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Velocity measurement by means of speckle method
Abstracts Polarimetric stress analysis of time- and space-dependent photoelasticity
Integrated
optical-frequency
shifter
Kazuhiko Oka, Yoshihiro Ohtsuka
Koichiro Miyagi. Hiroshi Shimotahira. Akihito Otani. Masaya Nanami
Faculty of Engineering.
Research
Hokkaido University
Laboratory.
Anritsu
Corporation
8th Meeting on Lightwave Sensing Technology. Japanese Society of Lightwave Sensing Technology. Japan Society of Applied Physics
8th Meeting on Lightwave Sensing Technology. Society of Lightwave Sensing Technology. Japan Applied Physics
This paper describes a novel polarimetric method for mapping the dynamic spatial distribution of principal stresses of a photoelastic sample under load. A circularly polarized wave of light turns into an elliptically polarized wave by transmitting this photoelastic sample. This elliptically polarized wave is interfered with paired orthogonal linearly polarized reference waves of light. Two kinds of interference patterns. formed over an array photodetector. are Fourier-transformed to offer the polarization parameters by which to determine the dynamic principal stress distributions.
We report an integrated two-frequency shifter of an optical heterodyne interferometer for sensing. The two-frequency shifter consists of 2D/3D-optical waveguides. two pairs of diffusion lenses and two SAW optical-frequency modulators. These optical elements were all made by the proton-exchange technique in order to keep away from the optical damage occurred in an LiNbO, optical waveguide. From the experimental results. the Sin ratio of the output beat signal was obtained to be better than 32 dB. Fringe pattern ferometry
Distributed
optical
fibre sensors
analysis
for automated
Japanese Society of
precision
inter-
Mitsuo Takeda
Fumio Wada Fujikura Ltd.
University of Electra-Communications. munication and Systems Engineering
8th Meeting on Lightwave Sensing Technology. Japanese Society of Lightwave Sensing Technology. Japan Society of Applied Physics
8th Meeting on Lightwave Sensing Technology, Society of Lightwave Sensing Technology. Japan Applied Physics
Optical sensors are categorized into point sensors and distributed sensors. Optical sensors are neither influenced by electrical noise nor radiate electrical noise. Distributed fibre sensors are based on the optical time domain reflectometry (OTDR). and measure the distributions of the physical quantities such as length. temperature. stress and so on. Those distributions have not been easily measured by conventional electric sensors. As far as the temperature distribution is concerned. some sensing systems have already been put into certification tests in fields like hazard monitoring systems for motorway tunnels. highrise buildings. high power electric cables. manufacturing plants. and so on. This paper reviews the principles of distributed sensors and gives some examples.
Fringe pattern analysis techniques for precision interferometry are reviewed with an emphasis on the basic principles of modern heterodyne interferometry. Characteristics of the temporal-carrier technique and the spatial-carrier technique are compared. and the relationship between the two techniques is clarified. A novel technique of spatio-temporal heterodyne interferometry is introduced.
Optical coherence domain reflectometry by synthesis of coherence function: improvement of the resolution with non-linearity compensation in frequency modulation Osamu Kamatani. Kazuo ffotate RCAST, Research Center for Advanced nology, The University of Tokyo
Science
8th Meeting on Lightwave Sensing Technology, Society of Lightwave Sensing Technology, Japan Applied Physics
and TechJapanese Society of
We have proposed a new reflectometry by the synthesis of coherence function using a laser diode as a light source. which can be used for high-resolution measurements of optical waveguide devices. This method needs no mechanical moving parts. The oscillation frequency of a laser diode is controlled by the injection current with an appropriate waveform. The coherence function of a delta-function shape along the optical path is synthesized to obtain the distribution of back-scattering intensity. In this paper, the spatial resolution is improved by the non-linearity compensation in direct frequency modulation of a multi-electrode DFB laser. For compensation. the relationship between the injection current and the induced laser frequency change at the modulation frequency is obtained from measured data when increasing the amplitude of a square waveform injection current. Spatial resolution of 2-4 mm is presented. Furthermore, demonstration of a measurement range flexibility of the OCDR is also shown.
160
1
Velocity
measurement
Department
of ComJapanese Society of
by means of speckle method
Masaaki Kawahashi. Kecji Hosoi Saitama
University
8th Meeting on Lightwave Sensing Technology, Society of Lightwave Sensing Technology. Japan Applied Physics
Japanese Society of
Speckle photography is a well-known technique fordeformation and strain measurement in solid mechanics. It can also be applied to velocity measurements of fluid flow seeded with small particle tield illuminated with laser light is recorded pattern in the laser speckle mode or in the particle depending upon the density of seeding particles in this report. the method of velocity measurements of means of a speckle method and its applications illumination techniques are described.
Recording and judging interferogram
of the direction
particles. The as a speckle image mode the fluid. In fluid llow by with various
of tilt in the
Kqji Tenjimhayashi Mechanical
Engineering
Laboratory
8th Meeting on Lightwave Sensing Technology. Society of Lightwave Sensing Technology, Japan Applied Physics
Japanese Society of
How to record and judge the direction of tilt in an interferogram is described here. It was theoretically and experimentally shown that the interferograms obtained in a Twyman-Green interferometer without an imaging lens had the tilt information of a mirror under test in their edges. The measurement errors introduced in such interferograms were discussed.
