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View Full Version : Heat Seekers and Thermal Imagers



Giant Baby
12-17-2010, 08:34 PM
I've been researching Heat Seekers and Thermal Imagers, and I've become hopelessly muddled in the conflicting information I'm finding. Essentially, I just want to know if there is any device (military, law enforcement, doesn't matter) that allows the user to detect human presence inside a home. I don't need pictures, just the ability to get a good idea visually of how many people are inside, and in what location of the house. Blobs of color or motion are fine.

I've seen it on TV, movies, etc., of course, but the Google keeps telling me, "despite what you see on TV..." I don't know if that's just for the cameras I'm coming up with, though, or for the technology in general.

Oh, and it's perfectly fine if it would not be legal for a civilian to own the device, if that's a thing.

Thanks!

Noah Body
12-17-2010, 09:34 PM
I'm not aware of any IR technology that can see through walls, since they're passive systems. You're talking about X-ray types of devices, which I don't think exist yet for that application. :)

Lhun
12-17-2010, 09:44 PM
It impossible to look through any wall, window or other insulated structure with an IR camera. They don't let IR radiation through, so there'll be nothing to see besides the temperature of the wall itself. Even glass windows, especially double pane glass, is opaque to IR.

Using other radiation is also something of a problem. You'd need some kind of radiation that passes a stone wall unperturbed, but gets reflected by a human body (too see said body) which doesn't exit, as far as i'm aware.

The best bet would be ultrasound, though i don't know whether that's only possible in theory, or if some device exists in practice. You almost certainly would need to put the ultrasound sensor directly against the surface you want to look through though.

Drachen Jager
12-17-2010, 09:53 PM
Well, they DO let IR through Lhun, it's just that the image is so scattered that you can't pick anything up from it. Contractors use IR cameras to detect spots of poor insulation on houses for example. Anything thicker than tent fabric would blur the outlines of people to the point where you can't tell how many people there are or if there's anyone there at all.

The only technology I know of which accomplishes the job you're looking for is a snake camera which may or may not help you out as it's not as simple to use as simply scanning the structure.

Giant Baby
12-17-2010, 10:32 PM
Thanks, Noah, Lhun, and Drachen. I can write around it, but the googling was getting out of hand! Appreciate the simple answer.

Lhun
12-17-2010, 11:13 PM
Well, they DO let IR through Lhun, it's just that the image is so scattered that you can't pick anything up from it.It's more than scattering with most materials, the IR gets absorbed and re-emitted. There are of course IR transparent materials (such as quartz) but they're not common building materials. You can see spots of bad insulation with an IR camera because they show up as hot, no matter whether they're actually transparent to IR from the inside, or hot by conduction.

Kenn
12-17-2010, 11:24 PM
Glass will let infra-red radiation through, but only if it is near infra-red (the shorter wavelength stuff). This is the type used for illumination by night vision cameras. Thermal infra-red is longer wavelength and doesn't go through glass. Neither of them go through walls, and that begs the question about the need to rely on infra-red if you can use visible light.

There are radio frequency devices that do the job you are after. For example:

http://www.camero-tech.com/xaver800.shtml

Giant Baby
12-18-2010, 12:30 AM
Holy crap, Kenn! That's perfect. I found YouTube video of it in action, and it's exactly the sort of thing I was hoping for! Thank you, thank you.

Drachen Jager
12-18-2010, 01:01 AM
That's a pretty cool system. I guess it uses similar technology to the ground penetrating radar police use to look for dead bodies or mining companies use to look for resources.

Crappy image resolution though, I presume, since it's a sales presentation they're showing the device working at it's best and it only tells you there's a couple of blobs, no indication of weapons and no real way to tell whether each one is a threat or a civilian. Given the bulkiness of the machine I'd say using a snake camera would be more effective 9 times in 10.


Glass will let infra-red radiation through, but only if it is near infra-red (the shorter wavelength stuff). This is the type used for illumination by night vision cameras. Thermal infra-red is longer wavelength and doesn't go through glass. Neither of them go through walls, and that begs the question about the need to rely on infra-red if you can use visible light.

There are radio frequency devices that do the job you are after. For example:

http://www.camero-tech.com/xaver800.shtml

Lhun
12-18-2010, 01:15 AM
Glass will let infra-red radiation through, but only if it is near infra-red (the shorter wavelength stuff). This is the type used for illumination by night vision cameras.It also depends on the glass. Some windows are more insulated than others. One could also create windows from the same material IR camera lenses, though there would be little point.
Here are a few nice pictures also one that nicely shows some car windows.

There are radio frequency devices that do the job you are after. For example:

http://www.camero-tech.com/xaver800.shtmlThat's very cool, looks like it works basically as a motion detector.