Proto-Model of an Infrared Wide-Field Off-Axis Telescope (original) (raw)
Related papers
Off-Axis Systems for 4-M Class Telescopes
Applied Optics, 1998
We describe here an off-axis design for a 4.0-m astronomical telescope. We show that the geometric optical performance of this configuration can equal that of an on-axis conventional configuration while the diffractive performance fundamentally surpasses conventional telescopes because of the absence of pupil obstruction. The specific optical design described here uses a single off-axis primary mirror to obtain three distinct final focus ports: an f͞10 port ͑with corrector͒ for wide-field imaging and spectroscopy with a field of view ͑FOV͒ of 15 arc min; a small-field, 2-reflection f͞10 port suitable for polarimetry and coronagraphy; and a slower, f͞16 ͑3-reflection͒ port with a 7 arc min FOV. For general astronomical observations requiring high optical throughput and low scattered light, this design is superior to conventional Ritchey-Chretien optical configurations.
Suitable off-axis space-based telescope designs
Astronomical …, 2004
We describe here several off-axis designs for space-based telescope optimized for low scattered light and low emissivity. We show how the geometric optical performance can equal that of an on-axis conventional telescope while the diffractive performance fundamentally surpasses conventional telescopes because of the absence of pupil obstruction. The off-axis concept also allows wide-field and versatile instrumentation configurations enabling a variety of observations -such as high photometric dynamic range objects -that are not possible with more conventional designs, even with much larger apertures.
Astrophysics and Space Science, 2001
We present the basic concepts of the two-mirror, three-reflection optical system (2MTRT), and discuss the important benefits of such a system for space projects: wide (∼ 2°) correctedand unvignetted FOV, without the use of refractive optics for thefield correction, planarity of the focal surface for an optimizedinstallation of wide area detectors, easy telescope adjustement, small volume and little mass.We also report the results of optical tests made with a 30 cm prototype,equipped with a 2k × 2k CCD camera, and give examples of scientific programmes which can be performed from space and in hostile terrestrial sites such as the Antarctic Plateau.
Alignment and integration off-axis mirrors for space applications
International Conference on Space Optics — ICSO 2020, 2021
The field of earth observation requires increasingly complex optical instruments to meet the final requirements. The anticipation of instrument integration and alignment activities on the subsystem side is essential. Thales SESO manufactures opto-mechanical subsystems assembled in such different space instruments. The evolution of instruments, as TMA type, concerning the reduction of the space allocated requires Thales SESO to offer opto-mechanical components and associated measurements that are increasingly precise and reliable. The challenge here for Thales SESO is to manufacture, integrate and measure off-axis mirrors while ensuring accurate apex positioning. We will share here the results on the instrument of the MTG program for Telescope Optics subsystems of the two instruments FCI and IRS. Through a specific metrology scheme, including accurate scanning of the optical surface Thales SESO delivers to the customer a reliable and accurate location of the optical reference frame of each subassembly toward its mechanical reference frame. From these relative location, the customer is able, in its assembly process, to "plug" the sub-assembly directly in its nominal position to start the alignment process with interferometric system. The data transmitted by Thales SESO made it possible to anticipate each adjustment of the optical subsystems and to make a very accurate prediction of the alignment requirement. With the data measures by Thales SESO, our customers realize a very quick final alignment procedure, with minimum displacements, to meet the final goal. In this process, the alignment budget is also minimized, leading to a final WFE largely under the predictions made by the customer before receiving the assemblies.
Optical design and testing of a fast, large aperture, infrared space telescope
Space Science Reviews, 1992
An optical design study for a next generation infrared space telescope has been performed, The concept is that of a passively cooled telescope of minium aperture 2.5 metre with an F/1.2 primary and wavelength coverage from A = 2 to at least 40 /zm, and possibly to 100 /~m. Compactness, low thermal emission from the optics and structure, diffraction limited imaging at A ----2/zm, and sensitivity to misalignment aberrations and manufacturing errors were the main considerations for this study. Ray tracing results are presented showing the characteristics of the various designs considered. A preliminary investigation of stray light properties is also given. Special emphasis has been placed on the testing of such a fast primary, and optical systems using a lateral shearing interferometer are described for testing both the primary and the primary/secondary combination.
