The Effect of Light Distribution of LED Luminaire on Human Ocular Physiological Characteristics

Light-emitting Diode (LED) has been considered as one of the new generation lighting sources with several merits such as high efficiency, high reliability, long lifespan, high-speed response, and energy saving. The optical performances of an LED luminaire, such as illuminance, luminance, correlated color temperature, and spectra power distribution, determine the lighting environment which can affect the human ocular physiological characteristics. To investigate the effect of optical performances on human vision, previous studies have assessed the subjective perception based on questionnaires. In this paper, we propose a novel method based on the aberrations and accommodations data from 150 human factor measurements on a total of 25 participants. The results show that: 1) optical performances of the LED luminaire have an influence on ocular physiological characteristics during the visual task duration, which can be quantized by the variations of physiological parameters; 2) the desk illuminance and light distribution curve are selected in this study as the optical parameters. The variations of ocular physiological characteristics reach the minimum values when the desk illuminance is 550 lux and the light distribution curve is large beam angle; and 3) ocular physiological characteristics are more sensitive to the light spatial distribution compared to the light quality. Thus, the proposed assessment method based on variations of ocular physiological characteristics in this paper is promising as one of the guidelines for the design and optimization of the LED luminaires.