非接触型光外差轮廓仪(英文)

Non-contact Optical Heterodyne Profilometry

本文介绍一种纳米级非接触型高精度光外差轮廓仪,它是基于普通光路的光外差干涉仪。工件表面被两束有微小频差的激光束所照射,其中一束经聚焦后用作测量光探针来扫描工件表面,另一束则用作参考光束。两束光经表面反射后产生干涉。测量信号和参考信号的相位差与表面的微不平值成正比。仪器的横向分辨率为2μm,高度分辨率为1 nm,它不需要对试样作大范围的调整,且可用试样自身作参考面。信号经光电转换后由微型计算机进行处理,它能快速完成测量、计算、显示及打印出各种参数和曲线。

--This paper describes the non-contact ultra-high accurate optical heterodyne profilometry for nanometer region. The tester is based on the heterodyne interferom-etry with common optical route. The surface of workpiece is illuminated by two laser beams with slightly different frequencies. One of the beams is focused as measuring optical probe to scan the surface of workpiece and the other is used as reference optical beam. The above two reflected beams are allowed to interfere. The optical phase difference of the measuring and the reference signals is in proportion to the variation of surface height. The lateral resolution is less than 2μm and the vertical resolution is less than Inm. No extensive alignment of the sample is needed and the sample is used as reference surface also. Through the opto-electronic converter, the signal is handled by microcomputer and the microcomputer can fast accomplish measuring, calculating, displaying and printing parameters, graphs and etc.