of fibre optic sensors characteristics and performances. A concise view into the structure of the guidelines is presented, emphasizing important aspects. The English version of the two guidelines will be available in autumn 2009.

  1. Get smart, go optical: example uses of optical fibre sensing technology for production optimisation and subsea asset monitoring

    NASA Astrophysics Data System (ADS)

    Staveley, Chris

    2014-06-01

    With the growth in deep-water oil and gas production, condition monitoring of high-value subsea assets to give early warning of developing problems is vital. Offshore operators can then transport and deploy spare parts before a failure occurs, so minimizing equipment down-time, and the significant costs associated with unscheduled maintenance. Results are presented from a suite of tests in which multiple elements of a subsea twin-screw pump and associated electric motor were monitored using a fibre optic sensing system based on fibre Bragg gratings (FBG) that simultaneously measured dynamic strain on the main rotor bearings, pressure and temperature of the lubricating oil, distributed temperature through the motor stator windings and vibration of the pump and motor housings.

  2. Further advancement of differential optical absorption spectroscopy: theory of orthogonal optical absorption spectroscopy.

    PubMed

    Liudchik, Alexander M

    2014-08-10

    A modified version of the differential optical absorption spectroscopy (DOAS) method is presented. The technique is called orthogonal optical absorption spectroscopy (OOAS). A widespread variant of DOAS with smoothing of the registered spectrum and absorption cross sections being made employing a polynomial regression is a particular case of OOAS. The concept of OOAS provides a variety of new possibilities for constructing computational schemes and analyzing the influence of different error sources on calculated concentrations. PMID:25320931

  3. Fibre optic sensors for temperature and pressure monitoring in laser ablation: experiments on ex-vivo animal model

    NASA Astrophysics Data System (ADS)

    Tosi, Daniele; Saccomandi, Paola; Schena, Emiliano; Duraibabu, Dinesh B.; Poeggel, Sven; Adilzhan, Abzal; Aliakhmet, Kamilla; Silvestri, Sergio; Leen, Gabriel; Lewis, Elfed

    2016-05-01

    Optical fibre sensors have been applied to perform biophysical measurement in ex-vivo laser ablation (LA), on pancreas animal phantom. Experiments have been performed using Fibre Bragg Grating (FBG) arrays for spatially resolved temperature detection, and an all-glass Extrinsic Fabry-Perot Interferometer (EFPI) for pressure measurement. Results using a Nd:YAG laser source as ablation device, are presented and discussed.

  4. Polymeric fibre optic sensor based on a SiO2 nanoparticle film for humidity sensing on wounds

    NASA Astrophysics Data System (ADS)

    Gomez, David; Morgan, Stephen P.; Hayes Gill, Barrie R.; Korposh, Serhiy

    2016-05-01

    Optical fibre sensors have the potential to be incorporated into wound dressings to monitor moisture and predict healing without the need to remove the dressing. A low cost polymeric optical fibre humidity sensor based on evanescent wave absorption is demonstrated for skin humidity measurement. The sensor is fabricated by coating the fibre with a hydrophilic film based on bilayers of Poly(allylamine hydrochloride) (PAH) and SiO2 mesoporous nanoparticles. The Layer-by-Layer method was used for the deposition of the layers. Multimode polymeric optical fibre with a cladding diameter of 250μm was covered by 7 layers of PAH/SiO2 film on the central region of an unclad fibre with a diameter of 190μm. The length of the sensitive region is 30mm. Experiment results show a decrease in light intensity when relative humidity increases due to refractive index changes of the fibre coating. The sensitivity obtained was 200mV/%RH and the sensor was demonstrated to provide a faster response to changes in the humidity of the skin microenvironment than a commercial sensor.

  5. Optical Spectroscopy of Stardust Samples

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.

    2006-01-01

    The Stardust spacecraft collected dust samples of the Kuiper belt comet 81P Wild-2 in aerogel and returned them to Earth January 15, 2006. Preliminary examination (PE) of the collected dust includes teams focused on mineralogy, chemical composition, isotopic measurements, organic analysis, cratering and spectroscopic properties. The main PE science goals are to provide an initial characterization of the returned samples with an emphasis on the capture process and its effects on the samples, a comparison of Stardust samples to other meteoritic materials, and the abundance of presolar materials in the Stardust samples. The science objectives of the Spectroscopy team are to obtain spectroscopic data on Stardust particles through infrared (IR), UV/Vis and Raman measurements of particles in aerogel, extracted particles, keystones, and microtome thin sections. These data will be used to answer fundamental science questions about the nature of the samples, but will also serve as preliminary mineralogical data to guide follow-on measurements that will be performed in the other preliminary examination teams. The IR characteristics of Stardust particles are measured to determine: 1) the nature of the indigenous 3.4 micron organic feature, is it detected and can it be differentiated/deconvolved from the contaminated aerogel? How does it compare to features observed in interplanetary dust particles (IDPs) and to astronomical measurements of comets and interstellar dust? 2) the shape and fine structure within the 10 micron silicate feature. Overlap with the strong Si-O stretching vibration from the aerogel complicates this analysis, but we hope to determine if the feature is dominated by amorphous silicates such as those observed in IDPs and comets and whether or not crystalline silicates (e.g. olivine, pyroxene, clays) are present, 3) the presence of secondary (alteration) phases. Deep Impact results suggest that IR observations of Stardust particles should be evaluated for

  6. Disinfection of the Optical Fibre of a Nd-YAP Laser Used in Dental Care.

    PubMed

    Rochd, T; Calas, P; Laffitte, F

    1999-03-01

    In order to set up a disinfection protocol, the tip of the optical fibre of an Nd-YAP laser, λ=1.34 μm, was contaminated in vitro with: Mycobacterium smegmatis (CIP 7326), Candida albicans (ATCC 2091), Bacillus stearothermophilus (ATCC 7953) or Streptococcus sanguis (ATCC 10556). It was then treated with various biocidal solutions, Septinol(®) V, glutaraldehyde 2%, ethanol 95° and NaOCl 6%, using one of two protocols: 10 s of contact, or 5 s of contact followed by 5 s of wiping. The latter technique proved to be the most effective. Whatever the biocidal solution used, all the bacteria adhering to the fibre were eliminated. The protocol was checked in vivo in the canals of 10 teeth presenting root canal infections. No bacteria withstood the treatment with Septinol(®) V. This treatment does not alter the qualities and performance of the fibre as far as light transmission is concerned. PMID:24584815

  7. Speckle interferometry, fibre optic sensors and laser induced ultrasounds as solutions to industrial demands

    NASA Astrophysics Data System (ADS)

    Corbani, Franco; Delvò, Pierino; Fiorina, Lorenzo; Rizzi, Cristina Mariottini e. Maria Luciana

    2002-04-01

    Industrial operators have been taking interest in optical diagnostics through years. Optical methods are mainly well appreciated for their attitude to be used as non-contact and non-invasive techniques. The paper presents three examples of applications carried-out by researchers of Centro Elettrotecnico Sperimentale Italiano (CESI) in collaboration with people working in industrial fields. The first part shows the applications of speckle interferometry to measure residual stresses in association with the traditional blind-hole drilling, while the second part presents the installation of fibre optic sensors in a power plant for monitoring possible overheating to avoid fires and finally the last presentation outlines a particular application in the field of laser generated ultrasounds that is the monitoring of the variation of ultrasonic speed propagation due to residual stresses.

  8. Laser machining of sensing components on the end of optical fibres

    NASA Astrophysics Data System (ADS)

    Albri, Frank; Li, Jun; Maier, Robert R. J.; MacPherson, William N.; Hand, Duncan P.

    2013-04-01

    Micro-cantilevers play a major role in sensing, especially since the invention of the atomic force microscope. Applications range from surface profiling to bio-medical sensing enabled through coating-activated cantilevers. Current readout methods are based on either optical deflection (of a laser beam reflected from the cantilever surface) or piezo-resistive response (of piezo-electric elements bonded to the cantilever surface). The first of these approaches requires significant space whilst the second is sensitive to electromagnetic effects. An alternative solution is to manufacture a cantilever onto the end of an optical fibre and use interferometry to monitor its deflection; in this paper we describe the development and application of a picosecond-laser machining process to fabricate such a device. The development of techniques to avoid cracking and debris re-deposition during this machining process is described, and a cantilever sensor with excellent optical performance is demonstrated and tested.

  9. CW-OSL measurement protocols using optical fibre Al2O3:C dosemeters.

    PubMed

    Edmund, J M; Andersen, C E; Marckmann, C J; Aznar, M C; Akselrod, M S; Bøtter-Jensen, L

    2006-01-01

    A new system for in vivo dosimetry during radiotherapy has been introduced. Luminescence signals from a small crystal of carbon-doped aluminium oxide (Al2O3:C) are transmitted through an optical fibre cable to an instrument that contains optical filters, a photomultiplier tube and a green (532 nm) laser. The prime output is continuous wave optically stimulated luminescence (CW-OSL) used for the measurement of the integrated dose. We demonstrate a measurement protocol with high reproducibility and improved linearity, which is suitable for clinical dosimetry. A crystal-specific minimum pre-dose is necessary for signal stabilisation. Simple background subtraction only partially removes the residual signal present at long integration times. Instead, the measurement protocol separates the decay curve into three individual components and only the fast and medium components were used. PMID:16990348

  10. Extreme electronic bandgap modification in laser-crystallized silicon optical fibres.

    PubMed

    Healy, Noel; Mailis, Sakellaris; Bulgakova, Nadezhda M; Sazio, Pier J A; Day, Todd D; Sparks, Justin R; Cheng, Hiu Y; Badding, John V; Peacock, Anna C

    2014-12-01

    For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon's transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100 nm. PMID:25262096

  11. Extreme electronic bandgap modification in laser-crystallized silicon optical fibres

    NASA Astrophysics Data System (ADS)

    Healy, Noel; Mailis, Sakellaris; Bulgakova, Nadezhda M.; Sazio, Pier J. A.; Day, Todd D.; Sparks, Justin R.; Cheng, Hiu Y.; Badding, John V.; Peacock, Anna C.

    2014-12-01

    For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon’s transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100 nm.

  12. Fibre-Optic Links For A Measurement And Control System At A HV Laboratory

    NASA Astrophysics Data System (ADS)

    Pluta, S.; Szczot, F.; Madej, M.; Zator, S.

    1990-01-01

    The paper presents a fibre-optic linking system for a measurement and control system installed at an industrial HV laboratory. The indirect voltage and current measurement system is furnished with the E0/0E transducers and FO links. The exploitation requirements on the adequate measurement accuracy and reliability have necessitated the inclusion of additional, digital PO link feedback from the computer control system. The proposed measurement system with the FO link has been installed at an HV laboratory transformer of an electric power station and successfully tested together with the overall equipment.

  13. Smart medical textiles with embedded optical fibre sensors for continuous monitoring of respiratory movements during MRI

    NASA Astrophysics Data System (ADS)

    Witt, J.; Narbonneau, F.; Schukar, M.; Krebber, K.; De Jonckheere, J.; Jeanne, M.; Kinet, D.; Paquet, B.; Depré, A.; D'Angelo, L. T.; Thiel, T.; Logier, R.

    2010-09-01

    We report on three respiration sensors based on pure optical technologies developed during the FP6 EU project OFSETH. The developed smart medical textiles can sense elongation up to 3%, while maintaining the stretching properties of the textile substrates for a good comfort of the patient. The sensors, based on silica and polymer fibre, are developed for monitoring of patients during MRI examination. The OFSETH harness allows a continuous measurement of respiration movements while all vitals organs are free for medical staff actions. The sensors were tested in MRI environment and on healthy adults.

  14. Measurement of unsteady gas temperature with optical fibre Fabry-Perot microsensors

    NASA Astrophysics Data System (ADS)

    Kilpatrick, J. M.; MacPherson, W. N.; Barton, J. S.; Jones, J. D. C.; Buttsworth, D. R.; Jones, T. V.; Chana, K. S.; Anderson, S. J.

    2002-05-01

    We describe the application of thin-film optical fibre Fabry-Perot (FFP) microsensors to high-bandwidth measurement of unsteady total temperature in transonic gas flows. An aerodynamic probe containing two temperature sensitive FFP microsensors was deployed in the rotor exit flow region of a gas turbine research rig. Measurements reveal gas temperature oscillations typically 4 K peak to peak at the blade passing frequency of 10 kHz with components to the third harmonic detected in the power spectrum of the temperature signal.

  15. Two-photon excited fluorescence in praseodymium doped fibre and its application in distributed optical fibre sensing of temperature

    NASA Astrophysics Data System (ADS)

    Dalzell, Craig J.; Han, Thomas P. J.; Ruddock, Ivan S.

    2011-05-01

    Distributed temperature sensing based on time-correlated two-photon excited fluorescence (TPF) in doped fibre is described. Counter-propagating laser pulses generate a TPF flash at the position of overlap which is scanned along the fibre by a variable relative time delay. The flash is detected and analysed at one end. With the fluorescence power being completely independent of excitation pulse duration and temporal profile, the sensor does not require ultrashort excitation pulses for operation. There is potential for high spatial resolution as the length of the sensed region depends only on pulse duration. TPF is reported in bulk glass doped with rare earths and in doped single-mode fibre. The suitability of fluorescence transitions for sensing is discussed taking into account the temperature dependence of the decay times, the location of the terminating energy level relative to the ground state, and the option of non-degenerate TPF.

  16. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

    NASA Astrophysics Data System (ADS)

    Aramaki, Mitsutoshi; Yoshimura, Shinji; Toda, Yasunori; Morisaki, Tomohiro; Terasaka, Kenichiro; Tanaka, Masayoshi

    2015-11-01

    Optical vortices (OV) are a set of solutions of the paraxial Helmholtz equation in the cylindrical coordinates, and its wave front has a spiral shape. Since the Doppler shift is caused by the phase change by the movement in a wave field, the observer in the OV, which has the three-dimensional structured wave front, feels a three-dimensional Doppler effect. Since the multi-dimensional Doppler components are mixed into a single Doppler spectrum, development of a decomposition method is required. We performed a modified saturated absorption spectroscopy to separate the components. The OV and plane wave are used as a probe beam and pump beam, respectively. Although the plane-wave pump laser cancels the z-direction Doppler shift, the azimuthal Doppler shift remains in the saturated dip. The spatial variation of the dip width gives the information of the azimuthal Doppler shift. The some results of optical vortex spectroscopy will be presented.

  17. High Efficiency Coupling of Optical Fibres with SU8 Micro-droplet Using Laser Welding Process

    NASA Astrophysics Data System (ADS)

    Yardi, Seema; Gupta, Ankur; Sundriyal, Poonam; Bhatt, Geeta; Kant, Rishi; Boolchandani, D.; Bhattacharya, Shantanu

    2016-09-01

    Apart from micro- structure fabrication, ablation, lithography etc., lasers find a lot of utility in various areas like precision joining, device fabrication, local heat delivery for surface texturing and local change of microstructure fabrication of standalone optical micro-devices (like microspheres, micro-prisms, micro-scale ring resonators, optical switches etc). There is a wide utility of such systems in chemical/ biochemical diagnostics and also communications where the standalone optical devices exist at a commercial scale but chip based devices with printed optics are necessary due to coupling issues between printed structures and external optics. This paper demonstrates a novel fabrication strategy used to join standalone optical fibres to microchip based printed optics using a simple SU8 drop. The fabrication process is deployed for fiber to fiber optical coupling and coupling between fiber and printed SU-8 waveguides. A CO2 laser is used to locally heat the coupling made up of SU8 material. Optimization of various dimensional parameters using design of experiments (DOE) on the bonded assembly has been performed as a function of laser power, speed, cycle control, spot size so on so forth. Exclusive optical [RF] modelling has been performed to estimate the transmissibility of the optical fibers bonded to each other on a surface with SU8. Our studies indicate the formation of a Whispering gallery mode (WGM) across the micro-droplet leading to high transmissibility of the signal. Through this work we have thus been able to develop a method of fabrication for optical coupling of standalone fibers or coupling of on-chip optics with off-chip illumination/detection.

  18. High Efficiency Coupling of Optical Fibres with SU8 Micro-droplet Using Laser Welding Process

    NASA Astrophysics Data System (ADS)

    Yardi, Seema; Gupta, Ankur; Sundriyal, Poonam; Bhatt, Geeta; Kant, Rishi; Boolchandani, D.; Bhattacharya, Shantanu

    2016-04-01

    Apart from micro- structure fabrication, ablation, lithography etc., lasers find a lot of utility in various areas like precision joining, device fabrication, local heat delivery for surface texturing and local change of microstructure fabrication of standalone optical micro-devices (like microspheres, micro-prisms, micro-scale ring resonators, optical switches etc). There is a wide utility of such systems in chemical/ biochemical diagnostics and also communications where the standalone optical devices exist at a commercial scale but chip based devices with printed optics are necessary due to coupling issues between printed structures and external optics. This paper demonstrates a novel fabrication strategy used to join standalone optical fibres to microchip based printed optics using a simple SU8 drop. The fabrication process is deployed for fiber to fiber optical coupling and coupling between fiber and printed SU-8 waveguides. A CO2 laser is used to locally heat the coupling made up of SU8 material. Optimization of various dimensional parameters using design of experiments (DOE) on the bonded assembly has been performed as a function of laser power, speed, cycle control, spot size so on so forth. Exclusive optical [RF] modelling has been performed to estimate the transmissibility of the optical fibers bonded to each other on a surface with SU8. Our studies indicate the formation of a Whispering gallery mode (WGM) across the micro-droplet leading to high transmissibility of the signal. Through this work we have thus been able to develop a method of fabrication for optical coupling of standalone fibers or coupling of on-chip optics with off-chip illumination/detection.

  19. Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillation-based polymer optical fibre sensor for real time monitoring of radiation dose in oncology

    NASA Astrophysics Data System (ADS)

    Lewis, E.; O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Mihai, L.; Sporea, D.; Santhanam, A.; Agazaryan, N.

    2014-05-01

    A PMMA based plastic optical fibre sensor for use in real time radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces when exposed to ionising radiation (X-Ray). The emitted visible light signal penetrates the sensor optical fibre and propagates along the transmitting fibre at the end of which it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.5% and the response is independent of dose rate.

  20. Dissemination of time and RF frequency via a stabilized fibre optic link over a distance of 420 km

    NASA Astrophysics Data System (ADS)

    Śliwczyński, Łukasz; Krehlik, Przemysław; Czubla, Albin; Buczek, Łukasz; Lipiński, Marcin

    2013-04-01

    In this paper we present the results of our work concerning the long-distance fibre optic dissemination of time (1 PPS) and frequency (10 MHz) signals generated by atomic sources, such as caesium clocks, hydrogen masers or caesium fountains. For these purposes we developed dedicated hardware (a fibre optic system with active stabilization of the propagation delay and bidirectional fibre optic amplifiers) together with a procedure to enable calibration of the time transfer. Our laboratory measurements performed over fibre lengths of up to 480 km showed an Allan deviation of the order of 4 × 10-17, time deviation below 1 ps (both at one-day averaging) and the possibility of calibration with picosecond accuracy even for the longest from evaluated links. After successful laboratory evaluation the system was next installed on a 421.4 km long route between the Central Office of Measures (GUM) in Warsaw, Poland, and the Astrogeodynamic Observatory (AOS) in Borowiec near Poznań, Poland. Experiments comparing the UTC(PL) and UTC(AOS) atomic timescales using the fibre optic link and TTS-4 dual-frequency GNSS time transfer receivers showed that the consistency of the results is within the calibration accuracy of the GPS receivers and with much better noise performance. The field operation of the system proved its full functionality and confirmed our previous laboratory evaluation to the maximum extent possible using the methods for comparing distant clocks available at GUM and AOS.

  1. FOSREM - Fibre-Optic System for Rotational Events&Phenomena Monitoring

    NASA Astrophysics Data System (ADS)

    Jaroszewicz, Leszek; Krajewski, Zbigniew; Kurzych, Anna; Kowalski, Jerzy; Teisseyre, Krzysztof

    2016-04-01

    We present the construction and tests of fiber-optic rotational seismometer named FOSREM (Fibre-Optic System for Rotational Events&Phenomena Monitoring). This presented device is designed for detection and monitoring the one-axis rotational motions, brought about to ground or human-made structures both by seismic events and the creep processes. The presented system works by measuring Sagnac effect and generally consists of two basic elements: optical sensor and electronic part. The optical sensor is based on so-called the minimum configuration of FOG (Fibre-Optic Gyroscope) where the Sagnac effect produces a phase shift between two counter-propagating light beams proportional to the measured rotation speed. The main advantage of the sensor of this type is its complete insensitivity to linear motions and a direct measurement of rotational speed. It may work even when tilted, moreover, used in continuous mode it may record the tilt. The electronic system, involving specific electronic solutions, calculates and records rotational events data by realizing synchronous in a digital form by using 32 bit DSP (Digital Signal Processing). Storage data and system control are realised over the internet by using connection between FOSREM and GSM/GPS. The most significant attribute of our system is possibility to measure rotation in wide range both amplitude up to 10 rad/s and frequency up to 328.12 Hz. Application of the wideband, low coherence and high power superluminescent diode with long fibre loop and suitable low losses optical elements assures the theoretical sensitivity of the system equal to 2·10-8 rad/s/Sqrt(Hz). Moreover, the FOSREM is fully remote controlled as well as is suited for continuous, autonomous work in very long period of time (weeks, months, even years), so it is useful for systematic seismological investigation at any place. Possible applications of this system include seismic monitoring in observatories, buildings, mines and even on glaciers and in

  2. Plasma Treatment of Natural Jute Fibre by RIE 80 plus Plasma Tool

    NASA Astrophysics Data System (ADS)

    Morshed, M. M.; Alam, M. M.; Daniels, S. M.

