Noncontact optoacoustic monitoring of flame temperature profiles

The first known totally noncontact optoacoustic measurement in a flame, using a pulsed laser to excite an acoustic pulse and observing the transient deflections of cw probe beams to detect the acoustic propagation, is described. All laser beams are coplanar, parallel, suitably displaced, and focused inside the flame. Such laser-based ultrasonic measurements provide a new way to map out temperature and flow profiles in flames or other hostile environments. © 1982 Optical Society of America.