Optics technology for large-aperture space telescopes: from fabrication to final acceptance tests
Advances in Optics and Photonics
This review paper addresses topics of fabrication, testing, alignment, and as-built performance of reflective space optics for the next generation of telescopes across the x-ray to far-infrared spectrum. The technology presented in the manuscript represents the most promising methods to enable a next level of astronomical observation capabilities for space-based telescopes as motivated by the science community. While the technology to produce the proposed telescopes does not exist in its final form, the optics industry is making steady and impressive progress toward these goals across all disciplines. We hope that through sharing these developments in context of the science objectives, further connections and improvements are enabled to push the envelope of the technology.
Ruhuna Journal of Science, 2020
Modern astronomical telescopes are comprised of high-quality optics and superior mounting designs to meet the standards and challenges of observational astronomy. Cost of commercial telescopes is a constraint for developing countries like Sri Lanka to be involved in astronomical related research. The objective of this research was to study the technological methods used in fabricating telescopes and to implement those methods to make economical telescopes locally. Therefore, a f/10 focal ratio Newtonian telescope consisting of a computerized friction drive alt-azimuth mount was fabricated with a locally ground thin telescope primary mirror made from Soda-lime glass plate having 0.25 m diameter and 0.012 m thickness. Deformation characteristics, profile formation and optical performance of the telescope primary mirror were investigated using finite element analysis, Polarization and Ronchi pattern analyses, respectively. Resolution, slew rate, torque and slippage of the fabricated friction drive were studied using a Computer Aided Design (CAD) model and an empirical approach. It was found that the profile of the mirror is a perfect parabola. The mirror was supported by a mirror cell with eighteen floating points and resultant root mean square wave-front error of the mirror due to the supporting points is 3.735x10-7 m. The friction drive with the computer controller can position the telescope to a given angle with accuracies of 0.421 degrees on altitude axis and 0.03 degrees on azimuth axis. The total cost of production of the prototype telescope is about US$ 750.00. It is shown that there is a significant cost reduction and increased optical and mechanical performances of the telescope due to using the thin mirror and the friction drive mount. In this paper, the system design and the performance evaluation of the mechanical positioning and optical quality of the telescope are presented.
A 1-degree FOV 30-meter telescope concept revisited
Ground-based Telescopes, 2004
The science case for wide fields on ELTs is well developed and justifies the implementation of 20 arc-minute and larger fields-of-view with seeing-limited performance on a 20 to 30-meter telescope. However, the practical implementation of a wide field can prove to be challenging with classical telescope design when low-thermal emissivity performance is also being optimized. Segmented mirrors assemblies need not be full aperture, axially symmetric structures. Space for secondary, tertiary, and quaternary mirror support structures that do not cross the optical path can be achieved with offaxis mirror assemblies. Barden, Harmer, Claver, and Dey 1 described a 4-mirror, 1-degree FOV 30-meter telescope. We take that concept further with an off-axis approach. Three conic mirrors are required to produce excellent image quality in the 1-degree FOV (diffraction limited across the central few arc-minutes, better than 0.3" imaging performance at the edge of the field). A flat quaternary mirror is utilized both as a beam steering mirror to different instrument ports on the lower side of the telescope and as an adaptive mirror for wind-buffeting and possible ground layer AO correction. The final f/2.2 focal ratio allows the use of an echidna-style fiber positioner for very dense target field acquisition. Extreme AO and Ground Layer AO ports can both be implemented as well. Diffraction characteristics may possibly be improved given the lack of a spider mount for the secondary mirror but will be elliptical rather than circular.
Design and development of a freeform active mirror for an astronomy application
Optical Engineering, 2014
The advent of extremely large telescopes will bring unprecedented light-collecting power and spatial resolution, but it will also lead to a significant increase in the size and complexity of focal-plane instruments. The use of freeform mirrors could drastically reduce the number of components in optical systems. Currently, manufacturing issues limit the common use of freeform mirrors at short wavelengths. This article outlines the use of freeform mirrors in astronomical instruments with a description of two efficient freeform optical systems. A new manufacturing method is presented which seeks to overcome the manufacturing issues through hydroforming of thin polished substrates. A specific design of an active array is detailed, which will compensate for residual manufacturing errors, thermoelastic deformation, and gravity-induced errors during observations. The combined hydroformed mirror and the active array comprise the Freeform Active Mirror Experiment, which will produce an accurate, compact, and stable freeform optics dedicated to visible and near-infrared observations.