    2010-06-01

    Plasma treatment can be used to modify the structure of natural fibre like jute for a variety of applications. Environmentally friendly jute fibre was treated with argon and oxygen plasma. The treated samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and optical microscope. The macromolecular and microstructural changes in cellulose confirmed the change by plasma treatment. The XRD results confirmed that the crystal size and the crystallinity of the plasma treated fibre increased. Argon plasma treated fibre had a smooth and compact surface, compared to oxygen plasma treated fibre. The maximum stain (i.e. stress) concentrated in the oxygen plasma treated fibre. Optical micrographs showed the oxygen plasma treated fibre tended to rupture due to higher strain (i.e., stress) compared to fibre with argon plasma treatment. FTIR results also provided the evidence of change in the chemical constituents with plasma treatment.

  3. Radiation dose to radiosensitive organs in PET/CT myocardial perfusion examination using versatile optical fibre

    NASA Astrophysics Data System (ADS)

    Salasiah, M.; Nordin, A. J.; Fathinul Fikri, A. S.; Hishar, H.; Tamchek, N.; Taiman, K.; Ahmad Bazli, A. K.; Abdul-Rashid, H. A.; Mahdiraji, G. A.; Mizanur, R.; Noor, Noramaliza M.

    2013-05-01

    Cardiac positron emission tomography (PET) provides a precise method in order to diagnose obstructive coronary artery disease (CAD), compared to single photon emission tomography (SPECT). PET is suitable for obese and patients who underwent pharmacologic stress procedures. It has the ability to evaluate multivessel coronary artery disease by recording changes in left ventricular function from rest to peak stress and quantifying myocardial perfusion (in mL/min/g of tissue). However, the radiation dose to the radiosensitive organs has become crucial issues in the Positron Emission Tomography/Computed Tomography(PET/CT) scanning procedure. The objective of this study was to estimate radiation dose to radiosensitive organs of patients who underwent PET/CT myocardial perfusion examination at Centre for Diagnostic Nuclear Imaging, Universiti Putra Malaysia in one month period using versatile optical fibres (Ge-B-doped Flat Fibre) and LiF (TLD-100 chips). All stress and rest paired myocardial perfusion PET/CT scans will be performed with the use of Rubidium-82 (82Rb). The optic fibres were loaded into plastic capsules and attached to patient's eyes, thyroid and breasts prior to the infusion of 82Rb, to accommodate the ten cases for the rest and stress PET scans. The results were compared with established thermoluminescence material, TLD-100 chips. The result shows that radiation dose given by TLD-100 and Germanium-Boron-doped Flat Fiber (Ge-B-doped Flat Fiber) for these five organs were comparable to each other where the p>0.05. For CT scans,thyroid received the highest dose compared to other organs. Meanwhile, for PET scans, breasts received the highest dose.

  4. Cellular biosensing using optical spectroscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wax, Adam

    2016-03-01

    The interaction of light with biological cells can provide a unique tool for studying their biophysical properties. Optical spectroscopy of biological cells can reveal detailed information on their structure and dynamics in a way that is not possible with traditional microscopy techniques. Histological evaluation can only obtain a snapshot of the activity of individual cells, relying instead on large ensembles to develop a picture of their temporal evolution. On the other hand optical spectroscopy can be applied to cells with little to no preparation and can enable studies of the same live cells at extended time intervals. Our research group has developed a suite of optical spectroscopic tools to assess the structure and function of biological cells and modulation due to the onset of disease. The wavelength dependence of the interaction of cells with light provides information of cell features through elastic scattering across the visible and near infrared spectrum. Alternatively, the angular dependence of scattered light can also be used to reveal cell properties. We will discuss how both modes of elastic scattering can be used to evaluate cell status. Finally, the recent advances in the use of optical phase imaging to create contrast in nearly transparent biological cells will also be discussed as related to the role of this modality in biosensing.

  5. Optical fibre long period grating spectral actuators utilizing ferrofluids as outclading overlayers

    NASA Astrophysics Data System (ADS)

    Konstantaki, M.; Candiani, A.; Pissadakis, S.

    2011-03-01

    Results are presented on the spectral tuning of optical fibre long period gratings utilizing water and oil based ferrofluids as outclading overlayers, under static magnetic field stimulus. Two approaches are adopted for modifying the ambient refractive index at the position of the long period grating. In the first approach, a water based ferrofluid is controllably translated along the length of the grating via a magnetic field. Changes as high as 7.5nm and 6.5dB are monitored in the wavelength and strength, respectively, of the attenuation bands of the grating. The repeatable performance of this device for repetitive forward and backward translation verifies that no ferrofluidic residue is left on the fibre, due to silanization cladding functionalisation. In the second approach, the refractive index of an oil based ferrofluidic overlayer is modified through the magneto-optical effect. For an applied static magnetic field in the order of 400 Gauss the strength of the attenuation band of the grating is modified by more than 10% while its spectral position remains unaffected. Accordingly for the implementation of the last approach, the magnetically induced refractive index changes of ferrofluids of different solution concentrations are studied by employing diffraction efficiency measurements.

  6. Physico-chemical properties of organically modified silicates' sol-gel layers for optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Chodkowska, Eliza; Rayss, Jan

    2006-10-01

    The paper concerns the investigation of modified silica gel materials applied in optical fibre sensors. These materials are products of a sol-gel process in which three kinds of alkoxysilanes undergo hydrolysis and condensation and may play a role of the matrices containing transducer's molecules in the active layer of the sensor. In the experiment presented below three different compositions comprising tetraethoxysilane (TEOS), methyltriethoxysilane (MTES) and phenyltriethoxysilane (PhTES) were used. The alkoxysilanes underwent hydrolysis and condensation and the obtained gels were investigated in order to determine their texture, strucuture, composition and chemical properties as far as the dependence of those characteristics on the hydrolysis time and the molar ratio of the ingredients in the initial sols. The methods employed in the experiment were: Atomic Force Microscopy (AFM) which delivered vital information about the gels' textures, contact angles' and surface charge's measurements serving to estimate chemical properties of the gels' surfaces, Nuclear Magnetic Resonance (NMR) which helped to evaluate the hydrolysis' rate and porosimetric measurements enabling a determination of BET surface area and average diametres of the pores. The results may occur important for improving the construction of optical fibre sensors in which organically modified silicates (ORMOSILs)-TEOS layes are used.

  7. Ultrastable optical frequency dissemination on a multi-access fibre network

    NASA Astrophysics Data System (ADS)

    Bercy, Anthony; Lopez, Olivier; Pottie, Paul-Eric; Amy-Klein, Anne

    2016-07-01

    We report a laboratory demonstration of the dissemination of an ultrastable optical frequency signal to two distant users simultaneously using a branching network. The ultrastable signal is extracted along a main fibre link; it is optically tracked by a narrow linewidth laser diode, which light is injected in a secondary link. The propagation noise of both links is actively compensated. We implement this scheme with two links of 50-km fibre spools, the extraction being set up at the mid-point of the main link. We show that the extracted signal at the end of the secondary link exhibits a fractional frequency instability of 1.4 × 10-15 at 1-s measurement time, almost equal to the 1.3 × 10-15 instability of the main link output end. The long-term instabilities are also very similar, at a level of 3-5 × 10-20 at 3 × 104-s integration time. We also show that the setting up of this extraction device, or of a simpler one, at the main link input, can test the proper functioning of the noise rejection on this main link. This work is a significant step towards a robust and flexible ultrastable network for multi-users dissemination.

  8. Thermography of target plates with near-infrared optical fibres at Tore Supra

    NASA Astrophysics Data System (ADS)

    Reichle, R.; Basiuk, V.; Bergeaud, V.; Cambe, A.; Chantant, M.; Delchambre, E.; Druetta, M.; Gauthier, E.; Hess, W.; Pocheau, C.

    2001-03-01

    First spectroscopic near-infrared thermography measurements in the range 0.9-1.95 μm performed with optical fibres are reported. Two set-ups served as test-beds for physical and technical questions for a security system based on fibre optical thermography. It was found that for the interesting temperature range above 600°C atomic and molecular line emission is negligible in comparison with thermal radiation. The observed near-infrared spectra are however different from simple blackbody radiation curves. They are explained by the coverage of the surface with dust and flakes. The dust particles are identified by their spectral emissivity falling off with the square of the wavelength. On one set-up, flakes were identifiable by fast cool-down times and confirmed by post-experiment inspection. In the absence of flakes, surface temperatures on a ripple protection plate were measured, that allowed to determine the mean energy of ripple trapped ions to be 200-300 keV.

  9. Turbo machine tip clearance and vibration measurements using a fibre optic laser Doppler position sensor

    NASA Astrophysics Data System (ADS)

    Pfister, T.; Büttner, L.; Czarske, J.; Krain, H.; Schodl, R.

    2006-07-01

    This paper presents a novel fibre optic laser Doppler position sensor for single blade tip clearance and vibration measurements at turbo machines, which offers high temporal resolution and high position resolution simultaneously. The sensor principle is based on the generation of a measurement volume consisting of two superposed fan-like interference fringe systems with contrary fringe spacing gradients using wavelength division multiplexing. A flexible and robust measurement system with an all-passive fibre coupled measurement head has been realized employing diffractive and refractive optics. Measurements of tip clearance and rotor vibrations at a transonic centrifugal compressor performed during operation at up to 50 000 rpm (833 Hz) corresponding to 21.7 kHz blade frequency and 586 m s-1 blade tip velocity are presented. The results are in excellent agreement with those of capacitive probes. The mean uncertainty of the position measurement was around 20 µm and, thus, considerably better than for conventional tip clearance probes. Consequently, this sensor is capable of fulfilling the requirements for future active clearance control systems and has great potential for in situ and online tip clearance and vibration measurements at metallic and non-metallic turbine blades with high precision.

  10. In vivo monitoring of the gastrooesophageal system using optical fibre sensors.

    PubMed

    Baldini, Francesco

    2003-03-01

    In the present paper optical fibre sensors for the detection of foregut diseases are described, in particular, sensors for the detection of bile, carbon dioxide and pH. Bile-containing refluxes are measured by means of a sensor which uses bilirubin as natural marker. The sensor, which is already present on the market, has been clinically validated by various hospitals. The clinically relevant parameter is the exposure time of the stomach/oesophagus mucosa to the bile. When measured in the oesophagus, it has been shown to be closely correlated with the onset of Barrett's oesophagus or general oesophagitis. Recently, optical fibres have been proposed for the continuous monitoring of carbon dioxide in the stomach: an important parameter in critically ill patients. A clinically validated prototype has shown its superiority in comparison with the traditional method, that is based on gastric tonometry. For the sake of completeness, also gastric pH sensors are considered, although at the moment their development is stationary at the laboratory stage. PMID:12664171

  11. Compact multipass optical cell for laser spectroscopy.

    PubMed

    Tuzson, Béla; Mangold, Markus; Looser, Herbert; Manninen, Albert; Emmenegger, Lukas

    2013-02-01

    A multipass cell (MPC) design for laser absorption spectroscopy is presented. The development of this new type of optical cell was driven by stringent criteria for compactness, robustness, low volume, and ease of use in optical systems. A single piece of reflective toroidal surface forms a near-concentric cavity with a volume of merely 40 cm(3). Contrary to traditional MPCs, this design allows for flexible path-length adjustments by simply changing the aiming angle of the laser beam at the entrance window. Two effective optical path lengths of 2.2 and 4.1 m were chosen to demonstrate the cell's suitability for high-precision isotope ratio measurements of CO(2) at 1% and ambient mixing ratio levels. PMID:23381403

  12. In-situ monitoring of carbon dioxide emissions from a diesel engine using a mid-infrared optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Lewis, Elfed; Clifford, John; Fitzpatrick, Colin; Dooly, Gerard; Zhao, Weizhong; Sun, Tong; Grattan, Ken; Lucas, James; Degner, Martin; Ewald, Hartmut; Lochmann, Steffan; Bramann, Gero; Merlone-Borla, Edoardo; Gili, Flavio

    2011-05-01

    A robust optical fibre based CO2 exhaust gas sensor operating in the mid infrared spectral range is described. It is capable of detecting on board carbon dioxide (CO2) emissions from both diesel and petrol engines. The optical fibre sensor is not cross sensitive to other gaseous species in the exhaust such as water vapour (H2O), carbon monoxide (CO), oxides of nitrogen (NOx) or oxides of sulphur (SOx).The response of the sensor to carbon dioxide present in the exhaust of Fiat Croma diesel engine are presented.

  13. AlGaInN laser diode technology for free-space and plastic optical fibre telecom applications

    NASA Astrophysics Data System (ADS)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Bóckowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.; Watson, M. A.; Blanchard, P.; White, H.

    2016-03-01

    Gallium Nitride laser diodes fabricated from the AlGaInN material system is an emerging technology for laser sources from the UV to visible and is a potential key enabler for new system applications such as free-space (underwater & air bourne links) and plastic optical fibre telecommunications. We measure visible light (free-space and underwater) communications at high frequency (up to 2.5 Gbit/s) and in plastic optical fibre (POF) using a directly modulated GaN laser diode.

  14. Polarization Maintaining Fibre Loop Mirror for NRZ-to-PRZ Conversion in All-Optical Clock Recovery

    NASA Astrophysics Data System (ADS)

    Xu, Fan; Zhang, Xin-Liang; Liu, Hai-Rong; Liu, De-Ming; Huang, De-Xiu

    2006-02-01

    We propose a novel configuration for clock extraction by converting the NRZ data into the PRZ data and by employing a polarization-maintaining fibre loop mirror (PMFLM) which is usually used as an optical comb filter. It is found that the PMFLM can simply be constructed by a polarization controller and polarization-maintaining fibre (PMF). We theoretically analyse the principle of PMFLM for the NRZ-to-PRZ conversion. Experimentally we demonstrate 10 Gbit/s all-optical clock recovery through our proposed setup. It is shown that recovered clock signal with an extinction ratio above 10 dB can be achieved.

  15. Application of the fibre-optic interferometer as a rotational seismograph type AFORS

    NASA Astrophysics Data System (ADS)

    Kurzych, Anna; Jaroszewicz, Leszek R.; Krajewski, Zbigniew; Teisseyre, Krzysztof P.; Kowalski, Jerzy K.

    2014-12-01

    In this article we show a fibre-optic device based on the Sagnac effect designed for measuring rotational motions which appear during seismic events. The experimental investigations of presented Autonomous Fiber-Optical Rotational Seismographs indicate that such devices keep the accuracy no less than 5.1·10-9 to 5.5·10-8 rad/s in the frequency band from 0.83 Hz to 106.15 Hz. Furthermore, their operations are controlled fully remotely via Internet. We present the comparison of results obtained by such system in the field test with a mechanical rotational seismometer which is mounted simultaneously in the seismological observatory in Książ, Poland.

  16. Design of the Polarimeter for the Fibre Arrayed Solar Optical Telescope

    NASA Astrophysics Data System (ADS)

    Dun, Guang-tao; Qu, Zhong-quan

    2013-01-01

    The theoretical design of the polarimeter used for the Fibre Arrayed Solar Optical Telescope (FASOT) is described. It has the following characteris- tics: (1) It is provided with the function of optical polarization switching, which makes the high-effciency polarimetry possible; (2) In the waveband of 750 nm, the polarimetric effciency is higher than 50% for the every Stokes parameter, and higher than 86.6% for the total polarization, thus an observer can make the simultaneous polarization measurements on multiple magnetosensitive lines in such a broad range of wavelength; (3) According to the selected photospheric and chromospheric lines, the measurement can be focused on either linear polarization or circular polarization; (4) The polarimeter has a loose tolerance on the manufacturing technology of polarimetric elements and installation errors. All this makes this polarimeter become a high-performance polarimetric device.

  17. In-situ monitoring of ammonia gas using an optical fibre based approach

    NASA Astrophysics Data System (ADS)

    Dooly, G.; Manap, H.; O'Keeffe, S.; Lewis, E.

    2011-08-01

    An optical fibre sensor for the monitoring of low level atmospheric ammonia concentrations is presented. The measuring technique employed is based on a differential optical absorption approach, rather than a semiconductor based technique which is generally exploited within comparable commercially available products. The sensor described herein demonstrates vast improvements in terms of sensitivity, selectivity and lifespan over ammonia sensors currently available commercially. Extensive laboratory-based experimental tests demonstrate the sensor's ability to monitor concentrations as low as 1ppm without any notable cross-sensitivity issues to atmospheric gases such as nitrogen, oxygen and carbon dioxide. Furthermore, in-situ experimental tests within an agricultural cattle enclosure demonstrate sensor's suitability to environments where low concentration monitoring of ammonia over extended periods of time is necessary.

  18. Single-pulse laser-induced breakdown spectroscopy of samples submerged in water using a single-fibre light delivery system

    NASA Astrophysics Data System (ADS)

    Beddows, D. C. S.; Samek, O.; Liška, M.; Telle, H. H.

    2002-09-01

    Using a novel laser-induced breakdown spectroscopy set-up, accurate quantitative analysis of samples submerged in liquids has been demonstrated. The measurements were conducted using a single-fibre plus plastic tube assembly of 20 m length. This delivered the ablation laser light pulse and a buffer gas flow to the sample surface, and collected the light emitted by the micro-plasma for analysis. No distil optics were used at the sample end of the fibre. Argon, nitrogen and compressed air were used as buffer gases; while the rare gas resulted in slightly better signal-to-noise ratios, most analytical measurements were carried out with nitrogen for convenience and to provide comparability with in-air measurements. Detection limits and reproducibility were comparable to those achieved for the same samples placed in standard ambient air, with all other experimental conditions unchanged. In standard steel samples, detection limits of 310±45, 325±48 and 455±55 ppm for Cr, Mn and Si, respectively, could be achieved. Pattern recognition algorithms were used to identify, for classification, spectra of specimen submerged in turbid and non-transparent liquids.

  19. Laser-tuned whispering gallery modes in a solid-core microstructured optical fibre integrated with magnetic fluids.

    PubMed

    Lin, Wei; Zhang, Hao; Liu, Bo; Song, Binbin; Li, Yuetao; Yang, Chengkun; Liu, Yange

    2015-01-01

    A laser-assisted tuning method of whispering gallery modes (WGMs) in a cylindrical microresonator based on magnetic-fluids-infiltrated microstructured optical fibres (MFIMOFs, where MF and MOF respectively refer to magnetic fluid and microstructured optical fibre) is proposed, experimentally demonstrated and theoretically analysed in detail. The MFIMOF is prepared by infiltrating the air-hole array of the MOF using capillary action effect. A fibre-coupling system is set up for the proposed MFIMOF-based microresonator to acquire an extinction ratio up to 25 dB and a Q-factor as large as 4.0 × 10(4). For the MF-infiltrated MOF, the light propagating in the fibre core region would rapidly spread out and would be absorbed by the MF-rod array cladding to induce significant thermal effect. This has been exploited to achieve a WGM resonance wavelength sensitivity of 0.034 nm/mW, which is ~20 times higher than it counterpart without MF infiltration. The wavelength response of the resonance dips exhibit linear power dependence, and owing to such desirable merits as ease of fabrication, high sensitivity and laser-assisted tunability, the proposed optical tuning approach of WGMs in the MFIMOF would find promising applications in the areas of optical filtering, sensing, and signal processing, as well as future all-optical networking systems. PMID:26632445

  20. Laser-tuned whispering gallery modes in a solid-core microstructured optical fibre integrated with magnetic fluids

    PubMed Central

    Lin, Wei; Zhang, Hao; Liu, Bo; Song, Binbin; Li, Yuetao; Yang, Chengkun; Liu, Yange

    2015-01-01

    A laser-assisted tuning method of whispering gallery modes (WGMs) in a cylindrical microresonator based on magnetic-fluids-infiltrated microstructured optical fibres (MFIMOFs, where MF and MOF respectively refer to magnetic fluid and microstructured optical fibre) is proposed, experimentally demonstrated and theoretically analysed in detail. The MFIMOF is prepared by infiltrating the air-hole array of the MOF using capillary action effect. A fibre-coupling system is set up for the proposed MFIMOF-based microresonator to acquire an extinction ratio up to 25 dB and a Q-factor as large as 4.0 × 104. For the MF-infiltrated MOF, the light propagating in the fibre core region would rapidly spread out and would be absorbed by the MF-rod array cladding to induce significant thermal effect. This has been exploited to achieve a WGM resonance wavelength sensitivity of 0.034 nm/mW, which is ~20 times higher than it counterpart without MF infiltration. The wavelength response of the resonance dips exhibit linear power dependence, and owing to such desirable merits as ease of fabrication, high sensitivity and laser-assisted tunability, the proposed optical tuning approach of WGMs in the MFIMOF would find promising applications in the areas of optical filtering, sensing, and signal processing, as well as future all-optical networking systems. PMID:26632445

  1. Laser-tuned whispering gallery modes in a solid-core microstructured optical fibre integrated with magnetic fluids

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Zhang, Hao; Liu, Bo; Song, Binbin; Li, Yuetao; Yang, Chengkun; Liu, Yange

    2015-12-01

    A laser-assisted tuning method of whispering gallery modes (WGMs) in a cylindrical microresonator based on magnetic-fluids-infiltrated microstructured optical fibres (MFIMOFs, where MF and MOF respectively refer to magnetic fluid and microstructured optical fibre) is proposed, experimentally demonstrated and theoretically analysed in detail. The MFIMOF is prepared by infiltrating the air-hole array of the MOF using capillary action effect. A fibre-coupling system is set up for the proposed MFIMOF-based microresonator to acquire an extinction ratio up to 25 dB and a Q-factor as large as 4.0 × 104. For the MF-infiltrated MOF, the light propagating in the fibre core region would rapidly spread out and would be absorbed by the MF-rod array cladding to induce significant thermal effect. This has been exploited to achieve a WGM resonance wavelength sensitivity of 0.034 nm/mW, which is ~20 times higher than it counterpart without MF infiltration. The wavelength response of the resonance dips exhibit linear power dependence, and owing to such desirable merits as ease of fabrication, high sensitivity and laser-assisted tunability, the proposed optical tuning approach of WGMs in the MFIMOF would find promising applications in the areas of optical filtering, sensing, and signal processing, as well as future all-optical networking systems.

