Optical Review
Print ISSN : 1340-6000
ISSN-L : 1340-6000
Volume 5, Issue 2
Displaying 1-12 of 12 articles from this issue
  • Takeshi KITATANI, Masahiko KONDOW, Koji NAKAHARA, M. C. LARSON, Kazuhi ...
    1998 Volume 5 Issue 2 Pages 69-71
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    Temperature stability of the threshold current and the lasing wavelength is investigated in a 1.3-μm GaInNAs/GaAs single quantum-well laser. The measured characteristic-temperature was 88 K. The small wavelength shift per change in temperature of 0.35 nm/°C was obtained, indicating the superior lasing-wavelength stability. Therefore, it is shown experimentally that GaInNAs is very promising material for the fabrication of light source with excellent high-temperature performance for optical fiber communications.
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  • Matthew R. JONES, Yukio YAMADA
    1998 Volume 5 Issue 2 Pages 72-76
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    We present a technique for determining the asymmetry parameter and scattering coefficient of turbid media from spatially resolved reflectance measurements. This technique will contribute to the development of medical applications in which it is necessary to predict the distribution and propagation of light in tissue. Based on Monte Carlo simulations, we derived correlations which relate the reduced scattering coefficient and the asymmetry parameter to the relative reflectance curve. Initial estimates of the optical properties are obtained from these correlations. Final values are obtained by adjusting the optical parameters and repeating the Monte Carlo simulations until the simulated reflectance pattern matches the measured reflectance pattern. Preliminary experimental results indicate that this technique can be used to determine the asymmetry parameter to within 10% and the reduced scattering coefficient to within 5%.
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  • Nobukatsu TAKAI
    1998 Volume 5 Issue 2 Pages 77-82
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    Talbot images of a two-dimensional array source such as a surface-emitting array laser are investigated with the help of the propagation law of a Gaussian beam. The effect of the phase fluctuation existing between the elements of the source on the formation of Talbot images is revealed by computer simulation. In the study, the correlation extent of the phase fluctuation is taken into consideration together with its magnitude (standard deviation), and Talbot images of good quality are found to be formed when the correlation extent is larger than the extent of the diffraction of a Gaussian beam in the observation plane. It is further shown that the contrast of Talbot images is governed, in a statistical sense, not by the magnitude of the phase itself but by the phase-fluctuation slope in the array source.
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  • Jun AMAKO, Masami MURAI, Tomio SONEHARA
    1998 Volume 5 Issue 2 Pages 83-88
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    Array illumination built on a binary phase grating with a green, Q-switched, pulse Nd:YAG laser is used for patterning indium-tin-oxide films into electrodes of liquid crystal display panels. To this end, even-fanout gratings are recursively designed by simulated-annealing algorithm and are realized in quartz glasses by dry- etching. While an array of identically intense beam spots strikes the film, a table supporting the film moves in a direction orthogonal to said spots array at a constant speed, forming a large group of equi-spaced grooves in the film. A machining yield of 1600 mm/s has been attained using a 32 grating.
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  • Kenji HARADA, Masahide ITOH, Igor N. KOMPANETS, Hiro MATSUDA, Alexande ...
    1998 Volume 5 Issue 2 Pages 89-92
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    We propose a new type of spatial light modulator using nonlinear organic polymer film as a phase modulation element. Using polymer poly-Disperse Red-19 Toluendiiso-cyanate, a more than 150:1 contrast ratio has been realized for electrical addressing in transverse geometry.
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  • Hideo FUJIKAKE, Kuniharu TAKIZAWA, Tahito AIDA, Hiroshi KIKUCHI, Takan ...
    1998 Volume 5 Issue 2 Pages 93-98
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    A high-speed controllable polarizing filter has been developed to eliminate obstructive polarized light reflected from glass and watery surfaces for image pickup in video media program producing and marine dynamic remote sensing. In this device, the polarization plane of incident light is rotated through 0 45 90or 135by an electrically-controllable polarization rotator composed of 45and 90twisted nematic liquid crystal cells, and the polarization component of reflected light is absorbed by a fixed polarizing film. It selectively absorbs more than 80% of incident white light linearly polarized in an arbitrary direction. With the drastic reduction of reflected light, the object images hidden by the bright reflected light are clearly captured in real time. Another type of polarizing filter, using a guest-host liquid crystal cell instead of the polarizing film, controls light absorption as well as polarization angle.
