Topic
Segmented mirror
About: Segmented mirror is a research topic. Over the lifetime, 618 publications have been published within this topic receiving 4819 citations.
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Book•
28 May 2009
TL;DR: A brief history of optical telescope systems can be found in this article, where the authors present a detailed overview of the fundamental requirements for optical mirror design and support mechanisms for optical mirrors.
Abstract: Table of Contents.- Dedication.- Contributing Authors.- Preface of English edition.- Preface of Chinese edition.- Acknowledgments.- Fundamentals of Optical Telescopes.- A brief history of optical telescopes.- General astronomical requirements.- Angular resolution.- Light collecting power.- Field-of-view and combined efficiency.- Atmospheric windows and site selection.- Fundamentals of astronomical optics.- Optical systems for astronomical telescopes.- Aberrations and their calculations.- Formulas of telescope aberrations.- Field corrector design.- Ray tracing, spot diagram, and merit function.- Modern optical theory.- Optical transfer function.- Wave aberrations and modulation transfer function.- Wavefront error and the Strehl ratio.- Image spatial frequency.- Image property of a segmented mirror system.- References.- Mirror Design of Optical Telescopes.- Specifications for optical mirror design.- Fundamental requirements for optical mirrors.- Mirror surface error and support systems.- Surface error fitting and slope error expression.- Lightweight primary mirror design.- Significance of lightweight mirrors for telescopes.- Thin mirror design.- Honeycomb mirror design.- Multi-mirror telescopes.- Segmented mirror telescopes.- Metal and lightweight mirrors.- Mirror polishing and mirror supporting.- Material properties of optical mirrors.- Optical mirror polishing.- Vacuum coating.- Mirror support mechanisms.- Mirror seeing and stray light control.- Mirror seeing effect.- Stray light control.- References.- Telescope Structures and Control System.- Telescope mounting.- Equatorial mounting.- Altitude-azimuth mounting.- Stewart platform mounting telescope.- Fixed mirror or fixed altitude mountings.- Telescope tube and other structure design.- Specifications for telescope tube design.- Telescope tube design.- Support vane design for secondary mirror.- Telescope bearing design.- Structural static analysis.- Telescope drive and control.- Specifications of telescope drive system.- Trends in drive system design.- Encoder systems for telescopes.- Pointing error corrections.- Servo control and distributed intelligence.- Star guiding.- Structural dynamic analysis.- Wind and earthquake spectrums.- Dynamic simulation of telescope structures.- Combined structural and control simulation.- Structural vibration control.- Telescope foundation design.- References.- Advanced Techniques for Optical Telescopes.- Active and adaptive optics.- Basic principles of active and adaptive optics.- Wavefront sensors.- Actuators, deformable mirrors, phase correctors, and metrology system.- Active optical system and phasing sensors.- Curvature sensors and tip-tilt devices.- Atmosphere disturbance and adaptive optics compensation.- Artificial laser guide star and adaptive optics.- Atmosphere tomography and multi-conjugate adaptive optics.- Adaptive secondary mirror design.- Optical interferometers.- Speckle interferometer technique.- Michelson interferometer.- Fizeau interferometry.- Intensity interferometry.- Amplitude interferometer.- References.- Space Telescopes and Their Development.- Orbit environmental conditions.- Orbit definition.- Orbit thermal conditions.- Other orbit conditions.- Attitude control of space telescopes.- Attitude sensors.- Attitude actuators.- Space telescope projects.- Hubble Space Telescope.- James Webb Space Telescope.- Space Interferometry Mission and other space programs.- References.- Fundamentals of Radio Telescopes.- Brief history of radio telescopes.- Scientific requirements for radio telescopes.- Atmospheric radio windows and site selection.- Parameters of radio antennas.- Radiation pattern.- Antenna gain.- Antenna temperature and noise temperature.- Antenna efficiency.- Polarization properties.- Optical arrangement of radio antennas.- Characteristics of offset antennas.- Radio telescope receivers.- References.- Radio Telescope Design.- Antenna tolerance and homologous design.- Transmission loss of electromagnetic waves.- Ante
116 citations
TL;DR: The LAMOST system as mentioned in this paper is a special reflecting Schmidt system that has an aperture of 4 m, f ratio of 5 and a 5 degree field of view, and the main optical axis is fixed on the meridian plane and tilted 25 degree(s) to the horizontal from south to north.
