ATLAS (Astrophysics Telescope for Large Area Spectroscopy) Probe is a mission concept for a NASA probe-class space mission with primary science goal the definitive study of galaxy evolution through the capture of 300,000,000 galaxy spectra up to z=7. It is made of a 1.5-m Ritchey-Chretien telescope with a field of view of solid angle 0.4 deg<sup>2</sup>. The wavelength range is at least 1 μm to 4 μm with a goal of 0.9 μm to 5 μm. Average resolution is 600 but with a possible trade-off to get 1000 at the longer wavelengths. The ATLAS Probe instrument is made of 4 identical spectrographs each using a Digital Micro-mirror Device (DMD) as a multi-object mask. It builds on the work done for the ESA SPACE and Phase-A EUCLID projects. Three-mirror fore-optics re-image each sub-field on its DMD which has 2048 x 1080 mirrors 13.6 μm wide with 2 possible tilts, one sending light to the spectrograph, the other to a light dump. The ATLAS Probe spectrographs use prisms as dispersive elements because of their higher and more uniform transmission, their larger bandwidth, and the ability to control the resolution slope with the choice of glasses. Each spectrograph has 2 cameras. While the collimator is made of 4 mirrors, each camera is made of only one mirror which reduces the total number of optics. All mirrors are aspheric but with a relatively small P-V with respect to their best fit sphere making them easily manufacturable. For imaging, a simple mirror to replace the prism is not an option because the aberrations are globally corrected by the collimator and camera together which gives large aberrations when the mirror is inserted. An achromatic grism is used instead. There are many variations of the design that permit very different packaging of the optics. ATLAS Probe will enable ground-breaking science in all areas of astrophysics. It will (1) revolutionize galaxy evolution studies by tracing the relation between galaxies and dark matter from the local group to cosmic voids and filaments, from the epoch of reionization through the peak era of galaxy assembly; (2) open a new window into the dark universe by mapping the dark matter filaments to unveil the nature of the dark Universe using 3D weak lensing with spectroscopic redshifts, and obtaining definitive measurements of dark energy and modification of gravity using cosmic large-scale structure; (3) probe the Milky Way's dust-shrouded regions, reaching the far side of our Galaxy; and (4) characterize asteroids and other objects in the outer solar systems.
The Mid-Infrared Instrument (MIRI), a result of the collaborative work of a consortium of European and US institutes, is the only Mid-IR science instrument on the James Webb Space Telescope (JWST). The combination of MIRI0 s sensitivity and angular resolution over the 5-28.5 <i>µm</i> wavelength range will enable investigations into many different science topics, ranging from the local to the high-redshift Universe. The MIRI team has defined and published a set of ”Recommended Strategies” to help observers optimally plan and execute their science programs. Some of these recommendations are generic and applicable to any science case; others are tailored to specific observing modes. Here we summarize key generic recommendations for MIRI observers, with emphasis on detector usage. All this information is available to observers as part of the James Webb Telescope User’s Documentation System and will be updated as needed.<sup>1</sup>
Time-variable phenomena such as transiting exoplanets will be a major science theme for the James Webb Space Telescope (JWST). For Guaranteed Time and Early Release Science Observations, over 500 hours of JWST time have been allocated to time series observations (TSOs) of transiting exoplanets. Several dedicated observing modes are available in the instrument suite, whose operations are specifically tailored to these challenging ob- servations. MIRI, the only JWST instrument covering the wavelength range longwards of 5 µm on JWST, will offer TSOs in two of its modes: the low resolution spectrometer, and the imager. In this paper we will describe these modes for MIRI, and discuss how they differ operationally from regular (non-TSO) observations. We will show performance estimates based on ground testing and modeling, discuss the most relevant detector effects for high precision (spectro-)photometry, and provide some guidelines for planning MIRI TSOs.
We report on tests of the Mid-Infrared Instrument (MIRI) focal plane electronics (FPE) and detectors conducted at the Jet Propulsion Laboratory (JPL). The goals of these tests are to: characterize the performance of readout modes; establish subarray operations; characterize changes to performance when switching between subarrays and/or readout modes; fine tune detector settings to mitigate residual artifacts; optimize anneal effectiveness; and characterize persistence. The tests are part of a continuing effort to support the MIRI pipeline development through better understanding of the detector behavior. An extensive analysis to determine the performance of the readout modes was performed. We report specifically on the comparison of the fast and slow readout modes and subarray tests.
