Showing papers in "Proceedings of SPIE in 2004"

The Liverpool Telescope: performance and first results

Abstract: The Liverpool Telescope is a 2.0 metre robotic telescope that is operating unattended at the Observatorio del Roque de Los Muchachos, Spain. This paper gives an overview of the design and implementation of the telescope and its instrumentation and presents a snapshot of the current performance during the commissioning process. Science observations are under way, and we give brief highlights from a number of programmes that have been enabled by the robotic nature of the telescope.

The Goodman spectrograph

Abstract: The Goodman Spectrograph is an imaging, multi-object spectrograph for the SOuthern Astrophysical Research telescope (SOAR). It is one of the first designed to take advantage of Volume Phase Holographic (VPH) gratings by employing an articulated camera. This aspect of the mechanical design has had complicating effects on a number of usually simple systems, and has led to some unorthodox solutions. The spectrograph is also highly optimized for efficiency from 320 to 850 nm, and designed for rapid configuration changes, so that its throughput makes it competitive with instruments on larger telescopes. We present the high level requirements that have driven the mechanical and electronic systems, and show their implementation in the completed instrument. It is too early to assess the overall system performance, but tests of the modular subsystems show promising results. We discuss the expected overall performance and discuss mitigation strategies should that performance fall short of our goals.

Development of the wide-field IFU PPak

Abstract: PPak is a new fiber-bundle, developed at the Astrophysical Institute Potsdam for the existing PMAS 3D-instrument. The intention of PPak is to provide a large integral field-of-view in combination with a large collecting area per fiber for the study of extended low-surface brightness objects. The PPak system consists of a focal reducer lens and a fiber bundle, featuring an innovative design with object, sky and calibration fibers. With a field-of-view of 74 x 65 arcseconds, PPak currently is the world's widest integral field unit that provides a semi-contiguous regular sampling of extended astronomical objects. Its pre-optics and fiber-diameter, combined with the versatility and efficiency of the PMAS spectrograph, allows PPak to make a unique trade-off between total light-collecting power and spectral resolution.

VISTA data flow system: pipeline processing for WFCAM and VISTA

Abstract: The UKIRT Wide Field Camera (WFCAM) on Mauna Kea and the VISTA IR mosaic camera at ESO, Paranal, with respectively 4 Rockwell 2kx2k and 16 Raytheon 2kx2k IR arrays on 4m-class telescopes, represent an enormous leap in deep IR survey capability. With combined nightly data-rates of typically 1TB, automated pipeline processing and data management requirements are paramount. Pipeline processing of IR data is far more technically challenging than for optical data. IR detectors are inherently more unstable, while the sky emission is over 100 times brighter than most objects of interest, and varies in a complex spatial and temporal manner. In this presentation we describe the pipeline architecture being developed to deal with the IR imaging data from WFCAM and VISTA, and discuss the primary issues involved in an end-to-end system capable of: robustly removing instrument and night sky signatures; monitoring data quality and system integrity; providing astrometric and photometric calibration; and generating photon noise-limited images and astronomical catalogues. Accompanying papers by Emerson etal and Hambly etal provide an overview of the project and a detailed description of the science archive aspects.

The South Pole telescope

Abstract: A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs a n off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and wil l feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key pro ject will be to conduct a survey over ∼ 4000 degrees for galaxy clusters using the Sunyaev-Zel’dov ich Effect. This survey should find many thousands of clusters with a mass selection c riteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable signifi cant constraints to be placed on the equation of state of the dark e nergy.

NIF optical materials and fabrication technologies: an overview

Abstract: The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics Advanced optical materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into production at key vendor sites Production rates are up to 20 times faster and per-optic costs 5 times lower than could be achieved prior to the NIF In addition, the optics manufactured for NIF are better than specification giving laser performance better than the design A suite of custom metrology tools have been designed, built and installed at the vendor sites to verify compliance with NIF optical specifications A brief description of the NIF optical wavefront specifications for the glass and crystal optics is presented The wavefront specifications span a continuous range of spatial scale-lengths from 10 μm to 05 m (full aperture) We have continued our multi-year research effort to improve the lifetime (ie damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric coatings New methods for post-processing the completed optic to improve the damage resistance have been developed and made operational This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as raster and full aperture defect mapping systems Research on damage mechanisms continues to drive the development of even better optical materials