  2. Electronic and optical spectroscopy of molecular junctions

    NASA Astrophysics Data System (ADS)

    Preiner, Michael J.

    Electronic transport through molecules has been intensively studied in recent years, due to scientific interest in fundamental questions about charge transport and the technological promise of nanoscale circuitry. A wide range of range of experimental platforms have been developed to electronically probe both single molecules and molecular monolayers. However, it remains challenging to fabricate reliable electronic contacts to molecules, and the vast majority of molecular electronic architectures are not amenable to standard characterization techniques, such as optical spectroscopy. Thus the field of molecular electronics has been hampered with problems of reproducibility, and many fundamental questions about electronic transport remain unanswered. This thesis describes four significant contributions towards the fabrication and characterization of molecular electronic devices: (1) The development of a new method for creating robust, large area junctions where the electronic transport is through a single monolayer of molecules. This method utilizes atomic layer deposition (ALD) to grow an ultrathin oxide layer on top of a molecular monolayer, which protects the molecules against subsequent processing. (2) A new method for rapid imaging and analysis of single defects in molecular monolayers. This method also electrically passivates defects as it labels them. (3) Hot carrier spectroscopy of molecular junctions. Using optically excited hot carriers, we demonstrate the ability to probe the energy level lineup inside buried molecular junctions. (4) Efficient coupling of optical fields to metal-insulator-metal (MIM) surface plasmon modes. We show both theoretical and experimental work illustrating the ability to create very intense optical fields inside MIM systems. The intense fields generated in this manner have natural extensions to a variety of applications, such as photon assisted tunneling in molecular junctions, optical modulators, and ultrafast optoelectronic

  3. Optical Spectroscopy of Marine Bioadhesive Interfaces

    NASA Astrophysics Data System (ADS)

    Barlow, Daniel E.; Wahl, Kathryn J.

    2012-07-01

    Marine organisms have evolved extraordinarily effective adhesives that cure underwater and resist degradation. These underwater adhesives differ dramatically in structure and function and are composed of multiple proteins assembled into functional composites. The processes by which these bioadhesives cure—conformational changes, dehydration, polymerization, and cross-linking—are challenging to quantify because they occur not only underwater but also in a buried interface between the substrate and the organism. In this review, we highlight interfacial optical spectroscopy approaches that can reveal the biochemical processes and structure of marine bioadhesives, with particular emphasis on macrofoulers such as barnacles and mussels.

  4. Assessing PDT response with diffuse optical spectroscopies

    NASA Astrophysics Data System (ADS)

    Rohrbach, Daniel J.

    Photodynamic therapy (PDT) is used to treat a variety of conditions including cancer. Effective PDT requires three components: a photosensitizer (PS), light of a specific wavelength to activate the PS and oxygen. When all three are present in a lesion it leads to cell death and vascular destruction. Optical techniques such as diffuse reflectance spectroscopy (DRS), diffuse fluorescence spectroscopy (DFS) and diffuse correlation spectroscopy (DCS) can be used to quantify vascular parameters and photosensitizer content before and after PDT, providing valuable information for assessing response. For the quantification of vascular parameters, a probe-specific empirical light transport model was developed. A look-up-table was constructed using tissue simulating phantoms made of Intralipid to control the scattering, India Ink to control the absorption and water. The empirical model allowed the quantification of optical properties as well as the vascular parameters blood volume fraction (BVf) and blood oxygen saturation (SO2) with DRS. Blood flow was measured using DCS. For the quantification of PS content two techniques were used. DRS was used to fit the absorption of the PS and DFS measured the fluorescence of the PS. For quantification of PS content from measured fluorescence, a correction factor was developed using Monte Carlo simulations to account for the optical properties at the excitation and emission wavelengths. The three techniques were used to assess PDT response in pre-clinical and clinical studies. For the preclinical study, mice were treated with HPPH-PDT and blood flow was measured continuously with DCS. Blood flow variables were compared to STAT3 crosslinking (a molecular marker for PDT photoreaction) and CD31 staining (to visualize intact endothelial cells after PDT). For the clinical study, patients in a clinical trial for HPPH-PDT were measured with DRS, DFS and DCS before and after treatment. Multiple parameters were compared to the clinical response

  5. Permanent installation of fibre-optic DTS cables in boreholes for temperature monitoring

    NASA Astrophysics Data System (ADS)

    Henninges, J.; Schrötter, J.; Erbas, K.; Böde, S.; Huenges, E.

    2003-04-01

    Temperature measurements have become an important tool for the monitoring of dynamic processes in the subsurface both in academia and industry. An innovative experimental design for the monitoring of spatial and temporal variations of temperature along boreholes was developed and successfully applied under extreme arctic conditions during a field experiment, which was carried out within the framework of the Mallik 2002 Production Research Well Program*. Three 40 m spaced, 1200 m deep wells were equipped with permanent fibre-optic sensor cables and the variation of temperature was measured deploying the Distributed Temperature Sensing (DTS) technology. The used DTS system enables the simultaneous online registration of temperature profiles along the three boreholes with a maximum spatial resolution of 0.25 m and a minimum sampling interval of 7 sec. After an individual calibration of the fibre-optic sensor cables a resolution of 0.3 °C of the measured temperature data could be achieved. A special feature of the experiment design is the installation of the sensor cables outside the borehole casing. The fibre-optic cables were attached to the outer side of the casing at every connector within intervals of approx. 12 m with cable clamps. The clamps enable a defined positioning of the cable around the perimeter of the casing and are protecting the cable from mechanical damage during installation. After completion the sensor cables are located in the cement annulus between casing and borehole wall. As an example of the performance of the described temperature logging technology data from the reaming of a 300 m thick cement plug inside the borehole is displayed, offering a unique opportunity to explore thermal processes in the near vicinity of a borehole during drilling. The temperature changes image the progress of the drill bit as well as changes in the mud circulation. Furthermore, local effects can be observed that relate to local thermal properties and technical

  6. A Fibre-Optic Based System For Chemical In Vivo Mapping Of The Human Body

    NASA Astrophysics Data System (ADS)

    Hougham, B.; Brown, R. S.; Krull, U. J.

    1987-01-01

    In vivo chemical mapping of the human body could be very useful in the treatment of patients undergoing surgery such as heart surgery, with acute conditions such as hepatitis, or chronic conditions such as diabetes. Chemical mapping would be a continuous analytical profile of physical parameters such as blood pressure, chemical parameters such as pH, pCO2 and p02, simple molecules such as glucose and large biomolecules such as serum glutamate-oxoloacetate trans-aminase (SGOT), serum glutamate-pyruvate transaminase (SGPT) and billirubin. The advantage of a particular mapping strategy employing fibre-optic sensors is that all these different chemical signals arriving from different sensors can be multiplexed and detected concurrently. Although physical sensors for parameters such as temperature, pressure and blood viscosity have not yet found their way into routine use, those which employ fibre-optics do already exist. Fibre-optic chemical sensors (FOCS) have been developed for pH, pCO2, p02 and 3lucose (for review see Ref. 1). The existing FOCS utilize absorption, reflectance and fluorescence spectro-photometry. An integrated system for chemical mapping could utilize FOCS which exclusively use fluorescence probes which have a high signal to noise ratio and are sensitive to trace amounts of chemicals and biochemicals. One proposed strategy for detecting physiological analytes is the use of fluorescently labelled immunochemicals. These are useful in that the antibodies can be tailored to selectively bind almost any antigen conceivable (2) but are limited in that these reactions are mainly irreversible which is an important consideration for in vivo probes. A second strategy proposed is a receptor-based system (3). While agonist-receptor systems are slightly less selective than antigen-antibody systems, these reactions are reversible which is an important consideration for in vivo probes. Using existing FOCS and a new family of fluorescent chemical sensors that use

  7. Measurement of stress-strain behaviour of human hair fibres using optical techniques.

    PubMed

    Lee, J; Kwon, H J

    2013-06-01

    Many studies have presented stress-strain relationship of human hair, but most of them have been based on an engineering stress-strain curve, which is not a true representation of stress-strain behaviour. In this study, a more accurate 'true' stress-strain curve of human hair was determined by applying optical techniques to the images of the hair deformed under tension. This was achieved by applying digital image cross-correlation (DIC) to 10× magnified images of hair fibres taken under increasing tension to estimate the strain increments. True strain was calculated by summation of the strain increments according to the theoretical definition of 'true' strain. The variation in diameter with the increase in longitudinal elongation was also measured from the 40× magnified images to estimate the Poisson's ratio and true stress. By combining the true strain and the true stress, a true stress-strain curve could be determined, which demonstrated much higher stress values than the conventional engineering stress-strain curve at the same degree of deformation. Four regions were identified in the true stress-strain relationship and empirical constitutive equations were proposed for each region. Theoretical analysis on the necking condition using the constitutive equations provided the insight into the failure mechanism of human hair. This analysis indicated that local thinning caused by necking does not occur in the hair fibres, but, rather, relatively uniform deformation takes place until final failure (fracture) eventually occurs. PMID:23237580

  8. Optical fibre pressure and temperature sensor system designed for urodynamic applications

    NASA Astrophysics Data System (ADS)

    Duraibabu, Dineshbabu; Kelly, Niall; Poeggel, Sven; Flood, Hugh; Yuan, Hongwei; Dooly, Gerard; McGrath, Deirdre; Tosi, Daniele; Lewis, Elfed; Leen, Gabriel

    2016-05-01

    This paper presents an optical fibre pressure and temperature sensor (OFPTS) system, which is adapted for use as a urodynamic pressure measurement system (UPS) for differential pressure measurement with temperature compensation. The OFTPS is based on a Fabry Perot interferometer (FPI), which acts as a pressure sensor and includes an embedded fibre Bragg grating (FBG) for temperature measurement. The sensor system is evaluated in a lower urinary tract (LUT) simulator, which simulates the bladder, rectum and detrusor muscle. The system was benchmarked against a commercially available urodynamic system, at the University Hospital Limerick (UHL) Urology Clinic. Both systems demonstrate a high correlation with a relative pressure variation of less than +/-2.8cmH2O for abdominal and +/-4cmH2O for vesical pressure. The repetitive measurement of the OFPTS system in the LUT simulator against the commercial system demonstrated the high repeatability. Furthermore, the low fabrication cost makes the OFPTS a potentially interesting instrument for urodynamic and other medical applications.

  9. Plastic Optical Fibre Sensor for Spine Bending Monitoring with Power Fluctuation Compensation

    PubMed Central

    Zawawi, Mohd Anwar; O'Keeffe, Sinead; Lewis, Elfed

    2013-01-01

    This paper presents the implementation of power fluctuation compensation for an intensity-based optical fibre bending sensor aimed at monitoring human spine bending in a clinical environment. To compensate for the light intensity changes from the sensor light source, a reference signal was provided via the light reflection from an aluminum foil surface fixed at a certain distance from the source fibre end tips. From the results, it was found that the investigated sensor compensation technique was capable of achieving a 2° resolution for a bending angle working range between 0° and 20°. The study also suggested that the output voltage ratio has a 0.55% diversion due to input voltage variation between 2.9 V and 3.4 V and a 0.25% output drift for a 2 h measurement. With the achieved sensor properties, human spine monitoring in a clinical environment can potentially be implemented using this approach with power fluctuation compensation. PMID:24233073

  10. Single-Mode Propagation in Optical Waveguides and Fibres: A Critical Review of its Treatment in Physics Textbooks

    ERIC Educational Resources Information Center

    Ruddock, Ivan S.

    2009-01-01

    The derivation and description of the modes in optical waveguides and fibres are reviewed. The version frequently found in undergraduate textbooks is shown to be incorrect and misleading due to the assumption of an axial ray of light corresponding to the lowest order mode. It is pointed out that even the lowest order must still be represented in…

  11. High temperature stability testing of Ge-doped and F-doped Fabry-Perot fibre optical sensors

    NASA Astrophysics Data System (ADS)

    Polyzos, Dimitrios; Mathew, Jinesh; MacPherson, William N.; Maier, Robert R...

    2016-05-01

    We present high temperature (~1100°C) stability tests of, Ge-doped and F-doped, optical fibre sensors. Our analysis includes the variation in their behaviours within high temperature environments and how the dopant diffusion affects their long term stability.

  12. Prospective Study on Retinal Nerve Fibre Layer Thickness Changes in Isolated Unilateral Retrobulbar Optic Neuritis

    PubMed Central

    Yau, Gordon S. K.; Lee, Jacky W. Y.; Lau, Patrick P. K.; Tam, Victor T. Y.; Wong, Winnie W. Y.; Yuen, Can Y. F.

    2013-01-01

    Purpose. To investigate the retinal nerve fibre layer (RNFL) thickness after unilateral acute optic neuritis using optical coherence tomography (OCT). Patients and Methods. This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis. RNFL thickness and visual acuity (VA) of the attack and normal fellow eye were measured at presentation and 3 months in both the treatment and nontreatment groups. Results. 11 subjects received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eye (P ≥ 0.4). At 3 months, the attack eye had a thinner temporal (P = 0.02) and average (P = 0.05) RNFL compared to the fellow eye. At 3 months, the attack eye had significant RNFL thinning in the 4 quadrants and average thickness (P ≤ 0.0002) compared to baseline. The RNFL thickness between the treatment and nontreatment groups was similar at baseline and 3 months (P ≥ 0.1). Treatment offered better VA at 3 months (0.1 ± 0.2 versus 0.3 ± 0.2 LogMAR, P = 0.04). Conclusion. Generalized RNFL thinning occurred at 3 months after a first episode of acute optic neuritis most significantly in the temporal quadrant and average thickness. Visual improvement with treatment was independent of RNFL thickness. PMID:24459442

  13. Using a fibre-optic cable as Distributed Acoustic Sensor for Vertical Seismic Profiling - Overview of various field tests

    NASA Astrophysics Data System (ADS)

    Götz, Julia; Lüth, Stefan; Henninges, Jan; Reinsch, Thomas

    2015-04-01

    Fibre-optic Distributed Acoustic Sensing (DAS) or Distributed Vibration Sensing (DVS) is a technology, where an optical fibre cable is used as a sensor for acoustic signals. An ambient seismic wavefield, which is coupled by friction or pressure to the optical fibre, induces dynamic strain changes along the cable. The DAS/DVS technology offers the possibility to record an optoelectronic signal which is linearly related to the time dependent local strain. The DAS/DVS technology is based on the established technique of phase-sensitive optical time-domain reflectometry (phi-OTDR). Coherent laser pulses are launched into the fibre to monitor changes in the resulting elastic Rayleigh backscatter with time. Dynamic strain changes lead to small displacements of the scattering elements (non-uniformities within the glass structure of the optical fibre), and therefore to variations of the relative phases of the backscattered photons. The fibre behaves as a series of interferometers whose output is sensitive to small changes of the strain at any point along its length. To record the ground motion not only in space but also in time, snapshots of the wavefield are created by repeatedly firing laser pulses into the fibre at sampling frequencies much higher than seismic frequencies. DAS/DVS is used e.g. for continuous monitoring of pipelines, roads or borders and for production monitoring from within the wellbore. Within the last years, the DAS/DVS technology was further developed to record seismic data. We focus on the recording of Vertical Seismic Profiling (VSP) data with DAS/DVS and present an overview of various field tests published between 2011 and 2014. Here, especially CO2 storage pilot sites provided the opportunity to test this new technology for geophysical reservoir monitoring. DAS/DVS-VSP time-lapse measurements have been published for the Quest CO2 storage site in Canada. The DAS/DVS technology was also tested at the CO2 storage sites in Rousse (France), Citronelle

  14. Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres

    NASA Astrophysics Data System (ADS)

    Gissibl, Timo; Thiele, Simon; Herkommer, Alois; Giessen, Harald

    2016-06-01

    Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of the single-mode fibres. We determine the accuracy of our optics by analysing the output patterns as well as interferometrically characterizing the surfaces. We find excellent agreement with numerical calculations. 3D printing of microoptics can achieve sufficient performance that will allow for rapid prototyping and production of beam-shaping and imaging devices.

  15. Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres.

    PubMed

    Gissibl, Timo; Thiele, Simon; Herkommer, Alois; Giessen, Harald

    2016-01-01

    Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of the single-mode fibres. We determine the accuracy of our optics by analysing the output patterns as well as interferometrically characterizing the surfaces. We find excellent agreement with numerical calculations. 3D printing of microoptics can achieve sufficient performance that will allow for rapid prototyping and production of beam-shaping and imaging devices. PMID:27339700

  16. Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres

    PubMed Central

    Gissibl, Timo; Thiele, Simon; Herkommer, Alois; Giessen, Harald

    2016-01-01

    Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of the single-mode fibres. We determine the accuracy of our optics by analysing the output patterns as well as interferometrically characterizing the surfaces. We find excellent agreement with numerical calculations. 3D printing of microoptics can achieve sufficient performance that will allow for rapid prototyping and production of beam-shaping and imaging devices. PMID:27339700

  17. Spectroscopy of Optical Excitations in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Yingzhong

    2006-03-01

    Understanding the optical spectra and electronic excited state dynamics of carbon naotubes is important both for fundamental research and a wide variety of potential applications. In this presentation, we will report the results of a systematic study on semiconducting single-walled carbon nanotubes (SWNTs) obtained by utilizing complementary femtosecond spectroscopic techniques, including fluorescence up-conversion, frequency-resolved transient absorption, and three-pulse photon echo peakshift (3PEPS) spectroscopy. Our efforts have focused on optically selective detection of the spectra and dynamics associated with structurally distinct semiconducting SWNT species. Using individual nanotube enriched micelle-dispersed SWNT preparations, in combination with resonant excitation and detection, has enabled us to independently access selected species, such as the (8,3), (6,5), (7,5), (11,0), (7,6) and (9,5) nanotubes. We will discuss the following topics: (1) the excitonic nature of the elementary excitation and its unambiguous identification from direct determination of the exciton binding energy for a selected semiconducting nanotube, the (8,3) tube; (2) the spectroscopic and dynamical signatures of exciton-exciton annihilation and its predominant role in governing ultrafast excited state relaxation; (3) the annihilation-concomitant exciton dissociation and the spectroscopic and dynamic features of the resulting electron-hole continuum; (4) timescales characterizing the ultrafast thermalization processes. In addition, we will demonstrate the power of 3PEPS spectroscopy to elucidate the spectral properties and dynamics of SWNTs. This work was supported by the NSF.

  18. Time transfer through optical fibres over a distance of 73 km with an uncertainty below 100 ps

    NASA Astrophysics Data System (ADS)

    Rost, M.; Piester, D.; Yang, W.; Feldmann, T.; Wübbena, T.; Bauch, A.

    2012-12-01

    We demonstrate the capability of accurate time transfer using optical fibres over long distances utilizing a dark fibre and hardware which is usually employed in two-way satellite time and frequency transfer (TWSTFT). Our time transfer through optical fibre (TTTOF) system is a variant of the standard TWSTFT by employing an optical fibre in the transmission path instead of free-space transmission of signals between two ground stations through geostationary satellites. As we use a dark fibre there are practically no limitations to the bandwidth of the transmitted signals so that we can use the highest chip rate of the binary phase-shift modulation available from the commercial equipment. This leads to an enhanced precision compared with satellite time transfer where the occupied bandwidth is limited for cost reasons. The TTTOF system has been characterized and calibrated in a common-clock experiment at PTB, and the combined calibration uncertainty is estimated as 74 ps. In a second step the remote part of the system was operated at Leibniz Universität Hannover, Institut für Quantenoptik (IQ) separated by 73 km from PTB in Braunschweig. In parallel, a GPS time transfer link between Braunschweig and Hannover was established, and both links connected a passive hydrogen maser at IQ with the reference time scale UTC(PTB) maintained in PTB. The results obtained with both links agree within the 1-σ uncertainty of the GPS link results, which is estimated as 0.72 ns. The fibre link exhibits a nearly ten-fold improved stability compared with the GPS link, and assessment of its performance has been limited by the properties of the passive maser.

  19. SOLITONS AND OPTICAL FIBERS: Self-Q-switched ytterbium-doped cladding-pumped fibre laser

    NASA Astrophysics Data System (ADS)

    Grukh, Dmitrii A.; Kurkov, Andrei S.; Razdobreev, I. M.; Fotiadi, A. A.

