SCUBA-2 is an innovative 10,000 pixel submillimeter camera due to be delivered to the James Clerk Maxwell Telescope in late 2006. The camera is expected to revolutionize submillimeter astronomy in terms of the ability to carry out wide-field surveys to unprecedented depths addressing key questions relating to the origins of galaxies, stars and planets. This paper presents an update on the project with particular emphasis on the laboratory commissioning of the instrument. The assembly and integration will be described as well as the measured thermal performance of the instrument. A summary of the performance results will be presented from the TES bolometer arrays, which come complete with in-focal plane SQUID amplifiers and multiplexed readouts, and are cooled to 100mK by a liquid cryogen-free dilution refrigerator. Considerable emphasis has also been placed on the operating modes of the instrument and the "common-user" aspect of the user interface and data reduction pipeline. These areas will also be described in the paper.
This paper describes the opto-mechanical design of a large instrument for sub-mm, SCUBA-2, to be commissioned at JCMT. The scientific requirements, specially the large fov and the constraints of the telescope mechanical structure, lead to a complex optical design using freeform aluminium mirrors . The mechanical design is also challenging with large modules to be mounted and aligned in the telescope as well as the cryogenic instrument containing the mirrors, the filters, the dichroics and the detector modules. The cryogenic isostatic mounting, the structural and thermal designs are presented. This includes details of the fabrication of the structure and design of a shutter mechanism for operation at 4K. The results of the first AIV cool-down are also presented.
The SCUBA-2 instrument is a new wide field submillimeter imager currently being designed for the James Clerk Maxwell telescope on Mauna Kea in Hawaii. The instrument will observe simultaneously in the 450 and 850 micron bands and has a field of view of approximately 50 square arcminutes. To meet the performance requirements the detectors require a heat sink at a temperature of 50 mK or lower, and must be surrounded by an enclosure at a temperature of 1.1 K or below.
Cooling is provided by the mixing chamber and still of a cryogen-free dilution refrigerator (DR), via thermal links of the order of a metre in length. A challenging set of requirements result from the need for a small temperature drop between the detectors and the refrigerator insert despite the large distance between them, the need to provide flexibility in the links to allow for movement during thermal contraction, and the need to allow for the detectors to be
removed from the cryostat. Further, the arrays require a mounting structure which provides rigid mechanical support from the 1-K stage yet causes a very small heat input to millikelvin stage. This paper describes the design which has been evolved to meet these difficult (and often conflicting) requirements.
The SCUBA-2 instrument is a new wide-field imager under development for the James Clerk Maxwell Telescope on Mauna Kea in Hawaii and due to be operational in 2006. The instrument has two separate focal planes and is designed to observe simultaneously at wavelengths of 450 and 850μm. The instrument cryostat will weigh around 2500kg and has a volume of approximately 2.4x1.8x2.0m. The two detector arrays are operated at ~100mK and are surrounded by a cold enclosure at ~1K. Both the arrays and cold enclosure are cooled by a novel, liquid cryogen-free dilution refrigerator. To reduce the thermal background on the arrays to a minimum the main optics structure, weighing in excess of 450kg, must be cooled to less than 15K. A pair of low vibration pulse tube coolers are used to cool this structure and a radiation shield at ~60K. This paper describes the cryo-mechanical design of SCUBA-2 and discusses some of the issues and techniques needed to both cool the instrument within a reasonable timescale, and operate it in the required temperature regime
UIST is a facility class near-infrared instrument recently commissioned at the UK Infrared Telescope (UKIRT). UIST provides a comprehensive imaging and spectroscopic facility with spatial resolution limited only by the delivered tip-tilt corrected seeing. In addition to long slit spectroscopic modes, UIST includes the first deployable cryogenic integral field unit in a common user instrument. We will present results obtained during the commissioning period in late 2002. These include measurements of the image quality and the sensitivities of the different observing modes of the instrument. We also discuss the use of an instrument-specific telescope pointing-model developed for UIST to allow the instrument to meet the stringent flexure requirements arising from the choice of 0.06arcsec/pixel and 0.12arcsec/pixel plate scales. We pay particular attention to the performance of the image slicing integral field unit (IFU). We will present astronomical results from the first year of UIST operations, during which time UIST carried out diverse programmes, from mineralogical studies of Mars to measuring the mass of the black hole at the centre of the most distant quasar.
