Wide-field off-axis telescope for the Mesospheric Airglow/Aerosol Tomography Spectroscopy satellite
Journal article, 2019

We present the development of a compact 𝑓/7.3 (𝐷=35  mm) three-mirror reflective telescope for the atmospheric-research microsatellite Mesospheric Airglow/Aerosol Tomography Spectroscopy (MATS). The telescope design was driven by the end users’ need for a reflective wide-field (5.67°×0.91°) optic with high stray light rejection and six detection channels with separate image sensors, operating at wavelengths 270–772 nm. For the first time, a design method for wide-field off-axis telescopes—in which linear astigmatism is eliminated—was applied and tested in practice. Single-point diamond turning was used to produce two sets of 37–110 mm large free-form aluminum mirrors with surface figure errors and roughness values of 34–62 nm (RMS)/193–497 nm (PV) and 2.8–3.5 nm (RMS), respectively. A method that combines precise machining and geometry measurements (using a coordinate measuring machine) was employed to fabricate an aluminum structure to accurately position the mirrors without the need for manual alignment. The telescope was tested with a network of plate beamsplitters and filters, which define the spectral selection for the six detection channels. Imaging performance measurements were carried out using a reflective off-axis collimator, which projects imaging targets at infinite focus. A modulation transfer function (MTF) value of 0.45 at 20 lp/mm was measured at ∼760  nm (diffraction limit: 0.85) using a slanted edge target. By modeling the measured mirror surfaces in optical design software, a reoptimization of the mirror positions could be performed and an improved MTF of ∼0.75 at 20 lp/mm was predicted. The results demonstrate design- and building methods that can be utilized to make off-axis telescopes for a vast range of applications.

optical testing

optical components

Diffraction limit

stray light


Arvid Hammar

Omnisys Instruments

Chalmers, Microtechnology and Nanoscience (MC2), Terahertz and Millimetre Wave Laboratory

Woojin Park

Kyung Hee University

Seunghyuk Chang

Korea Advanced Institute of Science and Technology (KAIST)

Soojong Pak

Kyung Hee University

Anders Emrich

Omnisys Instruments

Jan Stake

Chalmers, Microtechnology and Nanoscience (MC2), Terahertz and Millimetre Wave Laboratory

Applied Optics

1559-128X (ISSN) 2155-3165 (eISSN)

Vol. 58 6 1393-1397

THz optical components and systems

Swedish Research Council (VR) (2010-4040), 2011-01-01 -- 2016-12-31.

Areas of Advance

Information and Communication Technology

Driving Forces

Sustainable development

Innovation and entrepreneurship

Subject Categories

Aerospace Engineering

Other Electrical Engineering, Electronic Engineering, Information Engineering





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