Optics
Et Laser Technology Vol24 No 3 1992
Integrated
optical-frequency
shifter
Kazuhiko Oka, Yoshihiro Ohtsuka
Koichiro Miyagi. Hiroshi Shimotahira. Akihito Otani. Masaya Nanami
Faculty of Engineering.
Research
Hokkaido University
Laboratory.
Anritsu
Corporation
8th Meeting on Lightwave Sensing Technology. Japanese Society of Lightwave Sensing Technology. Japan Society of Applied Physics
8th Meeting on Lightwave Sensing Technology. Society of Lightwave Sensing Technology. Japan Applied Physics
This paper describes a novel polarimetric method for mapping the dynamic spatial distribution of principal stresses of a photoelastic sample under load. A circularly polarized wave of light turns into an elliptically polarized wave by transmitting this photoelastic sample. This elliptically polarized wave is interfered with paired orthogonal linearly polarized reference waves of light. Two kinds of interference patterns. formed over an array photodetector. are Fourier-transformed to offer the polarization parameters by which to determine the dynamic principal stress distributions.
We report an integrated two-frequency shifter of an optical heterodyne interferometer for sensing. The two-frequency shifter consists of 2D/3D-optical waveguides. two pairs of diffusion lenses and two SAW optical-frequency modulators. These optical elements were all made by the proton-exchange technique in order to keep away from the optical damage occurred in an LiNbO, optical waveguide. From the experimental results. the Sin ratio of the output beat signal was obtained to be better than 32 dB. Fringe pattern ferometry
Distributed
optical
fibre sensors
analysis
for automated
Japanese Society of
precision
inter-
Mitsuo Takeda
Fumio Wada Fujikura Ltd.
University of Electra-Communications. munication and Systems Engineering
8th Meeting on Lightwave Sensing Technology. Japanese Society of Lightwave Sensing Technology. Japan Society of Applied Physics
8th Meeting on Lightwave Sensing Technology, Society of Lightwave Sensing Technology. Japan Applied Physics
Optical sensors are categorized into point sensors and distributed sensors. Optical sensors are neither influenced by electrical noise nor radiate electrical noise. Distributed fibre sensors are based on the optical time domain reflectometry (OTDR). and measure the distributions of the physical quantities such as length. temperature. stress and so on. Those distributions have not been easily measured by conventional electric sensors. As far as the temperature distribution is concerned. some sensing systems have already been put into certification tests in fields like hazard monitoring systems for motorway tunnels. highrise buildings. high power electric cables. manufacturing plants. and so on. This paper reviews the principles of distributed sensors and gives some examples.
Fringe pattern analysis techniques for precision interferometry are reviewed with an emphasis on the basic principles of modern heterodyne interferometry. Characteristics of the temporal-carrier technique and the spatial-carrier technique are compared. and the relationship between the two techniques is clarified. A novel technique of spatio-temporal heterodyne interferometry is introduced.
Optical coherence domain reflectometry by synthesis of coherence function: improvement of the resolution with non-linearity compensation in frequency modulation Osamu Kamatani. Kazuo ffotate RCAST, Research Center for Advanced nology, The University of Tokyo
Science
8th Meeting on Lightwave Sensing Technology, Society of Lightwave Sensing Technology, Japan Applied Physics
and TechJapanese Society of
We have proposed a new reflectometry by the synthesis of coherence function using a laser diode as a light source. which can be used for high-resolution measurements of optical waveguide devices. This method needs no mechanical moving parts. The oscillation frequency of a laser diode is controlled by the injection current with an appropriate waveform. The coherence function of a delta-function shape along the optical path is synthesized to obtain the distribution of back-scattering intensity. In this paper, the spatial resolution is improved by the non-linearity compensation in direct frequency modulation of a multi-electrode DFB laser. For compensation. the relationship between the injection current and the induced laser frequency change at the modulation frequency is obtained from measured data when increasing the amplitude of a square waveform injection current. Spatial resolution of 2-4 mm is presented. Furthermore, demonstration of a measurement range flexibility of the OCDR is also shown.
160
1
Velocity
measurement
Department
of ComJapanese Society of
by means of speckle method
Masaaki Kawahashi. Kecji Hosoi Saitama
University
8th Meeting on Lightwave Sensing Technology, Society of Lightwave Sensing Technology. Japan Applied Physics
Japanese Society of
Speckle photography is a well-known technique fordeformation and strain measurement in solid mechanics. It can also be applied to velocity measurements of fluid flow seeded with small particle tield illuminated with laser light is recorded pattern in the laser speckle mode or in the particle depending upon the density of seeding particles in this report. the method of velocity measurements of means of a speckle method and its applications illumination techniques are described.
Recording and judging interferogram
of the direction
particles. The as a speckle image mode the fluid. In fluid llow by with various
of tilt in the
Kqji Tenjimhayashi Mechanical
Engineering
Laboratory
8th Meeting on Lightwave Sensing Technology. Society of Lightwave Sensing Technology, Japan Applied Physics
Japanese Society of
How to record and judge the direction of tilt in an interferogram is described here. It was theoretically and experimentally shown that the interferograms obtained in a Twyman-Green interferometer without an imaging lens had the tilt information of a mirror under test in their edges. The measurement errors introduced in such interferograms were discussed.
Optics
Et Laser Technology Vol24 No 3 1992