菲索干涉仪中精确移相的实现

为了实现移相式菲索干涉仪对光学元件面形的高精度测量,建立了干涉仪同步采集移相系统,并对精确移相方法进行了研究。介绍了移相系统的构成和工作原理,计算了测量过程中移相器的速度。针对PZT移相器在移相过程中会引入离焦误差,并存在加速段和减速段的问题,详细设计了移相器的行进过程。最后,对移相器的性能进行了标定。在改造后的干涉仪上开展了重复性验证实验,结果表明：干涉仪可以获得λ/11 340的RMS测量重复性。对改造后干涉仪与Zygo公司生产的Verifire XP/D干涉仪的测量精度做了比对实验,结果显示：相同元件下两者测量结果的面形RMS之差约为0.9 nm,表明提出的移相系统及移相方法在重复性和准确度方面都能满足纳米级面形测量的要求,为研制高精度移相干涉仪奠定了基础。

Implementation of accurate phase shift in Fizeau interferometer

To realize the high accuracy measurement of optical surfaces by a phase-shifting Fizeau interferome- ter, a synchronous acquisition phase-shifting system in the interferometer was established, and an accurate phase shifting method was researched. First, the composition and working principle of the phase-shifting sys- tem were introduced. Then, the velocity of PZT phase shifter during measurement was calculated. Since there exist defocus errors as well as speed-up and speed-down steps during phase shift, the moving process of phase shifter was detailedly designed. Finally, the phase shifter was calibrated. A verified experiment was carried out on the modified interferometer, and it shows that the RMS simple repeatability is A/ll 340. Comparative measurement was also carried out with two same components between the modified interferometer and the Veri- fire XP/D interferometer（Zygo company）, and the RMS difference is about 0. 9 nm. It can be seen that the repeatability and accuracy of this phase-shifting system and phase-shifting method have satisfied the requirement of nano-scale form measurement, which can provide references for developing high accuracy phase-shift- ing interferometers.