The Verification Model (VM) of MIRI has recently completed an extensive programme of cryogenic testing, with the
Flight Model (FM) now being assembled and made ready to begin performance testing in the next few months. By
combining those VM test results which relate to MIRI's scientific performance with measurements made on FM
components and sub-assemblies, we have been able to refine and develop the existing model of the instrument's
throughput and sensitivity.
We present the main components of the model, its correlation with the existing test results and its predictions for
MIRI's performance on orbit.
MIRI is one of four instruments to be built for the James Webb Space Telescope. It provides imaging, coronography and
integral field spectroscopy over the 5-28.5um wavelength range. MIRI is the only instrument which is cooled to 7K by a
dedicated cooler, much lower than the passively cooled 40K of the rest of JWST, and consists of both an Optical System
and a Cooler System. This paper will describe the key features of the overall instrument design and then concentrate on
the status of the MIRI Optical System development. The flight model design and manufacture is complete, and final
assembly and test of the integrated instrument is now underway. Prior to integration, all of the major subassemblies have
undergone individual environmental qualification and performance tests and end-end testing of a flight representative
model has been carried out. The paper will provide an overview of results from this testing and describe the current
status of the flight model build and the plan for performance verification and ground calibration.
The Mid-Infrared Instrument (MIRI) is a 5 to 28 micron imager and spectrometer that is slated to fly aboard the JWST in
2013. Each of the flight arrays is a 1024×1024 pixel Si:As impurity band conductor detector array, developed by Raytheon
Vision Systems. JPL, in conjunction with the MIRI science team, has selected the three flight arrays along with their spares.
We briefly summarize the development of these devices, then describe the measured performance of the flight arrays along
with supplemental data from sister flight-like parts.
Our group has developed the first 1024×1024 high background Si:As detector array, the Megapixel Mid-Infrared array
(MegaMIR). MegaMIR is designed to meet the thermal imaging and spectroscopic needs of the ground-based and airborne
astronomical communities. MegaMIR was designed with switchable capacitance and windowing capability to
allow maximum flexibility. We report initial test results for the new array.
We present the development of a Focal Plane Module (FPM) for the Mid-Infrared Instrument on JWST. MIRI will
include three FPMs, two for the spectrometer channels and one for the imager channel. The FPMs are designed to
support the detectors at an operating temperature of 6.7 K with high temperature stability and precision alignment while
being capable of surviving the launch environment. The flight units will be built and will undergo a rigorous test
program in the first half of 2008. This paper includes a description of the full test program and will present the results.
The Wide-field Infrared Survey Explorer is a NASA Midex mission launching in late 2009 that will survey the entire
sky at 3.3, 4.7, 12, and 23 microns (PI: Ned Wright, UCLA). Its primary scientific goals are to find the nearest stars
(actually most likely to be brown dwarfs) and the most luminous galaxies in the universe. WISE uses three dichroic
beamsplitters to take simultaneous images in all four bands using four 1024×1024 detector arrays. The 3.3 and 4.7
micron channels use HgCdTe arrays, and the 12 and 23 micron bands employ Si:As arrays. In order to make a
1024×1024 Si:As array, a new multiplexer had to be designed and produced. The HgCdTe arrays were developed by
Teledyne Imaging Systems, and the Si:As array were made by DRS.
All four flight arrays have been delivered to the WISE payload contractor, Space Dynamics Laboratory. We present
initial ground-based characterization results for the WISE arrays, including measurements of read noise, dark current,
flat field and latent image performance, etc. These characterization data will be useful in producing the final WISE data
product, an all-sky image atlas and source catalog.
