The luminous-efficiency functions for a centrally viewed 10° field were measured by heterochromat... more The luminous-efficiency functions for a centrally viewed 10° field were measured by heterochromatic brightness matching for various retinal illuminance levels of a reference field at various adapting levels. The subject was always presented with a 450 white adapting light except when the test field for brightness matching was substituted for the adapting field for 500 msec. In order to investigate the contributions of rods and cones to the brightness sensation, the luminous-efficiency curves obtained from two subjects were analyzed with the Ikeda-Shimozono formula. When the subject was presented with an adapting light above about 100 trolands (Td), the luminous-efficiency function became photopic at any luminance level of the test field; similarly, when the test field was at 100 Td, the luminous-efficiency function was photopic at any adapting level.
In this paper, a method to analyze the temperature and pressure dependences of the viscosity or o... more In this paper, a method to analyze the temperature and pressure dependences of the viscosity or of the structural relaxation time in supercooled liquids is shown from the point of view of chemical bonding. The model used in this analysis is the Bond Strength-Coordination Number Fluctuation (BSCNF) model originally proposed by one of the authors. A theoretical relationship between the Vogel temperature T 0 of the well-known Vogel-Flucher-Tammann (VFT) equation and our model parameters which contain some microscopic information on bonding connectivity among the structural units that form the melt has been obtained. Using the theoretical relationship, we analyzed the dynamics of two kinds of molecular glass forming liquids under pressure, (a) 4,4'-methylenebis(N,N-diglycidylaniline), and (b) BMPC: 1,1'-di(p-methoxyphenyl)cyclohexane. The result obtained suggests that by applying pressure in these materials, the intermolecular cooperativity is suppressed due to increases in the mean total bond strength and the fluctuations of the structural units.
Brightness-to-luminance (B/L) ratios based on It has long been known that luminance defined by Eq... more Brightness-to-luminance (B/L) ratios based on It has long been known that luminance defined by Eq. (1) does not correlate well with perceptual brightness. the CIE 1924 V (l) for 195 test stimuli equally sampled from the whole area of the CIE1976(u, v) chromaticity For example, highly saturated colored lights usually look brighter than a white light of the same luminance. This diagram were measured for four color normal observers. The results of two observers were similar to results in discrepancy between luminance and brightness has been studied for several decades in basic research in visual previous studies in that the B/L ratio increases as purity of the stimulus increases. However, the results of the other science. 1-14 It has been accepted that the discrepancy is caused by the wrong spectral sensitivity function for two observers showed very low B/L ratios, especially in the reddish region. The B/L ratios based on each observ-brightness in Eq. (1), and by additivity failure in heterochromatic brightness matching (HBM). 15 er's sensation luminance were also calculated. Although the contour lines of equal B/L ratio become less atypical The V (l) function in Eq. (1) is mainly based on the results of heterochromatic flicker photometry (HFP). The for the latter two observers, they still showed low B/L values compared to typical results. Large individual psychophysical criterion for HFP is a minimum flicker point presumed to be determined by an achromatic chan-differences of the B/L ratio in the whole area of the chromaticity diagram were indicated. ᭧ 1998 John Wiley & nel in the visual system. 16-18 Physiological studies have
Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest (IEEE Cat. No.01CH37170), 2001
Summary form only given. AlGaInN high power laser diodes (LDs) were fabricated on a thin epitaxia... more Summary form only given. AlGaInN high power laser diodes (LDs) were fabricated on a thin epitaxially laterally overgrown GaN (ELO-GaN) substrate. The LD characteristics were improved by using this ELO-GaN substrate. This is because ELO-GaN is quite effective in reducing dislocation density and in forming good cleaved facets. We have improved the characteristics by optimizing the parameters of the ridge stripe; ridge width and the distance between active layer and etched surface adjacent the ridge. We have also improved kink level by introducing a novel ridge stripe structure. The kink level of more than 80 mW was realized by the novel ridge structure. This value is considerably higher by about 30 mW higher than a conventional ridge structure. Consequently, lifetimes of LDs have exceeded 1000 h under 30 mW operation at 60 /spl deg/C.
