用于神冈引力波探测器（KAGRA）的先进光子校准器的研发。

Inoue Y, Hsieh B H, Chen K H, Chu Y K, Ito K, Kozakai C, Shishido T, Tomigami Y, Akutsu T, Haino S, Izumi K, Kajita T, Kanda N, Lin C S, Lin F K, Moriwaki Y, Ogaki W, Pang H F, Sawada T, Tomaru T, Suzuki T, Tsuchida S, Ushiba T, Washimi T, Yamamoto T, Yokozawa T

Physics Department, National Central University, Taoyuan 32001, Taiwan.

Center for High Energy and High Field Physics (CHiP), National Central University, Taoyuan 32001, Taiwan.

Rev Sci Instrum. 2023 Jul 1;94(7). doi: 10.1063/5.0147888.

The Kamioka Gravitational wave detector (KAGRA) cryogenic gravitational-wave observatory has commenced joint observations with the worldwide gravitational wave detector network. Precise calibration of the detector response is essential for accurately estimating parameters of gravitational wave sources. A photon calibrator is a crucial calibration tool used in laser interferometer gravitational-wave observatory, Virgo, and KAGRA, and it was utilized in joint observation 3 with GEO600 in Germany in April 2020. In this paper, KAGRA implemented three key enhancements: a high-power laser, a power stabilization system, and remote beam position control. KAGRA employs a 20 W laser divided into two beams that are injected onto the mirror surface. By utilizing a high-power laser, the response of the detector at kHz frequencies can be calibrated. To independently control the power of each laser beam, an optical follower servo was installed for power stabilization. The optical path of the photon calibrator's beam positions was controlled using pico-motors, allowing for the characterization of the detector's rotation response. Additionally, a telephoto camera and quadrant photodetectors were installed to monitor beam positions, and beam position control was implemented to optimize the mirror response. In this paper, we discuss the statistical errors associated with the measurement of relative power noise. We also address systematic errors related to the power calibration model of the photon calibrator and the simulation of elastic deformation effects using finite element analysis. Ultimately, we have successfully reduced the total systematic error from the photon calibrator to 2.0%.

神冈引力波探测器（KAGRA）低温引力波天文台已开始与全球引力波探测器网络进行联合观测。探测器响应的精确校准对于准确估计引力波源的参数至关重要。光子校准器是激光干涉引力波天文台（处女座和KAGRA）中使用的关键校准工具，它在2020年4月与德国的GEO600进行的联合观测3中得到了应用。在本文中，KAGRA实施了三项关键改进：高功率激光器、功率稳定系统和远程光束位置控制。KAGRA采用一台20瓦的激光器，分为两束光注入镜面。通过使用高功率激光器，可以校准探测器在千赫兹频率下的响应。为了独立控制每束激光的功率，安装了一个光学跟随伺服系统来实现功率稳定。使用皮安电机控制光子校准器光束位置的光路，从而能够表征探测器的旋转响应。此外，还安装了长焦相机和象限光电探测器来监测光束位置，并实施光束位置控制以优化镜面响应。在本文中，我们讨论了与相对功率噪声测量相关的统计误差。我们还解决了与光子校准器功率校准模型相关的系统误差，以及使用有限元分析对弹性变形效应的模拟。最终，我们成功地将来自光子校准器的总系统误差降低到了2.0%。