Fig. 1. TianQin and Taiji spacecraft in orbit around the Sun

Fig. 2. The inter-satellite link transmission

Fig. 3. The physical meaning of the pointing angle

Fig. 4. The comparison between numerical integration method and analytical expression of Gaussian beam

Fig. 5. The pointing jitter causes the phase noise

Fig. 6. The correlation between the coupling coefficient γ and Zernike indices at 700 nrad static angle.

Fig. 7. The contribution of aberrations to the jitter noise in the far-field of 50 nrad^[32]. (a) With θ; (b) With ψ

Fig. 8. Under different fitting orders, the maximum sensitivity error changes with RMS^[32]. (a) First order; (b) Second order; (c) Third order; (d) Fourth order