MIRI is the mid-IR instrument for the James Webb Space Telescope and provides imaging, coronography and integral
field spectroscopy over the 5-28μm wavelength range. MIRI is the only instrument which is cooled to 7K by a dedicated
cooler, much lower than the passively cooled 40K of the rest of JWST, which introduces unique challenges. The paper
will describe the key features of the overall instrument design. The flight model design of the MIRI Optical System is
completed, with hardware now in manufacture across Europe and the USA, while the MIRI Cooler System is at PDR
level development. A brief description of how the different development stages of the optical and cooling systems are
accommodated is provided, but the paper largely describes progress with the MIRI Optical System. We report the
current status of the development and provide an overview of the results from the qualification and test programme.
The Mid-Infrared Instrument (MIRI) is one of the three scientific instruments to fly on the James Webb Space
Telescope (JWST), which is due for launch in 2013. MIRI contains two sub-instruments, an imager, which has low
resolution spectroscopy and coronagraphic capabilities in addition to imaging, and a medium resolution IFU
spectrometer. A verification model of MIRI was assembled in 2007 and a cold test campaign was conducted between
November 2007 and February 2008. This model was the first scientifically representative model, allowing a first
assessment to be made of the performance. This paper describes the test facility and testing done. It also reports on the
first results from this test campaign.
The present paper describes the different steps leading to the Flight Model integration of the Mid-Infra Red IMager
Optical Bench MIRIM-OB which is part of the scientific payload of the JWST. In order to demonstrate a space
instrument capability to survive the challenging space environment and deliver the expected scientific data, a specific
development approach is applied in order to reduce the high level of risks. The global approach for MIRIM-OB, and the
principal results associated to the two main models, the Structural Qualification Model for vibration and the Engineering
and Test Model for optical performance measured in the infra red at cryogenic temperature will be described in this
A feasibility design study was undertaken to assess the requirements of a mid-infrared echelle spectrograph (MIRES)
with a resolving power of 120,000 and its associated mid-infrared adaptive optics (MIRAO) system on the Thirty-Meter
Telescope. Our baseline design incorporates a 2K×2K Si:As array or array mosaic for the spectrograph and a 1K×1K
Si:As array for the slit viewer. Various tradeoffs were studied to minimize risk and to optimize the sensitivity of the
instrument. Major challenges are to integrate the spectrograph to the MIRAO system and, later, to an adaptive
secondary, the procurement of a suitable window and large KRS-5 lenses, and the acquisition of large format mid-IR
detector arrays suitable for the range of background conditions. We conclude that the overall risk is relatively low and
there is no technical reason that should prevent this instrument from being ready for use at first light on the Thirty-
The Megapixel Mid-infrared Instrument (MegaMIR) is a proposed Fizeau-mode camera for the Large Binocular Telescope operating at wavelengths between 5 and 28 μm. The camera will be used in conjunction with the Large Binocular Telescope Interferometer (LBTI), a cryogenic optical system that combines the beams from twin 8.4-m telescopes in a phase coherent manner. Unlike other interferometric systems, the co-mounted telescopes on the LBT satisfy the sine condition, providing diffraction-limited resolution over the 40" field of view of the camera. With a 22.8-m baseline, MegaMIR will yield 0.1" angular resolution, making it the highest resolution wide field imager in the thermal infrared for at least the next decade. MegaMIR will utilize a newly developed 1024 x 1024 pixel Si:As detector array that has been optimized for use at high backgrounds. This new detector is a derivative of the Wide-field Infrared Survey Explorer (WISE) low-background detector. The combination of high angular resolution and wide field imaging will be a unique scientific capability for astronomy. Key benefits will be realized in planetary science, galactic, and extra-galactic astronomy. High angular resolution is essential to disentangle highly complex sources, particularly in star formation regions and external galaxies, and MegaMIR provides this performance over a full field of view. Because of the great impact being made by space observatories like the Spitzer Space Telescope, the number of available targets for study has greatly increased in recent years, and MegaMIR will allow efficient follow up science.
We present a description of a new 1024×1024 Si:As array designed for ground-based use from 5 - 28 microns. With a maximum well depth of 5e6 electrons, this device brings large-format array technology to bear on ground-based mid-infrared programs, allowing entry to the megapixel realm previously only accessible to the near IR. The multiplexer design features switchable gain, a 256×256 windowing mode for extremely bright sources, and it is two-edge buttable. The device is currently in its final design phase at DRS in Cypress, CA. We anticipate completion of the foundry run in October 2005. This new array will enable wide field, high angular resolution ground-based follow up of targets found by space-based missions such as the Spitzer Space Telescope and the Widefield Infrared Survey Explorer (WISE).