    2002-11-01

    A self-Q-switched ytterbium-doped double-clad fibre laser is described. A samarium-doped fibre is used as a filter for protecting a pump source. A fibre coupler is employed to obtain a nonlinear feedback. The mechanism of pulse formation in the laser is considered, and the dependence of its output pulse on the coupler parameters is studied.

  20. Experimental analysis of buckling in aircraft skin panels by fibre optic sensors

    NASA Astrophysics Data System (ADS)

    Güemes, J. A.; Menendez, J. M.; Frövel, M.; Fernandez, I.; Pintado, J. M.

    2001-06-01

    Three blade-stiffened CFRP panels with co-cured stiffener webs, manufactured by means of an elastomeric mould, have been tested under compressive load. Several Bragg grating sensors have been surface bonded on two of the stiffened panels and have been embedded into the stiffener webs of the third panel. The Bragg grating sensors measured the strain distribution in the stiffener web and in the skin panels. The bucking onset was clearly detected in every case, the post-buckling behaviour can be tracked, but the information is heavily dependent on the right choice of the sensor position and the buckling mode. To calibrate the system, and to evaluate the influence of different curing pressures, and the use of unidirectional or fabric prepreg material, tensile test specimens were made on flat panels. The strain measurements provided by the optical fibre sensors in tensile tests were compared with the strain measurements provided by conventional clamp extensometers.

  1. Thermoluminescent response of single mode optical fibre to x-ray irradiation

    NASA Astrophysics Data System (ADS)

    Che Omar, S. S.; Hashim, S.; Ibrahim, S. A.; Hassan, W. M. S. Wan; Mahdiraji, G. A.; Isa, N. Md; Mad Isa, M. J.; Abd Jalil, M. M.; Kadir, A. B.

    2014-11-01

    We present the characteristics of the thermoluminescence (TL) response of single mode optical fibre (SMF) subjected to 30 and 70 kV x-ray irradiation. The TL responses are compared with commercially available TLD-100 (rod types). The SMF and TLD-100 were irradiated with x-ray source by using X-rays Generator model Phillips MG 165 located at Malaysian Nuclear Agency. The SMF and TLD-100 show linear dose response subjected to 30 and 70 kV x-ray irradiation. The SMF shows TL response by 10 times and 8 times greater than TLD-100 for the above-mentioned energies. The TL sensitivity characteristics of SMF show promising results to be introduced as a TL dosimeter material. The SMF could be used in several applications in the fields of medicine, industry, and research purposes.

  2. Review of Trackside Monitoring Solutions: From Strain Gages to Optical Fibre Sensors.

    PubMed

    Kouroussis, Georges; Caucheteur, Christophe; Kinet, Damien; Alexandrou, Georgios; Verlinden, Olivier; Moeyaert, Véronique

    2015-01-01

    A review of recent research on structural monitoring in railway industry is proposed in this paper, with a special focus on stress-based solutions. After a brief analysis of the mechanical behaviour of ballasted railway tracks, an overview of the most common monitoring techniques is presented. A special attention is paid on strain gages and accelerometers for which the accurate mounting position on the track is requisite. These types of solution are then compared to another modern approach based on the use of optical fibres. Besides, an in-depth discussion is made on the evolution of numerical models that investigate the interaction between railway vehicles and tracks. These models are used to validate experimental devices and to predict the best location(s) of the sensors. It is hoped that this review article will stimulate further research activities in this continuously expanding field. PMID:26287207

  3. Review of Trackside Monitoring Solutions: From Strain Gages to Optical Fibre Sensors

    PubMed Central

    Kouroussis, Georges; Caucheteur, Christophe; Kinet, Damien; Alexandrou, Georgios; Verlinden, Olivier; Moeyaert, Véronique

    2015-01-01

    A review of recent research on structural monitoring in railway industry is proposed in this paper, with a special focus on stress-based solutions. After a brief analysis of the mechanical behaviour of ballasted railway tracks, an overview of the most common monitoring techniques is presented. A special attention is paid on strain gages and accelerometers for which the accurate mounting position on the track is requisite. These types of solution are then compared to another modern approach based on the use of optical fibres. Besides, an in-depth discussion is made on the evolution of numerical models that investigate the interaction between railway vehicles and tracks. These models are used to validate experimental devices and to predict the best location(s) of the sensors. It is hoped that this review article will stimulate further research activities in this continuously expanding field. PMID:26287207

  4. Smart current collector—fibre optic hit detection system for improved security on railway tracks

    NASA Astrophysics Data System (ADS)

    Schröder, Kerstin; Ecke, Wolfgang; Kautz, Michael; Willett, Simon; Unterwaditzer, Hansjörg; Bosselmann, Thomas; Rothhardt, Manfred

    2013-11-01

    In a deregulated EU railway market, monitoring the vehicle and infrastructure interfaces is mandatory for the enhanced availability of operation and for reducing costs. Therefore, infrastructure managers need monitoring tools on overhead contact lines (OCLs). We know from earlier investigations that a measurement of contact forces alone is not sufficient (Schröder et al 2013 Opt. Lasers Eng. 51 172-9). In this study, we introduce a system which is fast enough to detect short disturbances and which can be used with regular trains. It is based on fibre optic sensors integrated with conventional current collectors (CCs). The system is designed to monitor hard and soft hits on the CC in horizontal (driving) and vertical (contact) direction. It was systematically tested in the laboratory as well as in test runs on commercial railways in several countries. With its help, a variety of minor as well as serious defects have been discovered and repaired at the CC-OCL interface.

  5. Advanced fibre optical scanning in thin-layer chromatography for drug identification.

    PubMed

    Ahrens, Björn; Blankenhorn, Dirk; Spangenberg, Bernd

    2002-05-25

    A systematic toxicological analysis procedure using high-performance thin layer chromatography in combination with fibre optical scanning densitometry for identification of drugs in biological samples is presented. Two examples illustrate the practicability of the technique. First, the identification of a multiple intake of analgesics: codeine, propyphenazone, tramadol, flupirtine and lidocaine, and second, the detection of the sedative diphenhydramine. In both cases, authentic urine specimens were used. The identifications were carried out by an automatic measurement and computer-based comparison of in situ UV spectra with data from a compiled library of reference spectra using the cross-correlation function. The technique allowed a parallel recording of chromatograms and in situ UV spectra in the range of 197-612 nm. Unlike the conventional densitometry, a dependency of UV spectra by concentration of substance in a range of 250-1000 ng/spot was not observed. PMID:12016011

  6. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications.

    PubMed

    Di Sante, Raffaella

    2015-01-01

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques. PMID:26263987

  7. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    PubMed Central

    Di Sante, Raffaella

    2015-01-01

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques. PMID:26263987

  8. The application of fibre optic temperature sensing for under insulation monitoring of subsea infrastructure

    NASA Astrophysics Data System (ADS)

    Faichnie, David M.; Graham, Alan; McStay, Daniel

    2010-04-01

    The use of insulation within the oil and gas industry to provide heat retention during production downtime is important to reduce the risk of hydrate formation within the flow-loops in the subsea infrastructure. Hydrate formation can significantly decrease the production efficiency and hence the profitability of the well. Hydrates can also introduce serious safety risks, if formed with in critical components such as safety valves. During production downtime the elevated temperature of equipment such as XTs will begin to equalize to the ambient subsea temperature. The accurate assessment of the effectiveness of such insulation is thus critical. Monitoring insulation performance during cool down trials is typically performed during test and assembly of production equipment using a limited number of electrical sensors. The use of multiplexed fibre optic sensors offers a reduction in the number of penetrations in the insulation, when compared to traditional electrical sensors and thus allows far more representative temperature measurements to be made. Additionally, conventional electrical sensors will rapidly degrade in the subsea environment, making them unsuited for long term subsea monitoring. In this paper we report the use of embedded optical fibre sensors, which should maintain their full performance over the lifetime of the subsea equipment. This would enable the long term insulation performance to be assessed after a tree is recovered for maintenance, or even allow continuous monitoring of the insulation performance during service. Results of tests carried out in an environmental chamber to show the performance of the sensors during cooling cycles are reported and initial results taken during production testing prior to deployment of the equipment subsea are reported.

  9. Cavity-Enhanced Optical Frequency Comb Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ye, Jun; Thorpe, Michael J.; Adler, Florian; Cossel, Kevin C.

    2009-06-01

    Cavity-enhanced optical frequency comb spectroscopy is a new technique that realizes simultaneously broad spectral coverage and high spectral resolution provided by an optical frequency comb as well as ultrahigh detection sensitivities enabled with a high-finesse optical cavity [1]. These powerful capabilities have been demonstrated in a series of experiments where real-time detection and identification of many different molecular states or species are achieved in a massively parallel fashion [2,3]. We will discuss the principle, technical requirements, and various implementations for this spectroscopic approach, as well as applications that include trace gas detections, human breath analysis, and characterization of cold and ultracold molecules [4,5,6]. References: [1] M. J. Thorpe, K. D. Moll, B. Safdi, and J. Ye, Science 311, 1595 (2006). [2] M. J. Thorpe, D. D. Hudson, K. D. Moll, J. Lasri, and J. Ye, Opt. Lett. 32, 307 (2007). [3] C. Gohle, B. Stein, A. Schliesser, T. Udem, and T. W. Hänsch, Phys. Rev. Lett. 99, 263902 (2007). [4] M. J. Thorpe, D. Balslev-Clausen, M. Kirchner, and J. Ye, Opt. Express. 16, 2387 (2008). [5] M. J. Thorpe and J. Ye, Appl. Phys. B 91, 397 (2008). [6] M. J. Thorpe, F. Adler, K. C. Cossel, M. H. G. de Miranda, and J. Ye, Chem. Phys. Lett. 468, 1 (2009).

  10. Electrogenerated chemiluminescence of luminol for oxidase-based fibre-optic biosensors.

    PubMed

    Marquette, C A; Leca, B D; Blum, L J

    2001-01-01

    The luminol electrochemiluminescence has been exploited for the development of several fibre-optic biosensors allowing the detection of hydrogen peroxide and of substrates of H(2)O(2)-producing oxidases. Electro-optical flow injection analysis of glucose, lactate, cholesterol and choline are thus described. To perform the experiments, a glassy carbon electrode was polarized at a fixed potential. Luminol was then electrochemically oxidized and could react in the presence of hydrogen peroxide to produce light. Several parameters had to be optimized to obtain reliable optical biosensors. An optimum applied potential of +425 mV between the glassy carbon electrode and the platinum pseudo-reference electrode was determined, allowing the best signal: noise ratio to be obtained. It was also necessary to optimize the experimental conditions for the immobilization of the different oxidases involved (preactivated membranes, chemically activated collagen membranes, photopolymerized matrix). For each biosensor developed, the optimum reaction conditions have been studied: buffer composition, pH, temperature, flow rate and luminol concentration. Under optimal conditions, the detection limits (S/N = 3) were 30 pmol, 60 pmol, 0.6 nmol and 10 pmol for lactate, glucose, cholesterol and choline, respectively. The miniaturization of electrochemiluminescence-based biosensors has been realized using screen-printed electrodes instead of a glassy carbon macroelectrode, with choline oxidase as a model H(2)O(2)-generating oxidase. PMID:11312542

  11. Exploration of optical fibres as a carrier for new benzene and toluene matrix-free reference materials.

    PubMed

    Słomińska, Marta; Marć, Mariusz; Szczygelska-Tao, Jolanta; Konieczka, Piotr; Namieśnik, Jacek

    2015-07-01

    To meet high expectations concerning precision and accuracy of reference materials, preparation of matrix-free reference materials using thermal decomposition-gas chromatography-mass spectrometry (TD-GC-MS) was proposed in this study. In the paper, the results obtained in preparation of the new reference materials for benzene and toluene are presented, based on the thermal decomposition technique of compounds chemically bound to the surface of optical fibre segments. The results obtained at various stages of the research procedure (homogeneity, stability) confirmed the possibility of using prepared laboratory samples of materials as reference materials for benzene and toluene. For the prepared batch of materials, reference values 1.26 ± 0.91 (ng/fibre) for benzene and 11.3 ± 7.4 (ng/fibre) for toluene were determined. PMID:25976396

  12. Gamma-irradiation tests of IR optical fibres for ITER thermography--a case study

    SciTech Connect

    Reichle, R.; Pocheau, C.; Jouve, M.

    2008-03-12

    In the course of the development of a concept for a spectrally resolving infrared thermography diagnostic for the ITER divertor we have tested 3 types of infrared (IR) fibres in Co{sup 60} irradiation facilities under {gamma} irradiation. The fibres were ZrF{sub 4} (and HfF{sub 4}) fibres from different manufacturers, hollow fibres (silica capillaries with internal Ag/AgJ coating) and a sapphire fibre. For the IR range, only the latter fibre type encourages to go further for neutron tests in a reactor. If one restricted the interest onto the near infrared range, high purity core silica fibres could be used. This study might be seen as a typical example of the relation between diagnostic development for a nuclear environment and irradiation experiments.

  13. Hyperspectral fluorescence lifetime fibre probe spectroscopy for use in the study and diagnosis of osteoarthritis and skin cancer

    NASA Astrophysics Data System (ADS)

    Thompson, Alex; Manning, Hugh; Brydegaard, Mikkel; Coda, Sergio; Kennedy, Gordon; Patalay, Rakesh; Waitong-Braemming, Ulrika; De Beule, Pieter; Neil, Mark; Andersson-Engels, Stefan; Itoh, Yoshifumi; Bendsøe, Niels; Dunsby, Christopher; Svanberg, Katarina; French, Paul M.

    2011-03-01

    We present the application of two fibre-optic-coupled time-resolved spectrofluorometers and a compact steady-state diffuse reflected light/fluorescence spectrometer to in vivo and ex vivo studies of skin cancer and osteoarthritis. In a clinical study of skin cancer, 27 lesions on 25 patients were investigated in vivo before surgical excision of the region measured. Preliminary analysis reveals a statistically significant decrease in the autofluorescence lifetime of basal cell carcinomas compared to neighbouring healthy tissue. A study of autofluorescence signals associated with the onset of osteoarthritis indicates autofluorescence lifetime changes associated with collagen degradation.

  14. Intraocular tissue ablation using an optical fibre to deliver the 5th harmonic of a Nd:YAG

    NASA Astrophysics Data System (ADS)

    Miller, Joseph; Yu, Xiaobo; Yu, Paula K.; Cringle, Stephen J.; Yu, Dao-Yi

    2009-02-01

    We report the evaluation of a system which delivers the 5th harmonic of an Nd:YAG (213nm) via optical fibre to ocular tissue sites. The 213nm beam is concentrated, using a hollow glass taper, prior to launch into 200 μm or 600 μm core diameter silica/silica optical fibre. The fibre tip was tapered to enhance the fluence delivered. An operating window of fluence values that could be delivered via 330 - 1100mm lengths of optical fibre was determined. The lower value of 0.2J/cm2 determined by the ablation threshold of the tissue and the upper value of 1.3J/cm2 by the launch, transmission and tip characteristics of the optical fibre. The fluence output decreased as a function of both transmitted pulse energy and number of pulses transmitted. Fresh retinal tissue was cleanly ablated with minimal damage to the surrounding tissue. Lesions were generated using 1, 3 and 10 pulses with fluences from 0.2 to 1.0J/cm2. The lesion depth demonstrated clear dose dependence. Lesions generated in ex vivo preparations of human trabecular meshwork in a fluid environment also demonstrated dose dependence, 50 pulses being sufficient to create a hole within the trabecular meshwork extending to Schlemm's canal. The dose dependence of the ablation depth combined with the ability of this technique to create a conduit through to Schlemm's canal demonstrates the potential of this technique for ophthalmological applications requiring precise and controlled intraocular tissue removal and has potential applications in the treatment and management of glaucoma.

  15. Study on dietary fibre by Fourier transform-infrared spectroscopy and chemometric methods.

    PubMed

    Chylińska, Monika; Szymańska-Chargot, Monika; Kruk, Beata; Zdunek, Artur

    2016-04-01

    Fresh fruit is an important part of the diet of people all over the world as a significant source of water, vitamins and natural sugars. Nowadays it is also one of the main sources of dietary fibre. In fruit the dietary fibre is simply cell wall consisting essentially of polysaccharides. The aim of present study was to predict the contents of pectins, cellulose and hemicelluloses by partial least squares regression (PLS) analysis on the basis of Fourier transform-infrared (FT-IR) spectra of fruit cell wall residue. The second purpose was to analyse the composition of dietary fibre from fruit based on FT-IR spectral information in combination with chemometric methods (principle components analysis (PCA) and hierarchical cluster analysis (HCA)). Additionally the contents of polysaccharides in studied fruits were determined by analytical methods. It has been shown that the analysis of infrared spectra and the use of multivariate statistical methods can be useful for studying the composition of dietary fibre. PMID:26593472

  16. Optical spectroscopy of nanoscale and heterostructured oxides

    NASA Astrophysics Data System (ADS)

    Senty, Tess R.

    Through careful analysis of a material's properties, devices are continually getting smaller, faster and more efficient each day. Without a complete scientific understanding of material properties, devices cannot continue to improve. This dissertation uses optical spectroscopy techniques to understand light-matter interactions in several oxide materials with promising uses mainly in light harvesting applications. Linear absorption, photoluminescence and transient absorption spectroscopy are primarily used on europium doped yttrium vanadate nanoparticles, copper gallium oxide delafossites doped with iron, and cadmium selenide quantum dots attached to titanium dioxide nanoparticles. Europium doped yttrium vanadate nanoparticles have promising applications for linking to biomolecules. Using Fourier-transform infrared spectroscopy, it was shown that organic ligands (benzoic acid, 3-nitro 4-chloro-benzoic acid and 3,4-dihydroxybenzoic acid) can be attached to the surface of these molecules using metal-carboxylate coordination. Photoluminescence spectroscopy display little difference in the position of the dominant photoluminescence peaks between samples with different organic ligands although there is a strong decrease in their intensity when 3,4-dihydroxybenzoic acid is attached. It is shown that this strong quenching is due to the presence of high-frequency hydroxide vibrational modes within the organic linker. Ultraviolet/visible linear absorption measurements on delafossites display that by doping copper gallium oxide with iron allows for the previously forbidden fundamental gap transition to be accessed. Using tauc plots, it is shown that doping with iron lowers the bandgap from 2.8 eV for pure copper gallium oxide, to 1.7 eV for samples with 1 -- 5% iron doping. Using terahertz transient absorption spectroscopy measurements, it was also determined that doping with iron reduces the charge mobility of the pure delafossite samples. A comparison of cadmium selenide

  17. Optical Reflection Spectroscopy of GEO Objects

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Cardona, Tammaso; Lederer, Susan M.; Cowardin, Heather; Abercromby, Kira J.; Barker, Edwin S.; Bedard, Donald

    2013-01-01

    We report on optical reflection spectroscopy of geosynchronous (GEO) objects in the US Space Surveillance Network (SSN) catalog. These observations were obtained using imaging spectrographs on the 6.5-m Magellan telescopes at the Las Campanas Observatory in Chile. Our goal is to determine the composition of these objects by comparing these spectral observations with ground-based laboratory measurements of spacecraft materials. The observations are all low resolution (1 nm after smoothing) obtained through a 5 arcsecond wide slit and using a grism as the dispersing element. The spectral range covered was from 450 nm to 800 nm. All spectra were flux calibrated using observations of standard stars with the exact same instrumental setup. An effort was made to obtain all observations within a limited range of topocentric phase angle, although the solar incident angle is unknown due to the lack of any knowledge of the attitude of the observed surface at the time of observation.

  18. Adaptive Optics Imaging and Spectroscopy of Neptune

    NASA Technical Reports Server (NTRS)

    Johnson, Lindley (Technical Monitor); Sromovsky, Lawrence A.

    2005-01-01

    OBJECTIVES: We proposed to use high spectral resolution imaging and spectroscopy of Neptune in visible and near-IR spectral ranges to advance our understanding of Neptune s cloud structure. We intended to use the adaptive optics (AO) system at Mt. Wilson at visible wavelengths to try to obtain the first groundbased observations of dark spots on Neptune; we intended to use A 0 observations at the IRTF to obtain near-IR R=2000 spatially resolved spectra and near-IR A0 observations at the Keck observatory to obtain the highest spatial resolution studies of cloud feature dynamics and atmospheric motions. Vertical structure of cloud features was to be inferred from the wavelength dependent absorption of methane and hydrogen,

  19. On-line monitoring of biofilm formation in a brewery water pipeline system with a fibre optical device.

    PubMed

    Tamachkiarow, L; Flemming, H C

    2003-01-01

    Any advanced anti-fouling strategy must be based on early warning systems which allow for timely, precisely directed and optimized countermeasures. Such systems must be able to detect biofilm growth on representative surfaces. In order to meet this requirement, a fibre optical device (FOS) has been developed. It is based on light which is scattered by objects deposited on the tip of an optical fibre. A receiving fibre collects the signal and forwards it to a detection and quantification unit. Both the sending and the receiving fibre are mounted in a measuring head which is integrated evenly on the inner surface of a water pipeline at representative sites. This device was applied to a water system of a brewery in order toput its reliability to test under practical conditions. The FOS detected the build-up of a deposit which was identified independently as consisting of microorganisms, i.e., a biofilm. A stable, well detectable and reproducible signal could be obtained above a colonization of 10(5) cells cm-2. Adjustment of the sensitivity of the amplifier allowed for detection of biofilms up to 10(10) cells cm-2. Cleaning countermeasures could be detected clearly by a decrease of backscattered light intensity. The system proved to be suitable for on-line, non-destructive, real-time and automatic monitoring for a period of almost two years, and thus, provides an important constituent for an advanced anti-fouling strategy. PMID:12701901

  20. Micro-optical instrumentation for process spectroscopy

    NASA Astrophysics Data System (ADS)

    Crocombe, Richard A.; Flanders, Dale C.; Atia, Walid

    2004-12-01

    Traditional laboratory ultraviolet/visible/near-infrared spectroscopy instruments are tabletop-sized pieces of equipment that exhibit very high performance, but are generally too large and costly to be widely distributed for process control applications or used as spectroscopic sensors. Utilizing a unique, and proven, micro-optical technology platform origi-nally developed, qualified and deployed in the telecommunications industry, we have developed a new class of spectro-scopic micro-instrumentation that has laboratory quality resolution and spectral range, with superior speed and robust-ness. The fundamentally lower cost and small form factor of the technology will enable widespread use in process moni-toring and control. This disruption in the ground rules of spectroscopic analysis in these processes is enabled by the re-placement of large optics and detector arrays with a high-finesse, high-speed micro electro mechanical system (MEMS) tunable filter and a single detector, that enable the manufacture of a high performance and extremely rugged spectrome-ter in the footprint of a credit card. Specific process monitoring and control applications discussed in the paper include pharmaceutical, gas sensing and chemical processing applications.

