扩展差动共焦显微系统量程范围的方法与措施

An Approach to Expansion Measurement Range of Heterodyne ConfocalMicroscopy System

为扩展差动共焦显微镜(HCMS)的测量量程范围,使其满足三维微细结构和三维表面轮廓测量时的需求,基于环形光瞳滤波技术提出一种扩展HCMS测量范围的环形光瞳量程扩展方法与技术。该方法应用二元光学整形原理将HCMS中两探测器探测到的光强响应曲线的半高宽拓宽,继而达到扩展量程范围的目的。与常用的通过减小共焦显微系统物镜的数值孔来扩展量程范围的方法相比,整形环形光瞳量程扩展法在扩展量程范围的同时,还改善了HCMS的分辨特性,压缩其旁瓣,避免了因减小物镜数值孔径值引起的横向分辨力降低的不足。理论分析和实验表明:当环形光内、外径半径比ε=0.5时,环形光瞳量程扩展技术使HCMS的量程扩展了1倍,同时使其横向分辨力得到改善,旁瓣得到抑制。

In order to achieve the larger measurement range of heterodyne confocal microscopy system(HCMS) required for measurement of 3D microstructures and 3D surface profiles,a new approach based on annular pupil filter technique was proposed to expand HCMS measurement range.The method proposed uses binary optical shaping method to expand full width at half maximum of intensity response curve detected by two detectors in HCMS,thereby expanding the measurement range of the system.In comparison with the general method of measurement range expanded by decreasing objective numerical aperture of confocal microscopy system presently,the expansion method of shaping annular pupil used in HCMS expands the measurement range,improves HCMS resolution property,suppresses the effect of side lobe on the measurement,and avoids the reduction of HCMS lateral resolution caused by decreasing the objective numerical aperture.Analyses and experiments indicate that when ratio of inner aprture radius to outer aperture radius of the annular beam ε=0.5,annular pupil expansion technique of measurement range makes HCMS measurement range expanded one times,and makes HCMS lateral resolution improved and the side lobe suppressed.