Liu He-Shan, Dong Yu-Hui, Li Yu-Qiong, Luo Zi-Ren, Jin Gang
National Microgravity Laboratory (NML), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Rev Sci Instrum. 2014 Feb;85(2):024503. doi: 10.1063/1.4865121.
Heterodyne laser interferometry is considered as the most promising readout scheme for future space gravitational wave detection missions, in which the gravitational wave signals disguise as small phase variances within the heterodyne beat note. This makes the phasemeter, which extracts the phase information from the beat note, the key device to this system. In this paper, a prototype of phasemeter based on digital phase-locked loop technology is developed, and the major noise sources which may contribute to the noise spectra density are analyzed in detail. Two experiments are also carried out to evaluate the performance of the phasemeter prototype. The results show that the sensitivity is achieved 2π μrad/√Hz in the frequency range of 0.04 Hz-10 Hz. Due to the effect of thermal drift, the noise obviously increases with the frequencies down to 0.1 mHz.
外差激光干涉测量法被认为是未来空间引力波探测任务中最具前景的读出方案，在该方案中，引力波信号伪装成外差拍频中的小相位变化。这使得从拍频中提取相位信息的相位计成为该系统的关键设备。本文研制了一种基于数字锁相环技术的相位计原型，并详细分析了可能导致噪声谱密度的主要噪声源。还进行了两个实验来评估相位计原型的性能。结果表明，在0.04 Hz至10 Hz的频率范围内，灵敏度达到2π μrad/√Hz。由于热漂移的影响，在频率降至0.1 mHz时，噪声明显增加。
