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Growth of Hg1−xCdxTe by molecular beam epitaxy (MBE) has been under development since the early 1980s at Rockwell Scientific Company (RSC), formerly the Rockwell Science Center; and we have shown that high-performance and highly reproducible MBE HgCdTe double heterostructure planar p-on-n devices can be produced with high throughput for various single- and multiplecolor infrared applications. In this paper, we present data on Hg1−xCdxTe epitaxial layers grown in a ten-inch production MBE system. For growth of HgCdTe, standard effusion cells containing CdTe and Te were used, in addition to a Hg source. The system is equipped with reflection high energy electron diffraction (RHEED) and spectral ellipsometry in addition to other fully automated electrical and optical monitoring systems. The HgCdTe heterostructures grown in our large ten-inch Riber 49 MBE system have outstanding structural characteristics with etch-pit densities (EPDs) in the low 104 cm−2 range, Hall carrier concentration in low 1014 cm−3, and void density

Using a new f/31 secondary on a tip-tilt platform, we have built an image-stabilization system which has been used regularly for astronomical imaging and spectroscopy on the University of Hawaii 2.2 m telescope. Diffraction-limited cores of stellar point-spread functions are achieved in near-infrared imaging, with Strehl ratios as high as 0.47. K-band images with 03 FWHM resolution (without deconvolution) are routinely obtained. The construction, operation, and capability of the current system are described, a summary of recent scientific findings is presented, and future improvements are outlined.

Teledyne’s silicon hybrid CMOS focal plane array technology has matured into a viable, high performance and high- TRL alternative to scientific CCD sensors for space-based applications in the UV-visible-NIR wavelengths. This paper presents the latest results from Teledyne’s low noise silicon hybrid CMOS visible focal place array produced in 4K×4K format with 10 μm pixel pitch. The H4RG-10 readout circuit retains all of the CMOS functionality (windowing, guide mode, reference pixels) and heritage of its highly successful predecessor (H2RG) developed for JWST, with additional features for improved performance. Combined with a silicon PIN detector layer, this technology is termed HyViSI™ (Hybrid Visible Silicon Imager). H4RG-10 HyViSI™ arrays achieve high pixel interconnectivity (

In preparation for the large number of infrared pixels required in the era of Extremely Large Telescopes, Teledyne, in partnership with the University of Hawaii and GL Scientific, has been funded to develop the next generation of largeformat infrared focal plane array for ground-based astronomy; the 4096 × 4096 pixel (15 micron pitch) H4RG-15. Teledyne has successfully designed, produced, and tested the first generation H4RG-15 prototype arrays. This paper reports on the functionality and performance test results of the H4RG-15 prototypes and provides status of the 2012 pilot production effort.

Teledyne’s H2RG focal plane arrays have been widely used in scientific infrared and visible instruments for ground-based and space-based telescopes. The majority of applications use the H2RG with 2.5 micron cutoff HgCdTe detector pixel at an operating temperature of ~77 K (LN2). The exceptionally low dark current of the 2.5 micron H2RG allows for operation at higher temperatures which facilitates simplified instrument designs and therefore lower instrument cost. Performance data of 2.5 micron H2RG arrays at 77K, 100 K, and 120 K are presented and are discussed as a function of detector bias and pixel readout rate. This paper also presents performance data of 1.75 micron and 5.3 micron H2RG focal plane arrays and discusses some of the inherent performance differences compared to 2.5 micron cutoff arrays. A complete infrared camera system that uses the H2RG focal plane array and SIDECAR ASIC focal plane electronics is introduced.

The primary goal of the HAWAII 4RG-15 (H4RG-15) development is to provide a 16 megapixel 4096x4096 format at significantly reduced price per pixel while maintaining the superb low background performance of the HAWAII 2RG (H2RG). The H4RG-15 design incorporates several new features, notably clocked reference output and interleaved reference pixel readout, that promise to significantly improve noise performance while the reduction in pixel pitch from 18 to 15 microns should improve transimpedance gain although at the expense of some degradation in full well and crosstalk. During the Phase-1 development, Teledyne has produced and screen tested six hybrid arrays. In preparation for Phase-2, the most promising of these are being extensively characterized in the University of Hawaii’s (UH) ULBCam test facility originally developed for the JWST H2RG program. The end-to-end performance of the most promising array has been directly established through astronomical imaging observations at the UH 88-inch telescope on Mauna Kea. We report the performance of these Phase-1 H4RG-15s within the context of established H2RG performance for key parameters (primarily CDS read noise), also highlighting the improvements from the new readout modes.

We report on the final design and current status of a 1-5 micron infrared test bench at the ETH Zurich Institute for Astronomy. This facility will enable us to characterize infrared optics, both reflective and transmissive, at cryogenic operating temperatures for both ground- and space-based applications. A focus of our lab is to facilitate the detection and characterization of extra-solar planets. The test bench is designed to characterize a range of spectrally dispersive and diffraction suppression optics such as filters, grisms, gratings, as well as both focal and pupil plane coronagraphs. The test bench is built around a 2048x2048 HAWAII-2RG detector from Teledyne Imaging Systems. The optical bench is envisioned to operate down to 30 K. “First light” is expected in the second half of 2012. We outline the status of the project, and describe the capabilities of the test bench in detail in order to alert potential collaborators to this new capability.

