Xinetics has been investigating ferroelectric actuator materials to meet the greater amplitude and higher bandwidth operation for the large mirror actuators of the 21st Century. This class of actuators features precision displacement control in terms of set-point accuracy and resolution, exhibits excellent dynamic response in terms of bandwidth and temporal response and feature thermal stability in terms of low power dissipation and low thermal expansion. High strain single crystal Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) actuators exhibit strains 3 times greater than the current ferroelectric PMN-based ceramic formulation. In addition, the lower dielectric constant of the single crystal material enables increased bandwidth operation. The major limitation to bringing single crystal multilayer devices to production levels is assembly cost and high operating voltages. A new technology in which the grains in the ceramic material are oriented - Nanotextured Ceramics - offers a technology to achieve near single crystal performance in a low cost, low voltage cofired multilayer actuator device. In this paper, we will discuss Xinetics’ solid state actuator development from randomly oriented ceramic to single crystal oriented materials.
KEYWORDS: Actuators, Cryogenics, Mirrors, Deformable mirrors, Temperature metrology, James Webb Space Telescope, Interferometers, Capacitance, Space telescopes, Silicon
Xinetics is working with NASA to develop a cryogenic deformable mirror (DM) specific to the needs of future Origins Program missions such as TPF and JWST. Of utmost importance was the development of an electroceramic material that exhibited electrostrictive properties at cryogenic temperatures. In this paper, the actuator developmental tests and subsequent cryogenic deformable mirror design and cryogenic testing performance of the 349-channel discrete actuator deformable mirror demonstrator are discussed. The cofired actuator stroke response was nearly constant from 35 to 65 K such that at 150V the actuator free-stroke was ~3 microns. The 349-ch cryogenic DM was designed and built with as few parts and materials as possible to minimize the CTE mismatch. The polished mirror was cycled twice from 300 to 35 K. The rms surface figure was monitored using a Zygo interferometer on cooling and consistent data was measured
during both temperature cycles. The figure changed from 0.5 waves (P-V) at 300 K to 5 waves at 35 K and returned to 0.6 waves at 300K. The actuators were powered and the influence functions were measured between 35 and 65 K. Even though it is not a functional DM at 35 K, it is a substantial step forward in the development of a cryogenic
deformable mirror technology.
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