提出了一种以低频差横向塞曼双频激光器作光源的外差干涉共焦显微测量系统，该系统通过共焦显微的光强测量进行粗定位，其轴向台阶高度测量范围在5 μm以上。同时采用相位测量技术，实现了对半波长的3600细分，从而使测量分辨率达到0.1 nm。由此同时满足了高测量精度和较大测量范围的要求。实验结果表明系统在没有恒温的普通实验室条件下1 h内的漂移不超过15 nm，与差动纳米双频干涉仪的比对结果线性系数在0.9999以上，非线性误差约10 nm。

A novel measuring system is proposed in this paper, which is based on transverse Zeeman laser with low beat frequency and combined heterodyne interferometry and confocal microscopy. The range of height measurement reaches over 5 μm in term of intensity derived from the confocal system. Meanwhile the phase measurement technology is adopted to divide half wavelength by a factor of 3600, hence a resolution of 0.1nm can be attained. Accordingly the requirements of both high measurement resolution and relatively large measurement range are met simultaneously. The experimental results show that in ordinary laboratory condition, without constant temperature, the shift of phase measurement is about 15 nm. Calibration with differential dual-frequency interferometer gives the linealy correlation coefficient of 0.9999 and nonlinearity of about 10 nm.