Abstract Details

Name: Prasanna Deshmukh
Affiliation: Indian Institute of Astrophysics
Conference ID: ASI2021_55
Title : Warping Harness actuator for the Thirty Meter Telescope Primary Mirror segments
Authors and Co-Authors : Prasanna Deshmukh (Indian Institute of Astrophysics), Fred Kamphues (TMT International Observatory), Leon Chen (Smoothmotor), David Zhang (Smoothmotor), Run Sheng Yang (Smoothmotor), Josef Eder (EDER), Ludo Visser (S[&]T), Joost Geelhoed (S[&]T), Gian Paolo Guizzo (Guizzo Space), Alan Tubb (TMT International Observatory), Chris Carter (TMT International Observatory), Bryan Smith (TMT International Observatory), Austin Zapata (The Pilot Group).
Abstract Type : Poster
Abstract Category : Instrumentation and Techniques
Abstract : The Thirty Meter Telescope (TMT) Primary Mirror (M1) is composed of 492 hexagonal aspheric segments. In order to compensate for residual polishing errors, installation errors, gravity effects and parasitic forces in the whiffletree support, each segment is equipped with 21 Warping Harness (WH) mechanisms, which allow low order corrections to the optical surface. The primary mirror segment aberrations after shape corrections with warping harness have been identified as the single largest error term in the Thirty Meter Telescope (TMT) image quality error budget. The WH mechanism consists of a Linear Actuator, Ball Link, and a Leaf Spring with a strain gauge sensor. The Warping Harness key requirements are: high positioning accuracy, 50 years operational lifetime with minimum maintenance, low cost, high reliability, high resolution, low hysteresis, high stability in an unpowered state, large operational temperature range, low power dissipation, vacuum compatibility, and survival of accidental condensing conditions. Smoothmotor has developed a robust, low-cost linear actuator for the TMT M1 Warping Harness. A WH Accelerated Life Cycle Test with increased temperature extremes was successfully completed. Acceleration factors were calculated with the Coffin-Manson model for temperature. Compliance with the technical requirements for the WH system has been demonstrated.