Complications to optical measurements using a laser with an unstable resonator: A case study on laser-induced incandescence of soot

<p>Temporal behavior of pulses from a Q-switched Nd:YAG laser with an unstable resonator can vary significantly with radial position in the beam.&nbsp; Our laser provides pulses with position-dependent durations spanning 8-11.5 ns at 1064 nm and 7-10 ns at 532 nm.&nbsp; Pulses emerge first and have the longest duration at the center of the beam; they are shorter (by up to 4 ns) and increasingly delayed (by up to 10 ns) with increasing radial distance from the center.&nbsp; This behavior can have a dramatic effect on time-sensitive experiments, such as laser-induced incandescence of soot, if not taken into account.&nbsp;</p><!--StartFragment--><!--EndFragment-->