As I understand it, uncooled commercial IR cameras aren&#x27;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.<p>Higher-quality IR imaging equipment <i>is</i> 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.<p>See also <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Thermographic_camera" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Thermographic_camera</a> , which goes into detail on the different technologies involved.