The ability of space telescopes to see into nascent protostellar systems and even further into our universe is driven by the size of their deployable light collection area. While large monolithic mirrors typically weigh tons, inflatable membrane mirrors present a scalable, ultralightweight alternative. Leveraging decades of advances in adaptive optics technology, the possibility of a well-corrected 20 meter-class space observatory such as the Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) is strikingly feasible. However, with great aperture size, comes great metrology requirements. Membrane reflectors are characteristically structured as one transparent and one metallized polymer membrane sealed around a steel tensioning ring. The inflated surface does not naturally conform to a known or prescribed conic but an approximate Hencky surface. Furthermore, multiple internal reflections and polarization interactions between the dielectric and metal layers disturb coherent light that probes it. A non-contact, full-aperture testing method is needed and further, one that can test highly varying membranes after thermoforming too. We present our method in obtaining the absolute shape of thermally formed, inflatable reflectors for space telescopes. Our work measures a 1-meter prototype of the OASIS primary inflatable mirror. Evolving from laser distance scanning to photogrammetry to deflectometry, our survey of metrology techniques for inflatable membrane optics is discussed.
The SOAR Telescope Echelle Spectrograph - STELES - is part of the Brazilian participation on the 4.1m SOAR
telescope second-generation instrumentation. In view of SOAR´s high image quality and moderately large collecting
area and the near UV capability, it will be able to yield high quality spectroscopic data for a large variety of objects of
astrophysical interests. The spectrograph is a R4 cross-dispersed echelle fed by the SOAR Nasmyth focus, operating in a
quasi-Littrow white pupil configuration, and a resolving power of R ≈ 50,000, covering the 300-900nm spectral range in
STELES is a bench spectrograph which will be mounted vertically on one side of the SOAR Telescope fork. The ninetydegree
inversion of the mechanical components, due to the vertical position of the instrument, plus the close proximity of
most components, due to the spectrograph compactness, were requirements carefully observed during the mechanical
design process. This paper describes the mechanical characteristics of the individual assemblies that make up the
STELES mechanical design. The STELES instrument can be separated into two sections, the fore optics, and the
spectrograph. The fore optics has the mechanisms from the SOAR telescope down to the STELES bench spectrograph,
and the bench spectrograph has the mechanisms for the spectrograph covering the red and blue spectrum.
We present a summary of the concept design report of a new astronomical instrument: SPARC4, Simultaneous
Polarimeter and Rapid Camera in 4 bands. SPARC4 will provide photometry and polarimetry in four optical
broad bands (griz SDSS) simultaneously. This is achieved by the use of dichroic beam splitters. The square eld
of view is around 5.6 arcmin on a side. SPARC4 time resolution is sub-second for photometry and somewhat
longer for polarimetry. This is provided by the use of fast EMCCDs. The main motivation for building SPARC4
is to explore astrophysical objects which exhibit fast temporal variability in
ux and polarization. The instrument
will be installed at the 1.6-m telescope of the Observatorio do Pico dos Dias (Brazil).
Wide field-of-view, high-resolution near-infrared cameras on 4-m class telescopes have been identified by the astronomical community as critical instrumentation needs in the era of 8-m and larger telescopes. Acting as survey instruments, they will provide the input source discoveries for large-telescope follow-up observations. The NOAO Extremely Wide Field Infrared Mosaic (NEWFIRM) imaging instrument will serve this need within the US system of facilities. NEWFIRM is being designed for the National Optical Astronomy Observatory (NOAO) 4-m telescopes (Mayall at KPNO and Blanco at CTIO). NEWFIRM covers a 28 x 28 arcmin field of view over the 1-2.4 μm wavelength range with a 4k x 4k pixel detector mosaic assembled from 2k x 2k modules. Pixel scale is 0.4 arcsec/pixel. Data pipelining and archiving are integral elements of the instrument system. We present the science drivers for NEWFIRM, and describe its optical, mechanical, electronic, and software components. By the time this paper is presented, NEWFIRM will be in the preliminary design stage, with first light expected on the Mayall telescope in 2005.
The LSST Instrument is a wide-field optical (0.3 to 1um) imager designed to provide a three degree field-of-view with better than 0.2 arcsecond sampling. The image surface of the LSST is approximately 55cm in diameter with a curvature radius of 25 meters to flat. The detector format is currently defined to be a circular mosaic of 568 2k × 2k devices faceted to synthesize this surface within the constraints of LSST's f/1.25 focal ratio. This camera will provide over 2.2 Gigapixels per image with a 2 second readout time. With an expected typical exposure time of as short as 10s, this will yield a nightly data set on order of 3 terapixels. The scale of the LSST Instrument is equivalent to a square mosaic of 47k × 47k. The LSST Instrument will also provide a filter mechanism, as well as optical shuttering capability. Imagers of this size pose interesting challenges in many design areas including detectors, interface electronics, data acquisition and processing pipelines, dewar construction, filter and shutter mechanisms. Further more, the LSST 3 mirror optical system places this instrument in a highly constrained volume where these challenges are compounded. Specific focus is being applied to meeting defined scientific performance requirements with an eye to total cost, system complexity, power consumption, reliability, and risk. This paper will describe the current efforts in the LSST Instrument Concept Design.