The Atacama Submillimeter Telescope Experiment (ASTE)

Abstract: ASTE (Atacama Submillimeter Telescope Experiment) is a project to install and operate a 10-m submillimeter telescope in the high altitude site (4,800 m) in Atacama desert, northern Chile. The project is aimed to explore the southern sky with submillimeter waves as well as to develop and evaluate various instruments and observing techniques. The telescope was shipped and re-assembled in Chilean site in early 2002, including the establishment of the on site infrastructure. Following evaluation of the telescope and receivers, scientific observations such as supernova remnants, galaxies, star forming regions and proto-planetary nebulae, have been carried out since early 2003. The high-precision 10-m antenna was measured to have the surface accuracy of 18.9 mm and the relative pointing accuracy was 1.2" r.m.s. for both azimuth and elevation. The subreflector is equipped with wobbling capability. Several types of receivers have been on board the telescope; the heterodyne-receivers operating at 100, 230, 345, 500 and 800 GHz bands including cartridge-type receivers, as well as a bolometer system covering 350, 650 and 850 GHz. The spectrometer is equipped with an XF type digital auto-correlator with four channels each covering up to 512 MHz with 1024 bins, which leads to 2 GHz coverage. The control system is designed to be capable of remote control from several sites via network connection, from the base facility at San Pedro de Atacama (2,400 m altitude) or even from Japan.

Mass producing an efficient NIR spectrograph

Abstract: Four institutions are collaborating to design and build three near identical R ~2700 cross-dispersed near-infrared spectrographs for use on various 5-10 meter telescopes. The instrument design addresses the common observatory need for efficient, reliable near-infrared spectrographs through such features as broad wavelength coverage across 6 simultaneous orders (0.8 - 2.4 microns) in echelle format, real-time slit viewing through separate optics and detector, and minimal moving parts. Lastly, the collaborators are saving money and increasing the likelihood of success through economies of scale and sharing intellectual capital.

High-power optically pumped semiconductor lasers

Abstract: Optically pumped, external-cavity, surface emitting semiconductor lasers (also known as optically pumped semiconductor lasers, OPS lasers, and vertical external cavity surface emitting lasers, VECSELs) generate near-diffraction limited beams from low brightness diode-array pumps. We have demonstrated 30 W cw at 980 nm and 15 W cw at 488 nm in a single spatial mode from these emitters and believe they can be scaled to > 100 W. Potential applications we have explored for such devices include wavelength conversion, spectral and spatial brightness conversion.

Fundamental aspects in machining of metals with short and ultrashort laser pulses

Abstract: On the fast growing market of precision micro-machining of metals lasers do not only compete with other methods of structuring There is also strong competition among different laser-processing strategies and, especially, among laser sources with different pulse duration A comprehensive study of laser micro-machining with nanosecond, picosecond, and femtosecond laser pulses will be presented with a focus on fundamental aspects of the processes and on their practical consequences An analysis will be given of the potential or the limitations of these laser processes with respect to their industrial application

WIRCam: the infrared wide-field camera for the Canada-France-Hawaii Telescope

Abstract: WIRCam (Wide-field InfraRed Camera) is a near-infrared (0.9-2.4 microns) camera developed for the prime focus of the Canada France Hawaii Telescope (CFHT), a 3.6-m telescope located on Mauna Kea, Hawaii. WIRCam is based on 4 x 2048x2048 HAWAII2RG arrays, developed by Rockwell. The camera provides a 0.3"/pixel sampling, and the close packaging of the detectors allows to cover an almost contiguous field-of-view of 20.5' x 20.5'. All optical elements are assembled in a cryovessel and cooled down to 85K by a He closed cycle cryogenerator. The two filter wheels have capacity for 8 filters (110 mm in diameter), cooled at low temperature together with the Lyot stop. These wheels are mounted on sapphire ball bearings and powered by external motors. Passive spring indexers define their positioning. A fused-silica tip/tilt plate powered by voice coil type motors provides image stabilization in front of the cryovessel. It compensates for flexures as well as for low frequency telescope oscillations from wind shake. This paper describes the overall architecture of the camera, giving the optical estimated performances and details some specific points of the design such as filter wheels, thermal connections, etc.

