Kok Yitping, Ireland Michael J, Robertson J Gordon, Tuthill Peter G, Warrington Benjamin A, Tango William J
Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW, Australia.
Appl Opt. 2013 Apr 20;52(12):2808-14. doi: 10.1364/AO.52.002808.
A method capable of delivering relative optical path length metrology with nanometer precision is demonstrated. Unlike conventional dual-wavelength metrology, which employs heterodyne detection, the method developed in this work utilizes direct detection of interference fringes of two He-Ne lasers as well as a less precise stepper motor open-loop position control system to perform its measurement. Although the method may be applicable to a variety of circumstances, the specific application in which this metrology is essential is in an astrometric optical long baseline stellar interferometer dedicated to precise measurement of stellar positions. In our example application of this metrology to a narrow-angle astrometric interferometer, measurement of nanometer precision could be achieved without frequency-stabilized lasers, although the use of such lasers would extend the range of optical path length the metrology can accurately measure. Implementation of the method requires very little additional optics or electronics, thus minimizing the cost and effort of implementation. Furthermore, the optical path traversed by the metrology lasers is identical to that of the starlight or science beams, even down to using the same photodetectors, thereby minimizing the noncommon path between metrology and science channels.
展示了一种能够以纳米精度进行相对光程长度计量的方法。与采用外差检测的传统双波长计量不同，本工作中开发的方法利用对两台氦氖激光器干涉条纹的直接检测以及精度较低的步进电机开环位置控制系统来进行测量。尽管该方法可能适用于多种情况，但这种计量至关重要的具体应用是在用于精确测量恒星位置的天体测量光学长基线恒星干涉仪中。在我们将这种计量应用于窄角天体测量干涉仪的示例中，即使不使用频率稳定激光器也能实现纳米精度的测量，不过使用此类激光器将扩展该计量能够精确测量的光程长度范围。该方法的实施几乎不需要额外的光学器件或电子设备，从而将实施成本和工作量降至最低。此外，计量激光器所经过的光路与星光或科学光束的光路相同，甚至使用相同的光电探测器，从而将计量通道和科学通道之间的非公共光路降至最低。
