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Wideband phase demodulation in optical heterodyne interferometry
Optics & Laser
Abstracts
Technology
Road profile measuring system
High-accuracy length-measuring two-colour interferometer
Mitsutoshia Maeda, Hiroshi Ito, Yasuhiko Suzuki, Morihiro Matsuta
Hirokazu Matsumoto, Tokuyuki Honda
T o y o t a Central Research & D e v e l o p m e n t Laboratories, Inc. 9th Meeting on Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society o f Applied Physics Using laser displacement meters and accelerometers, a new road profile measuring system installed in a vehicle has been developed. The vehicle motion and the displacement between the vehicle body and the road surface are measured at the normal vehicle speed (20 -120 km h -j ) by use of the accelcrometer and the laser displacement meter respectively. The road profile was obtained by computing with these data and an accuracy of + 1.5 mm was achieved.
Wideband phase demodulation in optical heterodyne interferometry Kazuhiko Oka, Tomoo Mizuno, Yoshihiro Ohtsuka Faculty of Engineering, H o k k a i d o University 9th Meeting on Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society of Applied Physics A computer-based Fourier-transform method used for wide-band phasedemodulation has been developed for optical heterodyne interferometry. Fourier spectra of the signal and reference beat-photocurrents generated from a heterodyne interferometer are computed by means of the fast Fourier transform (FFT) technique. One side component of the paired Fourier spectra for each beat-photocurrent is filtered, and its Fourier inversion results in the significant parameters by which the wide-band phase of the signal beat-photocurrent can be demodulated.
National Research L a b o r a t o r y o f Metrology 9th Meeting o n Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society o f Applied Physics A two-colour interferometer, which uses a laser-diode pumped 1.06/Lm YAG laser and its second-harmonic wave, is described for obtaining geometrical lengths with a high accuracy in atmospheric air. In determining the refractive index of air, the averaging of the numbers of interference fringes counted is performed to improve the accuracy, because it is decreased by a coefficient 'A' in the two-colour method. For the average of 1000 measurements, the refractive index of air can be determined to an accuracy of 2 x 10 -7 at distances up to 50 era. Therefore, the geometrical length may be known within an accuracy of 0.1 pm.
Introductory talk--biosensing by Hghtwaves Ichirou Yamaguchi Optical Engineering L a b o r a t o r y , The Institute o f Physical and Chemical Research ( R I K E N ) 10th Meeting on Lightwave Sensing Technology, Japanese Society o f Lightwave Sensing Technology, J a p a n Society of Applied Physics Applications of lightwave sensing to biology are surveyed. After the advantages of lightwave sensing techniques applied to biological objects are presented, the uses of various techniques such as spectroscopy, measurement of blood flow, new microscopy, and optical tomography are reviewed. In conclusion, problems are introduced that have to be solved for extending the capabilities of the above applications.
Detection of small amplitude sound pressure by heterodyne fibre-optic underwater acoustic sensor
Measurement of riving organisms using optical methods
Sumio Takahashi*, Katsunori Okajima*, Osamu Sugiyama*, Koichi Hirama?, Masahiro Seya'~
Central Research Laboratory, H a m a m a t s u Photonics K.K.
*The N a t i o n a l Defense Academy, "~Toyo C o m m u n i c a t i o n E q u i p m e n t Co, Ltd 9th Meeting on Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society o f Applied Physics A quartz tuning fork radiates very weak sound with a frequency determined by temperature. If this sound is detected and the frequency is counted, it is possible to monitor temperature by acoustic remote sensing. An attempt was made to apply a heterodyne fibre-optic acoustic sensor to the detection of this sound in water. For this purpose, the sensitivity and S/N ratio were enhanced by frequency multiplication and sideband amplification after O/E conversion of the phase modulated optical signal. This paper describes the principle of this sensitivity enhancement and shows the result of the detection of the sound radiated from a quartz tuning fork.
264
Mitsuo Hiramatsu 10th Meeting on Lightwave Sensing Technology, Japanese Society o f Lightwave Sensing Technology, J a p a n Society of Applied Physics Optical approaches are promising to understand the function of living organisms. Three optical methods are presented in this paper. The first is an ultra-weak spontaneous emission from intact soybean roots in a completely dark box. Direct evidence of the ultra-weak emission from plant roots is shown as a series of two-dimensional images obtained from a photon counting method using a very high sensitivity camera. The second is a moisture measurement of hairless mice skin by a reflection method. An image of water distribution is obtained by using an infra-red vidicon, which is an image tube sensitive to infra-red light. The third is a measurement of ion concentrations in a cell, using a fluorescent method. The binding of a fluorescent reagent with an ion brings about a change in excitation or emission spectra, which enables us to obtain the information about the ion concentration in the cell. Optics & Laser Technology Vol 25 No 4 1993
Abstracts
Technology
Road profile measuring system
High-accuracy length-measuring two-colour interferometer
Mitsutoshia Maeda, Hiroshi Ito, Yasuhiko Suzuki, Morihiro Matsuta
Hirokazu Matsumoto, Tokuyuki Honda
T o y o t a Central Research & D e v e l o p m e n t Laboratories, Inc. 9th Meeting on Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society o f Applied Physics Using laser displacement meters and accelerometers, a new road profile measuring system installed in a vehicle has been developed. The vehicle motion and the displacement between the vehicle body and the road surface are measured at the normal vehicle speed (20 -120 km h -j ) by use of the accelcrometer and the laser displacement meter respectively. The road profile was obtained by computing with these data and an accuracy of + 1.5 mm was achieved.
