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Photonics
Special Issues
Active Optics
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Active Optics

A special issue of Photonics (ISSN 2304-6732).

Deadline for manuscript submissions: closed (15 March 2023) | Viewed by 6210

Special Issue Editors

Prof. Dr. Gerard René Lemaitre

E-Mail Website
Guest Editor
Laboratoire d’Astrophysique Marseille (LAM), Aix Marseille Université (AMU) and CNRS, 38 rue Frédéric Joliot-Curie, 13388 Marseille CX 13, France
Interests: optical design; active optics; fabrication; segmented telescopes; wide-field telescopes
Prof. Dr. Xiangqun Cui

E-Mail Website
Guest Editor
Nanjing Institute for Astronomy and Technology - NIAOT, CAS, Nanjing 210042, China
Interests: optical design; active optics; fabrication; segmented telescopes; wide-field telescopes
Dr. Andrew Rakich

E-Mail Website
Guest Editor
1. Robinson Research Center, Victoria University Wellington, Wellington 6140, New Zealand
2. Consultant at Mersenne Optical Consulting, Paraparaumu 5032, Wellington Region, New Zealand
Interests: optical design; active optics; wide-field telescope corrector
Dr. Xin Wang

E-Mail Website
Guest Editor
Shanghai Institute of Technical Physics – SITP, CAS, Shanghai 200083, China
Interests: optical design; fabrication; high-performance optical alignment

Special Issue Information

Dear Colleagues,

Over the past fifty years, active optics have provided high-deformation freeform surfaces (low-temporal-frequency) with extreme accuracy for large telescopes, spectrographs, and interferometers. Remote control positioning has also helped to improve image quality.

This Special Issue of Photonics seeks contributions dealing with high-angular resolution imaging and optical designs with a reduced number of optical surfaces.

Articles dealing with the following themes are welcome:

  • Freeform mirror or reflective diffraction grating surfaces: multi-mode aberration correction, off-axis paraboloid, toroid, axisymmetric aspheric, variable curvature, etc.
  • Freeform lens, lens-system, or refractive diffraction grating surfaces: toroid, coma correction, axisymmetric aspheric, deformable zoom lenses, etc.
  • Remote control positioning surfaces.

Prof. Dr. Gerard Lemaitre
Prof. Dr. Xiangqun Cui
Dr. Andrew Rakich
Dr. Xin Wang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Photonics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • active optics
  • stress polishing
  • deformable optics
  • optical design
  • mechanical design
  • control positioning
  • aberration correction
  • elasticity theory
  • finite element analysis
  • freeform surface
  • aspheric
  • replication techniques

Published Papers (3 papers)

