Low-cost thermal/multispectral imaging via mechanical slow-scan TV

[Thomas Shaddack]

Thermal imaging is a very powerful and very cool technology with many many 
applications in both security and engineering. However, the main obstacle 
for its wider usage in civilian sector is very high cost of the 
microbolometer array sensors.

However, there are affordably cheap remote thermometers on the market, 
using a thermopile or bolometric sensor, which can be considered to be the 
equivalent of a single-pixel array.

In the very beginnings of image transmission, there were various 
technologies being used, many of them using a single-"pixel" optical 
sensor and a mechanical scanning device - a spinning mirror, Nipkow's 
disk, etc..

Can this approach be used in combination with a thermopile sensor? The 
result could be a potentially quite cheap slow-scan thermal imager. 
Because of the lower energy radiated in far-infrared and longer reaction 
time of the sensors, we would have to have much slower scanning speed, not 
allowing real-time imaging, but still enough for engineering purposes, eg. 
finding thermal leaks of buildings or overheating parts on the boards or 
in power installations.

One possible construction is a two-axis polar mount, allowing the 
directional sensor to be aimed in any direction within a range of vertical 
and horizontal angle (eg. a camera tripod with two servos). This would 
have the advantage of being a generic base for any slow-scan multispectral 
imaging device - instead of a directional thermopile use a directional 2.4 
GHz antenna, and scan the city from a roof or a hilltop for the access 
points. (Or use 0.9/1..8/1.9 GHz, and look for cellular towers. Etc.) 
Position the device, set the pixel exposition time, set the angle range 
and step, run the "exposition".

What do you think? Opinions, comments?