The people and organizations who made this work possible are gratefully recognized. Roger Combs and Bob Kroutil of US Army ERDEC for funding analysis of voice coil performance; DOE/INEL for funding the University of Idaho to purchase the prototype instrument described here. Special thanks to the past, present and future customers of Manning Applied Technology. The Lincoln Laser Company is gratefully acknowledged for technical advice. Secondly, the people who actually helped with the work are recognized, Mike Itano for his many hours in front of computer monitors doing 3D modeling of pathlength variations and finite element modeling. Jeff Paul for assembling high-speed op amp circuits. Blayne Hirsche for helping to set up the rocket igniter measurement and setting up the data acquisitions PC. Matt Williamson for a lot of help with slides and manuscript. Finally, thanks to Richard Palmer, Peter Griffiths and Bruce Chase for advice and encouragement.