Gemini Preprint #12

Prototype Testing of a Surface Heating System for the Gemini 8-m Telescopes

Eric Hansen, David Hagelbarger, Earl Pearson
Gemini 8m Telescopes Project, 950 N. Cherry Ave., Tucson AZ 85719


The Gemini Project plans to implement thermal control of the primary mirror using two distinct systems. The first system consists of temperature controlled radiation panels behind the primary mirror that are used to control the bulk temperature of the primary. The second, a surface heating system, will be used to adjust the optical surface temperature by passing an electrical current through the reflective coating. Combining these two systems allows the optical surface temperature of large monolithic mirrors to follow nighttime ambient temperature fluctuations, minimizing mirror seeing effects. To aid in the design of a surface heating system for the Gemini 8-m primary mirror, a development program was initiated. As part of this program, analysis techniques were developed and prototype systems using mirrors up to 1-m were fabricated and tested. This paper reviews the progress and results of this surface heating development program to date.

Appears in Proc. SPIE 2871, "Optical Telescopes of Today and Tomorrow".

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Ruth A. Kneale / / November 15, 1996