Interference test procedures for telescopic mirrors

JSC "LZOS" manufactures astronomical mirrors from the stage of blanks to finished astronomical mirrors. During 1997-2002 JSC "LZOS" has fabricated a number of astronomical mirrors under the contracts with Carl Zeiss Jena, Germany, up to 2.6m in diameter and up to 100 μm asphericity. Concave surfaces are tested with lens and lens-mirror wavefront correctors of special design. The Hindle test set-up is used for convex hyperbolic surfaces. For high-aperture hyperbolic surface, we use two Hindle spheres to test one mirror. At the present time, we have developed the test procedures for high-aperture surfaces of primary (diameter 4100 mm, asphericity about 881 μm) and secondary (diameter 1240 mm, asphericity about 364 μm) mirrors for the VISTA Project as well as the Fizeau test set-up for the LAMOST MB sub-mirrors.