The Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) is a 20-meter class proposed space terahertz observatory supported by an inflatable membrane architecture. To measure 150 mm and 1m models of the A1 reflective membrane antenna, two deflectometry configurations were designed. The smaller assembly and its corresponding deflectometer were simulated, built in our laboratory, and produce a reconstructable signal for clocked measurements of the highly-sloped pneumatic surface. We use non-sequential raytracing simulation to bound the maximum contributions of all shape errors and suggest the N-Rotations algorithm to remove the remaining radially asymmetric errors. Then, the 1m prototype assembly was tested inside a thermal vacuum chamber (TVAC). Differential deflectometry measurements tracked the 1m surface shape changes as it was subjected to a variety of environmental setpoints, cycled between three inflation gases, and also during controlled puncture. We summarize our development and results for absolute measurements as well as from TVAC testing.
Deformable reflector technology has mainly been used for observations at visible and infrared wavelengths but has yet to be utilized for terahertz wavefront correction. We present an actuator for deformable reflectors that overcomes challenges particular to this wavelength such as a millimeter-scale stroke requirement. Bending moment actuators are used in both the radial and tangential directions to correct low-order wavefront aberrations. Strong and flexible materials such as Delrin are used for the reflector material. Such a deformable antenna can be used to correct wavefronts on future large radio antennae such as the Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS). This antenna uses a 20-meter thin membrane as its primary radio wave collector. A deformable reflector may be added to this system to allow for looser tolerances on the primary antenna shape and correct for wavefront errors inherent in an inflatable optic. To predict the wavefront errors that may be expected when using this type of thin membrane primary reflector, TVAC (Thermal Vacuum Chamber) test methods are also presented in these proceedings.
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