Measurement of the thermal-vacuum defocus of an objective lens for an imaging payload on a CubeSat

Edwin Magidimisha; Derek J. Griffith

doi:10.1117/12.2502328

24 January 2019 Measurement of the thermal-vacuum defocus of an objective lens for an imaging payload on a CubeSat

Proceedings Volume 11043, Fifth Conference on Sensors, MEMS, and Electro-Optic Systems; 1104318 (2019) https://doi.org/10.1117/12.2502328
Event: Fifth Conference on Sensors, MEMS, and Electro-Optic Systems, 2018, Skukuza, South Africa

Abstract

The paper presents a laboratory methodology for determining the space environmental effect on the focus of an objective lens for an earth imaging payload on a small satellite. Components used in space applications should undergo rigorous screening and testing, including thermal-vacuum (TVac) testing. These tests reduce risk and can provide critical information leading to risk mitigation strategies contributing to mission success. The global value and market for CubeSats for both commercial and scientific applications is fast growing and this has led to the demand for environmental test equipment. Existing facilities around the globe for satellite TVac testing are typically expensive and difficult to access and also oversized for nanosat applications. As a result, CSIR Optronic Sensor Systems embarked on developing a laboratory test procedure and a small scale TVac chamber based on commercial off-the-shelf (COTS) components. The specific purpose was to quantify the defocus of a COTS imaging lens under vacuum and over a specific operating temperature range. The TVac defocus is caused by variation of the refractive index of air with pressure and variation of the refractive index of glass with temperature. Temperature-related dimensional changes also contribute. The tests provided repeatable measurements leading to a TVac model for the defocus behaviour of the lens. The model allows for setting of a compensatory or “preemptive” defocus before launch.

Citation Download Citation

Edwin Magidimisha and Derek J. Griffith "Measurement of the thermal-vacuum defocus of an objective lens for an imaging payload on a CubeSat", Proc. SPIE 11043, Fifth Conference on Sensors, MEMS, and Electro-Optic Systems, 1104318 (24 January 2019); https://doi.org/10.1117/12.2502328

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KEYWORDS

Modulation transfer functions

Imaging systems

Satellites

Commercial off the shelf technology

Refractive index

Cameras

Sensors

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