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  • Bijan GHAFARY, Suo DONGHUI, Masakatsu OKADA
    1998 Volume 5 Issue 2 Pages 99-104
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    The switching time of an optically switched laser diode between a locked mode and free oscillation mode is studied. By starting with linear stability analysis, analytical expressions are developed to predict the switching time. It is shown that the switching of optical output between the locked and unlocked modes is governed by two relaxation processes with different time constants, and the change in the first relaxation process, dependent on the carrier density in the initial state, gives a strong effect on the total switching time, in contrast to the dynamic behavior of the carrier density dominated by a single relaxation process. Our analytical results show that larger detuning and power of optical input are effective in shortening the switching time and are believed useful to estimate the switching time of an optically switched bistable laser diode.
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  • Ribun ONODERA, Yukihiro ISHII, Vasilii V. SPIRIN, Alexei A. KAMSHILIN, ...
    1998 Volume 5 Issue 2 Pages 105-108
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    We report an experimental study of dynamic coupling of two laser diodes (LD's) with a double phase-conjugate mirror (DPCM) in a Bi12TiO20 fiber-like crystal. After the DPCM is recorded in the crystal, one of the LD's is switched to the multimode regime, while the other remains lasing in the single longitudinal mode. Nevertheless, the DPCM produces phase locking of the single-mode laser with one of the longitudinal modes of the multimode laser. Only the longitudinal mode survives after the transmission through the DPCM, demonstrating the coherence length recovery of the multimode laser.
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  • Yoshisato FUJIOKA
    1998 Volume 5 Issue 2 Pages 109-114
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    As the thickness of a disk base is varied, the variation of spherical aberration becomes remarkable. An objective lens system with compensating lenses on the light source side is designed. By moving the compensating lenses along the optical axis backward or forward, the spherical aberration caused by the variation in thickness of the disk base is corrected.
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  • Minoru SASAKI, Yuji ARAI, Kazuhiro HANE
    1998 Volume 5 Issue 2 Pages 115-118
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    The spatial filter of a Si micromachined pinhole integrated with photodiodes is fabricated. The photodiode cells placed around the center pinhole can detect the relative position between the incident beam spot and the pinhole. The position signal obtained from a two or four cell type photodiode and position sensitive detector show the sensitivity even when the beam spot is near the center pinhole. Combined with the feedback control of the shape memory alloy actuator based on the obtained position signal, the pinhole is aligned automatically.
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  • Masayuki TAMURA, Teruhiro SAKURAI, Hideo TAI
    1998 Volume 5 Issue 2 Pages 119-123
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    Simultaneous two-dimensional imaging of an unburnt area and a reacting area was performed using laser-induced fluorescence. Acetone was added to fuel as a tracer, and OH radical was used as a marker of the reacting area. A narrow band tunable KrF excimer laser (248 nm) was employed to excite acetone and OH simultaneously. Two intensified CCD cameras with different wavelength filters were used to detect these two kinds of species respectively. Detecting 294-314 nm (A-X (3,2), etc.) for OH and 335-410 nm for acetone, we obtained images of each species without interference of a signal from the other. The method was also successfully applied to flames in a pressurized combustion chamber under the pressure of 0.5 MPa.
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  • Katsunori OKAJIMA, Tatsumi ODA, Masanori TAKASE
    1998 Volume 5 Issue 2 Pages 124-127
    Published: April 01, 1998
    Released on J-STAGE: March 28, 2000
    JOURNAL FREE ACCESS
    We conducted experiments to investigate the effects of head-motion and object-motion to produce a perception of neon color spreading. Our experimental results indicated that a two-dimensional motion of yellow patches promoted the color spreading. A horizontal head-motion with motion parallax and three-dimensional pictorial depth information together with changing the viewing point stimulated the color spreading even, more than the two-dimensional motion. Thus, motion signals appear to offer useful information for the formation of a subjective contour and/or to activate the filling-in effect needed to generate neon color spreading. We also tested whether there was a difference between the effects of vertical and horizontal motion parallaxes for neon color spreading and found that there was none. This suggests that vertical head motion provides information in depth and surface perception equivalent to horizontal head motion.
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