Measuring 405nm UV light.

Hello, Bit of background, have an old 3D printer that shines 405nmUV light through a LED screen to expose layers of the liquid curable resin in a vat above it with the LCD masking off the areas not to cure.

As this is not an even light source I need to measure the scatter of a 405nm UV, as the UV light gets weaker towards the edges of the reflector so I can compensate with a mask in software, so just need a % difference of the brightness at multiple points.

My plan is to use an LM393 Light Sensor Module and switch out the LED for a 405nm LED, and just wanted some advice on if this is a good approach?

And if there is a simple example sketch that will just show me the values in the serial monitor?

Yes, the example you mention is in the IDE example sketches under "Analog".

aarg:
Yes, the example you mention is in the IDE example sketches under "Analog".

Thank you.

LEDs used as photodiodes are most sensitive to light about 30-50 nm "bluer" than the emission. So to detect 405 nm light, an LED that emits at about 450 nm would be best.

jremington:
LEDs used as photodiodes are most sensitive to light about 30-50 nm “bluer” than the emission. So to detect 405 nm light, an LED that emits at about 450 nm would be best.

Very interesting, I did not know that. Is this linear across all wavelengths or is there logistic, Parabolic curve up/down the spectrum?

The 30 to 50 nm shift is generally observed, for several different types of LEDs. Conservation of energy requires such a shift, as energy is lost during photon emission and detection.

Thank you very much for the information and that link, sincerely appreciated