APS Formation Sensor MECHANICAL DESIGN Rodger Farley 15 March 2002
Requirements Survive launch loads, of course. Once on orbit, to keep the 6 optics stable relative to each other to 10 microns. With an aluminum housing, this translates to keeping the temperature steady to ~ 0.25 deg C. Provide re-closable lid Provide 3 element filter wheel and unfiltered path, not particularly sensitive to positional placement or repeatability. Agility of the wheel is not yet specified.
Design Elements, Modules Total Mass ~ • Front Baffle Module • Baffle • Re-closable lid • Light ring • Telescope Tube Module • Outer tube, with proportional heater system • 2 optics sub modules • Isolation adapter module • Titanium thermal isolation housing • Filter wheel mechanism • Detector / camera module • Flexured base plate
Front Baffle Module • Baffle • Motorized lid with labyrinth edge, ‘spectralon’ surface on lid back • Ring of lights
Telescope Tube Module • Aluminum tube for good thermal conductivity, minimize gradients • Temperature controlled to room temp +/- 0.25 deg C with proportional thermal control system of heaters and sensors. • Optics aluminum sub modules with bonded glass elements on triangular shaped flexure blades. • Optical elements in sub modules are pre-metered for ease of integration, and have registration pads that can be lapped. • Sub modules are ‘muzzle loaded’ into the outer tube, and preloaded with compliance using a wave ring washer and threaded ring. The sub modules bear against their own registration pads and the outer tube registration surfaces.
Isolation Adaptor Module • Titanium housing, flexured from the telescope tube module • Filter wheel with 4 elements (one blank) • D.C. brushless motor with encoder
Flexured Base Plate • Titanium flexures • Honeycomb plate