| 摘要 |
A scanning interferometer that is capable of measuring the complete relative movement of up to 10 or more measurement sites on a test structure, to determine thermal distortion or expansion. The interferometer includes means for dividing a source beam into signal and reference beams, and an acousto-optic deflector for deflecting the signal beam in response to a control signal to produce a deflected signal beam. The control signal is generated such that deflected signal beams are sequentially directed to the different measurement sites. Reflection means at each measurement site reflects the deflected signal beam to produce a reflected signal beam. Each reflected signal beam is combined with the reference beam to produce an interference pattern, and a photodetector positioned in the interference pattern produces a fringe signal. Signal processing means are provided for periodically measuring the phase of the fringe signal for each deflected signal beam, to thereby measure the movement of each measurement site. In a preferred embodiment, each reflection means produces nine reflected signal beams, and the signal processing means simultaneously measures the phases of the nine resulting fringe signals.
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