[2005] Testing an off-axis parabola with a CGH and a spherical mirror as null lens

Zhao, Chunyu, et al. “Testing an off-axis parabola with a CGH and a spherical mirror as null lens.” Optical Manufacturing and Testing VI. Vol. 5869. SPIE, 2005.

Abstract:

Steward Observatory Mirror Lab is currently polishing an off-axis parabola which will be the primary mirror of the New Solar Telescope. To test this mirror, we built a test equipment to combine a spherical mirror and a Computer Generated Hologram (CGH) as null lens. The spherical mirror is tilted to compensate much of the astigmatism and some coma. And the CGH compensates rest of aberrations. The combination of a spherical mirror and a CGH makes the test system compact. The technology developed here will be used to test the Giant Magellan Telescope’s primary mirror segment–a five times larger off-axis parabola.

Link to publication.