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Akira ASANO, Tomonori SYUDOH, Shunsuke YOKOZEKI
1995 Volume 2 Issue 3 Pages
159-162
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
JOURNAL
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An efficient algorithm based on the simulated annealing for the learning optimization of morphological filters is proposed. The learning stage is divided into two consecutive parts; the initial-learning stage finds and fixes the most important parts of the structuring elements, and the precise-learning stage determines details of the rest. This method significantly reduces the number of trials for the modification of structuring elements. The proposed algorithm is applied to the learning optimization of the bipolar morphological operation, whose optimization problem has not yet been investigated. It is shown experimentally that the algorithm optimizes the operator as efficiently as the conventional one and reduces the amount of calculation.
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Akira ASANO, Takahiro HONDA, Shunsuke YOKOZEKI
1995 Volume 2 Issue 3 Pages
163-166
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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A simulator to aid in the design of nonlinear image processing filters is developed. This simulator assists the filter design by determining parameters manually by trial-and-error. The method is also useful for improving the results of the learning optimization methods. An example of the application of the technique to improve a resultant filter by a learning method of a mathematical morphological filter is shown.
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Norikazu NAKAYAMA, Satoru KIJIMA, Satoshi ITOH, Toyoharu OHATA, Akira ...
1995 Volume 2 Issue 3 Pages
167-170
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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Green light-emitting diodes (LEDs) were fabricated employing a ZnCdSe/ZnSSe triple quantum-well (TQW) active region surrounded by ZnMgSSe cladding layers grown on an n-type (1 0 0) GaAs substrate by molecular beam epitaxy (MBE). A 3.5 mW pure green emission was observed for the surface-emitting LED device at a peak wavelength of 513.3 nm (2.415 eV) with a spectral half-width of 11.7 nm (55 meV) under a 20 mA (4.6 V) direct current at room temperature (25°C). These correspond to an external quantum efficiency of 7.2%, a power conversion efficiency of 3.8%, a luminous current efficiency of 66 lm/A, and a luminous efficiency of 14 lm/W.
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Hirofumi IMAI, Masahiro DAIMON
1995 Volume 2 Issue 3 Pages
171-173
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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A new type of single-frequency solid state laser for achieving a highly stable second-harmonic generation in a simple configuration was developed using a quite thin laser medium. A 100-μm thick Nd:YVO
4 crystal with one side coated for high reflection in a 50-mm long cavity which serves as automatic gain discriminator was end-pumped by a laser diode. Single-frequency output powers of 100 mW and 17 mW were obtained for fundamental and second-harmonic waves respectively by 1-W excitation. No chaotic fluctuation was observed with the frequency-doubled output.
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Jun UOZUMI, Katsuhiro UNO, Toshimitsu ASAKURA
1995 Volume 2 Issue 3 Pages
174-180
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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Some first-order statistics of speckle fields obeying the complex Gaussian probability density are investigated with the special emphasis on a possibility for the speckle contrast to exceed unity. It is shown that such enhanced fluctuations of speckle fields are generated when the probability density of the complex amplitude is non-circular with the vanishing mean. This means that Gaussian speckles having the contrast of unity are not necessarily fully developed speckles. Some practical situations producing such enhanced fluctuations in speckle fields are discussed.
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Tsuyoshi TSUJIOKA, Toshio HARADA, Minoru KUME, Kazuhiko KUROKI, Masahi ...
1995 Volume 2 Issue 3 Pages
181-186
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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The possibility of a super-resolution optical memory using a photochromic mask layer was theoretically discussed. An equation which estimates the transmittance change of the mask layer was derived. The numerical simulation based on the equation showed that the reflectance increase of the layer by photo-irradiation is nonlinear when the optical density of the layer is high. The nonlinear response decreased the crosstalk in adjacent recording tracks and improved the MTF (modulation transfer function) characteristics, resulting in a higher recording density.
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Andreas JENDRAL, Ralf BRÄUER, Olof BRYNGDAHL
1995 Volume 2 Issue 3 Pages
187-188
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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Computer-generated image holograms are particularly useful for 3D-display applications. We discuss the properties of the reconstructions obtained with this hologram type. Conditions are given which must be fulfilled to ensure a disturbance free reconstruction. A new efficient algorithm is presented which implements the hidden surface effect for synthetic image holograms.