Whenever we enter a space illuminated differently from a previous space whether in color or in il... more Whenever we enter a space illuminated differently from a previous space whether in color or in illuminance, we can quickly adapt to the new atmosphere and can again perceive white for the originally white object; this is known as color constancy. This phenomenon is explained by rotation of the recognition axis of the recognized visual space of illumination (RVSI) toward the illumination color. The explanation then predicts that the color appearance of a test patch changes radically toward the opposite direction from the color of illumination when the physical property of the test patch is kept unchanged at a neutral white. This prediction was confirmed by Experiment 1, where eight different colors of illumination were employed. The test patch appeared very vivid in color and shifted toward the opposite direction from the color of the illumination. In RVSI theory the light source color mode is explained by the release of the test patch from the restriction of RVSI. The release can be achieved by increasing the luminance of the test patch and the color appearance of the patch should then return to its own color as it is no longer controlled by RVSI. In Experiment 2 these predictions were investigated by increasing the luminance of the test patch to a much higher level than that of the objects in the lit room fixed at an illuminance of about 100 Ix. The color appearance of the test patch indeed became the light source color and returned to the original neutral white. Emphasis was given in the course of the experiments that the subjects were observing the test patch presented in a real 3D space where the subjects also stayed inside so that they could properly construct RVSI for the space.
ABSTRACT ZnSSe and ZnMgSSe epitaxial layers grown on (001)GaAs substrates are characterized by et... more ABSTRACT ZnSSe and ZnMgSSe epitaxial layers grown on (001)GaAs substrates are characterized by etching and transmission electron microscopy (TEM). It is found that etch pits etched by bromine-methanol correspond to stacking faults in ZnSSe. These stacking faults, whose Burgers vector is 1/3 〈111〉, are extrinsic. It is found that stacking faults lying on (11) and (111) cannot be revealed by this etchant in ZnSSe. TEM establishes that etch pits in ZnMgSSe etched by HCl correspond not only to stacking faults but also to threading dislocations. Furthermore, all stacking faults lying on the four equivalent {111} planes can be observed as etch pits in ZnMgSSe.
The luminous-efficiency functions for a centrally viewed 10° field were measured by heterochromat... more The luminous-efficiency functions for a centrally viewed 10° field were measured by heterochromatic brightness matching for various retinal illuminance levels of a reference field at various adapting levels. The subject was always presented with a 450 white adapting light except when the test field for brightness matching was substituted for the adapting field for 500 msec. In order to investigate the contributions of rods and cones to the brightness sensation, the luminous-efficiency curves obtained from two subjects were analyzed with the Ikeda-Shimozono formula. When the subject was presented with an adapting light above about 100 trolands (Td), the luminous-efficiency function became photopic at any luminance level of the test field; similarly, when the test field was at 100 Td, the luminous-efficiency function was photopic at any adapting level.
In this paper, a method to analyze the temperature and pressure dependences of the viscosity or o... more In this paper, a method to analyze the temperature and pressure dependences of the viscosity or of the structural relaxation time in supercooled liquids is shown from the point of view of chemical bonding. The model used in this analysis is the Bond Strength-Coordination Number Fluctuation (BSCNF) model originally proposed by one of the authors. A theoretical relationship between the Vogel temperature T 0 of the well-known Vogel-Flucher-Tammann (VFT) equation and our model parameters which contain some microscopic information on bonding connectivity among the structural units that form the melt has been obtained. Using the theoretical relationship, we analyzed the dynamics of two kinds of molecular glass forming liquids under pressure, (a) 4,4'-methylenebis(N,N-diglycidylaniline), and (b) BMPC: 1,1'-di(p-methoxyphenyl)cyclohexane. The result obtained suggests that by applying pressure in these materials, the intermolecular cooperativity is suppressed due to increases in the mean total bond strength and the fluctuations of the structural units.
