Design of a prototype secondary mirror assembly for the Space Infrared Telescope FacilityThe design of a liquid helium temperature prototype secondary mirror assembly (PSMA) under development for the NASA Space Infrared Telescope Facility (SIRTF) program is described. The SIRTF assembly must operate below 4 K and provide the functions of highly precise two-axis periodic tilting ('chopping') in addition to the conventional functions of focus and collimation adjustment. The PSMA design 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 an aluminum flexure pivot of unique design and a four-actuator control system with feedback provided by pairs of differential position sensors. The voice coil actuators are mounted on a second flexure-pivoted mass to enhance servosystem stability and isolate the telescope from vibration-induced disturbances. The mirror/cruciform and reaction mass are attached to opposite sides of an aluminum mounting plate whose position relative to the outer housing is controlled by a six-degree-of-freedom focus and centering mechanism using pivoted actuation levers driven by lead screw/harmonic drive/stepper motor assemblies.
Document ID
19920030805
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Stier, Mark T. (Perkin-Elmer Corp. Danbury, CT, United States)
Bolin, Kenneth N. (Perkin-Elmer Corp. Danbury, CT, United States)
Duffy, Michael A. (Perkin-Elmer Corp. Danbury, CT, United States)
Gullapalli, Sarma N. (Perkin-Elmer Corp. Danbury, CT, United States)
Krim, Michael H. (Perkin-Elmer Corp. Danbury, CT, United States)
Rockwell, Richard A. (Perkin-Elmer Corp. Danbury, CT, United States)
Sileo, Francis R. (Perkin-Elmer Corp. Danbury, CT, United States)