National Measurement Institute, Bradfield Road, Lindfield, New South Wales 2070, Australia.
Opt Lett. 2010 Dec 15;35(24):4202-4. doi: 10.1364/OL.35.004202.
We present an all-digital phase meter for precision length measurements using heterodyne laser interferometry. Our phase meter has a phase sensitivity of 3 μrad/√Hz at signal frequencies of 1 Hz and above. We test the performance of our phase meter in an optical heterodyne interferometric configuration, using an active Sagnac interferometer test bed that is flexible and low noise. We demonstrate more than 70 dB of laser frequency noise suppression to achieve an optical phase sensitivity of 5 μrad/√Hz and a corresponding displacement sensitivity of 0.5 pm/√Hz at signal frequencies above 10 Hz. In addition, we demonstrate the ability of our phase meter to follow full fringe signals accurately at 100 Hz and to track large signal excursions in excess of 10(5) fringes without cycle slipping. Finally, we demonstrate a cyclic error of ≤1 pm/√Hz, above 10 Hz.
我们提出了一种用于使用外差激光干涉法进行精密长度测量的全数字相位计。我们的相位计在信号频率为 1 Hz 及以上时具有 3 μrad/√Hz 的相位灵敏度。我们在光学外差干涉配置中测试了相位计的性能，使用灵活且噪声低的主动萨格纳克干涉仪测试平台。我们实现了超过 70 dB 的激光频率噪声抑制，以在信号频率高于 10 Hz 时实现 5 μrad/√Hz 的光学相位灵敏度和相应的 0.5 pm/√Hz 位移灵敏度。此外，我们还证明了我们的相位计能够在 100 Hz 下准确地跟踪全条纹信号，并在不发生循环滑动的情况下跟踪超过 10(5)个条纹的大信号偏移。最后，我们证明了在 10 Hz 以上时，循环误差≤1 pm/√Hz。
