In order to generate a multifrequency laser emission, consisting of the entire rainbow of colors, two approaches are demonstrated and compared for commercial application, such as displays and illumination.  One approach uses a second harmonic emission of a Nd:YAG laser emitting at 532 nm as the main pump beam and a dye laser, which is pumped by a part of the Nd:YAG laser, as a seed beam.  These beams are coaxially aligned and are focused into two Raman cells filled with hydrogen to generate multifrequency laser emission based on four-wave Raman mixing.  The other approach is more straightforward and involves an elliptically polarized second harmonic emission of a Nd:YAG laser, instead of a two-color laser beam, which is simply focused into the Raman cells.  The entire rainbow colors (more than 20 emission lines from 400 nm to 800 nm) are generated in both the approaches.  More efficient generation of the regular (quasi-equally spaced) spectral lines with a flatter intensity distribution is achieved by the former approach.  The output power obtained is 600 mW (60 mJ x 10 Hz).

This paper deals with the analysis of a novel modified half-bridge type inverter for electronic ballast of fluorescent lamps, in which the functions of the active filter and inverter are combined, and the power factor and harmonic distortion in the input cur-rent are improved sufficiently. After discussing, the equivalent circuit model and the operation mode of the proposed half-bridge type inverter, we proceed to analyze its performance characteristics theoretically and experimentally. As a result, it is clarified that the new modified half-bridge type inverter has excellent characteristics such as high power factor over 0.97, low total harmonic distortion factor less than 11.3%, high power efficiency of 92% and low crest factor of 1.56.

A visual experiment was carried out to obtain the BCD luminance of a blinking light under the conditions of 0.1 to 100cd/m² of background luminance and a 1 to 16 Hz blink rate. The test light was a circle with diameter of 3 minutes (6.0'10^-7 sr). The experimental results showed that BCD luminance was highest in the case of a steady light with any background luminance, the BCD luminance was the lowest at around 5 to 8 Hz, and the blinking frequency corresponding to the minimum BCD luminance increased in parallel with an increase in the background luminance. Also it was found that the BCD luminance of the blinking light increased in parallel with an increase in the background luminance, a trend which was similar to the relationship between the BCD luminance of a steady light and the background luminance.

If a mere apparent color (apparent-color) from an object surface is equal to a color perception as an attribute of the same object surface (surface-color), this condition should be called "perfect color constancy." If not, the condition should be called "partial color constancy." We looked into the distinction betweeen these two classes of color constancy, while changing illuminant chromaticity around D₆₅. A small room with variable-chromaticity illuminant was used. The walls were painted with N5 gray. A CRT monitor was placed behind an aperture on the front wall, so that the observer perceived the CRT monitor as a reflecting surface on the wall. Observers were asked to make unique-white settings, in terms of both apparent-color and surface-color, under various chromaticites of illuminants. The shift in unique-white represents the shifts in visual sensitivity, and an analysis based on a simple von Kries type model was made. Cone weights for each cone class were defined to represent the state of chromatic adaptation. The change in cone weights show that the sensitivity shift in the visual system follows illuminant chromaticity change only around white, and the visual system was not able to follow illuminant chromaticity change for saturated illuminants. An additional experiment confirmed that these results had no contamination of simultaneous contrast effect. This result may correspond to the fact that "perfect color constancy" holds under whitish illuminant while "partial color contancy" holds under colored illuminants. In conclusion, we suggest that the "perfect color contancy" can be achieved only by von Kries-like sensitivity change, and the "partial color contancy" requires further processing at the higher stages of the human visual system.

key words:perfect color constancy, partial color constancy, chromatic adaptaion, unique-white, cone weight

It is difficult to describe the luminous intensity distribution (LID) of louver lighting analytically because the louver is composed of a lot of reflection sides which reflect each other. A widely used luminaire, twin fluorescent lamp with louver, is modeled and the influence of louver shape on LID is studied and investigated by means of the Monte Carlo (MC) simulation method. The theoretical analysis and research results show that the surface reflectance, pitch size, and depth of louver have a great influence on LID and the effect of lighting. A verification test done in a model room shows that the simulation results agree with the measured data well. This paper supplies a new way for the research and optimum design of louver lighting.

Keywords—Louver lighting, Monte Carlo method, Luminous Intensity Distribution