We present a novel application of optical tunneling in the context of high-angular resolution, high-contrast techniques with the aim of improving direct imaging capabilities of faint companions in the vicinity of bright stars. In contrast to existing techniques like coronagraphy, we apply well-established techniques from integrated optics to exclusively extinct a very narrow angular direction coming from the sky. This extinction is achieved in the pupil plane and does not suffer from diffraction pattern residuals. We give a comprehensive presentation of the underlying theory as well as first laboratory results.
A JWST OTE Pathfinder telescope that includes two spare primary mirror segments, a spare secondary mirror, and a large composite structure with a deployed secondary support structure is in the assembly stage and will be fully completed this year. This Pathfinder will check out key steps in the ambient mirror integration process and also be used at the Johnson Space Center (JSC) to check out the optical Ground Support Equipment (GSE) and associated procedures that will be used to test the full JWST telescope and instruments at JSC. This paper will summarize the Pathfinder integration and testing flow, the critical Ground Support Equipment it will test and the key tests planned with the Pathfinder.
The Multi-Object Broadband Imaging Echellette (MOBIE) is the seeing-limited, visible-wavelength imaging multiobject spectrograph (MOS) planned for first-light use on the Thirty Meter Telescope (TMT). The MOBIE project to date has been a collaboration lead by UC Observatories (CA), and including the UH Institute for Astronomy (HI), and the NAOJ (Tokyo, Japan). The current MOBIE optical design provides two color channels, spanning the 310–550nm and 550-1000nm passbands, and a combination of reflection gratings, prisms, and mirrors to enable direct imaging and three spectroscopic modes with resolutions (λ/triangle λ) of roughly 1000, 3000, and 8000 in both color channels, across a field of view that ranges from roughly 8x3 arcmin to 3x3 arcmin, depending on resolution mode. The conceptual design phase for the MOBIE instrument has been underway since 2008 and is expected to end in 2015. We report here on developments since 2010, including assembly of the current project team, instrument and camera optical designs, instrument control systems, atmospheric dispersion corrector, slit-mask exchange systems, collimator, dichroic and fold optics, dispersing and cross-dispersing optics, refracting cameras, shutters, filter exchange systems, science detector systems, and instrument structures.
The "Hot and Energetic Universe" has been selected as the science theme for ESA's L2 mission, scheduled for launch in 2028. The proposed Athena X-ray observatory provides the necessary capabilities to achieve the ambitious goals of the science theme. The X-ray mirrors are based on silicon pore optics technology and will have a 12 m focal length. Two complementary camera systems are foreseen which can be moved in and out of the focal plane by an interchange mechanism. These instruments are the actively shielded micro-calorimeter spectrometer X-IFU and the Wide Field Imager (WFI). The WFI will combine an unprecedented survey power through its large field of view of 40 arcmin with a high countrate capability (approx. 1 Crab). It permits a state-of-the-art energy resolution in the energy band of 0.1 keV to 15 keV during the entire mission lifetime (e.g. FWHM ≤ 150 eV at 6 keV). This performance is accomplished by a set of DEPFET active pixel sensor matrices with a pixel size matching the angular resolution of 5 arcsec (on-axis) of the mirror system. Each DEPFET pixel is a combined detector-amplifier structure with a MOSFET integrated onto a fully depleted 450 micron thick silicon bulk. The signal electrons generated by an X-ray photon are collected in a so-called internal gate below the transistor channel. The resulting change of the conductivity of the transistor channel is proportional to the number of electrons and thus a measure for the photon energy. DEPFETs have already been developed for the "Mercury Imaging X-ray Spectrometer" on-board of ESA’s BepiColombo mission. For Athena we develop enhanced sensors with integrated electronic shutter and an additional analog storage area in each pixel. These features improve the peak-to-background ratio of the spectra and minimize dead time. The sensor will be read out with a new, fast, low-noise multi-channel analog signal processor with integrated sequencer and serial analog output. The architecture of sensor and readout ASIC allows readout in full frame mode and window mode as well by addressing selectively arbitrary sub-areas of the sensor allowing time resolution in the order of 10 μs. The further detector electronics has mainly the following tasks: digitization, pre-processing and telemetry of event data as well as supply and control of the detector system. Although the sensor will already be equipped with an on-chip light blocking filter, a filter wheel is necessary to provide an additional external filter, an on-board calibration source, an open position for outgassing, and a closed position for protection of the sensor. The sensor concept provides high quantum efficiency over the entire energy band and we intend to keep the instrumental background as low as possible by designing a graded Z-shield around the sensor. All these properties make the WFI a very powerful survey instrument, significantly surpassing currently existing observatories and in addition allow high-time resolution of the brightest X-ray sources with low pile-up and high efficiency. This manuscript will summarize the current instrument concept and design, the status of the technology development, and the envisaged baseline performance.
