# 365NM 385NM 395NM or 405nm best for fluorescence?



## avalon11 (Nov 16, 2017)

I want to find UV LED‘s that produces not only strong but also wide range of fluorescence. I have built own lamp using Ebay 3W 365nm LED‘s expecting to get best quality clean UV light and was somewhat dissapointed. They do produce strong fluorescense of cellulose and phosphor based materials but rest looks like it is lit by dim white LED, they also get hot even with big heatsink so I figured out its had to come from UV radiation. I tested 14 of them and compared with 34W blacklight tube. 365nm LED's produce a lot lower material fluorescence range while blacklight tube has less wattage but produces significantly more fluorescence. I can so many invisible fluorescent things. I read that cheaper and longer wavelength UV LED‘s despite producing a lot of violet light also work better for fluorescesce. For example Chauvet uses 405nm LED‘s for club lights and works really great despite being so close to visible range. So can someone experienced with different UV light sources recommend which wavelength works best, 395nm, 405nm or maybe I need mixed LED‘s since blacklight tube emmits broader UV-A spectrum?


----------



## mercrazy (Nov 16, 2017)

i've only tested down to 380nm but i prefer lower wavelength due to less visible light. if the material you're trying see has enough fluorescence, lower wavelengths will show it great. some objects may have less fluorescence so higher wavelength visible light helps it show up better. depending on background, visible light can reduce visibility of fluorescent objects. a focusing lens will increase intensity.


----------



## avalon11 (Nov 16, 2017)

Yes, good quality UV LED lamps also have dichroic or Wood's glass filter to remove visible light. Problem is that they are also expensive. Where I can get cheaper filter?


----------



## mercrazy (Nov 16, 2017)

i bought filter glass for 380-390nm. it works to stop most visible light but if you use lower wavelengths, the glass isn't necessary. it also reduces uv power a little. found the filters on alibaba. you have to buy filter for the proper wavelength. there were 3 grades best i remember.


----------



## avalon11 (Nov 17, 2017)

I tested again 365nm lamp it can produce strong fluorescence in dyed cleaners, cotton fibers, paper or certain colored packages with only some white light but I really feel that I need to filter it out. Was that filter good quality from alibaba and didn't block UV? Can you give link? I tried using shard from blacklight bulb as filter and UV was blocked also, so that was probably bad quality contaminated glass. 
Blacklight tube produces as mention wider range of fluorescense, so for example I could see on bathroom tiles yellow stains while 365nm LED's on them look like dim white LED's. Violet colors also look way more cooler than white and produces beautiful contrast with yellowish and greenish fluorescence


----------



## mercrazy (Nov 17, 2017)

search UV pass filter glass. comes in 3 grades, ZWB1,2, or 3. get the 1 for the wavelength you plan to use. seems i got 3 for 380nm. 1 and 2 are for lower wavelengths. they make 20mm round ones for cameras. there are several suppliers. if you just want a few, i would check ebay.https://www.ebay.com/itm/2pcs-20mm-...066897?hash=item3adc0ee551:g:zVsAAOSwhlZYvOcU


----------

