Digital optical correlator x-ray telescope alignment monitoring system

Tomasz Lis; Jessica Gaskin; John Jasper; Don A. Gregory

doi:10.1117/1.OE.57.1.013104

22 January 2018 Digital optical correlator x-ray telescope alignment monitoring system

Tomasz Lis, Jessica Gaskin, John Jasper, Don A. Gregory

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Optical Engineering, Vol. 57, Issue 1, 013104 (January 2018). https://doi.org/10.1117/1.OE.57.1.013104

Abstract

The High-Energy Replicated Optics to Explore the Sun (HEROES) program is a balloon-borne x-ray telescope mission to observe hard x-rays ( ∼20 to 70 keV) from the sun and multiple astrophysical targets. The payload consists of eight mirror modules with a total of 114 optics that are mounted on a 6-m-long optical bench. Each mirror module is complemented by a high-pressure xenon gas scintillation proportional counter. Attached to the payload is a camera that acquires star fields and then matches the acquired field to star maps to determine the pointing of the optical bench. Slight misalignments between the star camera, the optical bench, and the telescope elements attached to the optical bench may occur during flight due to mechanical shifts, thermal gradients, and gravitational effects. These misalignments can result in diminished imaging and reduced photon collection efficiency. To monitor these misalignments during flight, a supplementary Bench Alignment Monitoring System (BAMS) was added to the payload. BAMS hardware comprises two cameras mounted directly to the optical bench and rings of light-emitting diodes (LEDs) mounted onto the telescope components. The LEDs in these rings are mounted in a predefined, asymmetric pattern, and their positions are tracked using an optical/digital correlator. The BAMS analysis software is a digital adaption of an optical joint transform correlator. The aim is to enhance the observational proficiency of HEROES while providing insight into the magnitude of mechanically and thermally induced misalignments during flight. Results from a preflight test of the system are reported.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Tomasz Lis, Jessica Gaskin, John Jasper, and Don A. Gregory "Digital optical correlator x-ray telescope alignment monitoring system," Optical Engineering 57(1), 013104 (22 January 2018). https://doi.org/10.1117/1.OE.57.1.013104

Received: 12 October 2017; Accepted: 19 December 2017; Published: 22 January 2018

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