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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。
A new type of laser heterodyne interferometer for on-line measurement of surface roughness has been developed. The instrument is small (25cm × 20cm × 10cm), anti-interference ability of the external environment. The instrument uses a frequency-stabilized semiconductor laser as the light source. A total of optical design, the measurement light and reference light along the same path incident on the measured surface. The heterodyne signal processing method, which combines the large number counting and the measuring decimal cycle, achieves a large dynamic measurement range and a high measurement resolution. At the same time also used total reflection critical angle method for automatic focusing. The vertical and horizontal resolution of the instrument were 0.39nm and 0.73μm respectively; the autofocus range was ± 0.5mm, the focusing accuracy was 1μm within the focal point ± 25μm; the whole machine stability was 80%: 3σ = 1 .95 nm.