Montage: a grid-enabled engine for delivering custom science-grade mosaics on demand

Abstract: This paper describes the design of a grid-enabled version of Montage, an astronomical image mosaic service, suitable for large scale processing of the sky. All the re-projection jobs can be added to a pool of tasks and performed by as many processors as are available, exploiting the parallelization inherent in the Montage architecture. We show how we can describe the Montage application in terms of an abstract workflow so that a planning tool such as Pegasus can derive an executable workflow that can be run in the Grid environment. The execution of the workflow is performed by the workflow manager DAGMan and the associated Condor-G. The grid processing will support tiling of images to a manageable size when the input images can no longer be held in memory. Montage will ultimately run operationally on the Teragrid. We describe science applications of Montage, including its application to science product generation by Spitzer Legacy Program teams and large-scale, all-sky image processing projects.

Pan-STARRS: a wide-field optical survey telescope array

Abstract: The Institute for Astronomy at the University of Hawaii is developing a large optical synoptic survey telescope system; the Panoramic Survey Telescope and Rapid Response System. Pan-STARRS will consist of an array of four 1.8m telescopes with very large (7 square degree) field of view, giving it an etendue larger than all existing survey instruments combined. Each telescope will be equipped with a 1 billion pixel CCD camera with low noise and rapid read-out, and the data will be reduced in near real time to produce both cumulative static sky and difference images, from which transient, moving and variable objects can be detected. Pan-STARRS will be able to survey up to ≈6,000 square degrees per night to a detection limit of approximately 24th magnitude. This unique combination of sensitivity and rate of area coverage will open up many new possibilities in time domain astronomy. A major goal for the project is to survey potentially dangerous asteroids, where Pan-STARRS will be able to detect most objects down to 300m size, much smaller than the km size objects accessible to existing search programs. In addition, the Pan-STARRS data products will used to address a wide range of astronomical problems in the Solar System, the Galaxy, and the Cosmos at large. Here, we first outline the Pan-STARRS science goals and describe the survey modes needed to support these. We then describe the design and performance goals, the data processing pipeline, and we review the basic data products. Finally, we present results from simulations that demonstrate Pan-STARRS' capability for detecting potentially hazardous asteroids.

Artificial compound eyes: different concepts and their application for ultraflat image acquisition sensors

Abstract: Two different approaches for ultra flat image acquisition sensors on the basis of artificial compound eyes are examined. In apposition optics the image reconstruction is based on moire- or static sampling while the superposition eye approach produces an overall image. Both types of sensors are compared with respect to theoretical limitations of resolution, sensitivity and system thickness. Explicit design rules are given. A paraxial 3×3 matrix formalism is used to describe the arrangement of three microlens arrays with different pitches to find first order parameters of artificial superposition eyes. The model is validated by analysis of the system with raytracing software. Measurements of focal length of anamorphic reflow lenses, which are key components of the superposition approach, under oblique incidence are performed. For the second approach, the artificial apposition eye, a first demonstrator system is presented. The monolithic device consists of a UV-replicated reflow microlens array on a thin silica-substrate with a pinhole array in a metal layer on the backside. The pitch of the pinholes differs from the lens array pitch to enable an individual viewing angle for each channel. Imaged test patterns are presented and measurements of the angular sensitivity function are compared to calculations using commercial raytracing software.

Recent advances in solar adaptive optics

Abstract: Solar adaptive optics has become an indispensable tool at ground based solar telescopes. Over the last few years several solar adaptive optics systems have been deployed at major ground based solar telescopes. These systems enable diffraction limited observations of the sun for a significant fraction of the available observing time at these telescopes. New ground breaking scientific results have been achieved with solar adaptive optics. This paper summarizes the recent progress in the field of solar adaptive optics.

In-flight performance and calibration of the Infrared Array Camera (IRAC) for the Spitzer Space Telescope

Abstract: The Infrared Array Camera (IRAC) is one of three focal plane instruments on board the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 μm in two nearly adjacent fields of view. We summarize here the in-flight scientific, technical, and operational performance of IRAC.

The infrared spectrograph on the Spitzer Space Telescope

Abstract: The Infrared Spectrograph (IRS) is one of three science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 μm with spectral resolutions, R~90 and 650, and it was optimized to take full advantage of the very low background in the space environment. The IRS is performing at or better than the pre-launch predictions. An autonomous target acquisition capability enables the IRS to locate the mid-infrared centroid of a source, providing the information so that the spacecraft can accurately offset that centroid to a selected slit. This feature is particularly useful when taking spectra of sources with poorly known coordinates. An automated data reduction pipeline has been developed at the Spitzer Science Center.

