Wizinowich P L
Appl Opt. 1990 Aug 1;29(22):3271-9. doi: 10.1364/AO.29.003271.
A modification to the usual phase shifting interferometry algorithm permits measurements to be taken fast enough to essentially freeze out vibrations. Only two interferograms are time critical in this 2 + 1 algorithm; the third is null. The implemented system acquires the two time critical interferograms with a 1-millisecond separation on either side of the interline transfer of a standard CCD video camera, resulting in a reduction in sensitivity to vibration of 1-2 orders of magnitude. The required phase shift is achieved via frequency shifting. Laboratory tests comparing this system with a commercial phase shifting package reveal comparable rms errors when vibrations are low; as expected from an analysis of potential phase errors. However, the 2 + 1 system also succeeded when vibrations were large enough to wash out video rate fringes.
对常规相移干涉测量算法的一种改进使得测量速度足够快，基本上能够消除振动的影响。在这种2 + 1算法中，只有两幅干涉图对时间要求严格；第三幅为零值干涉图。所实现的系统在标准CCD摄像机的行间转移两侧以1毫秒的间隔采集这两幅对时间要求严格的干涉图，从而使振动灵敏度降低1 - 2个数量级。所需的相移通过频移实现。实验室测试将该系统与商用相移软件包进行比较，结果表明在振动较小时，均方根误差相当；这与对潜在相位误差的分析预期一致。然而，当振动大到足以消除视频速率条纹时，2 + 1系统仍能成功测量。