In the past years, intensive Site Characterization campaigns have been performed to chose the sites for the future giant ELTs. Various atmospheric turbulence profilers with different resolution and sensed altitude ranges have been used, as well as climatological tools and satellite data analysis. Mixing long term statistics at low altitude resolution with high resolution data collected during short term campaigns allows to produce the reference profiles as input to the Adaptive Optics instrument performance estimators. In this paper I will perform a brief review of the principal and most used instruments and tools in order to give to the reader a panorama of the work and the efforts to monitor the atmospheric turbulence for astronomical purposes.
Within ESAs 2015 - 2025 Cosmic Vision framework the EUCLID mission satellite addresses cosmological questions related to dark matter and dark energy. EUCLID is equipped with two instruments that are simultaneously observing patches of > 0.5 square degree on the sky. The VIS visual light high spacial resolution imager and the NISP near infrared spectrometer and photometer are separated by a di-chroic beam splitter. Having a large FoV (larger than the full moon disk), together with high demands on the optical performance and strong requirements on in flight stability lead to very challenging demands on alignment and post launch { post cool-down optical element position. The role of an accurate and trust-worthy tolerance analysis which is well adopted to the stepwise integration and alignment concept, as well as to the missions stability properties is therefore crucial for the missions success. With this paper we present a new iteration of the baseline tolerancing concept for EUCLID NISP. All 7 operational modes being low resolution slit-less spectroscopy and three band Y, J& H+ band photometry are being toleranced together. During the design process it was noted that the desired performance can only be reached when alignment and tolerancing methods are closely connected and optimized together. Utilizing computer generated - multi zone - holograms to align and cross reference the four lenses of the NISP optical system. We show our plan to verify these holograms and what alignment sensitivities we reach. In the main section we present the result of the tolerancing and the main contributers that drive the mechanical and thermal design of the NISO optical subsystems. This analysis presents the design status of NISP at the system PDR of the mission.
The Japanese SPace Infrared telescope for Cosmology and Astrophysics, SPICA, aims to provide astronomers with a truly new window on the universe. With a large -3 meter class- cold -6K- telescope, the mission provides a unique low background environment optimally suited for highly sensitive instruments limited only by the cosmic background itself. SAFARI, the SpicA FAR infrared Instrument SAFARI, is a Fourier Transform imaging spectrometer designed to fully exploit this extremely low far infrared background environment. The SAFARI consortium, comprised of European and Canadian institutes, has established an instrument reference design based on a Mach-Zehnder interferometer stage with outputs directed to three extremely sensitive Transition Edge Sensor arrays covering the 35 to 210 μm domain. The baseline instrument provides R > 1000 spectroscopic imaging capabilities over a 2’ by 2’ field of view. A number of modifications to the instrument to extend its capabilities are under investigation. With the reference design SAFARI’s sensitivity for many objects is limited not only by the detector NEP but also by the level of broad band background radiation – the zodiacal light for the shorter wavelengths and satellite baffle structures for the longer wavelengths. Options to reduce this background are dedicated masks or dispersive elements which can be inserted in the optics as required. The resulting increase in sensitivity can directly enhance the prime science goals of SAFARI; with the expected enhanced sensitivity astronomers would be in a better position to study thousands of galaxies out to redshift 3 and even many hundreds out to redshifts of 5 or 6. Possibilities to increase the wavelength resolution, at least for the shorter wavelength bands, are investigated as this would significantly enhance SAFARI’s capabilities to study star and planet formation in our own galaxy.
MUSTANG 2 is a 223 element focal plane that operates between 75 and 105 GHz on the 100 meter Green Bank Telescope. It shares many of the science goals of its predecessor, MUSTANG, but will have fifteen times the sensitivity and five times the field-of-view. Angular scales from 900 to 60 will be recovered with high fidelity providing a unique overlap between high resolution instruments such as ALMA and lower resolution single dish telescopes such as ACT or SPT. Individual TES bolometers are placed behind feedhorns spaced by 1.9λ f and are read out using a microwave SQUID multiplexing system.
