"Some of these problems can be avoided by using very short pulses. Again you get into dwell, the short pulses -must- be made up for by increasing the PRR and this defeats the who purpose of the short pulses since you need more of them (we're talking an integration effect here so it doesn't take much to understand why duty cycle isn't as important as you make it out to be" IR is not particularly better than visible for most wavelengths, and fog is the real killer (as opposed to rain or even snow). But I know the LIDAR folks found that there ARE some nicer wavelength windows within the IR band. As for pulsed lasers, here's where my knowledge of military applications fails me (I used to work in civilian ultrafast/femtosecond optics.) As for pulsing such a laser, I can't quite imagine WHY this would be attempted for damage reasons (reconaissance is a different sotry). If the pulsing is in the millisecond regime or faster, I would imagine this is only to allow for population re-inversion of the laser material (ie, to keep it lasing at higher peak power). But I assume the military's laser research in the wavelengths of interest are well beyond the need for this. Of course, there's the easy possibility that the military does use fast pulses for the purpose of knocking out certain sensor materials via 2nd order/nonlinear processes. As we found out back in 92 or so (from some declassification), the military's optical research in Adaptive optics was in some ways 30 years ahead of the civilian world. Who the heck knows what they're doing with laser pulses. _________________________________________________________________ Unlimited Internet access -- and 2 months free! Try MSN. http://resourcecenter.msn.com/access/plans/2monthsfree.asp