using a UV led as a detector

[Peter Lynch]

The plan is to build some sort of meter for measuring the UV light
from the sun. Now I'm not talking about UV-indexes or any sort of
medical/lab-quality measurements, just a hobby level goofing around
project.
I know that a normal LED can be used "backwards" as a detector, so
one option I'm considering is to use an ultraviolet LED, with emmissions
around 395 nm as the detector. I realise it will probably detect
normal light too, but hopefuly with a bit of experimentation using LEDs
of different colours I can take this into account.

Has anyone got any experience of this kind of thing and in particular
will a uv LED actually detect at long-uv wavelengths?

Pete

 

[Vladimir Dergachev]

The plan is to build some sort of meter for measuring the UV light
from the sun. Now I'm not talking about UV-indexes or any sort of
medical/lab-quality measurements, just a hobby level goofing around
project.
I know that a normal LED can be used "backwards" as a detector, so
one option I'm considering is to use an ultraviolet LED, with emmissions
around 395 nm as the detector. I realise it will probably detect
normal light too, but hopefuly with a bit of experimentation using LEDs
of different colours I can take this into account.

Has anyone got any experience of this kind of thing and in particular
will a uv LED actually detect at long-uv wavelengths?

I am not certain about that - myself, I would try using UV-sensitive
photodiode (they do make them).

I would also suggest getting two of the devices, hooking to the opposite
ends of a differential amplifier and blocking one with glass (which filters
UV).

best

Vladimir Dergachev