Investigation on Circadian Action and Color Quality in Laser-Based Illuminant for General Lighting and Display

Shuo-Di Lei,Yu-Jia Gong,Yang Gao,Dong Wang,Zong-Jian Cai,Xiao-Ya Dong,Jian Xu,Ting-Zhu Wu,Yun-Xin Xu,Zhong Chen,Zi-Quan Guo,Yi-Jun Lu,Chen-Liang Zhou,Bi-Jing Liu

doi:10.1109/jphot.2020.3007529

Abstract

In this work, the genetic algorithm is employed to optimize both circadian action factor (CAF) and color quality of laser-based illuminants (LBIs) with three, four, and five spectral bands to disclose its possible use in two common white lighting applications, i.e. bedroom lighting and office lighting. Comparing all LBIs at a correlated color temperature (CCT) of 3000 K and a color rendering index of 80, the CAF of four-band LBIs reaches a minimum of 0.238 and maintains at a possibly highest luminous efficacy of radiation (LER) of 422 lm/W among all cases. The performances of white LBIs are also compared with those of white light-emitting diodes (LEDs). The results demonstrate that, under the same conditions of color rendering and color temperature, both four-band LBIs and four-band LEDs exhibit the largest circadian tunability of about 4.7, while four-band LBIs possess much higher LER at the same time compared with four-band LEDs. In addition, for the display application, the investigation on the optimal circadian tunability as a function of color gamut at two CCTs (3000 K and 6500 K) is also performed. We believe that this study can serve as a useful guidance for the application of LBIs in both the healthy general lighting and display.

Highlights

Solid-State lighting is one of the most promising lighting technologies in the 21st century, and has become the dominant technology for the general lighting [1]
Previous studies have shown that various coloured laser diodes (LDs) combinations, denoted as laser-based illuminants (LBIs) here, can generate the pure white light as well as light-emitting diodes (LEDs)-phosphor combinations [9], and the color rendering of LBIs can reach a level of LEDs [10]
They have proposed a parameter called as the circadian action factor (CAF) tunability, to describe the tunability from the lowest CAF to the highest CAF for the white light sources, especially the white LEDs and LBIs

Summary

Introduction

Solid-State lighting is one of the most promising lighting technologies in the 21st century, and has become the dominant technology for the general lighting [1]. The behavior of all living beings generally follows a regular change in a cycle of 24 hours, denoted as the circadian rhythm attributed to a third type of photoreceptor called as intrinsic photosensitive retinal ganglion cells [15] These cells play a key role in the formation and release of melatonin, cortisol and other hormones. Dai et al have carried out the optimization of solid-state lighting spectra to achieve beneficial and tunable circadian effects [18] In their studies, they have proposed a parameter called as the CAF tunability, to describe the tunability from the lowest CAF to the highest CAF for the white light sources, especially the white LEDs and LBIs. Till there are quite a lot of research studies on the improvement of color rendering and LER for LBIs [10], [19], but those referring to circadian effects are rarely reported. We investigate their optimal CAF tunabilities as a function of color gamut, described by the ITU-R Recommendation BT. 2020 (Rec. 2020) [20]

Experimental Details

Optimization for the General Lighting

Optimization for Display Application

Conclusion