- Email: [email protected]
Measurement of the thickness and refractive indices of multiple layers by a confocal interference microscope using a low coherence source
Abstracts Brillouin fibre-optic gyro with directional sensitivity Yosuke Tanaka’, Shigejiimi
Yamasaki*, Kazuo Hotate’
‘Research Center for Advanced Science and Technology, University of Tokyo *Opto-electronics Laboratory, Fujikura Ltd 17th Meeting
on Lightwave
The
Sensing Technology
The Brillouin fibre-optic gyro is a solid-state laser gyro, made of a fibre ring-resonator with high finesse. It utilizes the counterpropagating lasing of Stokes beams independently produced in the ring-resonator by the stimulated Brillouin scattering process. According to the Sagnac effect, the frequency difference between the counterpropagating Stokes beams shows the rotation rate applied to the ringresonator. The absolute value of this frequency difference is directly obtained as a beat note by coherently combining those two beams. However, the information on the positive or negative is lost in the process, which means no information on the rotation direction. To overcome this problem, we propose a new scheme based on the phase diversity detection, which gives a set of two beat notes with orthogonal polarization. From the phase difference between the beat notes, the rotation direction is easily recognized as well as its rate. Although the demonstrated experimental set-up includes bulk-optic components, they can be replaced by fibre-optic or integrated optic ones.
Measurement of the thickness and refractive indices of multiple layers by a confocal interference microscope using a low coherence source Taskashi Fukano’, Ichirou Yamaguchi’ ‘Optical Engineering Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2-l Hirosawa, Wako City, Saitama, 351 l-01, Japan *Graduate School of Science, Science University of Tokyo (SUT), 1-2, Kagurazaka, Shinjiku-ku, Tokyo, 162, Japan 17th Meeting
on Lightwave
Sensing Technology
(or lens). The moving distance and the corresponding optical path difference yield desirable values of n and c with short calculation. The measurement accuracy of ,< 0.1% is essentially obtained with 1 urn step-’ stages, when t 2 1 mm. The use of a more precise stage with a 0.1 urn step-’ should provide an accuracy of 0.1% even if I = 100 urn. The proposed method was experimentally verified using popular optical materials such as quartz, sapphire and so on, where the accuracy of 2 0.3% was achieved for the plate thickness I of nearly 1 mm. Our method is also applicable for determination of the index of biological tissue which can provide basic data in the field of biomedical optics. The measurement principle and the experimental verification are presented, as well as biomedical applications.
Measurement of the distance between cars from a stereo image using liquid crystal displays Kenichi Sakata, Osami Sasaki, Takamasa Suzuki Faculty of Engineering, Niigata 950-21, Japan 17th Meeting
Niigata
on Lightwave
University,
8050 Ikarashi
2,
Sensing Technology
We propose a new method for detecting the displacement of an object between two different images. These two images are displayed on two liquid crystal displays (LCDs), respectively, which are placed at a constant distance. Several plane waves of different propagating directions are illuminated on to the LCDs. We can obtain the displacement of the object by detecting which plane wave transmitted through the LCDs is strongest. The method is applied to measuring distance between cars from stereo images of the car.
Image processing by artificial retina chips Kazuo Kyuma Mitsubishi Electric Corporation, Advanced Technology R&D Center, 8-l-l Tsukaguchi-Honmachi, Amagasaki, Hyogo 661, Japan
We propose a novel technique for simultaneous measurement of layer thickness and refractive indices of multiple layers. It is based on a combination of a confocal microscope and low coherence interferometry. We derive an expression for geometrical thickness and refractive indices of each layer by both tracing a marginal ray accepted by a microscope objective and optical path matching conditions. Experimental verification of this method is presented by several samples having 13 layers maximum. The geometrical thickness and refractive indices derived agree well with those measured by a micrometer or those cited from literature.
We have developed a novel type of image sensor called an ‘artificial retina chip’ which combines the functions of a video camera and image processor. The device structure, fundamental performance, operation principle of image sensing/processing, processing functions and applications are described.
Simultaneous measurement of refractive index and thickness of transparent plates by low coherence interferometry: measurement principle and experimental verification
Department of Environmental Science and Human Engineering, Saitama University, 225 Shimo-okubo, Urawa, Saitama 338, Japan
17th Meeting
on Lightwave
Sensing Technology
Lightwave sensing of a colour image Satoru Toyooka
Hideyuki Masamitsu
Takehisa Tajiri’, Haruna’
Shiraishi’,
Masato
Ohmi’.
‘Faculty of Medicine, Osaka Unversity, ’ Faculty of Engineering, Osaka University, l-20, Machikaneyama, Toyonaka, Osaka 560, Japan 17th Meeting
on Lightwave
Sensing Technology
We recently proposed and demonstrated a novel technique for simultaneous measurement of the refractive index n and thickness t of transparent plates used as a measured object by low coherence interferometry, in which either a measured object or a focusing lens is scanned with a precise translation stage. An illuminating light is focused on the front and rear plane of the object by moving the object
Optics & Laser Technology Vol29 No 2 1997
17th Meeting
on Lightwave
Sensing Technology
Colour information provides quality measures in life. Usually, colour analysis is made using a three-dimensional colour coordinate system such as the RGB- and the Lab-models. However, they can represent only the visible wavelength region and there is a problem of metamerism. The spectral representation of colour requires its own colour space and its own technical implementation. In this paper, a subspace method or KL expansion is introduced to colour image analysis, to construct a colour space characteristic of the objective scene. Optical implementations of the inner product of a basis vector and objective spectrum are shown. Spectral reconstruction, classitication and parameter estimation are shown.