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Research

15 pages, 4660 KiB  
Article
Large Piston Error Detection Method Based on the Multiwavelength Phase Shift Interference and Dynamic Adjustment Strategy
by Rongjie Qin, Zihao Yin, Youlong Ke and Yinnian Liu
Photonics 2022, 9(10), 694; https://doi.org/10.3390/photonics9100694 - 26 Sep 2022
Cited by 2 | Viewed by 1442
Abstract
As the loading space in rockets and mirror fabrication technology is limited, optical systems in space cannot have large optical apertures. However, the successful launch and excellent performance of the James Webb Telescope indicate that segmented mirrors can help realize large-aperture optical systems [...] Read more.
As the loading space in rockets and mirror fabrication technology is limited, optical systems in space cannot have large optical apertures. However, the successful launch and excellent performance of the James Webb Telescope indicate that segmented mirrors can help realize large-aperture optical systems in space, owing to the fold–unfold mechanism in the telescope. However, all segments in the segmented mirror should be co-phased so that it is equivalent to a monolithic mirror. The co-phasing problem is significant in optical systems in space because of their low error tolerance. Owing to some accident factors, the piston error can be more than 1 mm after the unfolding process. Here, we introduced a multiwavelength interference method and dynamic adjusting strategy, aiming to solve the two problems of co-phasing: large detection range (~2 mm) and high detection precision (<1/20λ). Numerical simulations were performed, and a 400 mm aperture-segmented spherical mirror system was used to verify this method. The original piston error was set to 1 mm, after the coarse co-phasing, and the residual piston error to less than half the wavelength of the monochromatic light; for fine co-phasing, the achieved detection precision was approximately 1.2 nm. Full article
(This article belongs to the Special Issue Active Optics)
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9 pages, 17949 KiB  
Communication
Active Optics–Freeform Segment Mirror Replications from a Deformable Matrix
by Gerard R. Lemaitre and Patrick Lanzoni
Photonics 2022, 9(4), 206; https://doi.org/10.3390/photonics9040206 - 22 Mar 2022
Cited by 1 | Viewed by 1707
Abstract
We present a new active optics method for making smooth aspheric, or freeform, mirrors by replication technique from an elastically deformable matrix. The mirror replicas provide an equivalent aberration correction to that of an off-axis segment of a Schmidt plate. The method describes [...] Read more.
We present a new active optics method for making smooth aspheric, or freeform, mirrors by replication technique from an elastically deformable matrix. The mirror replicas provide an equivalent aberration correction to that of an off-axis segment of a Schmidt plate. The method describes geometry of a chromium stainless steel deformable matrix. Polished flat at rest, the matrix was used as submaster when in a bent state for single replications on a glass substrate. Two plane-aspheric segment mirror replicas are then used as a pair of correctors for a spectrograph telemeter. Located outside the Schmidt plate, in opposite diametric directions, the mirror replicas allow aberration compensation of the singlet convex-plane lens used both as collimator and camera-optics of a spectrograph where the beams are passed twice. The spectrograph design is a “white pupil mounting” for a Cassegrainian telescope. The detector focusing is controlled by fusion imaging from the two mirror replicas. Our results show that the He-Ne beams wave-front error performed by the spectrograph, with each of the two replica mirrors passed twice, compensates at least 93% of the required total aspheric sag. This provides satisfactory results for the telemeter focusing device, which then is quasi-diffraction-limited. A similar replication technique is proposed to obtain a pair of off-axis Schmidt plates for a unit magnification Schmidt-Offner “ideal imager”. Such a system is well suited for Laser Guide Star adaptive optics applications in modern astronomy. Full article
(This article belongs to the Special Issue Active Optics)
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23 pages, 9905 KiB  
Article
Active Optics—Advances of Cycloid-like Variable Curvature Mirrors for the VLTI Array
by Gerard Rene Lemaitre, Pascal Vola, Patrick Lanzoni, Silvio Mazzanti, Frederic J. Dérie and Frederic Y. Gonté
Photonics 2022, 9(2), 66; https://doi.org/10.3390/photonics9020066 - 26 Jan 2022
Cited by 1 | Viewed by 2237
Abstract
Elasticity theory and active optics led us to the discovery of three geometrical configurations of variable curvature mirrors (VCMs) that are either cycloid-like or tulip-like thickness distributions. Cycloid-like VCMs are generated by a uniform load—air pressure—applied over the mirror rear surface, and reacts [...] Read more.
Elasticity theory and active optics led us to the discovery of three geometrical configurations of variable curvature mirrors (VCMs) that are either cycloid-like or tulip-like thickness distributions. Cycloid-like VCMs are generated by a uniform load—air pressure—applied over the mirror rear surface, and reacts without any bending moment along its circular contour. This particular VCM configuration is of practical interest because it smoothly generates accurate optical curvatures, varying from plane at rest to spherical curvatures up to f/2.9 over 16-mm aperture under 6.5-bar air pressure. Starting from the thin plate theory of elasticity and modeling with NASTRAN finite element analysis, one shows that 3-D optimizations—using a non-linear static flexural option—provide an accurate cycloid-like thickness distribution. VCM elasticity modeling in quenched stainless steel–chromium substrates allows the obtaining of diffraction-limited optical surfaces: Rayleigh’s criterion is achieved over a zoom range from flat to f/3.6 over 13-mm clear aperture up to 6-bar loading. These VCMs were originally developed and built at the Marseille Observatory in 1975 and implemented as a cat’s-eye mirror of IR Fourier-transform interferometers for laboratory recording of fast events in gas molecular spectroscopy. Later, for high-angular resolution astronomy with the ESO VLTI array—an interferometer made of 8 m Unit Telescopes (UTs) and 1.8 m Auxiliary Telescopes (ATs)—such VCMs were inevitable components to provide in a 3″ co-phased field-of-view since 1998. They were implemented (1) as cat’s eye mirrors of the height delay-lines beam recombination lab and (2) as ATs mirror-pair for output pupil conjugation of the movable x–y baseline. From the ESO-AMU approved convention of making 10 VCM spares up to 2024, the present modeling should provide a diffraction-limited extended field-of-view. It is pure coincidence that present results from modeling with an outer collarette are identical to results from analytic theory without collarette. Full article
(This article belongs to the Special Issue Active Optics)
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