[SamBam]

Forgive my ignorance, but if this system would require liquid nitrogen cooling to detect heat from a human, how do commercial (now almost cheap) thermal cameras work? Are they not sensing IR? The can certainly distinguish the different temperatures of different people, without needing to be cooled themselves.

How is this system better than a commercial IR camera -- besides the very obvious and valid reason that this is DIY, and started long before those were cheap?

> "The most amazing part is not that it glows, but that it glows brightly enough to illuminate the stand. It’s not just the “temperature mapped to an image” of a regular heat vision camera, we see the actual long-wave light being emitted and reflected – a soldering iron turned into a lightbulb!"

How is that different from this image, which shows a duck's IR being reflected by water, made by a cheap-o "regular heat vision camera"? http://thermal-imaging-blog.com/wp-content/uploads/2012/05/d...

[JonathonW]

As I understand it, uncooled commercial IR cameras aren't photodetector-based: their sensors are actually heat-sensitive and rely on heating from IR to produce an image. This limits sensitivity and resolution and increases noise.

Higher-quality IR imaging equipment is photodetector based (as in, they operate on the photoelectric effect); these require very low temperatures to operate and need the sort of active cooling the author refers to.

See also https://en.wikipedia.org/wiki/Thermographic_camera , which goes into detail on the different technologies involved.