5,659 research outputs found
Development of a carbon fibre composite active mirror: Design and testing
Carbon fibre composite technology for lightweight mirrors is gaining
increasing interest in the space- and ground-based astronomical communities for
its low weight, ease of manufacturing, excellent thermal qualities and
robustness. We present here first results of a project to design and produce a
27 cm diameter deformable carbon fibre composite mirror. The aim was to produce
a high surface form accuracy as well as low surface roughness. As part of this
programme, a passive mirror was developed to investigate stability and coating
issues. Results from the manufacturing and polishing process are reported here.
We also present results of a mechanical and thermal finite element analysis, as
well as early experimental findings of the deformable mirror. Possible
applications and future work are discussed.Comment: Accepted by Optical Engineering. Figures 1-7 on
http://www.star.ucl.ac.uk/~sk/OEpaper_files
The Thirty Meter Telescope International Observatory facilitating transformative astrophysical science
The next major advancement in astronomy and cosmology will be driven by deep
observations using very sensitive telescopes with high spatial and spectral
resolution capabilities. An international consortium of astronomers, including
Indian astronomers are building the Thirty Meter Telescope to achieve
breakthroughs in different areas of astronomy starting from studies of the
solar system to that of the early universe. This article provides a brief
overview of the telescope, science objectives and details of the first light
instruments.Comment: 10 page
Making SPIFFI SPIFFIER: Upgrade of the SPIFFI instrument for use in ERIS and performance analysis from re-commissioning
SPIFFI is an AO-fed integral field spectrograph operating as part of SINFONI
on the VLT, which will be upgraded and reused as SPIFFIER in the new VLT
instrument ERIS. In January 2016, we used new technology developments to
perform an early upgrade to optical subsystems in the SPIFFI instrument so
ongoing scientific programs can make use of enhanced performance before ERIS
arrives in 2020. We report on the upgraded components and the performance of
SPIFFI after the upgrade, including gains in throughput and spatial and
spectral resolution. We show results from re-commissioning, highlighting the
potential for scientific programs to use the capabilities of the upgraded
SPIFFI. Finally, we discuss the additional upgrades for SPIFFIER which will be
implemented before it is integrated into ERIS.Comment: 20 pages, 12 figures. Proceedings from SPIE Astronomical Telescopes
and Instrumentation 201
Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope
An overview of the current status of the 8.2 m Subaru Telescope constructed
and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of
Japan is presented. The basic design concept and the verified performance of
the telescope system are described. Also given are the status of the instrument
package offered to the astronomical community, the status of operation, and
some of the future plans. The status of the telescope reported in a number of
SPIE papers as of the summer of 2002 are incorporated with some updates
included as of 2004 February. However, readers are encouraged to check the most
updated status of the telescope through the home page,
http://subarutelescope.org/index.html, and/or the direct contact with the
observatory staff.Comment: 18 pages (17 pages in published version), 29 figures (GIF format),
This is the version before the galley proo
Fast figuring of large optics by reactive atom plasma
The next generation of ground-based astronomical observatories will require fabrication and maintenance of extremely large segmented mirrors tens of meters in diameter. At present, the large production of segments required by projects like E-ELT and TMT poses time frames and costs feasibility questions. This is principally due to a bottleneck stage in the optical fabrication chain: the final figuring step. State-of-the-art figure correction techniques, so far, have failed to meet the needs of the astronomical community for mass production of large, ultra-precise optical surfaces. In this context, Reactive Atom Plasma (RAP) is proposed as a candidate figuring process that combines nanometer level accuracy with high material removal rates. RAP is a form of plasma enhanced chemical etching at atmospheric pressure based on Inductively Coupled Plasma technology. The rapid figuring capability of the RAP process has already been proven on medium sized optical surfaces made of silicon based materials. In this paper, the figure correction of a 3 meters radius of curvature, 400 mm diameter spherical ULE mirror is presented. This work demonstrates the large scale figuring capability of the Reactive Atom Plasma process. The figuring is carried out by applying an in-house developed procedure that promotes rapid convergence. A 2.3 ÎŒm p-v initial figure error is removed within three iterations, for a total processing time of 2.5 hours. The same surface is then re-polished and the residual error corrected again down to& lambda;/20 nm rms. These results highlight the possibility of figuring a metre-class mirror in about ten hours
Robotic processes to accelerate large optic fabrication
The manufacture of metre-scale optics for the next generation of extremely large
telescopes (and many other applications) poses a number of unique challenges. For the
primary mirror of the European Extremely Large Telescope, each of its 1.45 m
segments will need to be completed with nanometre scale accuracy. This demands an
unprecedented combination of hybrid fabricating technology to process nearly 1000
segments before the year 2024.
One important aspect in improving the current state-of-the-art manufacturing
developments is adding an efficient smoothing process that can achieve a faster, and
less expensive, manufacturing process-chain. The current process to finish a prototype
segment using CNC grinding and CNC polishing takes approximately 1-2 months, and a
significant contributing factor in this is the excessive processing times needed to correct
the local grinding marks. In this study, therefore, grolishing, an intermediate process
between grinding and polishing, is adopted to smooth the part and reduce the overall
manufacturing time.
This PhD work serves to advance the development of effective robotic grolishing
processes (RGP) by the following achievements: (1) to propose the specification and achieve the requirements; (2) to design tools and establish a mechanism for grolishing;
(3) to investigate and propose experimental methods to reduce process times while still
achieving high performance, reliability and quality surfaces; (4) to establish the RGP
and demonstrate that this process can smooth the errors from grinding and provide
superior surfaces for polishing to speed up the current process; (5) to develop prototype
metrology systems and algorithms to measure grolished surfaces; and, (6) to investigate
an innovative proposed method to control mid-spatial frequencies on complex surfaces
by using rotating rigid tools.
These novel achievements describe the newest fabrication technology, and anticipate
the evolution of the process-chain for future high-quality imaging systems for use in
astronomy, space-research and laser physics
Thin glass shells for active optics for future space telescopes
We present a method for the manufacturing of thin shells of glass, which
appears promising for the development of active optics for future space
telescopes. The method exploits the synergy of different mature technologies,
while leveraging the commercial availability of large, high-quality sheets of
glass, with thickness up to few millimeters. The first step of the method
foresees the pre-shaping of flat substrates of glass by replicating the
accurate shape of a mold via hot slumping technology. The replication concept
is advantageous for making large optics composed of many identical or similar
segments. After the hot slumping, the shape error residual on the optical
surface is addressed by applying a deterministic sub-aperture technology as
computer-controlled bonnet polishing and/or ion beam figuring. Here we focus on
the bonnet polishing case, during which the thin, deformable substrate of glass
is temporary stiffened by a removable holder. In this paper, we report on the
results so far achieved on a 130 mm glass shell case study.Comment: This is a pre-print of an article published in CEAS Space Journal.
The final authenticated version is available online at:
http://link.springer.com/article/10.1007/s12567-019-00259-
- âŠ