MR

[Eugen Leitl]

On Mon, Mar 22, 2004 at 11:46:27AM -0800, Steve Schear wrote:

> There are purported to be devices using ultra wideband RF and microwave
> frequencies and millimeter wave active or passive devices to do
> this.  Resolution of the microwave devices should be even lower than the IR

No, active devices should be able to image down to mm and better (T-ray).
Ultrawideband is good for a portable radar to penetrate wood/plaster (maybe
even brick and concrete, if not too thick), and pick up breathing and
heartbeat signatures, as it can resolve time domain very well.

Penetration depth depends on the wavelength: red penetrates deeper than blue,
NIR even deeper (it's being used to diagnose early stages of skin melanoma,
you look really mottled in NIR, try it; apparently it's being used for
transcranial infrared oxytometry and even stimulation), microwaves and T-ray
are cm to dm.
T-ray could augment x-Ray, since capable of instant portable imaging without
requiring ionizing radiation.

> and perhaps suitable only for determining occupant location, for example
> prior to breaking down the door during a SWAT raid. Millimeter waves are

If it's a wooden door I don't see why you can't resolve limbs and even
individual digits with active imaging.

> emitted by warm bodies, such as own own, and can be used to passively see
> thorough clothing.  Not sure if passive devices would work through walls
> due to attenuation, but active devices probably could.

This is very likely.

--
Eugen* Leitl <a href="http://leitl.org">leitl</a>
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