Fig. 1. Schematic diagram of the optical path stability measurement scheme for the gravitational wave telescope

Fig. 2. Interferometer optical path structure schematic. (a) Measuring interferometer; (b) Reference interferometer

Fig. 3. Schematic diagram of the optical path stability measurement device for the telescope

Fig. 4. Curve of equivalent optical path noise level introduced by different fiber length differences under different temperature fluctuations

Fig. 5. Schematic diagram of changes in the optical path of the reflecting mirror and beam splitter caused by temperature fluctuations. (a) Reflecting mirror; (b) Beam splitter

Fig. 6. Types of displacement of the standard plane mirror

Fig. 7. Schematic diagram of the off-axis four-mirror telescope optical system

Fig. 8. The optical path variation of the standard plane mirror system due to the inclination angle φ around the X-axis, Y-axis, and XY-axis. (a) Central beam; (b) Wave aberration

Fig. 9. Standard plane mirror compound tilt misalignment about the XY axis. (a) Curve of tilt-optical path coupling coefficient; (b) Curve of tilt-optical path noise

Fig. 10. Photograph of the integrated interferometric platform

Fig. 11. Interferometric measurement experimental setup

Fig. 12. Laser frequency noise background

Fig. 13. Noise curve of phase acquisition module. (a) Voltage background noise of the photodetector ineach gain mode; (b) Equivalent optical path noise of the phase meter

Fig. 14. Test curve of optical path noise level for the interferometric measurement system