Fig. 1. Relationship between effective anisoplanatic error and size of telescope aperture

Fig. 2. Relationship between double star spacing and effective anisoplanatic error with different isoplanatic angle

Fig. 3. Simulation of anisoplanatic error

Fig. 4. Experimental setup

Fig. 5. Distribution of 9×9 Shack-Hartmann subaperture and measured image

Fig. 6. Image of sub-aperture

Fig. 7. Image of Gaussian mask

Fig. 8. Convolution image, original image, and centroid position of sub-aperture

Fig. 9. Three methods to calculate piston-removed isoplanatic angle

Fig. 10. Isoplanatic angle and piston-removed isoplanatic angle measurement results of three sets of double stars

Fig. 11. Double stars trajectories

Fig. 12. Piston-removed isoplanatic angle measurement results of different locations