Smetana Jiri, Di Fronzo Chiara, Amorosi Anthony, Martynov Denis
Institute for Gravitational Wave Astronomy, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
Precision Mechatronics Laboratory, A&M Department, Université de Liège, Allé de la Découverte 9 B52/Quartier Polytec 1, B-4000 Liège, Belgium.
Sensors (Basel). 2023 Aug 30;23(17):7526. doi: 10.3390/s23177526.
Compact Michelson interferometers are well positioned to replace existing displacement sensors in the readout of seismometers and suspension systems, such as those used in contemporary gravitational-wave detectors. Here, we continue our previous investigation of a customised compact displacement sensor built by SmarAct that operates on the principle of deep frequency modulation. The focus of this paper is the linearity of this device and its subsequent impact on sensitivity. We show the three primary sources of nonlinearity that arise in the sensor: residual ellipticity, intrinsic distortion of the Lissajous figure, and distortion caused by exceeding the velocity limit imposed by the demodulation algorithm. We verify the theoretical models through an experimental demonstration, where we show the detrimental impact that these nonlinear effects have on device sensitivity. Finally, we simulate the effect that these nonlinearities are likely to have if implemented in the readout of the Advanced LIGO suspensions and show that the noise from nonlinearities should not dominate across the key sub-10 Hz frequency band.
紧凑型迈克尔逊干涉仪非常适合替代地震仪和悬挂系统读数中的现有位移传感器，比如当代引力波探测器中使用的那些。在此，我们继续之前对SmarAct制造的基于深度频率调制原理工作的定制紧凑型位移传感器的研究。本文的重点是该装置的线性度及其对灵敏度的后续影响。我们展示了传感器中出现的非线性的三个主要来源：残余椭圆率、李萨如图形的固有畸变以及超过解调算法所施加速度限制而导致的畸变。我们通过实验演示验证了理论模型，在实验中我们展示了这些非线性效应对器件灵敏度的有害影响。最后，我们模拟了如果在高级LIGO悬挂系统的读数中实施这些非线性可能产生的影响，并表明在低于10 Hz的关键频段内，非线性产生的噪声不应占主导地位。
