Overview: In order to achieve the measurement of gravitational wave signals in the millihertz frequency band, the space-based gravitational wave detection projects such as LISA, TianQin, and Taiji projects, which are based on laser interference systems, require the hardware noise floor of the interferometers to be lower than the interstellar weak light shot noise limit. This imposes stringent engineering specifications on the optical-mechanical design and the corresponding interferometer payload. This paper approaches the issue from the perspective of detection mode selection and derives the expressions of readout noise and stray light noise in the interference signal under the single detector mode and the balanced mode. Furthermore, a detailed discussion is provided on the weak-light interference process of the scientific interferometer. The results demonstrate that the balanced mode is capable of suppressing the interference phase noise caused by laser power fluctuations and backscattered stray light across multiple orders of magnitude. However, the suppression capability is constrained by the unequal splitting property of the beam combiner. To address this, a relative gain factor is introduced to compensate for the unequal splitting property of the beam combiner. Further analysis reveals that electronic gain compensation can only eliminate the impact of unequal splitting on one of the two noises rather than both simultaneously. Therefore, a balance must be struck in selecting gain compensation between the suppression of laser power fluctuation noise and stray light noise. Even with this consideration, the balanced mode still offers significant noise suppression capabilities at a magnitude difference, thus potentially reducing the engineering requirements for laser power fluctuations and telescope backscattered stray light.

针对现有中心偏差测量方法中测量精度低、透镜姿态调整人为干扰大的问题，提出一种差动共焦透镜中心偏自动测量方法。该方法通过差动共焦定焦技术，依据差动共焦轴向光强响应曲线的过零点精确对应被测镜特征点这一特性，实现对被测镜猫眼点及共焦点的精准定位；通过高精度气浮转轴驱动被测镜旋转，用位移传感器、圆光栅记录被测镜的位置信息，结合五维位姿自动调整机构，实现对被测镜姿态的高精度校正，消除姿态偏差，提高测量精度；最终，搭建了激光差动共焦透镜中心偏自动测量系统，实现了透镜中心偏的高精度自动测量。实验结果表明：透镜中心偏的测量精度可达0.41%，测量重复性优于100 nm。与现有的人工单次测量相比，该方法的测量重复性较好、随机误差小、测量精度高，为高精度透镜中心偏自动测量提供了一种技术途径。

为提高球面透镜曲率半径的测量精度，提出基于五维位姿监测调整的差动共焦曲率半径高精度测量方法。通过驱动被测样品回转，在探测器上监测被测件的共焦点轨迹，测量被测件球心点与测量光轴之间的偏心误差，结合位姿调整系统对偏心误差进行自动补偿，确保测量过程中被测件球心与测量光轴重合，消除被测样品球心离轴引入的测量余弦误差，进而消除每次装调的样品位姿误差对测量精度的影响。理论计算和初步实验表明：该方法对曲率半径的相对重复测量精度（RMS）可达到3.2×10^-6。该方法显著提升了曲率半径的重复测量精度，为曲率半径的精密测量提供了有效途径。同时，该方法还为透镜中心偏、焦距、厚度、镜组间隔等多种参数的高精度测量提供了有效方法。