  1. Fabry Perot polymer film fibre-optic hydrophones and arrays for ultrasound field characterisation

    NASA Astrophysics Data System (ADS)

    Cox, B. T.; Zhang, E. Z.; Laufer, J. G.; Beard, P. C.

    2004-01-01

    An optical ultrasound sensing method based upon the detection of acoustically-induced changes in the optical thickness of a Fabry Perot (FP) polymer film sensing interferometer has been developed as an alternative to piezoelectric based detection methods for ultrasound measurement applications. The technique provides an inherently broadband (~30 MHz) response and excellent detection sensitivities (<10 kPa), comparable to those of piezoelectric PVDF transducers. An important distinguishing feature however is that the sensing geometry is defined by the area of the polymer sensing film that is optically addressed. As a result, very small element sizes can be obtained to provide low directional sensitivity without compromising detection sensitivity—a key advantage over piezoelectric transducers. It also means that, by spatially sampling over a relatively large aperture, a high density ultrasound array can readily be configured. Other advantages are that, the sensing element can be inexpensively batch fabricated using polymer film deposition techniques, has the ability to self-calibrate, is electrically passive and immune to EMI. A range of measurement devices using this type of sensor have now been developed. These include a miniature (0.25 mm o.d.) optical fibre hydrophone for in situ measurements of diagnostic and therapeutic medical ultrasound exposure. By rapidly scanning a focused laser beam over a planar FP sensor, a notional array of 3 cm aperture, 50 µm element size and 200 µm interelement spacing has also been demonstrated for rapid transducer field mapping applications. It is considered that this ability to fabricate acoustically small, highly sensitive receivers in a variety of configurations offers the prospect of developing a valuable new set of ultrasound measurement tools.

  2. Sub-aquatic response of a scintillator, fibre optic and silicon photomultiplier based radiation sensor

    NASA Astrophysics Data System (ADS)

    Jackson, Sarah F.; Monk, Stephen D.; Stanley, Steven J.; Lennox, Kathryn

    2014-07-01

    We describe an attempt at the utilisation of two low level light sensors to improve on the design of a dose monitoring system, specifically for underwater applications with consideration for the effects of water attenuation. The gamma radiation ‘RadLine®’ detector consists of an inorganic scintillating crystal coupled to a fibre optic cable which transports scintillation photons, up to hundreds of metres, to an optical sensor. Analysed here are two contemporary technologies; SensL's MiniSL a silicon photomultiplier (SiPM) and a Sens-Tech photon counting photomultiplier tube (PMT). A clinical radiotherapy linear accelerator (linac) is implemented as test beam, subjecting the RadLine® to a highly controlled dose rate (ranging from 0 Sv h-1 to 320 Sv h-1), averaging at 2 MeV in energy. The RadLine's underwater dose monitoring capabilities are tested with the aid of epoxy resin ‘solid water’ phantom blocks, used as a substitute for water. Our results show that the MiniSL SiPM is unsuitable for this application due to extremely high background noise levels, however the Sens-Tech PMT performs satisfactorily and the detected dose rate due to the effects of water attenuation compares strongly with MCNP simulation data and NIST database values. We conclude that the PMT shows promise for its ultimate use in the First Generation Magnox Storage Pond (FGMSP) on the Sellafield site.

  3. Aerosol optical absorption measurements with photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  4. Effect of temperature on the active properties of erbium-doped optical fibres

    NASA Astrophysics Data System (ADS)

    Kotov, L. V.; Ignat'ev, A. D.; Bubnov, M. M.; Likhachev, M. E.

    2016-03-01

    We have studied the effect of heating on the performance of erbium-doped fibre based devices and determined temperaturedependent absorption and emission cross sections of the erbium ion in silica glass. The results demonstrate that heating of fibres in claddingpumped high-power (~100 W) erbium-doped fibre lasers causes no significant decrease in their efficiency. In contrast, superluminescent sources operating in the long-wavelength region (1565 – 1610 nm) are extremely sensitive to temperature changes.

  5. Optical-fibre sensor system for monitoring the performance of the gas propellant centrifuge separator of a spacecraft

    NASA Astrophysics Data System (ADS)

    Romo-Medrano, Katya E.; Khotiaintsev, Sergei N.; García-Garduño, Victor

    2004-08-01

    An optical-fibre sensor system is presented for monitoring void fraction distribution in a spacecraft's gas and propellant centrifuge separator. The system could be used at the separator development stage or for monitoring, during ground tests, the elements of the spacecraft propulsion system. Our sensor system employs an array of point optical-fibre refractometric transducers installed in the form of several linear radial arrays on the separator rotating blades. We employed a small-size hemispherical optical detection element as the transducer and we optimized its parameters through numerical ray-tracing. The aim is to minimize the effect of the thin film of liquid that forms on the transducer's surface in this application. The features of this sensor system are: (1) an efficient matrix-type multiplexing scheme, (2) the installation of the main optoelectronic unit of the sensor in a hermetically sealed container inside the separator tank located on the rotating shaft and (3) the spark-proof and explosion-proof design of the sensor circuits and elements. The sensor is simple, reliable, low-cost and is capable of withstanding the factors involved during operation of the propulsion system such as cryogenic temperatures and chemically aggressive liquids. The novel elements and design concepts implemented in this sensor system can also find applications in other sensors for spacecraft propulsion systems and also in a variety of optical-fibre sensors used in scientific research and industry.

  6. Fibre optics wavemeters calibration using a self-referenced optical frequency comb

    SciTech Connect

    Galindo-Santos, J.; Velasco, A. V.; Corredera, P.

    2015-01-15

    Self-referenced optical frequency combs enable the measurement of optical frequencies with a very high accuracy, achieving uncertainties close to the atomic clock used as reference (<10{sup −13} s). In this paper, we present the technique for the measurement of laser frequencies for optical communications followed at IO-CSIC and its application to the calibration of two wavemeters in the 1.5 μm optical communication window. Calibration uncertainties down to 12 MHz and 59 MHz were obtained, respectively, for each of the devices. Furthermore, the long-term behaviour of the higher resolution wavemeter was studied during a 750 h period of sustained operation, exhibiting a dispersion in the measurements of 7.72 MHz. Temperature dependence of the device was analysed, enabling to further reduce dispersion down to a 2.15 MHz range, with no significant temporal deviations.

  7. A novel low coherence fibre optic interferometer for position and thickness measurements with unattained accuracy

    NASA Astrophysics Data System (ADS)

    Wilhelm, Rainer; Courteville, Alain; Garcia, Fabrice

    2006-04-01

    This paper presents the second generation LISE-LI of the fibre-optics Low coherence Interferometric Sensor (LISE), recently developed by FOGALE nanotech. Based on the proven concept of partial coherence interferometry, the LISE system works as a comparator of optical group delays. The group delay along the optical axis in the probe interferometer arm containing the object to be measured is compared with the group delay along the optical axis of the reference interferometer arm containing a delay line. The latter consists of a mirror that can be linearly displaced on a translation stage. The light source is a super luminescent diode emitting at near infrared wavelength (typically 1.31 μm) with a spectral bandwidth of a few tens of nm. Thanks to the limited temporal coherence of the source, multiple surfaces of the object can be detected during a single scan of the delay line. Measurement ranges are between a few mm up to 600 mm (optical thickness). The measurement zone can be placed at a working distance of up to several meters away from the instrument's exit. Applications in industry and in research laboratories include thickness measurements of individual optical elements (e.g. lenses), technical multi-layer glasses, glue and varnish layers deposited on various substrates, Si or GaAs wafers, and position measurements of multiple elements of an optical system (e.g. a photographic lens). Compared to the first generation of the system, the absolute accuracy of the second generation system is about ten times better, reaching a level of +/-100 nm for thickness measurements over the full measurement range. Following an introductory description of the measurement principle, the first part of the paper focuses on the key elements in the system design, both in hardware and detection algorithm, that ensure the high accuracy level. The second part of the paper presents an experimental validation of the achieved accuracy level. We present results of thickness measurements on

  8. The use of Fourier transform-infrared (FTIR) and Raman spectroscopy (FTR) for the investigation of structural changes in wool fibre keratin after enzymatic treatment

    NASA Astrophysics Data System (ADS)

    Wojciechowska, Elżbieta; Rom, Monika; Włochowicz, Andrzej; Wysocki, Marian; Wesełucha-Birczyńska, Aleksandra

    2004-10-01

    Keratin of wool fibres obtained from Polish Merino Sheep was treated with proteolytic enzyme in buffered conditions. The zoll of orthosilicic acid was applied as a pretreatment, before enzymatic attack. It has been shown that buffer environment has significant influence on the changes in the structure of wool fibre keratin. Depending of the type of buffer utilised, different conformational changes are observed. Ammonia and tetraborate buffers were used (within pH=8.2). Each of the used buffers had a different influence on the changes in the structure of wool fibre keratin. Ammonia buffer caused bigger conformational changes in the region of disulphide bonds while tetraborate buffer disrupted the stability of amide components. To evaluate the changes of wool keratin structure infrared spectroscopy and Raman spectroscopy were applied.

  9. A systems engineering approach to structural health monitoring of composites using embedded optical fibre Bragg sensors for aeronautical applications

    NASA Astrophysics Data System (ADS)

    van Wyk, A. J.; Roberson, Craig V.

    2011-06-01

    The need to perform structural health monitoring on composite primary structures in real time for their life cycle has become cardinal because of the drastic increase in composite usage on aircraft, helicopters and unmanned aerial systems. The Systems Engineering approach was followed to ensure that these efficient low weight high strength components are optimally, economically and safely utilized. Details of the phases involved in this approach are outlined. In this document the activities associated with the preliminary design phase of the Systems Engineering process will be emphasised. Glass embedded optical fibre Bragg sensors were identified as the most appropriate for the strain measurement essential for the structural health monitoring of composites. The necessary Interrogator instrumentation subsystem for data acquisition and an Algorithm analysis subsystem are outlined. Detail design aspects of only the embedded optical fibre Bragg sensor subsystem will be covered in this paper.

  10. Enhanced accuracy sensors using multicore optical fibres based on RFBGs for temperatures up to 1000°C

    NASA Astrophysics Data System (ADS)

    Barrera, D.; Hervás, J.; Gasulla, I.; Sales, S.

    2016-05-01

    The use of multicore optical fibres (MCF) in optical sensing applications has gained increasing interest over the past years due to the benefits directly brought from their inherent spatial diversity. This property allows measuring either multiple physical magnitudes at the same time or the same magnitude with slight differences in order to compensate the cross-sensitivities. We have inscribed Regenerated Fibre Bragg Gratings (RFBGs) in MCFs with the aim of implementing temperature sensors with an enhanced accuracy and for a very wide temperature range (up to 1000°C). The sensors have been made in 4-core and 7-core commercially available homogeneous MCFs. The fabrication process has been designed to create different temperature sensitivities among the identical cores of the MCF. We have obtained significant wavelength-shift differences up to 1.2 nm at 765°C, what has been used to at least double the temperature accuracy.

  11. Study of local properties of fibre Bragg gratings by the method of optical space-domain reflectometry

    SciTech Connect

    Korolev, I G; Vasil'ev, Sergei A; Medvedkov, O I; Dianov, Evgenii M

    2003-08-31

    The method of optical space-domain reflectometry for measuring local spatial characteristics of fibre Bragg gratings (FBGs) is described in detail. It is demonstrated experimentally that, by using IR and UV radiation sources, this method provides good sensitivity ({approx}10{sup -4}) of measuring the modulation amplitude of the induced refractive index in the core of an optical fibre and a high spatial resolution ({approx}100 {mu}m and better). The factors affecting the accuracy of measurements as well as technical and methodological limitations of the method are considered. A comparative analysis of modern methods for studying the spatial properties of FBGs is performed and applications of these methods are considered. (special issue devoted to the memory of academician a m prokhorov)

  12. Optical Spectroscopy of Nano Materials and Structures

    NASA Astrophysics Data System (ADS)

    Guo, Wenhao

    In this thesis, nanostructures and nanomaterials ranging from 3D to OD will be studied compresively, by using optical methods. Firstly, for 3D and 2D nanomaterials, nanoporous zeolite crystals, such as AFI and AEL are introduced as host materials to accommodate diatomic iodine molecules. Polarized Raman spectroscopy is utilized to identify the two configurations of iodine molecules to stay in the channels of AEL: the lying mode (the bond of the two atoms is parallel to the direction of the channels) and the standing mode (the bond is perpendicular to the direction of the channels). The lying mode and standing mode are switchable and can be well controlled by the amount of water molecules inside the crystal, revealed by both molecule dynamics simulation and experiment observation. With more water molecules inside, iodine molecules choose to stay in the standing mode, while with less water molecules, iodine molecules prefer to lie along the channel. Therefore, the configurations of molecules could be precisely controlled, globally by the surrounding pressure and temperature, and locally by the laser light. Ii is believed that this easy and reversible control of single molecule will be valuable in nanostructured devices, such as molecular sieving or molecular detection. Secondly, for 1D case, the PL spectrum of ZnO nanowire under uniaxial strain is studied. When a ZnO nanowire is bent, besides the lattice constant induced bandgap change on the tensile and compressive sides, there is a piezoelectric field generated along the cross section. This piezoelectric potential, together with the bandgap changes induced by the deformation, will redistribute the electrons excited by incident photons from valence band to conduction band. As a result, the electrons occupying the states at the tensile side will largely outnumbered the ones at the compressive side. Therefore, the PL spectrum we collected at the whole cross section will manifest a redshift, other than the peak

  13. Embedded optical fibres as strain sensors in polymer matrix fibre composites: The influence of adhesion in strain transfer

    NASA Astrophysics Data System (ADS)

    Ekroth, M.

    1994-06-01

    Optical fibers can serve as strain sensors embedded in load carrying polymer matrix fiber composites. The aim of the study was to investigate the influence of chemical bonding between the optical fiber, its protective polyimide coating and the surrounding composite, in strain transfer from the composite to the optical fiber. The degree of adhesion was determined by measuring the force during debonding and pull-out of the optical fiber from the composite. Debonding occurred between the quartz fiber and the coating for both untreated and ammonia modified fibers. The PTFE coated fibers debonded between the coating and the composite. The modified fibers debonded at a lower applied load than the untreated fibers. The strain during tensile loading was measured both with conventional resistance strain gages mounted on the specimen surfaces, and optically with a Mach-Zehnder-interferometer. The optically measured strains, obtained with the untreated fiber and the modified fibers, were all in good agreement with the response from the resistance strain gages. It is concluded that the chemical bonding between the quartz fiber/coating/composite consequently has little or no influence on the strain transfer. Internal stresses (mechanical pressure and friction forces) arising from the laminate fabrication process are sufficient for strain transfer.

  14. SOLITONS: Bright and dark pulses in optical fibres in the vicinity of the zero-dispersion wavelength

    NASA Astrophysics Data System (ADS)

    Molotkov, I. A.; Bisyarin, M. A.

    2004-02-01

    The influence of the third-order dispersion on the propagation of short pulses in optical fibres is considered. The appearance of coupled nonlinear structures consisting of dark and bright envelope solitons is described. The wavelength range is found in the vicinity of the zero-dispersion wavelength where the effect of the third-order dispersion on the pulse propagation proves to be dominant. It is shown that in this case a nonlinear structure in the form of an embedded soliton appears.

  15. Optical multichannel analyzer techniques for high resolution optical spectroscopy

    SciTech Connect

    Chao, J.L.

    1980-06-01

    The development of optical multichannel analyzer techniques for UV/VIS spectroscopy is presented. The research focuses on the development of spectroscopic techniques for measuring high resolution spectral lineshape functions from the exciton phosphorescence in H/sub 2/-1,2,4,5-tetrachlorobenzene. It is found that the temperature dependent frequency shifts and widths confirm a theoretical model based on an exchange theory. The exchange of low energy phonon modes which couple with excited state exciton transitions is shown to display the proper temperature dependent behavior. In addition to the techniques for using the optical multichannel analyzer (OMA) to perform low light level target integration, the use of the OMA for capturing spectral information in transient pulsed laser applications is discussed. An OMP data acquisition system developed for real-time signal processng is described. Both hardware and software interfacing considerations for control and data acquisition by a microcomputer are described. The OMA detector is described in terms of the principles behind its photoelectron detection capabilities and its design is compared with other optoelectronic devices.

  16. Atherosclerosis diagnostic imaging by optical spectroscopy and optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Hewko, M. D.; Choo-Smith, L. P.; Ko, A. C. T.; Smith, M. S. D.; Kohlenberg, E. M.; Bock, E. R.; Leonardi, L.; Sowa, M. G.

    2006-02-01

    Atherosclerosis is traditionally viewed as a disease of uncontrolled plaque growth leading to arterial occlusion. More recently, however, occlusion of the arterial lumen is being viewed as an acute event triggered by plaque rupture and thrombosis. An atheromatous plaque becomes vulnerable to sudden activation and/or rupture when a constellation of processes are activated by various trigger mechanisms. There is growing evidence that the vulnerability (i.e. susceptibility to rupture) and thrombogenic nature of the plaque need to be taken into account in the planning and treatment of the disease. X-ray fluoroscopy and intravascular ultrasound, the current clinical diagnostic tools are not capable of the providing a complete histological picture of the plaque region. Intravascular diagnostic imaging of coronary atherosclerotic plaques by optical means to assess plaque, patient risk and assist in planning treatment strategies represents the future in angioplasty treatment by interventional cardiologists. The techniques which will enable a clinically acceptable and reliable intravascular diagnostic platform are currently being investigated and compared to the clinical standard of histology. Currently, we are investigating the use of a number of optical and imaging techniques for biochemical analysis of arterial tissue including Raman, near infrared and fluorescence spectroscopies. Biochemical imaging will provide compositional information on collagen, elastin, lipid and thrombogenic by-products as well as gauging inflammation and tissue remodeling activity levels. To complement the functional biochemical imaging, optical coherence tomography will be provide structural morphological imaging. The synergistic combination of functional and structural imagery will provide the interventional cardiologist with a complete clinical picture of the atherosclerotic plaque region. The clinician can use this diagnostic information to plan a personalized treatment procedure based on

  17. Effect of optical pumping on the refractive index and temperature in the core of active fibre

    SciTech Connect

    Gainov, V V; Ryabushkin, Oleg A

    2011-09-30

    This paper examines the refractive index change (RIC) induced in the core of Yb{sup 3+}-doped active silica fibres by pulsed pumping. RIC kinetic measurements with a Mach - Zehnder interferometer make it possible to separately assess the contributions of the electronic and thermal mechanisms to the RIC and evaluate temperature nonuniformities in the fibre.

  18. Optical spectroscopy of molecular junctions: Nonequilibrium Green's functions perspective.

    PubMed

    Gao, Yi; Galperin, Michael

    2016-05-01

    We consider optical spectroscopy of molecular junctions from the quantum transport perspective when radiation field is quantized and optical response of the system is simulated as photon flux. Using exact expressions for photon and electronic fluxes derived within the nonequilibrium Green function (NEGF) methodology and utilizing fourth order diagrammatic perturbation theory (PT) in molecular coupling to radiation field, we perform simulations employing realistic parameters. Results of the simulations are compared to the bare PT which is usually employed in studies on nonlinear optical spectroscopy to classify optical processes. We show that the bare PT violates conservation laws, while flux conserving NEGF formulation mixes optical processes. PMID:27155631

  19. Optical spectroscopy of molecular junctions: Nonequilibrium Green's functions perspective

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Galperin, Michael

    2016-05-01

    We consider optical spectroscopy of molecular junctions from the quantum transport perspective when radiation field is quantized and optical response of the system is simulated as photon flux. Using exact expressions for photon and electronic fluxes derived within the nonequilibrium Green function (NEGF) methodology and utilizing fourth order diagrammatic perturbation theory (PT) in molecular coupling to radiation field, we perform simulations employing realistic parameters. Results of the simulations are compared to the bare PT which is usually employed in studies on nonlinear optical spectroscopy to classify optical processes. We show that the bare PT violates conservation laws, while flux conserving NEGF formulation mixes optical processes.

