Electrical Engineering Asked on October 29, 2021
I’m trying to find high brightness UV LEDs appropriate for this project:
https://www.instructables.com/id/UV-LED-Exposure-Box/
which includes: "The most critical parts of this project are the UV LEDs, you are looking for 5mm Ultra Violet LED 2000mcd 395nm, 3.4V 20~25mA."
However, it appears that the mcd (luminous intensity) criteria is ambiguous for LEDs and other light sources that emit a peak wavelength that isn’t visible to the human eye, such that a directional (solid angle) emitted power (wattage) criteria would be more appropriate. That might explain why it’s so difficult to find anyone who can meet those specs. Is there anyone with experience in UV leds who can help? Thanks.
The datasheets can be a bit all over the place in terms of these units, especially with luminous intensity which is a function of how well the eye perceives the particular wavelength.
Since the application is a box, I would not worry too much about directivity (or the eye), and focus more on getting an LED with a respectable "Radiant power" (total radiated power) to electrical power ratio.
I have used "VLMU1610-365-135" (the datasheet is quite good in my opinion) for a project where it has P_rad=23mW at 20 mA. And it states a forward voltage of 3.5 V at 20 mA. So P_in=70mW, and thus we are around 33 % efficient in radiating light. I might have seen some with 50 % which seems to be around the top.
About this box, remember to be able to dissipate the heat from the LED's through the sides. LED's lose quite a lot of radiant performance when they run hot and the consultant who helped me said that it was the most common error in power LED applications.
Answered by Bonnevie on October 29, 2021
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