UV light and visible range

[mcjtom]

I found this neat visual comparison of 3 UV LEDs with and without filter:

2mm ZWB2 filter tested (visible light blocking filter suitable for 365nm UV flashlights)

disclaimer: I could have sufficed by just remarking: yeah, it works fine, but I can not resist doing a proper test, even for a simple optical filter [image] [image] In the the double-UV light group buy, this 20mm diameter, 2mm thick ZWB2 filter was discussed as a way to get rid of the large amount of visible light that chinese 365nm leds (and the Ledengin LZ1 365nm is just as bad) produce as an unwanted by-product. Being 20mm diameter it fits in the Convoy tube-style lights as replacement lens…