Characteristics of underwater lighting based on white LEDs

This work systematically analyzed the application of LEDs in underwater white lighting. The characteristics of a RGB-LED and a phosphor-converted LED (PC-LED) have been compared in different water types. The green light shows the smallest attenuation, while the red light has the greatest attenuation coefficient. Such different attenuation effects at different wavelengths lead to the different spectra, CIE coordinates and color rendering index (CRI) of the two kinds of LEDs. With increasing distance, the illuminance of the PC-LED decreases much more rapidly than the RGB-LED due to the stronger attenuation of the wide phosphor-based yellow spectrum. However, the CIE coordinates calculated from the spectra of the PC-LED vary little due to the wider yellow spectrum. On the contrary, the CIE coordinates shift is very clear for the RGB-LED. What's more, the CRI of the RGB-LED increases at distances from 0 to 1.5 m, and then decreases at longer distances, but the CRI of the PC-LED keeps decreasing at all distances, which can be explained by the variation of the R values of the color samples due to wavelength dependent light attenuation. This work will benefit the applications and designs of LED-based underwater lighting.