  20. Broadband optical parametric amplifier formed by two pairs of adjacent four-wave mixing sidebands in a tellurite microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Tuan, Tong-Hoang; Kawamura, Harutaka; Nagasaka, Kenshiro; Suzuki, Takenobu; Ohishi, Yasutake

    2016-05-01

    A broadband fibre-optical parametric amplifier (FOPA) operating at a novel wavelength region that is far from the pump wavelength has been demonstrated by exploiting two pairs of adjacent four-wave mixing (FWM) sidebands generated simultaneously in a tellurite microstructured optical fibre (TMOF). Owing to the large nonlinearity of the TMOF and the high pump peak power provided by a picosecond laser, a maximal average gain of 65.1 dB has been obtained. When the FOPA is operated in a saturated state, a flat-gain amplification from 1424 nm to 1459 nm can be achieved. This broadband and high-gain FOPA operating at new wavelength regions far from the pump offers the prospect of all-optical signal processing.

  1. Challenges in Ecohydrological Monitoring at Soil-Vegetation Interfaces: Exploiting the Potential for Fibre Optic Technologies

    NASA Astrophysics Data System (ADS)

    Chalari, A.; Ciocca, F.; Krause, S.; Hannah, D. M.; Blaen, P.; Coleman, T. I.; Mondanos, M.

    2015-12-01

    The Birmingham Institute of Forestry Research (BIFoR) is using Free-Air Carbon Enrichment (FACE) experiments to quantify the long-term impact and resilience of forests into rising atmospheric CO2 concentrations. The FACE campaign critically relies on a successful monitoring and understanding of the large variety of ecohydrological processes occurring across many interfaces, from deep soil to above the tree canopy. At the land-atmosphere interface, soil moisture and temperature are key variables to determine the heat and water exchanges, crucial to the vegetation dynamics as well as to groundwater recharge. Traditional solutions for monitoring soil moisture and temperature such as remote techniques and point sensors show limitations in fast acquisition rates and spatial coverage, respectively. Hence, spatial patterns and temporal dynamics of heat and water fluxes at this interface can only be monitored to a certain degree, limiting deeper knowledge in dynamically evolving systems (e.g. in impact of growing vegetation). Fibre optics Distributed Temperature Sensors (DTS) can measure soil temperatures at high spatiotemporal resolutions and accuracy, along kilometers of optical cable buried in the soil. Heat pulse methods applied to electrical elements embedded in the optical cable can be used to obtain the soil moisture. In July 2015 a monitoring system based on DTS has been installed in a recently forested hillslope at BIFoR in order to quantify high-resolution spatial patterns and high-frequency temporal dynamics of soil heat fluxes and soil moisture conditions. Therefore, 1500m of optical cables have been carefully deployed in three overlapped loops at 0.05m, 0.25m and 0.4m from the soil surface and an electrical system to send heat pulses along the optical cable has been developed. This paper discussed both, installation and design details along with first results of the soil moisture and temperature monitoring carried out since July 2015. Moreover, interpretations

  2. Optical Emission Spectroscopy in an Unmagnetized Plasma

    NASA Astrophysics Data System (ADS)

    Milhone, Jason; Cooper, Christopher; Desangles, Victor; Nornberg, Mark; Seidlitz, Blair; Forest, Cary; WiPAL Team

    2015-11-01

    An optical emission spectroscopic analysis has been developed to measure electron temperature, neutral burnout, and Zeff in Ar and He plasmas in the Wisconsin plasma astrophysics laboratory (WiPAL). The WiPAL vacuum chamber is a 3 meter diameter spherical vessel lined with 3000 SmCo permanent magnets (B > 3 kG) that create an axisymmetric multi-cusp ring for confining the plasma. WiPAL is designed to study unmagnetized plasmas that are hot (Te > 10 eV), dense (ne >1018), and with high ionization fraction. Electron temperature and density can be measured via Langmuir probes. However, probes can disturb the plasma, be difficult to interpret, and become damaged by large heat loads from the plasma. A low cost non-invasive spectroscopy system capable of scanning the plasma via a linear stage has been installed to study plasma properties. From the neutral particle emission, the neutral burnout and estimated neutral temperature can be inferred. A modified coronal model with metastable states is being implemented to determine Te for Ar plasmas.

  3. Optical Zeeman spectroscopy of calcium monohydride

    SciTech Connect

    Chen, Jinhai; Gengler, Jamie; Steimle, T. C.; Brown, John M.

    2006-01-15

    The Zeeman effect in the ground and low-lying excited electronic states of calcium monohydride CaH has been experimentally investigated using optical Zeeman spectroscopy of the (0,0) band of the B{sup 2}{sigma}{sup +}-X{sup 2}{sigma}{sup +} and the (0,0) band of the A{sup 2}{pi}-X{sup 2}{sigma}{sup +} systems. The observed Zeeman-induced shifts and splittings of numerous branch features recorded near the natural linewidth limit were successfully modeled using a traditional effective Hamiltonian approach to account for the interaction between the (v=0) A{sup 2}{pi} and (v=0) B{sup 2}{sigma}{sup +} states and explicit inclusion of the interaction matrix elements for the heterogeneous perturbations between the (v=1) A{sup 2}{pi} and (v=0) B{sup 2}{sigma}{sup +} states. The determined magnetic g factors for the X{sup 2}{sigma}{sup +}, B{sup 2}{sigma}{sup +}, and A{sup 2}{pi} states are compared with previously assumed values and those predicted by perturbation theory.

  4. Highly sensitive optical fibre long period grating biosensor anchored with silica core gold shell nanoparticles.

    PubMed

    Marques, L; Hernandez, F U; James, S W; Morgan, S P; Clark, M; Tatam, R P; Korposh, S

    2016-01-15

    An optical fibre long period grating (LPG), modified with a coating of silica core gold shell (SiO2:Au) nanoparticles (NPs) deposited using the layer-by-layer method, was employed for the development of a biosensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(allylamine hydrochloride) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The effect on sensitivity of increasing the surface area by virtue of the SiO2:Au nanoparticles' diameter and film thickness was studied. The lowest measured concentration of SV was 2.5nM, achieved using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film composed of SiO2 NPs of 300nm diameter with a binding constant of k=1.7(pM)(-1), sensitivity of 6.9nm/ng/mm(2) and limit of detection of 19pg/mm(2). PMID:26319165

  5. Use of fibre-optic endoscopes in studies of gastric digestion in carnivorous vertebrates.

    PubMed

    Jackson, S; Cooper, J

    1988-01-01

    1. Two methods of assessing gastric digestion rates of three prey types fed to Sooty albatrosses Phoebetria fusca were compared: removal of stomach contents, using a water-flushing stomach pump (a technique used commonly in diet studies), and inspection using a fibre-optic gastroscope (a previously unused technique). 2. The stomach pump yielded quantitative information, but proved stressful and resulted in incomplete recovery of meals ingested 3-6 hr before pumping. Gastric morphology of the animals studied and digestion state of their stomach contents may influence the effectiveness of this technique. 3. Inspection using the gastroscope yielded qualitative information only but permitted serial inspection of the same animal, and was less stressful than the stomach pump. Times for total evacuation of the stomach were 6-12 hr less when estimated using the gastroscope than when using the stomach pump. 4. The specifications of endoscopes relevant to their use by biologists are given. 5. Previous non-medical biological uses of endoscopes are given. Potential uses include underwater observations, sampling of digestive juices and stomach linings for enzyme analyses, observations of ingested prey, and assessment of parasite infestation. PMID:2904343

  6. Evaluation of glued-diaphragm fibre optic pressure sensors in a shock tube

    NASA Astrophysics Data System (ADS)

    Sharifian, S. Ahmad; Buttsworth, David R.

    2007-02-01

    Glued-diaphragm fibre optic pressure sensors that utilize standard telecommunications components which are based on Fabry-Perot interferometry are appealing in a number of respects. Principally, they have high spatial and temporal resolution and are low in cost. These features potentially make them well suited to operation in extreme environments produced in short-duration high-enthalpy wind tunnel facilities where spatial and temporal resolution are essential, but attrition rates for sensors are typically very high. The sensors we consider utilize a zirconia ferrule substrate and a thin copper foil which are bonded together using an adhesive. The sensors show a fast response and can measure fluctuations with a frequency up to 250 kHz. The sensors also have a high spatial resolution on the order of 0.1 mm. However, with the interrogation and calibration processes adopted in this work, apparent errors of up to 30% of the maximum pressure have been observed. Such errors are primarily caused by mechanical hysteresis and adhesive viscoelasticity. If a dynamic calibration is adopted, the maximum measurement error can be limited to about 10% of the maximum pressure. However, a better approach is to eliminate the adhesive from the construction process or design the diaphragm and substrate in a way that does not require the adhesive to carry a significant fraction of the mechanical loading.

  7. Fibre optic confocal imaging (FOCI) for subsurface microscopy of the colon in vivo.

    PubMed Central

    Delaney, P M; King, R G; Lambert, J R; Harris, M R

    1994-01-01

    Fibre optic confocal imaging (FOCI) is a new type of microscopy which has been recently developed (Delaney et al. 1993). In contrast to conventional light microscopy, FOCI and other confocal techniques allow clear imaging of subsurface structures within translucent objects. However, unlike conventional confocal microscopes which are bulky (because of a need for accurate alignment of large components) FOCI allows the imaging end to be miniaturised and relatively mobile. FOCI is thus particularly suited for clear subsurface imaging of structures within living animals or subjects. The aim of the present study was to assess the suitability of using FOCI for imaging of subsurface structures within the colon, both in vitro (human and rat biopsies) and in vivo (in rats). Images were obtained in fluorescence mode (excitation 488 nm, detection above 515 nm) following topical application of fluorescein. By this technique the glandular structure of the colon was imaged. FOCI is thus suitable for subsurface imaging of the colon in vivo. Images Fig. 2 Fig. 3 PMID:8157487

  8. Detection of premature browning in ground beef using an optical-fibre-based sensor

    NASA Astrophysics Data System (ADS)

    Sheridan, C.; O'Farrell, M.; Lewis, E.; Flanagan, C.; Kerry, J. F.; Jackman, N.

    2007-07-01

    This paper reports on an optical fibre based sensor system to detect the occurrence of premature browning in ground beef. Premature browning (PMB) occurs when, at a temperature below the pasteurisation temperature of 71°C, there are no traces of pink meat left in the patty. PMB is more frequent in poorer quality beef or beef that has been stored under imperfect conditions. The experimental work pertaining to this paper involved cooking fresh meat and meat that has been stored in a freezer for, 1 week, 1 month and 3 months and recording the reflected spectra and temperature at the core of the product, during the cooking process, in order to develop a classifier based on the spectral response and using a Self-Organising Map (SOM) to classify the patties into one of four categories, based on their colour. The combination of both the classifier and temperature data can be used to determine the presence of PMB for a given patty and can thus be used for Quality Control by food producers.

  9. Construction and laboratory test of a fibre optic sensor for rotational events recording

    NASA Astrophysics Data System (ADS)

    Kurzych, Anna; Krajewski, Zbigniew; Kowalski, Jerzy K.; Jaroszewicz, Leszek R.

    2016-05-01

    We present a novel and technically advanced system - Fibre-Optic System for Rotational Events & Phenomena Monitoring (FOSREM). It has been designed in order to register and monitor rotational events in seismological observatories, engineering constructions, mines and even on glaciers and in their vicinity. Its wide application field is a result of unique parameters and electronic solutions which give an opportunity to measure a component of rotation in the wide range of a signal amplitude from 10-8 rad/s to 10 rad/s, as well as a frequency from 0 Hz to the upper frequency between 2.56 Hz to 328.12 Hz. Moreover, the numerical analysis and simulations indicate that it keeps the theoretical sensitivity equal to 2·10-8 rad/s/Hz1/2. FOSREM is equipped with an advanced communication module which gives the possibility for a remote detection parameter control, as well as the recorded data receiving. It enables the sensor to assemble in any chosen place. In the paper we present laboratory investigations and tests which confirm the wide application field and practical aspects of FOSREM.

  10. Numerical modelling of interrogation systems for optical fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Oswald, Daniel; Richardson, Steven; Wild, Graham

    2011-12-01

    There are a number of interrogation methods that can be used in optical Fibre Bragg Grating (FBG) sensing system. For very high frequency signals interrogating the sensor signal from an FBG is limited to two intensiometric methods, edge filter detection and power detection. In edge filter detection, a broadband light source illuminates an FBG, the reflected spectrum is then passed through a spectral filter. In power detection, a narrowband light source with a wavelength corresponding to the 3dB point of the FBG is filtered by the FBG itself. Both methods convert the spectral shift of the FBG into intensity signals. These two categories each have a number of variations, all with different performance characteristics. In this work we present a numerical model for all of these interrogation systems. The numerical model is based on previous analytical modelling, which could only be utilised for perfect Gaussian profiles. However, interrogation systems can make use of non Gaussian shaped filters, or sources. The numerical modelling enables the different variations to be compared using identical component performance, showing the relative strengths and weakness of the systems in terms of useful parameters, including, signal-to-noise ratio, sensitivity, and dynamic resolution. The two different detection methods can also be compared side-by-side using the same FBG. Since the model is numerical, it enables real spectral data to be used for the various components (FBG, light source, filters). This has the added advantage of increasing the accuracy and usefulness of the model, over previous analytical work.

  11. Fibre optic chemical sensor based on graphene oxide-coated long period grating

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Cai, Qi; Sun, Zhongyuan; Xu, Baojian; Zhao, Jianlong; Zhang, Lin; Chen, Xianfeng

    2016-05-01

    In this work, a graphene oxide-coated long period fibre grating (GO-LPG) is proposed for chemical sensing application. Graphene oxide (GO) has been deposited on the surface of long period grating to form a sensing layer which significantly enhances the interaction between LPG propagating light and the surrounding-medium. The sensing mechanism of GO-LPG relies on the change of grating resonance intensity against surrounding-medium refractive index (SRI). The proposed GO-LPG has been used to measure the concentrations of sugar aqueous solutions. The refractive index sensitivities with 99.5 dB/RIU in low refractive index region (1.33-1.35) and 320.6 dB/RIU in high index region (1.42-1.44) have been achieved, showing an enhancement by a factor of 3.2 and 6.8 for low and high index regions, respectively. The proposed GO-LPG can be further extended to the development of optical biochemical sensor with advantages of high sensitivity, real-time and label-free sensing.

  12. SPIP: A computer program implementing the Interaction Picture method for simulation of light-wave propagation in optical fibre

    NASA Astrophysics Data System (ADS)

    Balac, Stéphane; Fernandez, Arnaud

    2016-02-01

    The computer program SPIP is aimed at solving the Generalized Non-Linear Schrödinger equation (GNLSE), involved in optics e.g. in the modelling of light-wave propagation in an optical fibre, by the Interaction Picture method, a new efficient alternative method to the Symmetric Split-Step method. In the SPIP program a dedicated costless adaptive step-size control based on the use of a 4th order embedded Runge-Kutta method is implemented in order to speed up the resolution.

  13. Strain and ground-motion monitoring at magmatic areas: ultra-long and ultra-dense networks using fibre optic sensing systems

    NASA Astrophysics Data System (ADS)

    Jousset, Philippe; Reinsch, Thomas; Henninges, Jan; Blanck, Hanna; Ryberg, Trond

    2016-04-01

    The fibre optic distributed acoustic sensing technology (DAS) is a "new" sensing system for exploring earth crustal elastic properties and monitoring both strain and seismic waves with unprecedented acquisition characteristics. The DAS technology principle lies in sending successive and coherent pulses of light in an optical fibre and measuring the back-scattered light issued from elastic scattering at random defaults within the fibre. The read-out unit includes an interferometer, which measures light interference patterns continuously. The changes are related to the distance between such defaults and therefore the strain within the fibre can be detected. Along an optical fibre, DAS can be used to acquire acoustic signals with a high spatial (every meter over kilometres) and high temporal resolution (thousand of Hz). Fibre optic technologies were, up to now, mainly applied in perimeter surveillance applications and pipeline monitoring and in boreholes. Previous experiments in boreholes have shown that the DAS technology is well suited for probing subsurface elastic properties, showing new ways for cheaper VSP investigations of the Earth crust. Here, we demonstrate that a cable deployed at ground surface can also help in exploring subsurface properties at crustal scale and monitor earthquake activity in a volcanic environment. Within the framework of the EC funded project IMAGE, we observed a >15 km-long fibre optic cable at the surface connected to a DAS read-out unit. Acoustic data was acquired continuously for 9 days. Hammer shots were performed along the surface cable in order to locate individual acoustic traces and calibrate the spatial distribution of the acoustic information. During the monitoring period both signals from on- and offshore explosive sources and natural seismic events could be recorded. We compare the fibre optic data to conventional seismic records from a dense seismic network deployed on Reykjanes. We show that we can probe and monitor earth

  14. Hybrid UWB and WiMAX radio-over-multi-mode fibre for in-building optical networks

    NASA Astrophysics Data System (ADS)

    Perez, J.; Llorente, R.

    2014-01-01

    In this paper the use of hybrid WiMedia-defined ultra-wideband (UWB) and IEEE 802.16d WiMAX radio-over-fibre is proposed and experimentally demonstrated for multi-mode based in-building optical networks with the advantage of great immunity to optical transmission impairments. In the proposed approach, spectral coexistence of both signals must be achieved with negligible mutual interference. The experimental study performed addressed an indoor configuration with 50 μm multi-mode fibres (MMF) and 850 nm vertical-cavity surface-emitting laser (VCSEL) transmitters. The results indicate that the impact of the wireless convergence in radio-over-multi-mode fibre (RoMMF) is significant for UWB transmissions, mainly due to MMF dispersion and electrooptical (EO) devices with limited bandwidth. On the other hand, WiMAX transmission is feasible for a 300 m MMF and 30 m wireless link in the presence of UWB, with -31 dBm WiMAX EVM.

  15. Photoacoustic endoscopy probe using a coherent fibre-optic bundle and Fabry-Pérot ultrasound sensor (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ansari, Rehman; Beard, Paul C.; Zhang, Edward Z.; Desjardins, Adrien E.

    2016-03-01

    There is considerable interest in the development of photoacoustic endoscopy (PAE) probes for the clinical assessment of pathologies in the gastrointestinal (GI) tract, guiding minimally invasive laparoscopic surgeries and applications in foetal medicine. However, most previous PAE probes integrate mechanical scanners and piezoelectric transducers at the distal end which can be technically complex, expensive and pose challenges in achieving the necessary level of miniaturisation. We present two novel all-optical forward-viewing endoscopic probes operating in widefield tomography mode that have the potential to overcome these limitations. In one configuration, the probe comprises a transparent 40 MHz Fabry-Pérot ultrasound sensor deposited at the tip of a rigid, 3 mm diameter coherent fibre-optic bundle. In this way, the distal end of coherent fibre bundle acts as a 2D array of wideband ultrasound detectors. In another configuration, an optical relay is used between the distal end face of flexible fibre bundle and the Fabry-Pérot sensor to enlarge the lateral field of view to 6 mm x 6 mm. In both configurations, the pulsed excitation laser beam is full-field coupled into the fibre bundle at the proximal end for uniform backward-mode illumination of the tissue at the probe tip. In order to record the photoacoustic waves arriving at the probe tip, the proximal end of the fibre bundle is optically scanned in 2D with a CW wavelength-tunable interrogation laser beam thereby interrogating different spatial points on the sensor. A time-reversal image reconstruction algorithm was used to reconstruct a 3D image from the detected signals. The 3D field of view of the flexible PAE probe is 6 mm x 6 mm x 6 mm and the axial and lateral spatial resolution is 30 µm and 90 µm, respectively. 3D imaging capability is demonstrated using tissue phantoms, ex vivo tissues and in vivo. To the best of our knowledge, this is the first forward-viewing implementation of a photoacoustic

  16. Fibre optic sensors for load-displacement measurements and comparisons to piezo sensor based electromechanical admittance signatures

    NASA Astrophysics Data System (ADS)

    Maheshwari, Muneesh; Annamdas, Venu Gopal Madhav; Pang, John H. L.; Tjin, Swee Chuan; Asundi, Anand

    2015-04-01

    Structural health monitoring techniques using smart materials are on rise to meet the ever ending demand due to increased construction and manufacturing activities worldwide. The civil-structural components such as slabs, beams and columns and aero-components such as wings are constantly subjected to some or the other forms of external loading. This article thus focuses on condition monitoring due to loading/unloading cycle for a simply supported aluminum beam using multiple smart materials. On the specimen, fibre optic polarimetric sensor (FOPS) and fibre Bragg grating (FBG) sensors were glued. Piezoelectric wafer active sensor (PWAS) was also bonded at the centre of the specimen. FOPS and FBG provided the global and local strain measurements respectively whereas, PWAS predicted boundary condition variations by electromechanical admittance signatures. Thus these multiple smart materials together successfully assessed the condition of structure for loading and unloading tests.

  17. Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

    PubMed Central

    Redding, Brandon; Schwab, Mark J.; Pan, Yong-le

    2015-01-01

    The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. PMID:26247952

  18. Application of a Fibre Optic Distributed Acoustic Sensor (DAS) for Shallow Seismic Investigations of a Fractured Dolostone Aquifer in Guelph, Ontario.

    NASA Astrophysics Data System (ADS)

    Munn, J. D.; Parker, B. L.; Coleman, T. I.; Mondanos, M.; Chalari, A.

