Althought the eye is about 1/2% as sensitive for this color as for the same amount of green light, the fluorescent effect using only one of these leds is remarkable and can be brought to spotlight with the proper secondairy optics , so you can build a powerfol coolant detector for the garage and... Althought the eye is about 1/2% as sensitive for this color as for the same amount of green light, the fluorescent effect using only one of these leds is remarkable and can be brought to spotlight with the proper secondairy optics , so you can build a powerfol coolant detector for the garage and other functions like markings made of fluorescent paint, human fluids etc. These leds are much brighter than you think, because the sensitive for nthis color is almost zero. Never the less they can (when collimated and close distance irritate your eyes, the pupilmof your eye does not work correctly withy this color and opens them wide wich can damage the retina like lasers do To make an array gives you a very powerfulle Blacklight, even stronger than 400 Watt high pressure mercury dichargebulbs with only 10 of these leds!! With perfect cooling 3 Watts are no problem , without cooling 0.3 Watts is about the limit. Used in completely dark circumstances they can irritat your eyes so better build them in a WF 501b and correct driver like I did my shelve. For blacklighteffects and for laboratory instruments , these leds are very convenient. Use a correct driver and use coolnig grease , mount them on a thick aluminum plate and , when used many, use a blower, the cooler they run the mure invisable blacklight you get, as almost any colorled, the wavelength depends on the temperature of the ledcristal. When they become hot, the wavelenght goes to 410 nM , whenn cool is stayes below 400nM what is much less visable. Read more