Detect UV light with iOS Camera

Question

Is there a way to detect the UV ray from the iPhone camera without any hardwares? I don't want to find the exact UV index of the light.

I tried to take a photo from a UV light, but if I analyse that photo, I can only get the RGB pixels. How do I get to know that the photo is taken from UV light? How do the photos taken from the UV light, are differ from the photos taken in the normal light?

I found an app called GammaPix in the app store which says it could detect the radio activity in an area by using only the camera. I want something like that to detect the UV rays.

Answer 1

Fundamentally, most CCD digital sensors can see UV light, but they contain filters to block light outside of the visible range from reaching the detector. There is a good discussion of this here: https://photo.stackexchange.com/questions/2262/are-digital-sensors-sensitive-to-uv

The spectral response of the iPhone drops to essentially zero for wavelengths shorter than 400 nm (edge of the visible) due to these filters. [See page 35 of http://epublications.uef.fi/pub/urn_nbn_fi_uef-20141156/urn_nbn_fi_uef-20141156.pdf]

Really high energy photons, like gamma rays, can pass through most materials and reach the sensor, even when visible light to the camera is completely blocked. This is how the GammaPix app likely works. This doesn't work for UV photons, since they will be blocked by the filters on the sensor.

So, unless you can somehow crack open the iPhone and remove the filters from the sensor (probably not possible without destroying the sensor), then it will not be able to detect UV photons.

To detect UV, a "windowless CCD" (or similar) is required: http://www.mightexsystems.com/index.php?cPath=1_88

Another option might be to use a material that can absorb UV photons and emit visible photons. For example, this card will glow when illuminated with UV light.