介绍一种可对大尺寸工件进行无导轨精密检测的方法及装置。该装置的工作方法类似一精密测距仪。它采用了一稳频双纵模激光作为光源，其拍频频率在６００ＭＨｚ～１ＧＨｚ之间，拍频波长为５００～３００ｍｍ，稳定度为１×１０７～１０－８。该系统确定整数倍拍频波长节点的精度为０．０５ｍｍ，测量两节点间距离的分辨率为０．０００１ｍｍ。其测量范围一般为０～２０ｍ，根据需要测量范围可增至４０ｍ。 A method and a device for precision testing of large size workpieces without guide rail are introduced. The device works like a precision range finder. It uses a frequency stabilized dual longitudinal mode laser as the light source, the beat frequency of 600MHz ~ 1GHz, beat frequency of 500 ~ 300mm, stability of 1 × 107 ~ 10-8. The system determines the accuracy of the integer times beat wavelength node is 0.05mm, the resolution of the distance between two nodes is 0.0001mm. The measurement range is generally 0 ~ 20m, according to the needs of the measurement range can be increased to 40m.