On Feb 27, 2016, at 6:47 PM, Jean-Paul Louis wrote: > David wanted deep UV, not near UV. 365nm is near UV. what he asked for wa= s 260ish nm. Actually, he asked for something that would be cut out by his UV filter, an= d it looks like 365nm would ALMOST do it: http://www.hoyafilter.com/picture= s/F0000021-transmission.gif (depending on the exact spectral output of the = 365nm LED.) I don=92t think he needs to go all the way to =93short wave UV= =94 (UVC) at 260nm. (OTOH, I=92m not sure that all those intermediate wave= lengths exist. Also, efficiency seems to go down pretty dramatically with = wavelength, and packaging starts to fluoresce and emit visible light, even = if the die doesn't :-( ) Aliexpress shows some ~300nm LEDs that might work. No direct experience. BillW --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .