Niklas Roy has written an article detailing his DIY thermal imaging with an IR thermometer:
I did not want to hack/destroy the brand new thermometer, as I still plan to use it in its original form later. For that reason, I decided to temporarily attach an old webcam to its back. This way, my laptop can read the temperature via the thermometer’s LCD display.
In a second step, I connected two RC servos to an Arduino. Those servos pan and tilt the thermometer – thus, the thermometer can scan an image. I also wrote a program in Processing, which sends the X and Y servo positions to the Arduino and at the same time reads the temperature via the webcam. The program draws a thermal image based on the measured temperatures.
More info at Niklas Roy’s project page.
Check out the video after the break.