The UIST instrument is a 1-5μm Imager Spectrometer for the UKIRT telescope. The instrument has a high spatial resolution, and is designed to critically sample image sizes of 0.24arcsec. The instrument weighs 750kg and measures approximately 1100x1000x700mm. The flexure specification for the instrument is to maintain the image at the slit within 10% of the narrowest slit width, which is 44μm wide. However combined flexure of the instrument and its supporting structure is expected to be many times more than this. To meet the UIST flexure requirements we propose use of an instrument specific component in the telescope pointing model, to correct for repeatable flexure. Two designs for mounting regimes are presented, together with flexure test results and a discussion of the use of a simple pointing correction. The first, flexible, truss design did not meet requirements and was replaced with a rigid truss system. The paper describes some lessons learned during the development of the UIST mounting scheme, which can be applied in other instrument designs.
SCUBA-2 is a second generation, wide-field submillimeter camera under development for the James Clerk Maxwell Telescope. With over 12,000 pixels, in two arrays, SCUBA-2 will map the submillimeter sky ~1000 times faster than the current SCUBA instrument to the same signal-to-noise. Many areas of astronomy will benefit from such a highly sensitive survey instrument: from studies of galaxy formation and evolution in the early Universe to understanding star and planet formation in our own Galaxy. Due to be operational in 2006, SCUBA-2 will also act as a "pathfinder" for the new generation of submillimeter interferometers (such as ALMA) by performing large-area surveys to an unprecedented depth. The challenge of developing the detectors and multiplexer is discussed in this paper.
We present results on the integration and testing of an imaging spectrometer for the 1-5micrometers wavelength band. UIST offers high angular resolution imaging and spectroscopy and has been designed to exploit the best performance of the UK IR Telescope. In addition to imaging with 0.24arcsec and 0.12arcsec resolution, long-slit and cross-dispersed spectroscopy, UIST has an integral field mode using a reflective image slicer. An image rotator allows the slits and the rectangular field of view of the IFU to be oriented at any position angle on the sky. The UIST optical design relies on refractive optics with the spectroscopy provided by both replicated and direct-ruled grisms. The lenses are mounted in mechanical modules which also contain the mechanisms, such as the filter and slit wheels. The integration of the opto-mechanical system will be discussed. The high tolerances on positioning the optical components to be used under cryogenic conditions are achieved by mechanical alignment on an optical bench which is an integral part of the instrument. Initial tests of the cryogenic performance of the optics will be presented. The UIST detector is an 1024 by 1024 InSb 'ALADDIN' array from the Raytheon IR Center of Excellence. The array controller is modified from 'EDICT', a VME processor based system which was developed at the UK ATC to control the mid-IR arrays used in the MICHELLE spectrometer. Progress on the integration of the UIST detector and controller will be discussed.
High-quality, efficient calibration instruments is a pre- requisite for the modern observatory. Each of the Gemini telescopes will be equipped with identical facility calibration units (GCALs) designed to provide wavelength and flat-field calibrations for the suite of instruments. The broad range of instrumentation planned for the telescopes heavily constrains the design of GCAL. Short calibration exposures are required over wavelengths from 0.3micrometers to 5micrometers , field sizes up to 7 arcminutes and spectral resolution from R-5 to 50,000. The output from GCAL must mimic the f-16 beam of the telescope and provide a uniform illumination of the focal plane. The calibration units are mounted on the Gemini Instrument Support Structure, two meters from the focal pane, necessitating the use of large optical components. We will discuss the opto-mechanical design of the Gemini calibration unit, with reference to those feature which allow these stringent requirements to be met. A novel reflector/diffuser unit replaces the integration sphere more normally found in calibration systems. The efficiency of this system is an order of magnitude greater than for an integration sphere. A system of two off-axis mirrors reproduces the telescope pupil and provides the 7 foot focal plane. The results of laboratory test of the uniformity and throughput of the GCAL will be presented.