Measuring laser flow fields with a 64-channel heterodyne interferometer

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Abstract
The digital heterodyne interferometer has been equipped to simultaneously measure and record phase at 64 discrete locations on a single beam. The measurements are obtained at 10-μsec time intervals and have a resolution in phase of 1/500 of a wave rms and a full scale accuracy of 1/100 of a wave rms. Associated with each phase detector is a dedicated data recording system 16 bits wide and 4096 words deep. Additionally, the system records simultaneously the rigid body motions of the interferometer optics, allowing the post priori removal of the corrupting motions of the interferometer optics. This instrument was used to obtain measurements of the optical quality of the media of a transverse-flow electron beam-pumped laser simulator.