Cryogenic nano-positioner development and test for space applications

Abstract

An effort has been in place at Ball Aerospace & Technologies Corp. (BATC) for over three years to develop a mechanism for precise positioning of optical elements for such applications as the Next Generation Space Telescope (NGST). It is desired for such a mechanism to be of low mass, to have nanometer-level positioning capability over a comparatively large range of travel, to be both ambient and cryogenically capable, and to have high strength and stiffness capabilities. The development effort has resulted in a simple 288-gram mechanism that meets these requirements, and does so with a single stepper motor and a simple control system. Performance has been verified at both ambient and cryogenic temperatures, and the mechanism design is currently being implemented on BATC's Advanced Mirror System Demonstrator program (AMSD). The current design achieves steps of less than 10 nanometers per step over more than 20mm of travel. We will present an overview of the capabilities of the mechanism, as well as a discussion of the test results achieved to date. Test results will include both ambient and cryogenic performance, hysteresis and stiffness measurement, as well as verification of single-stepping capability.