Fig. 1. Principle of the SAP test.

Fig. 2. Profiling pattern of 64 scan arcs used for measuring the 1.4 m convex asphere; coordinate units are mm (Ref. [1], Fig. 3).

Fig. 3. Profile pattern of 72 scan circles.

Fig. 4. Geometrical diagram of Q intersections.

Fig. 5. Area distribution of corresponding gridding of the intersections.

Fig. 6. Normalized sampling area density distribution of different scan arcs used.

Fig. 7. (a) Profile pattern and (b) geometrical diagram of Q intersections for the outer region of the SSAP test.

Fig. 8. (a) Stitching profile pattern for 3 m diameter mirror. (b) Ratio of sampling area density.

Fig. 9. (a) Calibration of sensor on SPDT and (b) noise from the sensor.

Fig. 10. Noise of the SAP system with arm length of 758 mm.

Fig. 11. Noise of the SSAP system with arm length of 467 mm.

Fig. 12. SAP in situ measuring a 3 m concave aspheric mirror with swing radius of 758 mm.

Fig. 13. (a), (b) Comparison of SAP test data in 72 scan arcs. (c) Difference with first 37 low-order Zernike aberration terms removed.

Fig. 14. (a), (b) Comparison of SAP test data in 144 scan arcs. (c) Difference with 37 low-order Zernike aberration terms removed.

Fig. 15. SAP in situ measuring with small swing radius of 460 mm. (a) Scan test for inner region. (b) Scan test for outer region.

Fig. 16. (a), (b) SSAP test results for 3 m mirror. (c) Test repeatability with 37 low-order Zernike aberration terms removed.