Two-dimensional optical wavefront measurements using a small-aperture beamtechnique derivative instrument

Results obtained from a new, 600-Hz, 624-subaperture, two-dimensional optic al wavefront sensor for fluid-optic interaction applications are presented. This instrument can operate at 1 kHz as currently configured and is extend able to 8 kHz with a minor modification. The new sensor uses the small-aper ture beam technique for measurements in the streamwise direction, and scann ed beams for cross-stream wavefront measurements. Wavefront aberrations pro duced by a low-speed, heated mixing layer are presented, and the accompanyi ng measurement uncertainty is evaluated, (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)02012-2].