在线测量表面粗糙度的共光路激光外差干涉仪

一种新型的、用于在线测量表面粗糙度的激光外差干涉仪已研制完成。该仪器体积小（２５ｃｍ×２０ｃｍ×１０ｃｍ）、抗外界环境干扰能力强。仪器以稳频半导体激光器作为光源。共光路设计，使测量光和参考光沿同一路径入射到被测表面上。计大数和测小数周期相结合的外差信号处理方法，实现了大的动态测量范围和很高的测量分辩率。同时还采用了全反射临界角法进行自动聚焦。该仪器的纵向和横向分辨率分别为０．３９ｎｍ和０．７３μｍ；自动聚焦范围为±０．５ｍｍ，在焦点±２５μｍ范围内，聚焦精度为１μｍ；８０分钟内整机稳定性：３σ＝１．９５ｎｍ。

Common Path Laser Heterodyne Interferometer for On-Line Measuring Surface Roughness

A novel laser heterodyne interferometer used for on-line measuring surface roughness has been developed. It features compact volume (25 cm×20 cm×10 cm) and excellent immunity to environmental disturbances. The system employs a frequency-stabilized laser diode. The design of common path makes the measurement beam and the reference beam incident on the surface along the same way. The processing method of heterodyne signals combines integer measurement with fraction period measurement, so it has wide dynamic range and high resolution. In addition, critical angle method is introduced for automatic focusing. The height and lateral resolutions of the system are 0.39 nm and 0.73 μm respectively. The maximum range of automatic focusing is ±0.5 mm and the focusing accuracy is 1 μm within ±25 μm of the focus. The stability during 80 minutes is 1.95 nm (3σ).