Fig. 1. Schematics of lateral shear interference principle. (a) Schematic of lateral shear interference in the x-direction; (b) schematic of lateral shear interference in the y-direction

Fig. 2. Schematic of lateral shear interference

Fig. 3. Flow chart of the lateral shear interference wavefront reconstruction algorithm without directional constraint

Fig. 4. Simulated data. (a) 36-term Zernike polynomial coefficients in wavefront to be measured; (b) wavefront to be measured

Fig. 5. Lateral shear interferogram showing different directions of wavefront to be measured

Fig. 6. Residual error maps for wavefront reconstruction using any two directions interferograms.(a) 0°, 30°; (b) 0°, 45°; (c) 0°, 60°; (d) 0°, 90°; (e) 0°, 135°; (f) 30°, 45°; (g) 30°, 135°; (h) 30°, 180°

Fig. 7. Relationship between shear direction angle and wavefront reconstruction accuracy. (a) PV residual error value of wavefront reconstruction; (b) RMS residual error value of reconstruction wavefront

Fig. 8. Curves of noise level versus wavefront reconstruction error under different angles. (a) PV residual error curves; (b) RMS residual error curves

Fig. 9. Impact of shear rate error on precision of wavefront reconstruction under various angles. (a) PV residual error value curves of wavefront reconstruction; (b) RMS residual error value curves of wavefront reconstruction

Fig. 10. Schematic of multi-directional synchronous phase shift lateral shear interference

Fig. 11. Experimental devices

Fig. 12. CCD acquisition of interferograms with different shear directions. (a) 0°; (b) 5°; (c) 10°; (d) 15°; (e) 25°; (f) 30°; (g) 45°；(h) 60°; (i) 75°; (j) 90°

Fig. 13. Experimental interferogram reconstruction results in any two directions. (a) 0°, 25°; (b) 0°, 30°; (c) 0°, 45°; (d) 0°, 60°; (e) 0°, 75°; (f) 0°, 90°