MLCD: overview of NASA's Mars laser communications demonstration system

Abstract: NASA is presently overseeing a project to create the world's first free-space laser communications system that can be operated over a range much larger than the near-earth ranges that have been demonstrated to date.

The Michigan Infrared Combiner (MIRC): IR imaging with the CHARA Array

Abstract: We present the design of the Michigan Infra-Red Combiner (MIRC). MIRC is planned for deployment at the Georgia State University CHARA array to simultaneously combine all six telescope beams in an image-plane combiner. The novel design incorporates spatial-filtering with single-mode fiber optics, a synthetic (densified) pupil, and a low-resolution spectrometer to allow good calibration and efficient aperture synthesis imaging in the near-infrared. In addition, the focalization and spectrometer optics can accommodate an integrated optics component with minimal re-alignment. The MIRC concept can be scaled-up for interferometer arrays with more telescopes.

Overview and applications of Grating-Light-Valve-based optical write engines for high-speed digital imaging

Abstract: The Grating Light Valve (GLV) is a diffractive MOEMS spatial light modulator capable of very high-speed modulation of light combined with fine gray-scale attenuation. GLV-based products are field-proven in a variety of applications. In this paper, we describe the GLV device, its structure, theory of operation, and optical performance. The versatility and speed of the GLV device are described. We explain how the GLV device is integrated into an optical write engine to create a complete digital imaging system. In addition to the MOEMS die and drive electronics, the light engine also comprises illumination optics, Fourier filter, and imaging optics. We present current applications of the GLV device for high-resolution displays, and computer-to-plate printing, as well as future plans for digital imaging applications opened up by the unique properties of this diffractive MOEMS technology.

High-power All-Fiber components: the missing link for high-power fiber lasers

Abstract: Fiber lasers have shown extraordinary progress in power level, reaching the kilowatt range. These results were achieved with large mode area fibers pumped with high power laser diodes coupled with bulk-optics. To enable the commercial development of these high power fiber lasers, we have demonstrated several All-Fiber components, which replace the bulk-optic interface in the present laser configurations. These components include multimode fused fiber bundle combiners with or without signal fiber feed-through, Bragg gratings and mode field adaptors. The multimode fibers are used to couple several fiber pigtailed pump diodes to a double-clad fiber. Such combiners may contain a signal fiber to provide an input or output for the core modes of the double-clad fiber. Mode field adaptors perform fundamental mode matching between different core fibers. Bragg gratings are used as reflectors for the laser cavity. These components exhibit low-loss and high power handling of 200 Watts has been demonstrated. They enable the design of true high power single-mode All-Fiber lasers that will be small, rugged and reliable.

AAOmega: a scientific and optical overview

Abstract: AAOmega is a new spectrograph for the existing 2dF and SPIRAL multifibre systems on the Ango-Australian Telescope. It is a bench-mounted, dual-beamed, articulating, all-Schmidt design, using volume phase holographic gratings. The wavelength range is 370-950nm, with spectral resolutions from 1400-10000. Throughput, spectral coverage, and maximum resolution are all more than doubled compared with the existing 2dF spectrographs, and stability is increased by orders of magnitude. These features allow entirely new classes of observation to be undertaken, as well as dramatically improving existing ones. AAOmega is scheduled for delivery and commissioning in Semester 2005B.

NIF final optics system: frequency conversion and beam conditioning

Abstract: Installation and commissioning of the first of forty-eight Final Optics Assemblies on the National Ignition Facility was completed this past year. This activity culminated in the delivery of first light to a target. The final optics design is described and selected results from first-article commissioning and performance tests are presented.

The JWST MIRI instrument concept

Abstract: The MIRI is the mid-IR instrument for JWST and provides imaging, coronography and low and medium resolution spectroscopy over the 5-28μm band. In this paper we provide an overview of the key driving requirements and design status.

Self-organized coherence in fiber laser arrays

Abstract: Self-organized coherence between fiber lasers has been reported both via all-fiber 2x2 directional coupler trees and in spatially multi-core fibers. We have taken this a major step forward, coupling together a number of independent fiber lasers to obtain a spatially and spectrally coherent far field, with no active length, polarization, or amplitude control. The near field output comes from a spatial array rather than from a single fiber, making this approach scalable to extremely high power.

