A dual-frequency laser interferometer is established based on a frequency-stabilized 543.5nm Zeeman He-Ne laser. The
interferometer has been tested in displacement measuring experiments in comparison with a commercial 632.8nm dualfrequency
laser interferometer. Test results show that the achieved stability and the accuracy of the dual-frequency green
laser interferometer have reached the level in commercial dual-frequency interferometers. Apart from being capable in
heterodyne interferometry as a single-wavelength interferometer, the 543.5nm dual-frequency interferometer is also
promising in two-wavelength interferometry when combined with the commercial 632.8nm dual-frequency
interferometer, where both a high resolution and a relatively large range in displacement measurement can be achieved.