title: Cryogenic optical measurements of 12-segment-bonded carbon-fiber-reinforced silicon carbide composite mirror with support mechanism.
abstract: A 720 mm diameter 12-segment-bonded carbon-fiber-reinforced silicon carbide (C/SiC) composite mirror has been fabricated and tested at cryogenic temperatures. Interferometric measurements show significant cryogenic deformation of the C/SiC composite mirror, which is well reproduced by a model analysis with measured properties of the bonded segments. It is concluded that the deformation is due mostly to variation in coefficients of thermal expansion among segments. In parallel, a 4-degree-of-freedom ball-bearing support mechanism has been developed for cryogenic applications. The C/SiC composite mirror was mounted on an aluminum base plate with the support mechanism and tested again. Cryogenic deformation of the mirror attributed to thermal contraction of the aluminum base plate via the support mechanism is highly reduced by the support, confirming that the newly developed support mechanism is promising for its future application to large-aperture cooled space telescopes.
authors.affiliation: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 229-8510, Japan. kaneda@ir.isas.jaxa.jp
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kaneda
authors.forename: Takao
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Onaka
authors.forename: Keigo
authors.initials: K
authors.lastname: Enya
authors.forename: Sin'itirou
authors.initials: S
authors.lastname: Makiuti
authors.forename: Junji
authors.initials: J
authors.lastname: Takaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Haruna
authors.forename: Masami
authors.initials: M
authors.lastname: Kume
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ozaki