    2014-12-01

    Understanding groundwater flow and contaminant transport in fractured bedrock aquifers requires detailed characterization of the discrete features that control flow, as well as the properties of the rock matrix. This requires multiple, high-resolution, depth discrete datasets that provide different, but complementary information. Distributed fibre optic sensing is a relatively new technology used to continuously monitor properties along the entire length of an optical fibre. Technological advances over the past few years have brought the sensitivity and spatial resolution to the point where shallow (<200m) borehole applications are practicable. Recent studies using fibre optic distributed temperature sensors (DTS) have shown excellent application of DTS for characterizing groundwater flow in both continuously sealed and open boreholes. This presentation highlights the results of a field trial at the Bedrock Aquifer Research Station on the University of Guelph campus (Ontario, Canada) where a single fibre optic cable was interrogated by both a DTS (Ultima-DTS) and a Distributed Acoustic Sensor (iDAS). DAS is a relatively recent development that allows an optical fibre to be used as a receiver for seismic imaging. These seismic images are produced by sending an optical pulse down the fibre and analyzing the effects of seismic waves on the propagating light. Numerous vertical seismic profiles were collected and the effects of different fibre optic cable structures and coupling techniques were examined. The seismic profiles will help delineate structural features and lithological contacts away from the borehole wall, and will assist in correlating other geophysical, hydraulic, or geological logs collected in the boreholes across the site. Preliminary results show promise for shallow seismic imaging and continued field trials will allow refinement of the technique.

  19. Cone penetrometer fiber optic raman spectroscopy probe assembly

    DOEpatents

    Kyle, Kevin R.; Brown, Steven B.

    2000-01-01

    A chemically and mechanically robust optical Raman spectroscopy probe assembly that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

  20. Cone penetrometer fiber optic Raman spectroscopy probe assembly

    SciTech Connect

    Kyle, K.R.; Brown, S.B.

    2000-01-25

    A chemically and mechanically robust optical Raman spectroscopy probe assembly is described that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

  1. In vivo study for the discrimination of cancerous and normal skin using fibre probe-based Raman spectroscopy.

    PubMed

    Schleusener, Johannes; Gluszczynska, Patrycja; Reble, Carina; Gersonde, Ingo; Helfmann, Jürgen; Fluhr, Joachim W; Lademann, Jürgen; Röwert-Huber, Joachim; Patzelt, Alexa; Meinke, Martina C

    2015-10-01

    Raman spectroscopy has proved its capability as an objective, non-invasive tool for the detection of various melanoma and non-melanoma skin cancers (NMSC) in a number of studies. Most publications are based on a Raman microspectroscopic ex vivo approach. In this in vivo clinical evaluation, we apply Raman spectroscopy using a fibre-coupled probe that allows access to a multitude of affected body sites. The probe design is optimized for epithelial sensitivity, whereby a large part of the detected signal originates from within the epidermal layer's depth down to the basal membrane where early stages of skin cancer develop. Data analysis was performed on measurements of 104 subjects scheduled for excision of lesions suspected of being malignant melanoma (MM) (n = 36), basal cell carcinoma (BCC) (n = 39) and squamous cell carcinoma (SCC) (n = 29). NMSC were discriminated from normal skin with a balanced accuracy of 73% (BCC) and 85% (SCC) using partial least squares discriminant analysis (PLS-DA). Discriminating MM and pigmented nevi (PN) resulted in a balanced accuracy of 91%. These results lie within the range of comparable in vivo studies and the accuracies achieved by trained dermatologists using dermoscopy. Discrimination proved to be unsuccessful between cancerous lesions and suspicious lesions that had been histopathologically verified as benign by dermoscopy. PMID:26010742

  2. Clinical NIR spectroscopy and optical tomography of the testis

    NASA Astrophysics Data System (ADS)

    Hampel, Uwe; Schleicher, Eckhard; Zepnick, H.; Freyer, Richard

    2001-10-01

    Optical tomography and NIR spectroscopy are potential methods to improve the diagnosis of testicular pathologies. To evaluate the methods clinically we developed a special measurement device with the capability of spatially resolved laser spectroscopy and optical tomography of the testis. Simple spectroscopy is primarily used to obtain global tissue optical properties of the testis and to find correlations of optical parameters with type and stage of certain pathologies. Optical tomography is applied to visualize spectral contrasts in limited tissue volumes, such as tumors. In the course of the study we will determine whether NIR techniques posses the required specifity and sensitivity to give additional quantitative information about tissue perfusion parameters and to serve for a tumor differentiation.

  3. In vivo optical investigation of short term skin water contact and moisturizer application using NIR spectroscopy.

    PubMed

    Qassem, M; Kyriacou, P A

    2013-01-01

    Nowadays, a number of noninvasive methods and instruments are available to inspect the biophysical properties and effects of various applicants on human skin, providing quantitative measurements and more details regarding the interactions between skin and various products. Such methods include Near Infrared Spectroscopy (NIRS), a technique which over the years, has gained quite a reputation in being able to accurately determine moisture levels and water contents due to its sensitivity to hydrogen bonding. This paper reports preliminary results of an in vivo study carried out on the skin of a small number of human participants, investigating the optical response of human skin after direct short-term contact with water followed by application of a moisturizer, using a highly advanced spectrophotometer in the region of 900-2100 nm, and equipped with a reflectance fibre optic probe. Results obtained here certainly raise some questions regarding the optical characteristics of different skin types and the influence of frequent moisturizer use, as well as the varying response between different water bands in the NIR region. Future work will focus on gaining more knowledge about these, in order to further improve optical skin measurements, and hopefully support the design and development of a portable and/or miniaturized optical device that could provide reliable, accurate and fast skin hydration readings in real time. PMID:24110207

  4. Bismuth-ring-doped fibres

    SciTech Connect

    Zlenko, Aleksandr S; Dvoirin, Vladislav V; Bogatyrev, Vladimir A; Firstov, Sergei V; Akhmetshin, Ural G

    2009-11-30

    A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO{sub 2} content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications. (optical fibres and fibreoptic sensors)

  5. On-line monitoring of multi-component strain development in a tufting needle using optical fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Chehura, Edmon; Dell'Anno, Giuseppe; Huet, Tristan; Staines, Stephen; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.

    2014-07-01

    Dynamic loadings induced on a tufting needle during the tufting of dry carbon fibre preform via a commercial robot-controlled tufting head were investigated in situ and in real-time using optical fibre Bragg grating (FBG) sensors bonded to the needle shaft. The sensors were configured such that the axial strain and bending moments experienced by the needle could be measured. A study of the influence of thread and thread type on the strain imparted to the needle revealed axial strain profiles which had equivalent trends but different magnitudes. The mean of the maximum axial compression strains measured during the tufting of a 4-ply quasi-isotropic carbon fibre dry preform were - 499 ± 79 μɛ, - 463 ± 51 μɛ and - 431 ± 59 μɛ for a needle without thread, with metal wire and with Kevlar® thread, respectively. The needle similarly exhibited bending moments of different magnitude when the different needle feeding configurations were used.

  6. Fibre positioning algorithms for the WEAVE spectrograph

    NASA Astrophysics Data System (ADS)

    Terrett, David L.; Lewis, Ian J.; Dalton, Gavin; Abrams, Don Carlos; Aguerri, J. Alfonso L.; Bonifacio, Piercarlo; Middleton, Kevin; Trager, Scott C.

    2014-07-01

    WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in La Palma, Canary Islands, Spain. It is a multi-object "pick and place" fibre fed spectrograph with more than one thousand fibres, similar in concept to the Australian Astronomical Observatory's 2dF1 instrument with two observing plates, one of which is observing the sky while other is being reconfigured by a robotic fibre positioner. It will be capable of acquiring more than 10000 star or galaxy spectra a night. The WEAVE positioner concept uses two robots working in tandem in order to reconfigure a fully populated field within the expected 1 hour dwell-time for the instrument (a good match between the required exposure times and the limit of validity for a given configuration due to the effects of differential refraction). This presents additional constraints and complications for the software that determines the optimal path from one configuration to the next, particularly given the large number of fibre crossings implied by the 1000 fibre multiplex. This paper describes the algorithms and programming techniques used in the prototype implementations of the field configuration tool and the fibre positioner robot controller developed to support the detailed design of WEAVE.

  7. Tunable error-free optical frequency conversion of a 4ps optical short pulse over 25 nm by four-wave mixing in a polarisation-maintaining optical fibre

    NASA Astrophysics Data System (ADS)

    Morioka, T.; Kawanishi, S.; Saruwatari, M.

    1994-05-01

    Error-free, tunable optical frequency conversion of a transform-limited 4.0 ps optical pulse signalis demonstrated at 6.3 Gbit/s using four-wave mixing in a polarization-maintaining optical fibre. The process generates 4.0-4.6 ps pulses over a 25nm range with time-bandwidth products of 0.31-0.43 and conversion power penalties of less than 1.5 dB.

  8. Investigation of Lamb Waves Propagation by Fibre-Coupling Optical Beam Deflection Detection Technique and Finite Element Method

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Xu, Bo-qiang; Xu, Rong-qing; Shen, Zhong-hua; Lu, Jian; Ni, Xiao-wu

    2004-02-01

    Measurement of laser-generated transient Lamb waves propagation has been performed in 0.25 mm-thick iron plate by using a fibre sensor based on optical beam deflection technique. The detection principle of this optical method is discussed in detail. A high-powered Q-switched Nd:YAG laser was used to excite Lamb waves on the polished surface of iron plate. The well-defined Lamb waveforms, as well as their properties of oscillation and dispersion are presented in this paper. Furthermore, according to the ablation model, the development and propagation of Lamb waves are numerical simulated by the finite element method that has been widely used in laser ultrasonic field. The experimental results show good agreement with the numerical simulation. Therefore, this optical detection technique has considerable potential in ultrasonic field.

  9. Evaluating a novel application of optical fibre evanescent field absorbance: rapid measurement of red colour in winegrape homogenates

    NASA Astrophysics Data System (ADS)

    Lye, Peter G.; Bradbury, Ronald; Lamb, David W.

    Silica optical fibres were used to measure colour (mg anthocyanin/g fresh berry weight) in samples of red wine grape homogenates via optical Fibre Evanescent Field Absorbance (FEFA). Colour measurements from 126 samples of grape homogenate were compared against the standard industry spectrophotometric reference method that involves chemical extraction and subsequent optical absorption measurements of clarified samples at 520 nm. FEFA absorbance on homogenates at 520 nm (FEFA520h) was correlated with the industry reference method measurements of colour (R2 = 0.46, n = 126). Using a simple regression equation colour could be predicted with a standard error of cross-validation (SECV) of 0.21 mg/g, with a range of 0.6 to 2.2 mg anthocyanin/g and a standard deviation of 0.33 mg/g. With a Ratio of Performance Deviation (RPD) of 1.6, the technique when utilizing only a single detection wavelength, is not robust enough to apply in a diagnostic sense, however the results do demonstrate the potential of the FEFA method as a fast and low-cost assay of colour in homogenized samples.

  10. Blood detection in the spinal column of whole cooked chicken using an optical fibre based sensor system

    NASA Astrophysics Data System (ADS)

    Sheridan, C.; O'Farrell, M.; Lyons, W. B.; Lewis, E.; Flanagan, C.; Jackman, N.

    2005-01-01

    An optical fibre based sensor has been developed to aid the quality assurance of food cooked in industrial ovens by monitoring the product in situ as it cooks. The sensor measures the product colour as it cooks by examining the reflected visible light from the surface as well as the core of the product. This paper examines the use of the sensor for the detection of blood in the spinal area of cooked whole chickens. The results presented here show that the sensor can be successfully used for this purpose.

  11. Design and synthesis of a fluorescent molecular imprinted polymer for use in an optical fibre-based cocaine sensor

    NASA Astrophysics Data System (ADS)

    Wren, Stephen P.; Piletsky, Sergey A.; Karim, Kal; Gascoine, Paul; Lacey, Richard; Sun, Tong; Grattan, Kenneth T. V.

    2014-05-01

    Previously, we have developed chemical sensors using fibre optic-based techniques for the detection of Cocaine, utilising molecularly imprinted polymers (MIPs) containing fluorescein moieties as the signalling groups. Here, we report the computational design of a fluorophore which was incorporated into a MIP for the generation of a novel sensor that offers improved sensitivity for Cocaine with a detection range of 1-100μM. High selectivity for Cocaine over a suite of known Cocaine interferants (25μM) was also demonstrated by measuring changes in the intensity of fluorescence signals received from the sensor.

  12. Detection of volatile organic compounds using optical fibre long period grating modified with metal organic framework thin films

    NASA Astrophysics Data System (ADS)

    Hromadka, Jiri; Tokay, Begum; Korposh, Sergiy; James, Stephen; Tatam, Ralph P.

    2015-09-01

    An optical fibre long period grating (LPG) modified with a thin film of ZIF-8, a zeolitic immidazol framework (ZIF) material, a subgroup of the metal organic framework (MOF) family, was employed for the detection of organic vapours. ZIF-8 film was deposited onto the surface of the LPG using an in-situ crystallization technique. The sensing mechanism is based on the measurement of the refractive index (RI) change induced by the penetration of the chemical molecules into the ZIF-8 pores. An LPG modified with 5 growth cycles of ZIF-8 responded to exposure to methanol and ethanol vapours.

  13. Photochemical changes in hydrogen-loaded optical fibres with application to Bragg grating formation

    NASA Astrophysics Data System (ADS)

    Nguty, T. A.; Potton, R. J.

    1997-10-01

    The sensitization to UV-induced refractive-index changes, by hydrogen, of germanosilicate glass is important in the production of in-fibre Bragg gratings. During grating formation fluorescence from germanium lone-pair centres is excited in the core of the fibre by the UV exposure. This fluorescence has been used to monitor photochemical reduction of substituted tetravalent germanium atoms by hydrogen. The photoreduced atoms occupy 0957-0233/8/10/004/img1 sites and absorb fluorescent radiation. Together with 0957-0233/8/10/004/img2 ions they are responsible for the refractive-index changes exploited in the holographic formation of Bragg gratings in hydrogen-loaded, germanium-doped fibres.

  14. IR luminescence of tellurium-doped silica-based optical fibre

    SciTech Connect

    Dianov, Evgenii M; Alyshev, S V; Shubin, Aleksei V; Khopin, V F; Gur'yanov, Aleksei N

    2012-03-31

    Tellurium-doped germanosilicate fibre has been fabricated by the MCVD process. In contrast to Te-containing glasses studied earlier, it has a broad luminescence band (full width at half maximum of {approx}350 nm) centred at 1500 nm, with a lifetime of {approx}2 {mu}s. The luminescence of the fibre has been studied before and after gamma irradiation in a {sup 60}Co source to 309 and 992 kGy. The irradiation produced a luminescence band around 1100 nm, with a full width at half maximum of {approx}400 nm and lifetime of {approx}5 {mu}s. (letters)

  15. Measurement of medullation in wool and mohair using an Optical Fibre Diameter Analyser.

    PubMed

    Lupton, C J; Pfeiffer, F A

    1998-05-01

    We conducted three experiments to evaluate the Optical Fibre Diameter Analyser (OFDA) for estimating medullation (med [M], kemp [K], and total [T] medullated fiber content) in mohair and wool produced by Angora goats and sheep, respectively. Medullation can be a beneficial characteristic in certain types of wool, but it is highly undesirable in mohair and apparel wools. Current techniques for evaluating medullation in animal fibers are laborious, slow, and expensive. The OFDA had been modified by the manufacturer to measure fiber opacity distribution, a characteristic known to be indicative of medullation in white fibers, and was capable of providing such measurements in a very short time. Measurements made on magnified fiber images produced with a projection microscope (PM) were used as a reference for M, K, and T in fiber samples. An initial experiment with 124 mohair samples (T = .10 to 9.10%) seemed to indicate that OFDA estimates of M, K, and T were only poorly correlated with corresponding PM values (r2 = .5409, .1401, and .5576, respectively). However, a second experiment using wool and mohair samples containing a wider range of medullation (T = .58 to 26.54%) revealed that OFDA estimates of M, K, and T for wool were highly correlated with PM measurements (r2 = .9853, .9307, and .9728, respectively). Evidence was also obtained indicating that the low r2 values associated with mohair relationships were likely due to a combination of factors: 1) high variation among the standard PM measurements and 2) the relatively low M, K, and T contents of the mohair samples compared with wool. In a third experiment, greater accuracy was obtained in the PM measurements by evaluating many more individual fibers per sample (10,000). In this case, OFDA estimates of M, K, and T for mohair were highly correlated with corresponding PM measurements (r2 = .8601, .9939, and .9696, respectively). However, the two sets of linear regression equations obtained for wool and mohair were

  16. Tissue optics, light distribution, and spectroscopy

    NASA Astrophysics Data System (ADS)

    Tuchin, Valery V.; Utz, Sergei R.; Yaroslavsky, Ilya V.

    1994-10-01

    A model of multilayered tissue is considered. The Monte Carlo simulation technique is used to study laser beam transport through tissues with varying optical properties for each layer (absorption, scattering, scattering anisotropy factor, and refractive index). Calculations are performed for some models of the human skin and adjacent tissues for visible and UV wavelength ranges. New technology for human epidermis optical parameters determination is presented. This technology includes epidermis upper layers glue stripping; in vitro measurements of total transmission, diffuse reflection, and angular scattering of stripping samples; and using an inverse calculation technique based on four-flux approximation of radiation transport theory. The technology was successfully used for depth dependence monitoring of epidermis optical parameters. An inverse Monte Carlo technique for determining the optical properties of tissues based on spectrophotometric measurements is developed. This technique takes into accounts the 2-D geometry of the experiment, finite sizes of incident beam and integrating sphere ports, boundary conditions, and sideways losses of light.

  17. Efficiency of nonstationary transformation of the spatial coherence of pulsed laser radiation in a multimode optical fibre upon self-phase modulation

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2007-08-31

    The model scheme of the nonlinear mechanism of transformation (decreasing) of the spatial coherence of a pulsed laser field in an extended multimode optical fibre upon nonstationary interaction with the fibre core is theoretically analysed. The case is considered when the spatial statistics of input radiation is caused by phase fluctuations. The analytic expression is obtained which relates the number of spatially coherent radiation modes with the spatially energy parameters on the initial radiation and fibre parameters. The efficiency of decorrelation of radiation upon excitation of the thermal and electrostriction nonlinearities in the fibre is estimated. Experimental studies are performed which revealed the basic properties of the transformation of the spatial coherence of a laser beam in a multimode fibre. The experimental results are compared with the predictions of the model of radiation transfer proposed in the paper. It is found that the spatial decorrelation of a light beam in a silica multimode fibre is mainly restricted by stimulated Raman scattering. (fiber and integrated optics)

  18. Multi-object spectroscopy with an automatic fibre positioning system in a one-degree field

    NASA Astrophysics Data System (ADS)

    Bellenger, R.; Dreux, M.; Felenbok, P.; Fernandez, A.; Guerin, J.; Schmidt, R.; Avila, G.; D'Odorico, S.; Eckert, W.; Rupprecht, G.

    1991-09-01

    A prototype version of Meudon-ESO Fiber Optics Spectrograph (MEFOS) tested at La Silla in January 1991 is briefly described. Computation results which take into account telescope, fiber and spectrograph effects show that MEFOS should be about 25 percent more efficient than OPTOPUS.

  19. Sulphur-doped silica fibres

    SciTech Connect

    Gerasimova, V I; Rybaltovskii, A O; Chernov, P V; Mashinsky, V M; Sazhin, O D; Medvedkov, O I; Rybaltovsky, A A; Khrapko, R R

    2003-01-31

    An optical fibre with low optical losses is manufactured from a sulphur-doped quartz glass. Optical absorption spectra are measured for various parts of the fibre core. Most of the bands of these spectra are assigned to oxygen-deficient centres and colour centres containing sulphur atoms. The photosensitivity of glasses exposed to laser radiation at wavelengths of 193 and 244 nm is investigated to estimate the possibility of their application for producing photorefracting devices. A Bragg grating of the refractive index with {Delta}n = 7.8 x 10{sup -4} is written in a sulphur-doped silica fibre. (fibre optics)

  20. Hyper-Ramsey spectroscopy of optical clock transitions

    SciTech Connect

    Yudin, V. I.; Taichenachev, A. V.; Oates, C. W.; Barber, Z. W.; Lemke, N. D.; Ludlow, A. D.; Sterr, U.; Lisdat, Ch.; Riehle, F.

    2010-07-15

    We present nonstandard optical Ramsey schemes that use pulses individually tailored in duration, phase, and frequency to cancel spurious frequency shifts related to the excitation itself. In particular, the field shifts and their uncertainties can be radically suppressed (by two to four orders of magnitude) in comparison with the usual Ramsey method (using two equal pulses) as well as with single-pulse Rabi spectroscopy. Atom interferometers and optical clocks based on two-photon transitions, heavily forbidden transitions, or magnetically induced spectroscopy could significantly benefit from this method. In the latter case, these frequency shifts can be suppressed considerably below a fractional level of 10{sup -17}. Moreover, our approach opens the door for high-precision optical clocks based on direct frequency comb spectroscopy.

