Tarquin Ralph D, Altin Paul A, Rabeling David S, McClelland David E, Shaddock Daniel A
Appl Opt. 2017 Mar 10;56(8):2353-2358. doi: 10.1364/AO.56.002353.
We present a new technique for the fine alignment sensing of optical interferometers. Unlike conventional wavefront sensing systems, which use multielement photodiodes, this approach works with a single-element photodiode, in combination with a spatial light modulator (SLM) and digitally enhanced heterodyne interferometry. As all signals pass through a single photodetection and analog path, the technique exhibits high common-mode rejection to low frequency errors present in conventional systems. By changing the modulation pattern on the SLM, the technique can also be extended to sensing higher-order wavefront errors. In this paper, we demonstrate the technique experimentally and compare performance with a conventional heterodyne wavefront sensing system. This may improve and simplify alignment systems in space-based interferometers such as the planned LISA gravitational wave detector and provide a way to optimize the power in laser cavities not possible with the traditional segmented diode approach.
我们提出了一种用于光学干涉仪精细对准传感的新技术。与使用多元素光电二极管的传统波前传感系统不同，这种方法采用单元素光电二极管，结合空间光调制器（SLM）和数字增强外差干涉测量法。由于所有信号都通过单一的光电探测和模拟路径，该技术对传统系统中存在的低频误差具有很高的共模抑制能力。通过改变SLM上的调制图案，该技术还可以扩展到检测高阶波前误差。在本文中，我们通过实验演示了该技术，并与传统外差波前传感系统的性能进行了比较。这可能会改进和简化诸如计划中的LISA引力波探测器等天基干涉仪中的对准系统，并提供一种优化激光腔功率的方法，而这是传统分段二极管方法无法实现的。
