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Proceedings Paper

Design of off-axial Gregory telescope design with freeform mirror corrector
Author(s): Yu. Bazhanov; V. Vlakhko
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Paper Abstract

In this paper a well-known approach is used for calculation of off-axis three-mirror telescope. It includes usage of conic cross-sections properties, each of the sections forming a stigmatic image. To create a compact optical system, a flat mirror aberration corrector is introduced, which is at later stage transformed into a free-form surface in order to compensate field aberrations. Similarly, one can introduce such a corrector in finalized layout for its further optimization and getting a suitable form, including the conversion of multimirrors axial optical system into decentered one. As an example, off-axial Gregory telescope embodiment is used for infrared waveband region, due to the fact that, unlike the Cassegrain telescope, it provides a real exit pupil, and usage of the mirror corrector brings several advantages. Firstly, this feature may be used to include cold stop or adaptive mirror in the exit pupil, wherein corrector is introduced into a converging beam before the focus of the first mirror. Secondly, when placing corrector in the exit pupil of the optical system it is possible to eliminate high and low order aberrations of center point, which in turn improves optical system f-number, and minimize field aberrations. As another example, off-axial Ritchey-Chretien telescope embodiment is used as a good fit for visible region systems. Analysis and calculation results of optical systems with free-form correctors with surfaces, defined by Power polynomial series are presented in this paper. Advantages of different freeform surfaces usage depends on optical system layouts specifics.

Paper Details

Date Published: 23 August 2017
PDF: 7 pages
Proc. SPIE 10375, Current Developments in Lens Design and Optical Engineering XVIII, 103750W (23 August 2017); doi: 10.1117/12.2272183
Show Author Affiliations
Yu. Bazhanov, Precision Systems and Instruments Corp. (Russian Federation)
V. Vlakhko, Dynaoptics (Singapore)

Published in SPIE Proceedings Vol. 10375:
Current Developments in Lens Design and Optical Engineering XVIII
R. Barry Johnson; Virendra N. Mahajan; Simon Thibault, Editor(s)

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