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.
Modelling the scientific performance of infrared instruments during the design and definition phase of a project is an essential part of the system design optimisation for both the instrument and the observatory. This is particularly so in the case of space observatories where the opportunities for correcting design errors or omissions following launch are limited. We describe the approach taken to the estimation of the sensitivity of the Mid Infrared Instrument (MIRI) operating from 5 to 28 microns on the NASA/ESA James Webb Space Telescope (JWST) due for launch in 2011. We show how the sensitivity is estimated both for the photometric imager and the integral field spectrometer using a model that includes the effects of background radiation from the telescope and its surroundings; diffraction effects and detector performance and operations.
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.
A long-wavelength large format Quantum Well Infrared Photodetector (QWIP) focal plane array has been successfully used in a ground based astronomy experiment. QWIP arrays afford greater flexibility than the usual extrinsically doped semiconductor infrared (IR) arrays. Recently, we operated an infrared camera with a 256x256 QWIP array sensitive at 8.5 μm at the prime focus of the 5-m Hale telescope, obtaining the images. The remarkable noise stability - and low 1/f noise - of QWIP focal plane arrays enable camera to operate by modulating the optical signal with a nod period up to 100 s. A 500 s observation on dark sky renders a flat image with little indication of the low spatial frequency structures associated with imperfect sky substration or detector drifts. At low operating temperatures for low-background irradiance levels, high resistivity of thick barriers in the active region of QWIPs impeded electrons from entering the detector from the opposite electrode. This could lead to a delay in refilling the space-charge buildup, and result in a lower responsitivity at high optical modulation frequencies. In order to overcome this problem we have designed a new detector structure, the blocked intersubband detector (BID) with separate active quantum well region and blocking barrier.
A long-wavelength large format Quantum Well Infrared Photodetector (QWIP) focal plane array has been successfully used in a ground based astronomy experiment. QWIP arrays afford greater flexibility than the usual extrinsically doped semiconductor infrared arrays. The wavelength of the peak response and cutoff can be continuously tailored over a range wide enough to enable light detection at any wavelength range between 6 - 20 micrometers .
One of the simplest device realizations of the classic particle- in-the-box problem of basic quantum mechanics is the Quantum Well Infrared Photodetector (QWIP). In this paper we discuss the effect of focal plane array non-uniformity on the performance, optimization of the detector design, material growth and processing that has culminated in realization of large format long-wavelength QWIP cameras, holding forth great promise for many applications in 6-18 micron wavelength range in science, medicine, defense and industry. In addition, we present the recent developments in long-wavelength/very long-wavelength dualband QWIP imaging camera for various applications.
Quantum Well IR Photodetectors (QWIPs) afford greater flexibility than the usual extrinsically doped semiconductor IR detectors. The wavelength of the peak response and cutoff can be continuously tailored over a range wide enough to enable light detection at any wavelength range between 6-20 micrometers . The spectral band width of these detectors can be tuned from narrow to wide allowing various applications. Also, QWIP device parameters can be optimized to achieve extremely high performance sat lower operating temperatures due to exponential suppression of dark current. Furthermore, QWIPs offer low cost per pixel and highly uniform large format focal plane arrays (FPAs) mainly due to mature GaAs/AlGaAs growth and processing technologies. The other advantages of GaAs/AlGaAs based QWIPs are higher yield, lower 1/f noise and radiation hardness. Recently, we operated an IR camera with a 256 by 256 QWIP array sensitive at 8.5 micrometers at the prime focus of the 5-m Hale telescope, obtaining the images. The remarkable noise stability - and low 1/f noise - of QWIP focal plane arrays enable camera to operate by modulating the optical signal with a nod period up to100 s. A 500 s observation on dark sky renders a flat image with little indication of the low spatial frequency structures associated with imperfect sky subtraction or detector drifts.