Over its two decades of science operations, the W.M. Keck Observatory computing environment has evolved to contain a distributed hybrid mix of hundreds of servers, desktops and laptops of multiple different hardware platforms, O/S versions and vintages. Supporting the growing computing capabilities to meet the observatory’s diverse, evolving computing demands within fixed budget constraints, presents many challenges. This paper describes the significant role that virtualization is playing in addressing these challenges while improving the level and quality of service as well as realizing significant savings across many cost areas. Starting in December 2012, the observatory embarked on an ambitious plan to incrementally test and deploy a migration to virtualized platforms to address a broad range of specific opportunities. Implementation to date has been surprisingly glitch free, progressing well and yielding tangible benefits much faster than many expected. We describe here the general approach, starting with the initial identification of some low hanging fruit which also provided opportunity to gain experience and build confidence among both the implementation team and the user community. We describe the range of challenges, opportunities and cost savings potential. Very significant among these was the substantial power savings which resulted in strong broad support for moving forward. We go on to describe the phasing plan, the evolving scalable architecture, some of the specific technical choices, as well as some of the individual technical issues encountered along the way. The phased implementation spans Windows and Unix servers for scientific, engineering and business operations, virtualized desktops for typical office users as well as more the more demanding graphics intensive CAD users. Other areas discussed in this paper include staff training, load balancing, redundancy, scalability, remote access, disaster readiness and recovery.
Gemini South's instrument suite has been completely transformed since our last biennial update. We commissioned the Gemini Multi-Conjugate Adaptive Optics System (GeMS) and its associated Gemini South Adaptive Optics Imager (GSAOI) as well as Flamingos-2, our long-slit and multi-object infrared imager and spectrograph, and the Gemini Planet Imager (GPI). We upgraded the CCDs in GMOS-S, our multi-object optical imager and spectrograph, with the GMOS-N CCD upgrade scheduled for 2015. Our next instrument, the Gemini High-resolution Optical SpecTrograph (GHOST) is in its preliminary design stage and we are making plans for the instrument to follow:Gen4#3.
A 2.5 degree field diameter corrector lens design for the Cassegrain focus of the VISTA 4 meter telescope is presented. It comprises four single elements of glasses with high UV transmission, all axi-symmetric for operation at the zenith. One element is displaced laterally to provide atmospheric dispersion correction. A key feature, especially beneficial for the VISTA application, is that the ADC element can be mounted so it is driven simply by gravity; thus its operation needs no motors, encoders, cabling, or software control. A simple mechanical design to achieve this and the optical performance details are described.
A Search for Extraterrestrial Life (SETI), based on the possibility of interstellar communication via laser signals, is being designed to extend the search into the near-infrared spectral region (Wright et al, this conference). The dedicated near-infrared (900 to 1700 nm) instrument takes advantage of a new generation of avalanche photodiodes (APD), based on internal discrete amplification. These discrete APD (DAPD) detectors have a high speed response (< 1 GHz) and gain comparable to photomultiplier tubes, while also achieving significantly lower noise than previous APDs. We are investigating the use of DAPD detectors in this new astronomical instrument for a SETI search and transient source observations. We investigated experimentally the advantages of using a multiple detector device operating in parallel to remove spurious signals. We present the detector characterization and performance of the instrument in terms of false positive detection rates both theoretically and empirically through lab measurements. We discuss the required criteria that will be needed for laser light pulse detection in our experiment. These criteria are defined to optimize the trade between high detection efficiency and low false positive coincident signals, which can be produced by detector dark noise, background light, cosmic rays, and astronomical sources. We investigate experimentally how false coincidence rates depend on the number of detectors in parallel, and on the signal pulse height and width. We also look into the corresponding threshold to each of the signals to optimize the sensitivity while also reducing the false coincidence rates. Lastly, we discuss the analytical solution used to predict the probability of laser pulse detection with multiple detectors.
The High Optical Resolution Spectrograph (HORS) is a proposed high-resolution spectrograph for the 10-m Gran Telescopio Canarias (GTC) based on components from UES, a spectrograph which was in use at the 4.2-m William Herschel Telescope (WHT) between 1992 and 2001. HORS is designed as a cross-dispersed echelle spectrograph to observe in the range 380-800 nm with a FWHM resolving power of about 50,000. HORS would operate on the GTC as a general-purpose high-resolution spectrograph, and it would serve as a test-bed for some of the technologies proposed for ESPRESSO – an ultra-high stability spectrograph planned for the Very Large Telescope (VLT) of the European Southern Observatory. The HORS spectrograph will be placed in the Coudé room, where it can enjoy excellent thermal and mechanical stability, fiber fed from the Nasmyth focus, which is shared with OSIRIS. Inside the spectrograph, incoming light will hit a small folder mirror before reaching the collimator. After a second folder, the light will go through a set of three prisms and an Echelle grating before entering the spectrograph camera and, finally, reaching the detector. This manuscript contains a summary of the whole process that has transformed UES into HORS, with all the mechanical and optical modifications that have been introduced to reach the final layout.