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Neil MCARDLE, Mohammad R. TAGHIZADEH
1995 Volume 2 Issue 3 Pages
189-193
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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In this letter we describe the advantages of a dynamic optical interconnection system for parallel information processing applications. The system is based on a liquid crystal television which acts as a binary phase-only spatial light modulator. We describe example algorithms where reconfigurable interconnects would be useful and present results of several interconnection topologies which have been implemented.
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Norihiko ODA, Jun HASEGAWA, Tetsuo NONAMI, Masahiro YAMAGUCHI, Nagaaki ...
1995 Volume 2 Issue 3 Pages
194-198
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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We propose a new method to measure surface topography using a monocular endoscope. The surface structure is obtained up to a scale factor from an image sequence taken through a conventional CCD endoscope. The scale factor is determined by a photometric method, and the actual size of the object can be determined. The principle and experimental results are presented.
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Sten HELMFRID, Tetsuo ANDOU, Shinichi NAKATSUKA, Kimio TATSUNO
1995 Volume 2 Issue 3 Pages
199-203
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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When mini-solid-state lasers are end-pumped by diode lasers, it is important to have a good overlap between the pump beam and the oscillating mode and to have a pump spectrum that is narrow compared to the width of the absorption peak in the gain medium. We have theoretically studied the influence of the beam radius and the spectral width of the pump on the performance of diode-pumped devices. From the rate equations, the lasing threshold and the circulating intensity is evaluated numerically and the results can be used as a guideline in the design of intracavity doubling lasers. It is also shown that single-mode operation is more difficult when the pump spectrum becomes to wide.
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Francisco J. ARANDA, Devulapalli V. G. L. N. RAO, Chi L. WONG, Ping Z ...
1995 Volume 2 Issue 3 Pages
204-206
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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Nonlinear refractive index coefficient n
2 of bacteriorhodopsin suspensions in water is measured by the Z-scan technique with a low power continuous wave laser at 647.1 manometer wavelength. Our results indicate that both the magnitude and the sign of n
2 depend strongly on the light intensity. Negative values for n
2 are obtained for on axis laser irradiance at the focus above 3 W/cm
2. The observed self-defocusing phenomena can be attributed to the index change due to the light induced transition between the photochromic states. The results elucidate the origin of n
2 and offer a plausible explanation for the differences in the reported n
2 measurements.
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Naomasa SHIRAISHI, Koichi MATSUMOTO
1995 Volume 2 Issue 3 Pages
207-210
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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A new imaging method using an incoherent-type pupil filter: SFINCS (Spatial Filter for INCoherent Stream) is presented. The new filter divides the imaging beam into several incoherent beams at the pupil plane thereby enlarging the depth-of-focus (DOF). The capabilities of SFINCS are studied by simulations and several ways to realize the method are also discussed. The experimental results show that SFINCS has excellent DOF expanding capabilities for a point-image such as a hole pattern in VLSI lithography, and that 1.7 μm DOF is obtained with a 0.30 μm hole pattern by an i-line projection lens with 0.57 NA (numerical aperture).
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Shin MASUDA, Toshiaki NOSE, Susumu SATO
1995 Volume 2 Issue 3 Pages
211-216
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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A radially and homogeneously aligned LC cell as a polarization controlling device is fabricated using a memory effect in an axially symmetric electrical field. Optical properties and the molecular orientation of the LC cell are investigated and the conversion property of the polarization states of the cell is discussed in detail from the molecular orientation in the cell.
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Christopher J. SOLOMON, J. Christopher DAINTY, Nicholas J. WOODER
1995 Volume 2 Issue 3 Pages
217-220
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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We describe an optimal solution for the modal reconstruction of wavefronts distorted by Kolmogorov turbulence. The approach is Bayesian and calculates the maximum a posteriori (MAP) estimate for the Karhunen-Loeve expansion coefficients.
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Christian WERNER, Grigorii KOKHANENKO, Gennadii MATVIENKO, Vitalii SHA ...
1995 Volume 2 Issue 3 Pages
221-224
Published: June 01, 1995
Released on J-STAGE: March 28, 2000
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First, in this report an overview is given on the use of the Russian laser altimeter in space “LORA” as a lidar for cloud measurements. Secondly, the influence of multiple scattering is verified by analysis of the backscatter signals from clouds having the excellent range resolution of a rangefinder.
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