Abstract: The optical system of LAMOST is a special reflecting Schmidt system. It has an aperture of 4 m, f ratio of 5 and a 5 degree(s) field of view. The main optical axis is fixed on the meridian plane and tilted 25 degree(s) to the horizontal from south to north. The celestial objects were observed for 1.5 hours when they pass through the meridian. The reflecting Schmidt plane, MA, and the spherical mirror, MB, are segmented mirrors. MB is fixed on the foundation. The shape of the reflecting Schmidt plate has to be changed with different declination (delta) and in the tracking process. This is achieved with active optics. About 4000 optical fibers are planed to put on the focal surface. Some key technologies for LAMOST have been studied and presented in this paper: the calculation and testing method for thin mirror and segmented mirror active optics; the preliminary calculation and the experiment for active optics; the simulated calculation for optical image quality in 1.5 hours observation; a preliminary design of the alt-azimuth mounting and tracking system of MA.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
103 citations
TL;DR: It is demonstrated that the pyramid can successfully simultaneously sense the piston, tip, and tilt of a segmented mirror, making this technique very attractive in phasing and aligning astronomical segmented telescopes such as extremely large telescopes currently under extensive studies.
Abstract: We report what is to our knowledge the first laboratory experiment that shows the use of a pyramid wavefront sensor to cophase and align segmented mirrors having three degrees of freedom per segment, i.e., piston, tip, and tilt. In the laboratory the iterative alignment procedure reached a wavefront residual error of about 10 nm. The residual error was equally distributed between piston, tip, and tilt. These results demonstrate that the pyramid can successfully simultaneously sense the piston, tip, and tilt of a segmented mirror. This last feature makes this technique very attractive in phasing and aligning astronomical segmented telescopes such as extremely large telescopes currently under extensive studies.
102 citations
TL;DR: In this paper, the first on-sky results with the fibered aperture masking instrument First have been obtained on the Shane 3m telescope at Lick Observatory, where the entrance pupil is divided into sub-pupils feeding single-mode fibers.
Abstract: Aims. In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single-mode fibers, a novel technique that is aimed at high dynamic range imaging with high angular resolution.Methods. The prototype has been tested with the Shane 3-m telescope at Lick Observatory. The entrance pupil is divided into sub-pupils feeding single-mode fibers. The flux injection into the fibers is optimized by a segmented mirror. The beams are spectrally dispersed and recombined in a non-redundant exit configuration in order to retrieve all contrasts and phases independently.Results. The instrument works at visible wavelengths between 600 nm and 760 nm and currently uses nine of the 30 43 cm sub-apertures constituting the full pupil. First fringes were obtained on Vega and Deneb. Stable closure phases were measured with standard deviations on the order of 1 degree. Closure phase precision can be further improved by addressing some of the remaining sources of systematic errors. While the number of fibers used in the experiment was too small to reliably estimate visibility amplitudes, we have measured closure amplitudes with a precision of 10% in the best case. Conclusions. These first promising results obtained under real observing conditions validate the concept of the fibered aperture masking instrument and open the way for a new type of ground-based instrument working in the visible. The next steps of the development will be to improve the stability and the sensitivity of the instrument in order to achieve more accurate closure phase and visibility measurements, and to increase the number of sub-pupils to reach full pupil coverage.
86 citations
TL;DR: In this article, a segmented mirror array and a 2D mechanical scanner are used to perform both angular and spatial multiplexing in a LiNbO3 crystal with reference and signal beams entering orthogonal crystal faces.
74 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2022 | 1 |
| 2021 | 15 |
| 2020 | 34 |
| 2019 | 22 |
| 2018 | 35 |
| 2017 | 25 |