Electronic – How does IR thermal vision work

heatimage-sensorinfraredopticsthermal

How are IR thermal-vision devices able to present us with "invisible" imagery in such a way that we can actually interpret it?

What I'm really trying to wrap my head around is:

  1. How a sensor can "see" colours that I can't. (I understand it's probably like trying to explain colour to somebody born without sight).

  2. How it can "pitch-shift" to a visible wavelength/frequency. (I understand that terminology is probably incorrect when talking about light as opposed to sound, but you get the idea).

  3. Not to mention, in some situations, it seems to have this uncanny ability to "see through" solid, opaque materials & detect objects obscured by obstacles etc. (Like military & DEA aerial surveillance, for example).

Aerial Thermal IR Surveillance
Aerial Thermal IR Surveillance
Macro Thermal IR Fusebox
Aerial Thermal IR Motorist
Macro Thermal IR Connectivity
Macro Thermal IR Plumbing

Best Answer

What I'm really trying to wrap my head around is (firstly) how a sensor can "see" colours that I can't. (I understand it's probably like trying to explain colour to somebody born without sight).

The sensor is just converting some physical measurement — in this case, the temperatures of a whole lot of little thermal sensors — into a 2-dimensional array of data. The thermal sensors (microbolometers) get their temperature from the fact that a point on some distant object is focused on each one by a lens that is transparent to long-wave IR.

And (secondly) how it can "pitch-shift" to a visible wavelength/frequency. (I understand that terminology is probably incorrect when talking about light as opposed to sound, but you get the idea)

The sensor isn't doing that at all. Any 2-D array of data can be represnted visually by mapping colors (or grayscale values) to the numbers. It is the display device (eg., LCD) that is producing the visible light that you see.

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