  1. 29Si NMR investigation of ORMOSIL layers used as luminophores' sol-gel matrices in a UV optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Chodkowska, Eliza M.; Rayss, Jan

    2007-07-01

    The paper concerns the results of ORMOSIL layer's applied in an optical fibre ultraviolet sensor Nuclear Magnetic Resonance investigation. The layer which substituted for optical fibre's cladding in device's sensing part acted as a matrix for a coumarin's derivative. The dye is able to convert ultraviolet into visible radiation which could be easily detected. Thanks to the fact that the refractive indices of ORMOSIL layers may be controlled and reach a value characteristic for the fused silica glass a satisfying sensitivity of the device can be achieved. However it may be expected that both the structure and the composition of ORMOSIL matrices could influence the organic dye's behaviour. The aim of the experiment presented in the paper was to prove a relation between the sol's condensation time and a composition of the obtained gel's structure. The obtained NMR spectra gave the evidence of non-condensed -Si-O-C IIH 5(H) moieties existence in the solid gels. Moreover, even a 42-days-long process does not lead to the total condensation of ethoxysilanes' molecules. It is probable that the remaining ethoxy or silanol groups interact with transducer's molecules as well as influence the refractive index of the gel layer.

  2. Fibres get functional

    NASA Astrophysics Data System (ADS)

    Graham-Rowe, Duncan

    2011-02-01

    New forms of advanced optical fibres featuring exotic glasses, carefully designed microstructures and cores that are either hollow, fluidic, semiconductor or piezoelectric are giving light guides a new lease of life, reports Duncan Graham-Rowe.

  3. On the suitability of fibre optical parametric amplifiers for use in all-optical agile photonic networks

    NASA Astrophysics Data System (ADS)

    Gryspolakis, Nikolaos

    The objective of this thesis is to investigate the suitability of fibre optical parametric amplifiers (FOPAs) for use in multi-channel, dynamic networks. First, we investigate their quasi-static behaviour in such an environment. We study the behaviour of a FOPA under realistic conditions and we examine the impact on the gain spectrum of channel addition for several different operating conditions and regimes. In particular, we examine the impact of surviving channel(s) position, input power and channel spacing. We see how these parameters affect the gain tilt as well as its dynamic characteristics, namely the generation of under or over-shoots at the transition point, possible dependence of rise and fall times on any of the aforementioned parameters and how the gain excursions depend on those parameters. For these studies we assume continuous wave operation for all signals. We observe that the gain spectrum changes are a function of the position and the spacing of the channels. We also find that the gain excursion can reach several dBs (up to 5 dB) in the case of channel add/drop and are heavily dependent on the position of the surviving channels. The channels located in the middle of the transmission band are more prone to channel add/drop-induced gain changes. Moreover, we investigate for the first time the FOPA dynamic behaviour in a packet switching scenario. This part of the study assumes that all but one channels normally vary in a packet-switched fashion. The remaining channel (probe channel) is expected to undergo gain variations due to the perturbation of the system experienced by the other channels. Furthermore, we consider several different scenarios for which the channels spacing, per channel input power (PCIP), variance of the power fluctuation and position of the probe channel will change. We find that when the FOPA operates near saturation the target gain is not achieved more than 50% of the time while the peak-to-peak gain excursions can exceed 1 d

  4. Multiplexed spectroscopy with holographic optical tweezers

    NASA Astrophysics Data System (ADS)

    Cibula, Matthew A.; McIntyre, David H.

    2014-09-01

    We have developed a multiplexed holographic optical tweezers system with an imaging spectrometer to manipulate multiple optically trapped nanosensors and detect multiple fluorescence spectra. The system uses a spatial light modulator (SLM) to control the positions of infrared optical traps in the sample so that multiple nanosensors can be positioned into regions of interest. Spectra of multiple nanosensors are detected simultaneously with the application of an imaging spectrometer. Nanosensors are capable of detecting changes in their environment such as pH, ion concentration, temperature, and voltage by monitoring changes in the nanosensors' emitted fluorescence spectra. We use streptavidin labeled quantum dots bound to the surface of biotin labeled polystyrene microspheres to measure temperature changes by observing a corresponding shift in the wavelength of the spectral peak. The fluorescence is excited at 532 nm with a wide field source.

  5. Development of fiber optic spectroscopy for in-vitro and in-planta detection of fluorescent proteins

    NASA Astrophysics Data System (ADS)

    Liew, Oi Wah; Chen, Jun-Wei; Asundi, Anand K.

    2001-10-01

    The objective of this project is to apply photonics technology to bio-safety management of genetically modified (GM) plants. The conventional method for screening GM plants is through selection using antibiotic resistance markers. There is public concern with such approaches and these are associated with food safety issues, escape of antibiotic resistance genes to pathogenic microorganisms and interference with antibiotic therapy. Thus, the strategy taken in this project is to replace antibiotic resistance markers with fluorescent protein markers that allow for rapid and non-invasive optical screening of genetically modified plants. In this paper, fibre optic spectroscopy was developed to detect and quantify recombinant green (EGFP) and red (DsRED) fluorescent proteins in vitro and in planta. In vitro detection was first carried out to optimize the sensitivity of the optical system. The bacterial expression vectors carrying the coding regions of EGFP and DsRED were introduced into Escherichia coli host cells and fluorescent proteins were produced following induction with IPTG. Soluble EGFP and DsRED proteins were isolated from lysed bacterial cells and serially diluted for quantitative analysis by fibre optic spectroscopy using different light sources, namely, blue LED (475 nm), tungsten halogen (350 - 1000 nm) and double frequency Nd:YAG green laser (532 nm). Fluorescence near the expected emission wavelengths could be detected up to 320X dilution for EGFP and DsRED with blue LED and 532 nm green laser, respectively, as the excitation source. Tungsten halogen was found to be unsuitable for excitation of both EGFP and DsRED. EGFP was successfully purified by size separation under non-denaturing electrophoretic conditions and quantified. The minimum concentration of EGFP detectable with blue LED excitation was 5 mg/ml. To determine the capability of spectroscopy detection in planta, transgenic potato hairy roots and whole modified plant lines expressing the

  6. Inertial and interference effects in optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Karstens, W.; Y Smith, D.

    2015-04-01

    Interference between free-space and material components of the displacement current plays a key role in determining optical properties. This is illustrated by an analogy between the Lorentz optical model and a-c circuits. Phase shifts in material-polarization currents, which are inertial, relative to the non-inertial vacuum-polarization current cause interference in the total displacement current and, hence, variation in E-M wave propagation. If the displacement-current is reversed, forward propagation is inhibited yielding the semimetallic reflectivity exhibited by intrinsic silicon. Complete cancellation involves material currents offsetting free-space currents to form current-loops that correspond to plasmons.

  7. Optical Fiber Sensing Based on Reflection Laser Spectroscopy

    PubMed Central

    Gagliardi, Gianluca; Salza, Mario; Ferraro, Pietro; Chehura, Edmond; Tatam, Ralph P.; Gangopadhyay, Tarun K.; Ballard, Nicholas; Paz-Soldan, Daniel; Barnes, Jack A.; Loock, Hans-Peter; Lam, Timothy T.-Y.; Chow, Jong H.; De Natale, Paolo

    2010-01-01

    An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs) and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented. PMID:22294902

  8. Asbestos as 'toxic short-circuit' optic-fibre for UV within the cell-net: — Likely roles and hazards for secret UV and IR metabolism

    NASA Astrophysics Data System (ADS)

    Traill, Robert R.

    2011-12-01

    The most toxic asbestos fibres have widths 250nm-10nm, and this toxicity is "physical", which could mean either mechanical or optical: Tangling with chromosomes is a •mechanical hazard occasionally reported, and fibres <100nm wide would probably be most knife-like. Our other concern here is •optical: Calculations for fibres <=300nm reveal such a transmission possibility, but only when the amphibole fibres (brown and blue asbestos) are >100nm wide — or chrysotile (white asbestos) is >150nm. In both cases, UVA/UVB -transmission would then predominate. (Chrysotile 150nm might be benign — escaping both mechanical and optical!). But what would generate such UV, and why would its transmission be toxic? Thar and Kühl (J.Theor.Biol.:2004) explain that the long mitochondria on microtubules may be able to act as UV-lasers, (and many observers since Gurwitsch 1923 have reported ultraweak UV emissions escaping from all types of living bio-tissue). That all suggests some universal secret role for UV, apparently related to mitosis. Insertion of fibre "short-circuits" could then cause upsets in mitosis-control, and hence DNA irregularities. Such UV-control could parallel similar lower-powered Infra-Red control-systems (as considered elsewhere for coaxial myelin; or as portrayed by G.Albrecht-Buehler's online animations etc.); and the traditional short mitochondria seem better suited for this IR task.

  9. Optical recording of electrical activity from parallel fibres and other cell types in skate cerebellar slices in vitro.

    PubMed Central

    Konnerth, A; Obaid, A L; Salzberg, B M

    1987-01-01

    1. A reliable and simple fish brain slice preparation was obtained from the cerebellum of the skate, and its properties were described. 2. A potentiometric oxonol dye, RH-482, and multiple site optical recording of transmembrane voltage (MSORTV) were used to reveal the electrophysiological properties of the parallel fibre action potential and to measure its conduction (0.13 m/s). The parallel fibre action potential was blocked in the presence of tetrodotoxin (TTX) and prolonged by tetraethylammonium (TEA), suggesting that the upstroke depends upon sodium entry and the repolarization upon potassium efflux. An after-hyperpolarization results from a calcium-dependent potassium conductance. 3. A second potentiometric dye, RH-155, differing only slightly from RH-482, exhibited a high affinity for glial cell membrane, and could be used to monitor changes in extracellular potassium concentration by detecting changes in glial membrane potential. 4. Calcium channel blockers such as cadmium ions blocked the optical signal that reflected the extracellular accumulation of potassium. 5. Interventions that modified the extracellular volume, and thereby affected the accumulation of potassium, produced large changes in the optical signal that monitored glial depolarization. Hypertonic and hypotonic bathing solutions resulted in decreases and increases, respectively, in the magnitude of the extrinsic absorption change that tracked potassium accumulation. 6. Blocking sodium-potassium pump activity by means of ouabain prolonged the time course of the optical signal that was related to potassium accumulation in the extracellular space. 7. Extracellular potassium accumulation was revealed to be critically dependent upon intracellular calcium ions. Images Fig. 2 PMID:3446807

  10. The application of Fourier-transform infrared (FTIR) and Raman spectroscopy (FTR) to the evaluation of structural changes in wool fibre keratin after deuterium exchange and modification by the orthosilicic acid

    NASA Astrophysics Data System (ADS)

    Wojciechowska, Elżbieta; Włochowicz, Andrzej; Wysocki, Marian; Pielesz, Anna; Wesełucha-Birczyńska, Aleksandra

    2002-09-01

    An injury of hair macrostructure and substantial alkalinity of the water-lipid shield medium on wool fibre surface is conducive to a transition of heavy metal elements into ion forms. It also helps SiO 2 in a transition into a colloidal form of orthosilicic acid and its penetration in this form of the wool fibre structure. Consequently, it leads to the biomineralization of the wool fibre [J. Mol. Struct. 511-512 (1999) 307; J. Mol. Struct. 511-512 (2000) 397]. Changes taking place in the process of biomineralization, mainly in the amorphous region, may be responsible for the effectiveness of the technological processes and the properties of ready wool products [3]. Wool fibres obtained from Polish Merino sheep were treated with solution of orthosilicic acid (H 4SiO 4· nH 2O) in experimental conditions during which fibres first underwent extraction with methylene chloride and them with asolution of orthosilicic acid in alkaline medium. Studies of deuterium exchange in the wool fibre keratin were applied to study changes in the structure of wool fibre keratin in the process of orthosilicic acid treatment. The changes in the structure of wool fibre were studied by means of infrared spectroscopy (FTIR) and Raman spectroscopy (FTR).

  11. Advances in Optical Spectroscopy and Imaging of Breast Lesions

    SciTech Connect

    Demos, S; Vogel, A J; Gandjbakhche, A H

    2006-01-03

    A review is presented of recent advances in optical imaging and spectroscopy and the use of light for addressing breast cancer issues. Spectroscopic techniques offer the means to characterize tissue components and obtain functional information in real time. Three-dimensional optical imaging of the breast using various illumination and signal collection schemes in combination with image reconstruction algorithms may provide a new tool for cancer detection and monitoring of treatment.

  12. History of Diffuse Optical Spectroscopy of Human Tissue

    NASA Astrophysics Data System (ADS)

    Huppert, Theodore J.

    Diffuse optical spectroscopy is a noninvasive method that uses low levels of near-infrared light to measure blood oxygenation in the brain. Over the last 35 years, the number of diffuse optical studies and the range of clinical and research applications have grown steadily. Compared to other neuroimaging methods to measure cerebral blood oxygenation, such as magnetic resonance imaging or positron emission tomography, diffuse optical imaging (DOI) is more cost effective and often uses small portable instrumentation. Wireless and bedside optical systems are currently produced commercially. The portability of these instruments has extended the use of optical methods into several unique applications including brain imaging in infants and children, studies of the brain during ambulatory tasks such as walking or balance, and interoperative brain assessments. This chapter will introduce the history and basic principles of DOI including discussion of the factors contributing to the optical properties of tissue, instrumentation, and an overview of applications of the technology.

  13. Adaptive optics high resolution spectroscopy: present status and future direction

    SciTech Connect

    Alcock, C; Angel, R; Ciarlo, D; Fugate, R O; Ge, J; Kuzmenko, P; Lloyd-Hart, M; Macintosh, B; Najita, J; Woolf, N

    1999-07-27

    High resolution spectroscopy experiments with visible adaptive optics (AO) telescopes at Starfire Optical Range and Mt. Wilson have demonstrated that spectral resolution can be routinely improved by a factor of - 10 over the seeing-limited case with no extra light losses at visible wavelengths. With large CCDs now available, a very wide wavelength range can be covered in a single exposure. In the near future, most large ground-based telescopes will be equipped with powerful A0 systems. Most of these systems are aimed primarily at diffraction-limited operation in the near IR. An exciting new opportunity will thus open up for high resolution IR spectroscopy. Immersion echelle gratings with much coarser grooves being developed by us at LLNL will play a critical role in achieving high spectral resolution with a compact and low cost IR cryogenically cooled spectrograph and simultaneous large wavelength coverage on relatively small IR detectors. We have constructed a new A0 optimized spectrograph at Steward Observatory to provide R = 200,000 in the optical, which is being commissioned at the Starfire Optical Range 3.5m telescope. We have completed the optical design of the LLNL IR Immersion Spectrograph (LISPEC) to take advantage of improved silicon etching technology. Key words: adaptive optics, spectroscopy, high resolution, immersion gratings

  14. Raman and optical spectroscopy of eumelanin films

    NASA Astrophysics Data System (ADS)

    Capozzi, V.; Perna, G.; Gallone, A.; Biagi, P. F.; Carmone, P.; Fratello, A.; Guida, G.; Zanna, P.; Cicero, R.

    2005-06-01

    Melanin obtained from the liver of Rana esculenta L., was isolated from melanosomes and deposited as thin film on quartz substrate, in order to perform Raman, absorption and photoluminescence measurements at room temperature. The Raman spectrum was analysed by considering the contribution of the vibrational modes from different functional groups of the melanin structure. The absorption and photoluminescence measurements support the model that melanin consists of nano-aggregates of oligomeric structures rather than extended heteropolymer. An optical gap value of about 0.6 eV was estimated by considering the Tauc model. The largest size group of clusters mainly contribute to determine the optical gap value, whereas the PL emission is due to groups of clusters which are selectively pumped.

  15. HOMES Holographic Optical Method for Exoplanet Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ditto, Thomas D.; McGrew, Stephen P.

    2013-09-01

    A novel telescope architecture is proposed specifically for the purpose of taking spectra of exoplanets orbiting stars within 10 pc ("the neighborhood"). The primary objective and the secondary spectrograph are holographic optical elements (HOEs) formed on flat membrane substrates of low areal mass that can be transported on cylinder rolls that are compatible with the payload geometry of delivery vehicles. Ribbon-shaped HOEs of up to 100 x 10 meters are contemplated. Computer models are presented with these dimensions. The models predict resolving power better than 10 mas. Because the primary separates wavelengths, we consider coronagraphs that use the divide and conquer strategy of one wavelength at a time. After delivery at the second Lagrange point, the stowed membranes are unfurled into flat holographic optics positioned in a four part formation spanning 1 km of open space.

  16. Photonic bandgap guiding into a composite AgPO3-glass/silica microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Konidakis, Ioannis; Zito, Gianluigi; Pissadakis, Stavros

    2012-04-01

    Infiltration of glass matrices inside Photonic Crystals Fibres (PCFs) for achieving photonic bandgap (PBG) guidance and expand devices development capabilities has been recently demonstrated. Herein, we report the fabrication of an all-solid PBG guiding PCF by suction-assisted infiltration of molten silver-metaphosphate (AgPO3) glass into the air capillaries of a commercial solid core PCF. The relatively low viscosity of the AgPO3 glass melt permitted infiltration at ~ 700 °C inside an annealing oven apparatus by applying suction with the use of a standard mechanical vacuum pump, while its low glass transition temperature of ~ 190 °C allows structural relaxations at temperatures close to ambient and the formation of high quality glass strands inside the silica structure of the PCF. The AgPO3/silica PCF was characterized by means of its transmission spectrum that showed PBG guidance over the measurement range (350-1650nm). The effect of the AgPO3 glass photosensitivity on the guiding properties of the AgPO3/silica PCF was explored by employing a 355nm, 150 ps laser irradiation. The exposure gave rise to a photo-induced enhancement of the transmission-to-stop-band extinction ratio by ~60 dB/cm as well as bandwidth tuning. Numerical calculations of the transmission spectra of the AgPO3/silica PCF have been performed for confirming the experimental results and modelling the photo-induced variation of the two-glass fibre transmission. We believe that the fabrication of the AgPO3/silica PBG fibre constitutes a strong base for the development of new in-fibre sensing and scattering-based devices, by exploiting the high photosensitivity of silver and its specific plasmon absorption properties.

  17. Nanoscale optical tomography with cathodoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Atre, Ashwin C.; Brenny, Benjamin J. M.; Coenen, Toon; García-Etxarri, Aitzol; Polman, Albert; Dionne, Jennifer A.

    2015-05-01

    Tomography has enabled the characterization of the Earth's interior, visualization of the inner workings of the human brain, and three-dimensional reconstruction of matter at the atomic scale. However, tomographic techniques that rely on optical excitation or detection are generally limited in their resolution by diffraction. Here, we introduce a tomographic technique—cathodoluminescence spectroscopic tomography—to probe optical properties in three dimensions with nanometre-scale spatial and spectral resolution. We first obtain two-dimensional cathodoluminescence maps of a three-dimensional nanostructure at various orientations. We then use the method of filtered back-projection to reconstruct the cathodoluminescence intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. The experimental signal can be further correlated with the radiative local density of optical states in particular regions of the reconstruction. We demonstrate how cathodoluminescence tomography can be used to achieve nanoscale three-dimensional visualization of light-matter interactions by reconstructing a three-dimensional metal-dielectric nanoresonator.

  18. Effect of small variations in the refractive index of the ambient medium on the spectrum of a bent fibre-optic Fabry - Perot interferometer

    SciTech Connect

    Kulchin, Yurii N; Vitrik, O B; Gurbatov, S O

    2011-09-30

    The phase of light propagating through a bent optical fibre is shown to depend on the refractive index of the medium surrounding the fibre cladding when there is resonance coupling between the guided core mode and cladding modes. This shifts the spectral maxima in the bent fibre-optic Fabry - Perot interferometer. The highest phase and spectral sensitivities achieved with this interferometer configuration are 0.71 and 0.077, respectively, and enable changes in the refractive index of the ambient medium down to 5 Multiplication-Sign 10{sup -6} to be detected. This makes the proposed approach potentially attractive for producing highly stable, precision refractive index sensors capable of solving a wide range of liquid refractometry problems.

  19. A simple pendulum borehole tiltmeter based on a triaxial optical-fibre displacement sensor

    NASA Astrophysics Data System (ADS)

    Chawah, P.; Chéry, J.; Boudin, F.; Cattoen, M.; Seat, H. C.; Plantier, G.; Lizion, F.; Sourice, A.; Bernard, P.; Brunet, C.; Boyer, D.; Gaffet, S.

    2015-11-01

    Sensitive instruments like strainmeters and tiltmeters are necessary for measuring slowly varying low amplitude Earth deformations. Nonetheless, laser and fibre interferometers are particularly suitable for interrogating such instruments due to their extreme precision and accuracy. In this paper, a practical design of a simple pendulum borehole tiltmeter based on laser fibre interferometric displacement sensors is presented. A prototype instrument has been constructed using welded borosilicate with a pendulum length of 0.85 m resulting in a main resonance frequency of 0.6 Hz. By implementing three coplanar extrinsic fibre Fabry-Perot interferometric probes and appropriate signal filtering, our instrument provides tilt measurements that are insensitive to parasitic deformations caused by temperature and pressure variations. This prototype has been installed in an underground facility (Rustrel, France) where results show accurate measurements of Earth strains derived from Earth and ocean tides, local hydrologic effects, as well as local and remote earthquakes. The large dynamic range and the high sensitivity of this tiltmeter render it an invaluable tool for numerous geophysical applications such as transient fault motion, volcanic strain and reservoir monitoring.

  20. Doppler optical mixing spectroscopy in multiparticle scattering fluids

    SciTech Connect

    Dubnishchev, Yu N

    2011-03-31

    We discuss the basic scheme of laser Doppler optical mixing spectroscopy for the analysis of media with multiparticle scattering. It is shown that the Rayleigh scheme, in contrast to the heterodyne and differential schemes, is insensitive to the effects of multiparticle scattering. (laser applications and other aspects of quantum electronics)