Fig. 1. Gravitational wave spectrum

Fig. 2. Developing space gravitational wave detectors

Fig. 3. Schematic diagram of space gravitational wave detectors. (a) Triangular constellation and six links of detectors; (b) Laser links between two spacecrafts^[9]

Fig. 4. Main research progress of spaceborne telescopes for gravitational wave detection^{[15-18,21-36]}

Fig. 5. Space gravitational wave detection spaceborne telescope ground integrated test platform

Fig. 6. LISA telescope assembly dimensional stability test by Verlaan et al. (a) Schematic of TA’s length metrology platform; (b) Thermal vacuum test scheme^[28,47]

Fig. 7. Optical path length stability test of LISA telescope based on heterodyne interferometry at the University of Florida. (a) Schematic of optical path length stability test platform; (b) ULE proto-TTS^[32]

Fig. 8. TTS and dimension test result of ULE pTTS. (a) OptoCAD model of TTS; (b) Length noise test results of reference cavity and ULE pTTS and LISA requirement^[32]

Fig. 9. Stability test of SiC frame of Taiji telescope based on fiber interferometer by Sang et al. (a) Principle of stability testing with fiber optic interferometer; (b) Schematic of the frame stability test platform; (c)Test platform pictures^[33]

Fig. 10. SiC frame dimensional stability test and numerical simulation results. (a) Power spectrum of room temperature environment test; (b) Power spectrum of in-orbit numerical simulation^[33]

Fig. 11. Dimensional stability test of Taiji telescope’s C/SiC support frame by Shen et al. (a) The thermal design of the test structure; (b) The multi-channel heterodyne interferometer test platform^[34]

Fig. 12. Schematic of the optical path length stability measurement scheme for the space gravitational wave detection spaceborne telescope^[50]

Fig. 13. Schematic of the coherent stray light detection based on the heterodyne interferometry^[35]