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A stroboscopic interferometer that can be used as either a Fizeau or a holographic interferometer is described. The instrument has been developed for real-time evaluation of dynamic optical components and for remote-site operation of an interferometer in the presence of severe acoustical noise and mechanical vibration effects.

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The effectiveness of holographic interferometry for displacement studies was investigated and profiles of the fringe patterns characteristic of the basic displacement modes were developed. In addition, techniques were established for determining displacement directions and measuring displacement magnitudes. Procedures were also established for extending these studies to evaluate complex displacements. A quantitative theory for predicting fringe pattern formation was developed.

The phase-sensitive 3.39 μm Doppler interferometer is designed to make relative optical phase measurements by permitting measurements of optical phase independent of the source amplitude fluctuations. This interferometer utilizes a Doppler shifting technique to produce relative optical path length information from the optical component under test. This information is in the form of phase differences between two audio frequencies. These phase differences are sensed and displayed by a high-resolution zero crossing electronic phase meter. The phase angle displayed is directly correlated with the optical phase difference between the sample and the reference beam. Normal laboratory environment accuracy of the instrument is λ/16 at 3.39 μm.