Study Of Key Techniques Of Microscopic Interferometry In Mini-surface Geometry

Geometric parameters of the surfaces of mini-optics,like surface figure and radius of curvature(ROC),play a decisive role in assuring optical performance.As apertures of mini-optics are very small,it is hard to precisely measure such parameters by ordinary interferometers.Based on microscopic interferometry,systematic research is made on their measuring methods and related key techniques in three respects,fringe analysis technique (FAT),phase-shift interferometry(PSI)and virtual grating phase-shift technique(VGPT).As for FAT,besides automatic analysis techniques,emphatic research is done on the least square fitting algorithm of ROC calculation by all extreme points of refined fringes so as to fully suppress noise influence.As for PSI,measuring principle is studied on mini-surface figure and the ROC of a mini-sphere.For phase unwrapping,an improved path first searching,algorithm(PFS)is given.And by applying the algorithm to the unwrapping of practical wrapped phase maps,it is indicated that,the algorithm can result in correct unwrapping in the case of noise and big blocks of ineffective zones.By comparing the sensitivity of overlapping averaging 4-bucket algorithm(OAF)to phase shift errors with those of other common phase stepping algorithms,a conclusion is obtained that OAF algorithm is more insensitive and can result in less ROC measurement errors.Meanwhile,a small resultant error is obtained by applying OAF to ROC measurement.As for VGPT,research work is done on the principles of surface profiling and of spherical ROC measurement.Adopting Linnik-type optical path,a digitalized PZT phase-shifting microscopic interference system is designed.While testing and correcting the nonlinearity of the phase shifter,the systematic error of the set-up is analyzed and measured by applying frequency-carrying PSI technique,with peak-to-valley value of wave aberration obtained asλ/10.37.According to fringe analysis,PSI and virtual gratings techniques described in the dissertation,determinations are made of the ROCs of mini-sphere templates.In the mean time,experimental resUlts are compared with those by imported instruments.Finally,measuring methods are studied on the apex offset and fiber height of a fiber connector end face.Directed at the stem request,under the general "apex-core method",of a precise tilt adjustable mechanism for accurate apex offset measurement,a novel "rotatingπmethod" is presented based on a common 5-dimentional adjustable support.Resultant errors through theoretical analysis indicate that the same measurement accuracy can be obtained by applying rotatingπmethod,which is confirmed by experiments.Therefore the developing cost of a measuring set-up can be greatly reduced if adopting rotatingπmethod.