| Name: | Karthic Kumar |
| Affiliation: | Indian Institute of Astrophysics Bangalore |
| Conference ID: | ASI2025_483 |
| Title: | Development of Metrology Station an XYZ gantry for the Sub Aperture Interferometer in Thirty Meter Telescope Project. |
| Authors: | Karthic Kumar, Prasanna Deshmukh, Alikhan, Pramod Panchal, Arun Kumar, Sriram, Mahesh Dalavi, Phanindra D V S. |
| Authors Affiliation: | Indian Institute of Astrophysics |
| Mode of Presentation: | Poster |
| Abstract Category: | Facilities, Technologies and Data science |
| Abstract: | This paper presents the design, development, installation, and testing of the Metrology Station—an XYZ gantry system developed to support a Sub-Aperture Interferometer, which performs surface frequency validations for the mirror segments of the Thirty Meter Telescope (TMT). TMT employs Stressed Mirror Polishing technology to polish its mirror segments, transforming spherical meniscus glass blanks into precise aspheric forms by applying forces around the mirror edges with warping arms and polishing under stress. Following this shaping process, the segments are cut into hexagonal forms, necessitating strict surface accuracy validation through metrology tools. The Sub-Aperture Interferometer plays a critical role in measuring mid-spatial frequency ranges from 50 mm to 80 mm, essential for these verifications.
The India TMT Coordination Centre (ITCC) developed the XYZ gantry to support an interferometer weighing approximately 350 kg on a platform with a travel range of 2500 mm along the X-axis and 2000 mm along the Y-axis. This movement is powered by two synchronized servo motors on the Y-axis and one servo motor on each of the X and Z axes. Designed for high precision, the system provides an overall positioning accuracy of 50 microns and an incremental accuracy of 10 microns, achieved through optical encoders placed on both the X and Y axes. Fully programmable, the gantry includes a camera for aligning polished mirrors with respect to its axes and a pen on the Z-axis to make precise markings on the polished mirror required to perform the interferometric inspection, ensuring seamless integration and optimal performance for the interferometer inspection.
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