System for precise temperature sensing and thermal control of borosilicate honeycomb mirrors during polishing and testing

Michael Lloyd-Hart

doi:10.1117/12.19249

1 July 1990 System for precise temperature sensing and thermal control of borosilicate honeycomb mirrors during polishing and testing

Michael Lloyd-Hart

Author Affiliations +

Proceedings Volume 1236, Advanced Technology Optical Telescopes IV; (1990) https://doi.org/10.1117/12.19249
Event: SPIE Astronomical Telescopes and Instrumentation for the 21st Century, 1990, Tucson, AZ, United States

Abstract

The Steward Observatory Mirror Laboratory has implemented a large borosilicate honeycomb telescope mirror polishing system in which thermal distortion is reduced to negligible levels by maintaining the glass in an isothermal state to within 0.1 C. Testing of the polished surface is conducted in air, using a laser and interferometer mounted above the mirror; the control of refractive index variation in the laser's light-path entails that the air also be isothermal, to within 0.2 C. Thermocouples are used as sensors in the polishing room, in air ducts, and on the mirror. Measurements are made to an accuracy of 0.005 C at the rate of one thermocouple/sec.

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Michael Lloyd-Hart "System for precise temperature sensing and thermal control of borosilicate honeycomb mirrors during polishing and testing", Proc. SPIE 1236, Advanced Technology Optical Telescopes IV, (1 July 1990); https://doi.org/10.1117/12.19249

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