Wideband phase demodulation in optical heterodyne interferometry Kazuhiko Oka, Tomoo Mizuno, Yoshihiro Ohtsuka Faculty of Engineering, H o k k a i d o University 9th Meeting on Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society of Applied Physics A computer-based Fourier-transform method used for wide-band phasedemodulation has been developed for optical heterodyne interferometry. Fourier spectra of the signal and reference beat-photocurrents generated from a heterodyne interferometer are computed by means of the fast Fourier transform (FFT) technique. One side component of the paired Fourier spectra for each beat-photocurrent is filtered, and its Fourier inversion results in the significant parameters by which the wide-band phase of the signal beat-photocurrent can be demodulated.
National Research L a b o r a t o r y o f Metrology 9th Meeting o n Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society o f Applied Physics A two-colour interferometer, which uses a laser-diode pumped 1.06/Lm YAG laser and its second-harmonic wave, is described for obtaining geometrical lengths with a high accuracy in atmospheric air. In determining the refractive index of air, the averaging of the numbers of interference fringes counted is performed to improve the accuracy, because it is decreased by a coefficient 'A' in the two-colour method. For the average of 1000 measurements, the refractive index of air can be determined to an accuracy of 2 x 10 -7 at distances up to 50 era. Therefore, the geometrical length may be known within an accuracy of 0.1 pm.
Introductory talk--biosensing by Hghtwaves Ichirou Yamaguchi Optical Engineering L a b o r a t o r y , The Institute o f Physical and Chemical Research ( R I K E N ) 10th Meeting on Lightwave Sensing Technology, Japanese Society o f Lightwave Sensing Technology, J a p a n Society of Applied Physics Applications of lightwave sensing to biology are surveyed. After the advantages of lightwave sensing techniques applied to biological objects are presented, the uses of various techniques such as spectroscopy, measurement of blood flow, new microscopy, and optical tomography are reviewed. In conclusion, problems are introduced that have to be solved for extending the capabilities of the above applications.
Detection of small amplitude sound pressure by heterodyne fibre-optic underwater acoustic sensor
Measurement of riving organisms using optical methods
Sumio Takahashi*, Katsunori Okajima*, Osamu Sugiyama*, Koichi Hirama?, Masahiro Seya'~
Central Research Laboratory, H a m a m a t s u Photonics K.K.
*The N a t i o n a l Defense Academy, "~Toyo C o m m u n i c a t i o n E q u i p m e n t Co, Ltd 9th Meeting on Lightwave Sensing Technology, Japanese Society of Lightwave Sensing Technology, J a p a n Society o f Applied Physics A quartz tuning fork radiates very weak sound with a frequency determined by temperature. If this sound is detected and the frequency is counted, it is possible to monitor temperature by acoustic remote sensing. An attempt was made to apply a heterodyne fibre-optic acoustic sensor to the detection of this sound in water. For this purpose, the sensitivity and S/N ratio were enhanced by frequency multiplication and sideband amplification after O/E conversion of the phase modulated optical signal. This paper describes the principle of this sensitivity enhancement and shows the result of the detection of the sound radiated from a quartz tuning fork.
264
Mitsuo Hiramatsu 10th Meeting on Lightwave Sensing Technology, Japanese Society o f Lightwave Sensing Technology, J a p a n Society of Applied Physics Optical approaches are promising to understand the function of living organisms. Three optical methods are presented in this paper. The first is an ultra-weak spontaneous emission from intact soybean roots in a completely dark box. Direct evidence of the ultra-weak emission from plant roots is shown as a series of two-dimensional images obtained from a photon counting method using a very high sensitivity camera. The second is a moisture measurement of hairless mice skin by a reflection method. An image of water distribution is obtained by using an infra-red vidicon, which is an image tube sensitive to infra-red light. The third is a measurement of ion concentrations in a cell, using a fluorescent method. The binding of a fluorescent reagent with an ion brings about a change in excitation or emission spectra, which enables us to obtain the information about the ion concentration in the cell. Optics & Laser Technology Vol 25 No 4 1993