Green LED Light – Unique Attributes and Applications

Green LED light has a variety of unique attributes and benefits. Most high brightness green LEDs emit light centered around 540 nanometers (nm).  This wavelength nearly matches the optimum sensitivity of the human eye in daytime and nighttime conditions.  For the human eye accustomed to daytime light (photopic vision) the maximum efficiency is for light centered at 555 nm.  For the human eye adapted for night vision (scotopic vision), the maximum efficiency is for light centered at 510 nm, which is a wavelength that corresponds to blue-green light.  Because green LEDs so closely match the optimum performance point of the human eye, their light enables objects to be seen with high resolution and in high contrast while having minimal impact on night vision. 

Green LED light also has excellent transmission through water.  The visible wavelength that transmits the furthest through water is 480 nm, which corresponds to a true blue-green.  As a corollary to this, one my think that blue-green light would also transmit the furthest through clouds and fog, since they are comprised of water in vapor form.  Clouds and fog are white however because they uniformly scatter all visible wavelengths ranging from 400 to 750 nm.  One might ask then, why are fog lights yellow?  The answer to this is three fold.  First, longer wavelengths (reds, oranges and yellows) scatter off of water droplets less than shorter wavelengths (purples, blues and greens).  Consequently, less light will be scattered back towards the vehicle’s driver if longer wavelength light is used.  This in turn will minimize the potentially blinding  ”wash out” effect.  Second, as already stated, the human eye is most sensitive to yellow light.   So, the best compromise between eye sensitivity and minimal scattering is yellow light.  Third, sodium vapor lamps are extremely efficient at converting electrical energy into yellow light.  Sodium lamps also have long operational lifetimes, are easy to manufacture and are relatively inexpensive.

Green LED light can also be used to illuminates insects such as scorpions and millipedes.  Though these insects fluoresce green when illuminated with UV light, their exoskeletons reflect green light quite effectively.  Green LED light can also be used to attract many species of fish.  Fish eyes, like human eyes, are extremely sensitive to green light.  Green light scattered off potential food (such as fishing lures), will immediately grab the attention of fish swimming in the area – and because green light travels great distances through water, the area can be quite large.