根据以前双纵模绝对距离测量中合成波长过大导致误差较大的缺点,设计了一种新型多波长绝对距离干涉测量系统。采用633 nm双纵模He-Ne激光器中的一个纵模和629 nm波长的He-Ne激光组成117μm合成波长,使用双外差干涉技术对距离改变进行精密测量。静态稳定度和动态测量实验表明,由于采用了较小的合成波长,系统的测量不确定度可以达到3.8×10-6L+57 nm,在500 mm的距离上不确定度小于2μm。最后从合成波长不确定性的角度,对干涉系统中的误差作了分析。该系统如能与双纵模拍波测量作衔接则可实现对被测距离由粗至精的测量。 According to the shortcomings of the former two longitudinal mode absolute distance measurement in the large error of the synthetic wavelength, a new multi-wavelength absolute distance interferometry system is designed. A longitudinal mode of 633 nm He-Ne laser and a He-Ne laser of 629 nm wavelength were used to synthesize a wavelength of 117 μm. The distance variation was measured by double heterodyne interferometry. Static stability and dynamic measurement experiments show that the system’s measurement uncertainty can reach 3.8 × 10-6L + 57 nm due to the smaller synthesis wavelength, and the uncertainty is less than 2μm at the distance of 500 mm. Finally, from the perspective of the synthetic wavelength uncertainty, the errors in the interfering system are analyzed. If the system can be used with dual longitudinal mode beat wave measurement for the convergence of the measured distance from coarse to fine measurement.