90prime: a prime focus imager for the Steward Observatory 90-in. telescope

Abstract: Steward Observatory is currently commissioning a prime focus wide-field imager for the 90-inch telescope located at Kitt Peak. The camera's focal plane array is populated with a mosaic of four thinned Lockheed 4096 x 4096 pixel CCDs. The f/2.98 system provides a plate scale of 0.45"/pixel and a total field-of-view of 1.16° x 1.16°. The optical design includes a four element corrector and six position filter wheel. The first science run was conducted in November 2003. We will describe the design of the "90prime" instrument and results from the commissioning runs.

Coronagraph contrast demonstrations with the high-contrast imaging testbed

Abstract: Predictions of contrast performance for the Eclipse coronagraphic telescope are based on computational models that are tested and validated with laboratory experience. We review recent laboratory work in the key technology areas for an actively-corrected space telescope designed for extremely high contrast imaging of nearby planetary systems. These include apodized coronagraphic masks, precision deformable mirrors, and coronagraphic algorithms for wavefront sensing and correction, as integrated in the high contrast imaging testbed at JPL. Future work will focus on requirements for the Terrestrial Planet Finder coronagraph mission.

Gemini South Adaptive Optics Imager (GSAOI)

Abstract: The Gemini South Adaptive Optics Imager (GSAOI) is the science camera and commissioning instrument for the Multi-Conjugate Adaptive Optics (MCAO) system on the Gemini South telescope. GSAOI is required to deliver diffraction-limited performance at near-infrared wavelengths over a 85"×85" field of view. It must be delivered on a short timescale commensurate with MCAO delivery. GSAOI will use a high throughput, all-refractive optical design and a mosaic of four HAWAII-2RG detectors to form an imager focal plane of 4080x4080 pixels with a fixed scale of 0.02"/pixel. The On-Detector Guide Window (ODGW) capability of the HAWAII-2RG detectors will be used for flexure monitoring and as near-infrared substitutes for MCAO natural guide star wave front sensors. The imager will include a pupil viewer for accurate alignment to MCAO and defocus lenses to measure wave front phase errors at the science detector using the curvature technique. Non-common path wave front errors will be nulled by setting the base shapes of the three MCAO deformable mirrors. The science drivers, performance predictions, optical design issues, and detector system for the instrument are described.

Panic: a near-infrared camera for the magellan telescopes

Abstract: PANIC (Persson's Auxiliary Nasmyth Infrared Camera) is a near-infrared camera designed to operate at any one of the f/11 folded ports of the 6.5m Magellan telescopes at Las Campanas Observatory, Chile. The instrument is built around a simple, all-refractive design that reimages the Magellan focal plane to a plate scale of 0.125"/pixel onto a Rockwell 1024x1024 HgCdTe detector. The design goals for PANIC included excellent image quality to sample the superb seeing measured with the Magellan telescopes, high throughput, a relatively short construction time, and low cost. PANIC has now been in regular operation for over one year and has proved to be highly reliable and produce excellent images. The best recorded image quality has been ~0.2" FWHM.

Silicon pore optics: novel lightweight high-resolution X-ray optics developed for XEUS

Abstract: The next generation astronomical X-ray telescopes (e.g. XEUS) require extremely large collecting area (10 m2) in combination with good angular resolution (5 arcsec). The existing technologies such as polished glass, nickel electroforming and foil optics would lead to excessively heavy and expensive optics, and/or are not able to produce the required large area or resolution. We have developed an entirely novel technology for producing X-ray optics which results in very light, stiff and modular optics which can be assembled into almost arbitrarily large apertures, and which are perfectly suited for XEUS. The technology makes use of commercially available silicon wafers from the semiconductor industry. The latest generation silicon wafers have a surface roughness that is sufficiently low for X-ray reflection, are planparallel to better than a micrometer, have almost perfect mechanical properties and are considerably cheaper than other high-quality optical materials. The wafers are bent into an accurate cone and assembled to form a light and stiff pore structure with pores of the order of a millimeter. The resulting modules form a small segment of a Wolter-I optic, and are easily assembled into an optic with large collecting area. We present the production principle of these silicon pore optics, the facilities that have been set up to produce these modules and experimental results showing the excellent performance of the first modules that have been produced. With further improvement we expect to be able to match the XEUS requirements for imaging resolution and mass.