Study On Blue Light Hazard And Non-visual Biological Effect Of Various Light Sources

In recent years, LED products, which are high efficiency, energy saving, and environmentally friendly, have slipped into our daily life. As most of LEDs obtained white lighting through exciting the yellow phosphor by blue light, it has become the focus of attention:Whether a long time exposure in this kind of indoor light source will lead to blue light hazard on human eyes or affect circadian rhythm? In order to solve these problems, the blue light hazard efficiency and non-visual biological effect of various light sources are studied, such as incandescent lamps, fluorescent lamps, LEDs and so on.In Chapter One, the international previous researches on blue light hazard and non-visual biological effect of light sources are stated, pointing out the importance of this research. At the same time, this chapter also outlines the related international and domestic standards, introduces the research methods and evaluated system, as well as puts forward the innovation of this study.In Chapter Two, the spectrums of various light sources are obtained by both experiment and the Gaussian Distribution fitting, which are applied to analysis their characteristic.In Chapter Three, the blue light hazard is evaluated through experimental measurement as well as theoretical calculation. On the one hand, the blue light hazard efficiency and the maximum blue light safe radiance or irradiance are obtained through experimental study for compact fluorescent lamps and LEDs, whose correlated color temperatures (CCT) range from 2700 K to 6500 K. The results show that both of the two values are related to the CCT of light sources, which means the higher the CCT is, the higher they are. On the other hand, the Gaussian Distribution fitting comes on the stage in order to confirm the results of experimental study and extend it to a wider color temperature range. The white LED spectra are mixed of three colors (red, green and blue) or four colors (red, green, cyan and blue), whose CCT is 2500-10000 K. And then the calculated blue light hazard efficiency is compared with the experimental results. Moreover, the grid analysis of brightness distribution is firstly introduced, which realizes the derivation from the measured eigenvalue of blue light weighted radiance to the application value on different observation distances.In Chapter Four, the effect of CCT on the circadian efficiency and irradiance of various light sources are calculated. The results show that these two parameters are linearly increased with the CCT of light sources.In Chapter Five, the research results are summarized.