The progress of grating coupled surface emitting distributed feedback semiconductor lasers
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At present, grating coupled surface emitting distributed feedback semiconductor lasers has been the focus of the laser field due to a number of excellent performance, such as high brightness, high power, low divergence, easy packaging etc, compared with the conventional edge-emitting semiconductor lasers. In this paper, the progress of research at home and abroad were summed and reviewed. And then, the further research and development trend has been discussed based on all of these progress.Several new spatial brightness evaluation methods have been proposed in recent years. Although these new methods provide us to evaluate spatial brightness which is difficult by measuring horizontal illuminance, there is little agreement for a room with uneven distribution of light. In this study, we examined the relationship between spatial brightness, suitability of spatial brightness and luminance distribution for such a non-uniformly illuminated room. We found applied conditions of averaged luminance to estimate spatial brightness or suitability of spatial brightness for uneven lighting environment. We also found that suitability of spatial brightness correlated to spatial brightness evaluation well.
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In this study, the concentration and brightness measured by fluorescence correlation spectroscopy (FCS) in samples containing multiple species with different brightness levels was demonstrated. FCS measurements of such samples are generally difficult. However, the calculation we introduced here can provide the measurement results of the FCS. The effectiveness of the calculation was investigated based on simulations and experiments in the case of a mixture of fluorescent beads with known brightness and other fluorescent beads with unknown brightness. The results show that the concentration of the known brightness agrees well with the expected values. The obtained concentration and brightness of the species with unknown brightness is possible, and it worked well in the simulation; however, the accuracy for the species was lower than that of the species with known brightness. As a result, the calculation is useful in measuring the concentration of species with known brightness in samples containing undesired bright species, such as aggregation. The calculation for the species with unknown brightness may also be useful if good protocols or instruments are established in the future.
Fluorescence Correlation Spectroscopy
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Proposed scales of apparent brightness are introduced, which were reported by S. S. Stevens and R. G. Hopkinson. Procedures for designing visual environment were briefly stated on the basis of the scales of apparent brightness.The present authors propose following further studies on the application of apparent brightness to illuminating engineering: 1) Consideration of effect of brightness contrast and constancy in addition to adaptation on prediction of apparent brightness. 2) Relations between visual functions and apparent brightness. 3) Specification of pleasant or comfort distribution of apparent brightness in visual environment. 4) Specification of the design procedure of visual environment based on apparent brightness for easier use. 5) Necessity to use apparent brightness meter, which is similar to the color appearance meter desingned by R. W. G. Hunt. 6) Necessity of interim international unification of scales of apparent brightness. 7) Necessity to establish the system to appraise visual environment subjectively, which woluld calrify the relation between the pleasantness (or comfortability) and apparent brightness.
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Central composite design
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BY MEASURING THE SUBJECTIVE REACTIONS AND EYE MOVEMENTS OF SUBJECTS LOOKING AT PAIRS OF NEUTRAL GRAY CHIPS VARYING IN EITHER BRIGHTNESS, BRIGHTNESS RATIO, OR BRIGHTNESS AND BRIGHTNESS RATIO, IT WAS POSSIBLE TO ASSESS THE ROLE OF THESE PARAMETERS IN ATTENTION VALUE. EACH VARIABLE CONTROLLED ATTENTION WHEN COMPOUNDED. WHEN THE TWO PARAMETERS VARIED SUMULTANEOUSLY, BRIGHTNESS RATIO PREDOMINATED, BUT A HIGH BRIGHTNESS ENHANCED THE ATTENTION- GETTING VALUE OF HIGH CONTRAST. THIS WAS MORE EVIDENT IN THE NEGATIVE THAN IN THE POSITIVE CONTRAST DIRECTION. IT IS SUGGESTED THAT ADDITION OF A FACTOR CONSIDERING HIGH RELATIVE BRIGHTNESS IN COMBINATION WITH HIGH RELATIVE BRIGHTNESS RATIO WOULD REFINE THE FORBES ET AL MODELS OF HIGHWAY SIGN ATTENTION VALUE. /AUTHOR/
Contrast ratio
Value (mathematics)
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Our recent studies have shown that the main factor for determining of envionmental brightness is the perceived amount of light filling a space. Therefore, to estimate the environmental brightness from the physical properties of a space, we have to compute the physical quantity that corresponds to the perceived amount of light filling the space. We propose using the virtual luminance distribution methods (VLDM) to estimate environmental brightness. Because our past results did not show that VLDM is more effective than other environmental brightness indices, we performed a new experiment. In the experiment, the subjects evaluate enviromntal brightness of the inside of test boxes with variant reflectance of the walls and variant lighting patterns by using the magnitude estimation method. The brightness estimated using VLDM correlated well with that evaluated by the subjects. However, the vertical illuminance at the point of the subjects' eyes correlated poorly the estimated brightness. This demonstrates that VLDM is valid for brightness estimation. We performed another experiment in order to investigate the difference between using VLDM and the reference matching method (RMM) for brightness evaluation. The results show that it is possible to estimate the brightness evaluation using RMM by considering photometry and brightness unlinearity. This suggests there is a similarity between the psychological process of brightness evaluation using RMM and the computation process of brightness estimation using VLDM.
Apparent magnitude
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Because the changing range of environmental brightness is wide, brightness of LED CMS(Changing Message Sign) should be adjusted according to the changes of environmental brightness in order to guarantee that the displayed information could be clear under different lumina. This paper will discuss brightness adjusting design for LED CMS from three different angles: visual characteristics of eyes, the relationship between luminescence brightness and environmental brightness and the ways of brightness adjusting, and give final testing results.
LED display
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In this study, a luminance image measured in an experimental room was first converted into a brightness image based on the prediction formula proposed by Nakamura et.al. Then the brightness values in the brightness image were checked experimentally by brightness matching test. The result showed there was good correlation between the values in the image and subjective assessments. Finally the probability that the room brightness can be predicted by using the average brightness value in the brightness image of a room was suggested.
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