This was a fun project – develop a technique to measure the sensitivity of a camera sensor from the UV and IR. I designed and built my own system when enabled me to measure sensor sensitivity curves between 280nm and 800nm, quickly and easily, using a wide range of cameras, lenses and filters.
As with all new techniques, I did what anybody who actually believes in their science should do, I put it out through peer review to be published. It has now been published in the Royal Photographic Society Imaging Science Journal, and you can find a copy of it here.
So what does it enable me to measure? Effectively the response of a cameras sensor to light of different wavelengths from the UV through to the IR. An example plot is shown below, for an un-modified camera, showing the response from each of the 4 colour channels;
As you can see, the un-modified camera is only sensitive to light between 400nm and 700nm due to the presence of internal filters which block the UV and IR. Modifying the camera, by removing these filters, makes the camera sensitive to UV and IR, as shown below;
Modifying the camera, by removing the internal filters, opens up the possibility of imaging in the UV and IR parts of the spectrum. Measurement of the sensitivity as a function of the wavelength enables the end user the better understand what their images mean in terms of what wavelength are being imaged, and to quantify what it is they are seeing.
I can now offer this measurement service, to anyone interested in knowing their camera sensitivity. If you think this may be of interest, please get in touch through my Contact page.