MANIFEST is a fibre feed system for the Giant Magellan Telescope that, coupled to the seeing-limited instruments GMACS and G-CLEF, offers qualitative and quantitative gains over each instrument’s native capabilities in terms of multiplex, field of view, and resolution. The MANIFEST instrument concept is based on a system of semi-autonomous probes called “Starbugs” that hold and position hundreds of optical fibre IFUs under a glass field plate placed at the GMT Cassegrain focal plane. The Starbug probes feature co-axial piezoceramic tubes that, via the application of appropriate AC waveforms, contract or bend, providing a discrete stepping motion. Simultaneous positioning of all Starbugs is achieved via a closed-loop metrology system.
Starbugs are miniature piezoelectric 'walking' robots that can be operated in parallel to position many payloads (e.g. optical fibres) across a telescope's focal plane. They consist of two concentric piezo-ceramic tubes that walk with micron step size. In addition to individual optical fibres, Starbugs have moved a payload of 0.75kg at several millimetres per second. The Australian Astronomical Observatory previously developed prototype devices and tested them in the laboratory. Now we are optimising the Starbug design for production and deployment in the TAIPAN instrument, which will be capable of configuring 300 optical fibres over a six degree field-of-view on the UK Schmidt Telescope within a few minutes. The TAIPAN instrument will demonstrate the technology and capability for MANIFEST (Many Instrument Fibre-System) proposed for the Giant Magellan Telescope. Design is addressing: connector density and voltage limitations, mechanical reliability and construction repeatability, field plate residues and scratching, metrology stability, and facilitation of improved motion in all aspects of the design for later evaluation. Here we present the new design features of the AAO TAIPAN Starbug.
Commissioning time for an instrument at an observatory is precious, especially the night time. Whenever astronomers come up with a software feature request or point out a software defect, the software engineers have the task to find a solution and implement it as fast as possible. In this project phase, the software engineers work under time pressure and stress to deliver a functional instrument control software (ICS). The shortness of development time during commissioning is a constraint for software engineering teams and applies to the ARGOS project as well. The goal of the ARGOS (Advanced Rayleigh guided Ground layer adaptive Optics System) project is the upgrade of the Large Binocular Telescope (LBT) with an adaptive optics (AO) system consisting of six Rayleigh laser guide stars and wavefront sensors. For developing the ICS, we used the technique Test- Driven Development (TDD) whose main rule demands that the programmer writes test code before production code. Thereby, TDD can yield a software system, that grows without defects and eases maintenance. Having applied TDD in a calm and relaxed environment like office and laboratory, the ARGOS team has profited from the benefits of TDD. Before the commissioning, we were worried that the time pressure in that tough project phase would force us to drop TDD because we would spend more time writing test code than it would be worth. Despite this concern at the beginning, we could keep TDD most of the time also in this project phase This report describes the practical application and performance of TDD including its benefits, limitations and problems during the ARGOS commissioning. Furthermore, it covers our experience with pair programming and continuous integration at the telescope.
We designed the interferometric test of a 300 mm flat mirror, based onto a spherical mirror and a dedicated CGH. The spherical beam of the interferometer is quasi collimated to the desired diameter by the spherical mirror, used slightly off-axis, and the CGH performs the residual wavefront correction. We performed tests on a 200 mm and 300 mm flat mirrors, and compared the results to the ones obtained by stitching, showing an accuracy well within the designed value. The possibility to calibrate the cavity by subtracting out the figure errors of the spherical mirror has also been evaluated.
We describe the design, development, and laboratory test results of cryogenic probe arms feeding deployable integral field units (IFUs) for the Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS) - a near-infrared multi-object echelle spectrograph for the 10.4-meter Gran Telescopio Canarias. MIRADAS selects targets using 20 positionable pickoff mirror optics on cryogenic probe arms, each feeding a 3.7x1.2-arcsec field of view to the spectrograph integral field units, while maintaining excellent diffraction-limited image quality. The probe arms are based on a concept developed for the ACES instrument for Gemini and IRMOS for TMT. We report on the detailed design and opto-mechanical testing of MIRADAS prototype probe arms, including positioning accuracy, repeatability, and reliability under fully cryogenic operation, and their performance for MIRADAS. We also discuss potential applications of this technology to future instruments.
