Laser pulse stretching via enhanced closed loop control with slow Q-switching

In testing a holographic particle track recording system for the Fermilab 15 foot bubble chamber, it was shown that the peak power of Q-switched laser pulses (50ns duration) at the required energy gave rise to boiling during the chamber expansion. A pulse stretching technique is described which was developed to reduce the peak power. Applied to a ruby laser (oscillator and three amplifiers) with a maximum Q-switched output of 30J, pulses of up to 10-μs duration with coherence up to and exceeding 11 m at 2.5μs were produced. The considerably increased coherence length will find applications in many fields of pulsed holography, and its use with fiber optics is particularly promising