在精密测量领域, He-Ne 激光器是制造激光干涉仪的首选光源, 因波长作为测量的“尺子”, 激光器的频率稳定性至关重要。介绍了双频激光器的稳频技术原理, 利用调谐腔中平行光和垂直光的等光强点作为稳频点, 以光强平衡为依据设计热伺服控制电路, 采用数字和模拟电路共同控制, 实现了He-Ne双折射塞曼双频激光器的频率稳定。对大频差(7.95 MHz)的双频激光器进行拍频测试, 单次频率稳定度达10-9量级, 重复多次多日测量, 频率不确定度达1.074×10-8(k=2)。同时对频差稳定度进行测试, 频差波动范围在8 kHz以内, 相对偏差度为0.001, 完全达到商用双频干涉仪的标准。

In the field of precision measurement, He-Ne lasers are the prior choice to manufacture laser interferometer, which takes the wavelength as the scale in measurement. Therefore, the frequency stability is of great significance. The theories of frequency stabilization in dual-frequency lasers was studied and the isocandela points of the parallel and vertical light were utilized as frequency stabilization points. By designing thermal servo control circuit based on light intensity balance and controlling in both analog and digital methods, the frequency stabilization in Zeeman-birefringence He-Ne dual-frequency lasers was accomplished. Beat frequency experiments were carried on a Zeeman-birefringence He-Ne laser with 7.95 MHz frequency difference, the frequency stability index can reach the level of 10-9. The uncertainty in frequency was better than 1.074×10-8(k=2) in repeated measurements. Meanwhile, the stablity of the frequency difference was measured. The variation of the frequency difference was within 8 kHz and the relative deviation was 0.001, which can totally meet the demands of commercial dual-frequency laser interferometers.