22 July 2016 Polishing and testing of the 3.4 m diameter f/1.5 primary mirror of the INO telescope
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Abstract
Polishing and testing methods used in the manufacture of the 3.4 m primary mirror of the Iranian National Observatory (INO) telescope are described and the test results of the finished mirror are presented. Mirror lapping and polishing was performed using several rectangular non-rotating tools arranged in a linear array across the mirror radius. Each tool is equipped with two computer controlled force actuators for regulating the surface pressure and removal efficiency during the lapping and polishing operations. The same tool system was used from the lapping phase to the end of the final polishing. The principal optical test method was the interferometric Hartmann test with the aid of a two component null lens in the mirror center of curvature. Mirror measurements were made also with pentaprism test to verify its correct conic constant. The mirror was finished to extremely good surface accuracy and smoothness.
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Tapio Korhonen, Perttu Keinänen, Mikko Pasanen, Ahmad Darudi, Jonathan Maxwell, "Polishing and testing of the 3.4 m diameter f/1.5 primary mirror of the INO telescope", Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 99120Q (22 July 2016); doi: 10.1117/12.2232691; https://doi.org/10.1117/12.2232691
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