an old a by now extremely old and unused webcam with an astonishing resolution of 320 x 240 pixels, and removed the original filter for visible light with a lot of vinegar and sheer force. Afterwards, I added a few layers of exposed and developed film as a low-pass filter. Because the used CCDs will typically cover a range for the visible light spectrum plus a huge stretch into the infrared wavelengths, these modifications effectively turn the old webcam into a camera for infrared light.
Despite its really low resolution, the results
are quite promising were mind blowing back in the times when I tried this: