22 July 2014 SALT segmented primary mirror: inductive edge sensors
Author Affiliations +
Proceedings Volume 9145, Ground-based and Airborne Telescopes V; 91454X (2014); doi: 10.1117/12.2056217
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada
The development of an inductive edge sensor is in process for the control of the Southern African Large Telescope’s (SALT)1 segmented mirror primary. The original capacitive edge sensing system was not capable of maintaining the figure of the primary mirror due to excessive noise and a severe sensitivity to humidity despite exhaustive attempts at characterisation1. The prototype of the inductive edge sensor has progressed to a mature industrialised version that is in the process of being installed and commissioned on SALT. The performance of the sensor in response to temperature and RH is very good with a maximum error of 10nm typical after temperature compensation. The noise and control characteristics of the array have been simulated in order to establish the maximum cumulative error and error rate tolerable for the SALT specific case. It has been established through simulation that over the expected 5 day alignment cycle, a maximum cumulative error of 30nm can be tolerated.
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Hitesh Gajjar, John Menzies, David Buckley, Christian Neel, Philippe Parbaud, Stéphane Royet, "SALT segmented primary mirror: inductive edge sensors", Proc. SPIE 9145, Ground-based and Airborne Telescopes V, 91454X (22 July 2014); doi: 10.1117/12.2056217; https://doi.org/10.1117/12.2056217


Temperature metrology




Environmental sensing

Process control

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