Lightweight Cold Mirror And Fixation

J. Espiard; J. Paseri; G. Cerutti-Maori; C. Singer

doi:10.1117/12.951932

1 May 1986 Lightweight Cold Mirror And Fixation

J. Espiard, J. Paseri, G. Cerutti-Maori, C. Singer

Proceedings Volume 0589, Instrumentation for Optical Remote Sensing from Space; (1986) https://doi.org/10.1117/12.951932
Event: 1985 International Technical Symposium/Europe, 1985, Cannes, France

Abstract

This paper presents the main results of a feasibility study (ESTEC contract n° 6122/84/NL/GM with AEROSPATIALE and REOSC) of a cold lightweight mirror. This is the pri-mary mirror of a RITCHEY-CHRETIEN telescope for the ISO satellite, diffraction limited at 5 μm ( λ/14 RMS). The following points are the main difficulties which must be taken into account to define the mirror : - Choice of mirror material, based on the best optical suitability, homogeneity of the thermal expansion coefficient and straylight characteristics. The available materials are ZERODUR optical grade and fused silica HERASIL 1 grade. Fused silica seems to be the best material because there is no deformation of a sample under radiations and no hysterisis during temperature cycles, opposite to ZERODUR. - Lightweighting, REOSC know-how with numerical machine tools allows to reach a weight of 20 kg (instead of 57 kg) and in terms of aspherical coefficient, the wave front er-ror is about λ/86 in RMS value at 5 μm. - Mirror fixation device, based on a patented fixation for ambient temperature, does not introduce torque in the mirror and take up the differential thermal expansion between the mirror and the optical support structure. A calculation gives a wave front error of λ/70 RMS at 5 μm. - Mirror cooling, temperature of the mirror in space has to be less than 10° K. It is necessary to bond thermal straps at the rear of the optical surface of the mirror in lightweighting holes. The number of straps necessary to cool down to 10° K the mirror in 48 hours must be over 40. The number of holes in the mirror is 57.

Citation Download Citation

J. Espiard, J. Paseri, G. Cerutti-Maori, and C. Singer "Lightweight Cold Mirror And Fixation", Proc. SPIE 0589, Instrumentation for Optical Remote Sensing from Space, (1 May 1986); https://doi.org/10.1117/12.951932

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available