论文标题
跟踪来自数字相锁定环读数的杂化干涉仪中象限光二极管的差异波前传感信号
Tracking length and differential wavefront sensing signals from quadrant photodiodes in heterodyne interferometers with digital phase-locked loop readout
论文作者
论文摘要
我们提出了一种方法，用于跟踪来自杂化激光干涉仪中象限光电二极管（QPD）的信号，该干涉仪采用数字相锁环进行相位读数。该方法没有单独跟踪QPD的四个段，然后将结果组合为长度和差分波前传感（DWS）信号，而是采用了一组直接在组合长度和角度信号上运行的耦合跟踪循环。收益增加了循环中信噪比的比率，并且可能使循环带宽适应所跟踪的信号的不同动力学行为，这现在与物理上有意义的可观察物相对应。我们证明了在单段跟踪中最多可改善6 dB，这使得该方案成为在超低光条件下精确的卫星间激光干涉仪的应用的有吸引力的解决方案。
We propose a method to track signals from quadrant photodiodes (QPD) in heterodyne laser interferometers that employ digital phase-locked loops for phase readout. Instead of separately tracking the four segments from the QPD and then combining the results into length and Differential Wavefront Sensing (DWS) signals, this method employs a set of coupled tracking loops that operate directly on the combined length and angular signals. Benefits are increased signal-to-noise ratio in the loops and the possibility to adapt the loop bandwidths to the different dynamical behavior of the signals being tracked, which now correspond to physically meaningful observables. We demonstrate an improvement of up to 6 dB over single-segment tracking, which makes this scheme an attractive solution for applications in precision inter-satellite laser interferometry in ultra-low-light conditions.
