The Art of Submarine Warfare

[Dave Emery]

On Fri, Jun 22, 2001 at 11:50:04PM -0700, Steve Schear wrote:
> 
> No need to use something so targeted at the cop camera, just install 
> rear-facing infrared floods and keep them on all the time.  (Cadillac 
> drivers with the new night-driving, IR, heads-up displays will be 
> particularly upset..)

	Not sure this is true.  Last I knew, the Caddy stuff was a true
FLIR, based on sensing thermal IR from warm objects and not an old
fashioned WW II/Korea era near IR sniperscope based on IR illumination
by an IR floodlight.   I suppose this may have changed with actual
product introduction, but I think the images in their ads were clearly
FLIR thermal IR images.

	(And lest the distinction not be clear, thermal IR at room
temperatures is long wave IR as black bodies at 20 C don't radiate a
hell of a lot at say 900 nm.).   An illuminator that would activate the
video AGC or light sensors on camcorders would obviously have to be near
IR as the optics and sensors used don't pass or detect much long wave IR
at all.

	


 The IR cut-off filters of most cameras are too broad 
> to block invisible near IR, so the floods will cause the AGC to greatly 
> darken the image as described above.
> 
	That is certainly true, although most CCD sensors will nicely
detect and image the bright spot from the IR tail lights or whatever, and
that would be a very good (and preserved on tape) indication of a
deliberate intent which could easily result in nastier and more
aggressive prosecution than might result from anything else during
the stop.


> steve

-- 
	Dave Emery N1PRE,  die at die.com  DIE Consulting, Weston, Mass. 
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