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Optimization based telescope passive auto-focusing through image quality assessment for Thai National Space object Observation
Author(s)
Anutarawiramkul, Rungrit
Butpan, Pathompong
Palee, Kritsada
Prasit, Pakawat
Manathasna, Shariff
Mongkolves, Sirapop
Masri, Tanawish
Maksin, Nattida
Leckngam, Apichart
Datephanyawat, Jetanat
Patcharin, Kamsing
Date Issued
January 1, 2022
Type
Conference Paper
Abstract
The coming years, the growth of orbital debris in the Resident of Space Objects (RSOs) could be a serious issue for operational spacecraft and manned spaceflight. To prevent debris-related risks in operational orbit, a ground-based passive optical telescope was used as a fundamental imaging sensor for Space Situation Awareness to periodically maintain the orbital parameters of a space object in RSOs through an astrometry engineering approach. In the case of a small and dim space object, it produces low contrast images and suffers from a lack of sharpness which are easily influenced by background interference. Normally, a manual adjustment of a preliminary focus range of the telescope is one of the tedious practices that astronomers constantly face for the high-contrast image capturing before beginning a tracking procedure. Therefore, the passive automatic focusing process was initially required for a robotic telescope as a function of image quality assessment. Technically, the auto-focusing is a combination of processes between software and motorized focusing hardware with position feedback. In this paper, we investigate a new approach and software for passive automatic focusing charge-coupled device based telescope systems for finding a focal-point of an imaging system that minimizes objectives while satisfying constraints. These systems are most appropriate for unobserved all-night telescope operations as an asteroid and/or orbital debris monitoring. Based on the image quality assessment, a function of Full-Width Half Maximum was applied, the auto-focusing algorithm of the telescope system was realized via the golden section optimizer through the least square method. The experimental results were obtained during the commissioning of an alt-azimuth mounting equipped with a 0.7-meter optical aperture telescope from two observation sites at the National Astronomical Research Institute of Thailand. Two state-of-the-art methods were used for demonstrating and presenting method efficiency. Final results denote that the presented proposed algorithm improves the quality of the image contrast and can provide clearer details and information.
Citation
Proceedings of the International Astronautical Congress Iac, 2022-September, 2022