采用拍频法对两台同类型号独立激光器的稳定度进行了测量。从拍频理论出发，得到了拍频信号稳定度与待测激光器和参考激光器稳定度三者所满足的平方和关系，对于稳定度一致的两台同类型号激光器，由拍频信号稳定度可以得到待测激光器的稳定度。实验中将New Focus公司生产的两台同类型号激光器(TLB-6017)进行拍频，根据拍频信号稳定度测得激光器稳定度为1.36×10-8，频率漂移量为5.1 MHz(1 s积分时间)。实验结果与激光器出厂指标[稳定度1×10-8、频率漂移量5 MHz(1 s积分时间)]相比，稳定度在同一量级，频率漂移量的相对误差为2%。此方法避免了通常测量激光器稳定度时所需的高稳定度参考光源的限制，为激光器稳定度的测量提供了一定的参考。

Frequency stability of two independent lasers with the same model is measured by using beat frequency technology. By using the theory of beat frequency, frequency stability of the beat signal is deduced, which can be expressed by the sum of squares of the frequency stability of the reference laser and the measured laser. From the above relationship, the frequency stability of measured laser with the same model with reference laser can be obtained. Two independent lasers (TLB-6017) with the same model produced by New Focus company are used in the experimental measurement, and the results show that the frequency stability of the measured laser is about 1.36×10-8 and the frequency shift is 5.1 MHz at the averaging time of 1 s. Frequency stability is in the same level with the technical specification (frequency stability is about 1×10-8 and frequency shift is about 5 MHz at the averaging time of 1 s), and the relative error of frequency shift is about 2%. The provided method avoids conventional limitations which need a higher stability laser as reference laser.