Yamasaki*, Kazuo Hotate’
‘Research Center for Advanced Science and Technology, University of Tokyo *Opto-electronics Laboratory, Fujikura Ltd 17th Meeting
on Lightwave
The
Sensing Technology
The Brillouin fibre-optic gyro is a solid-state laser gyro, made of a fibre ring-resonator with high finesse. It utilizes the counterpropagating lasing of Stokes beams independently produced in the ring-resonator by the stimulated Brillouin scattering process. According to the Sagnac effect, the frequency difference between the counterpropagating Stokes beams shows the rotation rate applied to the ringresonator. The absolute value of this frequency difference is directly obtained as a beat note by coherently combining those two beams. However, the information on the positive or negative is lost in the process, which means no information on the rotation direction. To overcome this problem, we propose a new scheme based on the phase diversity detection, which gives a set of two beat notes with orthogonal polarization. From the phase difference between the beat notes, the rotation direction is easily recognized as well as its rate. Although the demonstrated experimental set-up includes bulk-optic components, they can be replaced by fibre-optic or integrated optic ones.
Measurement of the thickness and refractive indices of multiple layers by a confocal interference microscope using a low coherence source Taskashi Fukano’, Ichirou Yamaguchi’ ‘Optical Engineering Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2-l Hirosawa, Wako City, Saitama, 351 l-01, Japan *Graduate School of Science, Science University of Tokyo (SUT), 1-2, Kagurazaka, Shinjiku-ku, Tokyo, 162, Japan 17th Meeting
on Lightwave
Sensing Technology
(or lens). The moving distance and the corresponding optical path difference yield desirable values of n and c with short calculation. The measurement accuracy of ,< 0.1% is essentially obtained with 1 urn step-’ stages, when t 2 1 mm. The use of a more precise stage with a 0.1 urn step-’ should provide an accuracy of 0.1% even if I = 100 urn. The proposed method was experimentally verified using popular optical materials such as quartz, sapphire and so on, where the accuracy of 2 0.3% was achieved for the plate thickness I of nearly 1 mm. Our method is also applicable for determination of the index of biological tissue which can provide basic data in the field of biomedical optics. The measurement principle and the experimental verification are presented, as well as biomedical applications.
Measurement of the distance between cars from a stereo image using liquid crystal displays Kenichi Sakata, Osami Sasaki, Takamasa Suzuki Faculty of Engineering, Niigata 950-21, Japan 17th Meeting
Niigata
on Lightwave
University,
8050 Ikarashi
2,
Sensing Technology
We propose a new method for detecting the displacement of an object between two different images. These two images are displayed on two liquid crystal displays (LCDs), respectively, which are placed at a constant distance. Several plane waves of different propagating directions are illuminated on to the LCDs. We can obtain the displacement of the object by detecting which plane wave transmitted through the LCDs is strongest. The method is applied to measuring distance between cars from stereo images of the car.
Image processing by artificial retina chips Kazuo Kyuma Mitsubishi Electric Corporation, Advanced Technology R&D Center, 8-l-l Tsukaguchi-Honmachi, Amagasaki, Hyogo 661, Japan
We propose a novel technique for simultaneous measurement of layer thickness and refractive indices of multiple layers. It is based on a combination of a confocal microscope and low coherence interferometry. We derive an expression for geometrical thickness and refractive indices of each layer by both tracing a marginal ray accepted by a microscope objective and optical path matching conditions. Experimental verification of this method is presented by several samples having 13 layers maximum. The geometrical thickness and refractive indices derived agree well with those measured by a micrometer or those cited from literature.
We have developed a novel type of image sensor called an ‘artificial retina chip’ which combines the functions of a video camera and image processor. The device structure, fundamental performance, operation principle of image sensing/processing, processing functions and applications are described.
Simultaneous measurement of refractive index and thickness of transparent plates by low coherence interferometry: measurement principle and experimental verification
Department of Environmental Science and Human Engineering, Saitama University, 225 Shimo-okubo, Urawa, Saitama 338, Japan
17th Meeting
on Lightwave
Sensing Technology
Lightwave sensing of a colour image Satoru Toyooka
Hideyuki Masamitsu
Takehisa Tajiri’, Haruna’
Shiraishi’,
Masato
Ohmi’.
‘Faculty of Medicine, Osaka Unversity, ’ Faculty of Engineering, Osaka University, l-20, Machikaneyama, Toyonaka, Osaka 560, Japan 17th Meeting
on Lightwave
Sensing Technology
We recently proposed and demonstrated a novel technique for simultaneous measurement of the refractive index n and thickness t of transparent plates used as a measured object by low coherence interferometry, in which either a measured object or a focusing lens is scanned with a precise translation stage. An illuminating light is focused on the front and rear plane of the object by moving the object
Optics & Laser Technology Vol29 No 2 1997
17th Meeting
on Lightwave
Sensing Technology
Colour information provides quality measures in life. Usually, colour analysis is made using a three-dimensional colour coordinate system such as the RGB- and the Lab-models. However, they can represent only the visible wavelength region and there is a problem of metamerism. The spectral representation of colour requires its own colour space and its own technical implementation. In this paper, a subspace method or KL expansion is introduced to colour image analysis, to construct a colour space characteristic of the objective scene. Optical implementations of the inner product of a basis vector and objective spectrum are shown. Spectral reconstruction, classitication and parameter estimation are shown.