FOCUS (Focal Optical Control Using Steppers) - "Stepping" into the Future of Autonomous Focal Plane Control

The alignment of optical components in infrared telescopes is an involved process. The FOCUS design is presented to ensure that optics stay in the proper orientation at cryognic temperatures. FOCUS is based on converting the infinite rotary motion supplied by a stepper motor into linear motion. This motion is used to create a three point actuation system to control the focus and tilt of a focal plane. This system can be modified to actuate any element of the satellite needing three axis positioning. Emphasis has been placed on the mechanical aspects of the design with the knowledge that the controls can later be designed to yield a completely autonomous system. Testing of a prototype shows that linear travel of 0.26 mm with resolution of 0.01 mm may be accomplished. Tilt tests of the same system indicate that angular travel of 192 arcsec with 15 arcsec resolution is possible.