27 April 1988 Prototype Secondary Mirror Assembly For The Space Infrared Telescope Facility
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Abstract
We describe our concept for a liquid helium temperature prototype secondary mirror assembly (PSMA) for the Space Infrared Telescope Facility. SIRTF, a NASA "Great Observatory" to be launched in the 1990's, is a superfluid heliumcooled 1-meter class telescope with much more stringent performance requirements than its precursor the Infrared Astronomical Satellite (IRAS). The SIRTF secondary mirror assembly must operate near 4 K and provide the functions of 2-axis dynamic tilting ("chopping") in addition to the conventional functions of focus and centering. The PSMA must be able to withstand random vibration testing and provide all of the functions needed by the SIRTF observatory. Our PSMA concept employs a fused quartz mirror kinematically attached at its center to an aluminum cruciform. The mirror/cruciform assembly is driven in tilt about its combined center of mass using a unique flexure pivot and a four-actuator control system with feed-back provided by pairs of eddy current position sensors. The actuators are mounted on a second flexure-pivoted mass providing angular momentum compensation and isolating the telescope from vibration-induced disturbances. The mirror/cruciform and the reaction mass are attached to opposite sides of an aluminum mounting plate whose AL/L characteristics are nominally identical to that of the aluminum flexure pivot material. The mounting plate is connected to the outer housing by a focus and centering mechanism based upon the six degree of freedom secondary mirror assembly developed for the Hubble Space Telescope.
© (1988) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. Stier, M. Stier, M. Duffy, M. Duffy, S. Gullapalli, S. Gullapalli, R. Rockwell, R. Rockwell, F. Sileo, F. Sileo, M. Krim, M. Krim, } "Prototype Secondary Mirror Assembly For The Space Infrared Telescope Facility", Proc. SPIE 0973, Cryogenic Optical Systems and Instruments III, (27 April 1988); doi: 10.1117/12.948332; https://doi.org/10.1117/12.948332
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