Brightness-to-luminance (B/L) ratios based on It has long been known that luminance defined by Eq... more Brightness-to-luminance (B/L) ratios based on It has long been known that luminance defined by Eq. (1) does not correlate well with perceptual brightness. the CIE 1924 V (l) for 195 test stimuli equally sampled from the whole area of the CIE1976(u, v) chromaticity For example, highly saturated colored lights usually look brighter than a white light of the same luminance. This diagram were measured for four color normal observers. The results of two observers were similar to results in discrepancy between luminance and brightness has been studied for several decades in basic research in visual previous studies in that the B/L ratio increases as purity of the stimulus increases. However, the results of the other science. 1-14 It has been accepted that the discrepancy is caused by the wrong spectral sensitivity function for two observers showed very low B/L ratios, especially in the reddish region. The B/L ratios based on each observ-brightness in Eq. (1), and by additivity failure in heterochromatic brightness matching (HBM). 15 er's sensation luminance were also calculated. Although the contour lines of equal B/L ratio become less atypical The V (l) function in Eq. (1) is mainly based on the results of heterochromatic flicker photometry (HFP). The for the latter two observers, they still showed low B/L values compared to typical results. Large individual psychophysical criterion for HFP is a minimum flicker point presumed to be determined by an achromatic chan-differences of the B/L ratio in the whole area of the chromaticity diagram were indicated. ᭧ 1998 John Wiley & nel in the visual system. 16-18 Physiological studies have
Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest (IEEE Cat. No.01CH37170), 2001
Summary form only given. AlGaInN high power laser diodes (LDs) were fabricated on a thin epitaxia... more Summary form only given. AlGaInN high power laser diodes (LDs) were fabricated on a thin epitaxially laterally overgrown GaN (ELO-GaN) substrate. The LD characteristics were improved by using this ELO-GaN substrate. This is because ELO-GaN is quite effective in reducing dislocation density and in forming good cleaved facets. We have improved the characteristics by optimizing the parameters of the ridge stripe; ridge width and the distance between active layer and etched surface adjacent the ridge. We have also improved kink level by introducing a novel ridge stripe structure. The kink level of more than 80 mW was realized by the novel ridge structure. This value is considerably higher by about 30 mW higher than a conventional ridge structure. Consequently, lifetimes of LDs have exceeded 1000 h under 30 mW operation at 60 /spl deg/C.
Whenever we enter a space illuminated differently from a previous space whether in color or in il... more Whenever we enter a space illuminated differently from a previous space whether in color or in illuminance, we can quickly adapt to the new atmosphere and can again perceive white for the originally white object; this is known as color constancy. This phenomenon is explained by rotation of the recognition axis of the recognized visual space of illumination (RVSI) toward the illumination color. The explanation then predicts that the color appearance of a test patch changes radically toward the opposite direction from the color of illumination when the physical property of the test patch is kept unchanged at a neutral white. This prediction was confirmed by Experiment 1, where eight different colors of illumination were employed. The test patch appeared very vivid in color and shifted toward the opposite direction from the color of the illumination. In RVSI theory the light source color mode is explained by the release of the test patch from the restriction of RVSI. The release can be achieved by increasing the luminance of the test patch and the color appearance of the patch should then return to its own color as it is no longer controlled by RVSI. In Experiment 2 these predictions were investigated by increasing the luminance of the test patch to a much higher level than that of the objects in the lit room fixed at an illuminance of about 100 Ix. The color appearance of the test patch indeed became the light source color and returned to the original neutral white. Emphasis was given in the course of the experiments that the subjects were observing the test patch presented in a real 3D space where the subjects also stayed inside so that they could properly construct RVSI for the space.
ABSTRACT ZnSSe and ZnMgSSe epitaxial layers grown on (001)GaAs substrates are characterized by et... more ABSTRACT ZnSSe and ZnMgSSe epitaxial layers grown on (001)GaAs substrates are characterized by etching and transmission electron microscopy (TEM). It is found that etch pits etched by bromine-methanol correspond to stacking faults in ZnSSe. These stacking faults, whose Burgers vector is 1/3 〈111〉, are extrinsic. It is found that stacking faults lying on (11) and (111) cannot be revealed by this etchant in ZnSSe. TEM establishes that etch pits in ZnMgSSe etched by HCl correspond not only to stacking faults but also to threading dislocations. Furthermore, all stacking faults lying on the four equivalent {111} planes can be observed as etch pits in ZnMgSSe.
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Papers by Mitsuo Ikeda