The basic idea here is making an image one pixel at a time. This could really just as easily be done with a photodiode (or other light sensor) to create a black and white image as well. However in this case instead of focusing on the "light" part of the electromagnetic spectrum, we move down to the realm of heat rays (or lack there of, depending on what you are imaging). Now I am fully aware that the cost of thermal cameras is becoming more accessible and that there are also sensors which instead of a single thermopile, they contain a small array... but I didn't have either. I had a single thermal sensor, some old stepper motors, some wood and other random electronic parts. Plus it was late at night and not to many places where open.
I really did throw this together. No really! Being late at night I didn't even bother cutting the wood in fear of waking up my kids, so I just grabbed scrap pieces and used them as is. I found the balancing point of the top piece with the motor on it, the extra length and weight of the wood ended up serving as a counter balance to the hardware. I used epoxy putty, super glue, two kinds of tape (electrical and kapton) and even baling wire... oh yeah! While I waited for glue to dry (or cure) I wrote the firmware and a processing sketch to create the final images.
So how does it work? It is like a one pixel thermal camera. It scans up and down, left and right and makes the image one pixel at a time. Similar to slowly scanning an entire scene with an infrared thermometer.
I did another shot of my desk and the incandescent light before moving outside to take a scan of my backyard. In the bottom picture (the one of my yard) you can see how my concrete patio was still warm even long after the sun had gone down. The device was siting on my fake wood back porch so that is the pinkish stretched out rectangle you see at the very bottom of the image. For the backyard one I had it scan pretty long, so it is like a panorama, that is why things are so distorted.