The definition of light, as applied to artificial light sources, is rather distinct. Visible light is only between 400 nanometers (nm) and 780 nm, but “light” is actually more than just what your eye can perceive. When we look at sunlight, we have a much broader spectral range, from somewhere around 300 nm up to 2,000 nm or so. Interestingly, different spectral has effects on living things. Our circadian rhythm is modulated by light.
Red (610-700 nm) and blue (450-500 nm) wavelengths are most effective in promoting photosynthesis. Green (500-570 nm) light is least effective – it is not absorbed by plants but is reflected which is why green plants appear to be green.
Solid state lighting can be produced with different spectral to cater for very niche application. Horticulture grow light can be designed to optimize plant growth.
One niche LED lighting is the Yellow LED tube used in Photo-lithography process.
The wafer fabrication is a Class 1 clean room environment that has strict particle count control. A simple light replacement could disrupt the operation. The T8 Yellow LED tube is specially designed with less than 0.01% blue spectral. It has near zero UV, long lasting. The current approach is using a 36 watts fluorescent with specialty yellow sleeve to remove the UV lighting.
The Yellow LED tube is 17 watts, 1800 lm, Ra 40. and long lasting; a good replacement for old generation Yellow light.
Solid State Lighting (SSL) can designed to cater for different light sensitive applications.
A yellow light can be designed with no UV. Horticulture light is programmable with different spectral to cater for different stages of plant growth. SSL could also be designed with high Ra 95, less blue or programmable.
With digital electronic control, LED could be programmed to emulate the circadian rhythm; thus, a good technology for human centric lighting.