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From: Andy Resnick <andy.resn...@op.case.edu>
Newsgroups: sci.optics,alt.electronics,alt.sci.physics,aus.electronics,sci.electronics,sci.physics
Subject: Re: How could the camera on missiles and smart bombs keep its focus?
Date: Fri, 18 Mar 2005 08:37:39 -0500
Organization: Case Western Reserve University, Cleveland, OH, USA
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Sea Squid wrote:
> I was watching the documenrary Century of Warfare. It has some
> segments of how the video shot when missiles and bombs are closing
> on the target. I guess the missile will fly to the target at 334m/s so the
> camera must have a extremely fast zooming and autofocus trick. Can
> anybody here provide me with some information?

AFAIK, The systems I worked on several years ago were non-imaging: a 
quadrant dectector or reticle was used to determine pointing.  Also, 
tracking wasn't performed in the final hundred yards or so- the missile 
flew blind at that point.  Most missiles use radar and thermal sensing 
rather than visual optics.

It's not clear what you saw on tv- usually there is a video feed on the 
aircraft that paints the target, or that drops the ordinance- is that 
what you were seeing?

Another consideration is that low f-number optics, which can help in 
terms of sensor systems that only have to look straight ahead, have very 
large depths of field (as another poster pointed out).

Finally, note that air-to-air and air-to-ground systems are very 
different, and have different closing speeds and target tracking 
technologies.

-- 
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University