With high-powered lasers, one of the important destructive mechanisms is blast - the outer layer of the illuminated object vaporizes, and flies away from the rest of the target. The reactive force of this gives the target a hell of a kick. Kicking off strict alignment with it's flight path, or putting a big dent (or even better a hole) in the side of a missile under several G's of stress traveling at a high Mach number is not healthy for the missile. Laser's have problems though - as they heat the air the refractive index changes, leading to 'blooming' or beam expansion. At too high a power density they can also ionize the air, which makes it effectively opaque. Dust, haze, and clouds are also problems. Using *very* short pulses eliminates many of these problems. Peter Trei

---------- From: Steve Schear[SMTP:schear@lvcm.com] Sent: Monday, July 23, 2001 1:34 AM To: cypherpunks@lne.com Subject: Re: Air Force Turns 747 Into Holster for Giant Laser (washingtonpost.com)

At 09:14 AM 7/22/2001 -0500, you wrote:

...

Point this baby at the ground...

http://washingtonpost.com/wp-dyn/articles/A27248-2001Jul20.html

I wonder what the destructive mechanism is for this system? Heat by radiant absorption seems an obvious but impractical method. If it is, then as the article mentions there may be some inexpensive and practical countermeasures to such a system, such as making the exterior of the missile body into a multi-faceted mirror able to reflect both IR and radar

energy (although doing the same for the nose cone might prove more difficult due to aerodynamics).

steve