This paper summarizes the findings of the Next Generation Space Telescope (NGST) Detector Requirements Review Panel. This panel was comprised of NGST Integrated Science Instrument Module study representatives, detector specialists, and members of the NGST project science team. It has produced a report that recommends detector performance levels, and has provided rationale for deriving these levels from basic, anticipated NGST science goals and programs. Key parameters such as detector array format, quantum efficiency, and noise are discussed and prioritized.
One of the simplest device realizations of the classic particle-in-the-box problem of basic quantum mechanics is the Quantum Well Infrared Photodetector (QWIP). In this paper we discuss the effect of focal plane array non-uniformity on the performance, optimization of the detector design, material growth and processing that has culminated in realization of large format long-wavelength QWIP cameras, holding forth great promise for many applications in 6 - 18 micron wavelength range in science, medicine, defense and industry. In addition, we present the recent developments in long-wavelength/very long-wavelength dualband QWIP imaging camera for various applications.
We present diffraction limited 2-25 micrometers images, obtained with the W.M. Keck 10-m telescopes that spatially resolve the cool Galactic Center source IRS 21, an enigmatic object that has alluded classification. Modeled as a Gaussian, the azimuthally averaged intensity profile of IRS 21, an enigmatic object that has alluded classification. Modeled asa a Gaussian, the azimuthally averaged intensity profile of IRS 21 has a HWHM radius of 740 +/- 30 AU at 2.2 micrometers and an average HWHM radius of 1540 +/- 90 AU at mid-IR wavelength. These sizes along with its color temperature favor the hypothesis that IRS 21 is self-luminous rather than an externally heated dust clump. Based on the size alone, the remaining possible dust geometries are (1) an intrinsic inflow or outflow or (2) an extrinsic dust distribution, in which case IRS 21 could be simply embedded in the Northern Arm. A simple SED model of the IR photometry from the literature and our mid-IR images reveal that the near-IR radiation is scattered light from an unknown embedded source while the mid-IR radiation is the remaining re-radiated light. The agreement between the 2.2 micrometers polarization angle for IRS 21 and the 12.5 micrometers polarization angle at the position of IRS 21, the symmetric shape of its intensity profiles, as well as the similarity of the observed properties of all the Northern Arm sources, lead us to conclude that the scattering dust around IRS 21 is extrinsic to the central source and is associated with the Northern Arm.
In recent years, many research groups in the world have demonstrated large format quantum well IR photodetector (QWIP) focal pane arrays for various thermal imaging applications. QWIPs as opposed to conventional low bandgap IR detectors, are limited by thermionic dark current and not tunneling current down to 30K or less. As a result the performance of QWIPs can be substantially improved by cooling from 70K to 30K. Cooling does not induce any nonuniformity or 1/f noise in QWIP focal plane arrays. In this paper, we discuss the development of highly uniform long-wavelength QWIPs for astronomical applications.
One of the simplest device realizations of the classic particle-in-the-box problem of basic quantum mechanics is the Quantum Well Infrared Photodetector (QWIP). In this paper we discuss the optimization of the detector design, material growth and processing that has culminated in realization of 15 micron cutoff 128 X 128 QWIP focal plane array camera, hand-held and palmsize 256 X 256 long-wavelength QWIP cameras and 648 X 480 long-wavelength camera, holding forth great promise for myriad applications in 6 - 25 micron wavelength range in science, medicine, defense and industry. In addition, we present the recent developments in broadband QWIPs, mid-wavelength/long-wavelength dualband QWIPs, long- wavelength/very long-wavelength dualband QWIPs, and high quantum efficiency QWIPs for low background applications in 4 - 26 micrometer wavelength region for NASA and DOD applications.
ProtoCAM, a new infrared array camera, has been built for the NASA 3-m Infrared Telescope Facility (IRTF). The camera is built around a 62 x 58 InSb hybrid array and is sensitive throughout the 1-5-micron atmospheric windows. The camera is equipped with standard astronomical filters as well as a full complement of continuously variable filters providing a spectral resolution down to 1 percent. On the IRTF, the platescale is variable real-time from 0.14 to 0.35 arcsec. The camera, the electronics, the software, and the performances are discussed, and some preliminary astronomical results are presented.