The Orthogonal Transfer Array (OTA) is a monolithic array of small CCDs that are 4-side buttable and can be mosaicked to make the 40K×40K focal plane required by Pan-STARRS. These devices have other interesting properties such as a 'Deep Depletion' structure which enables 75 µm thick devices to be fully depleted with modest charge diffusion, while offering 35 % QE at 1 µm. Pan-STARRS has evaluated OTAs from a test lot, and is now fabricating the first two production lots. We expect to deploy the first of four cameras in June 2006.

The Pan-STARRS project will undertake repeated surveys of the sky, finding "Killer Asteroids" and everything which moves or blinks, as well as building an unprecedentedly deep and accurate image of the sky. The key technology for this is the next generation of large format cameras, which will offer an order of magnitude improvement in size, speed, and cost relative to existing instruments. This is achieved in part by the integrated design of telescope, detectors, controllers, software, and scientific direction.

The orthogonal-transfer array (OTA) is a new charge-coupled device (CCD) concept for wide-field imaging in groundbased astronomy based on the orthogonal-transfer CCD (OTCCD). This device combines an 8×8 array of small OTCCDs, each about 600×600 pixels with on-chip logic to provide independent control and readout of each CCD. The device provides spatially varying electronic tip-tilt correction for wavefront aberrations, as well as compensation for telescope shake. Tests of prototype devices have verified correct functioning of the control logic and demonstrated good CCD charge-transfer efficiency and high quantum efficiency. Independent biasing of the substrate down to -40 V has enabled fully depleted operation of 75-μm-thick devices with good charge PSF. Spurious charge or "glow" due to impact ionization from high fields at the drains of some of the NMOS logic FETs has been observed, and reprocessing of some devices from the first lot has resolved this issue. Read noise levels have been 10 - 20 e-, higher than our goal of 5 e-, but we have identified the likely sources of the problem. A second design is currently in fabrication and uses a 10-μm pixel design resulting in a 22.6-Mpixel device measuring 50×50 mm. These devices will be deployed in the U. of Hawaii Pan-STARRS focal plane, which will comprise 60 OTAs with a total of nearly 1.4 Gpixels.

The University of Hawaii Wide-Field Imager (UHWFI) is a focal compressor system designed to project the full half-degree field of the UH 2.2 m telescope onto the refurbished UH 8Kx8K CCD camera. The optics use Ohara glasses and are mounted in an oil-filled cell to minimize light losses and ghost images from the large number of internal lens surfaces. The UHWFI is equipped with a six-position filter wheel and a rotating sector blade shutter,both driven by stepper motors. The instrument saw first light in 2004 in an engineering mode. After filling the lens cell with index matching oil, integration of all software components into the user interface, tuning of the CCD performance, and the purchase of the final filter set, UHWFI is now fully commissioned at the UH 2.2 m telescope., Comment: 13 pages of text, 2 tables, 8 figures

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.

The NIRCam instrument will fly ten of Rockwell Scientific’s infrared molecular beam epitaxy HgCdTe 2048x2048 element detector arrays, each the largest available with current technology, for a total of 40 Megapixels. The instrument will have two varieties of MBE HgCdTe, a SWIR detector with λco = 2.5 μm, for the shortwave channel of NIRCam (0.6-2.3 μm); and a MWIR detector with λco = 5.3 μm, for the longwave channel of NIRCam (2.4-5.0 μm). Demonstrated mean detector dark currents less than 0.01 electrons per second per pixel at operating temperatures below 42 K for the MWIR and below 80 K for the SWIR, combined with quantum efficiency in excess of 80 percent and read noise below 6 electrons rms, make these detector arrays by far the most sensitive SWIR and MWIR devices in the world today. The unique advantages of molecular beam epitaxy as well as FPA data on noise, dark current, quantum efficiency, and other performance metrics will be discussed. In addition, the focal plane assembly package designs will be presented and discussed.

The orthogonal-transfer array (OTA) is a new CCD architecture designed to provide wide-field tip-tilt correction of astronomical images. The device consists of an 8x8 array of small (~500x500 pixels) orthogonal-transfer CCDs (OTCCD) with independent addressing and readout of each OTCCD. This approach enables an optimum tip-tilt correction to be applied independently to each OTCCD across the focal plane. The first design of this device has been carried out at MIT Lincoln Laboratory in support of the Pan-STARRS program with a collaborative parallel effort at Semiconductor Technology Associates (STA) for the WIYN Observatory. The two versions of this device are functionally compatible and share a common pinout and package. The first wafer lots are complete at Lincoln and at Dalsa and are undergoing wafer probing.

CFHT is planning to upgrade its adaptive optics system, PUEO, to a high order system with 104 elements, PUEO NUI. Currently PUEO uses a 19 element deformable mirror with the equivalent 19 avalanche photodiode (APD) detectors as its curvature wavefront sensor. PUEO NUI plans to implement the curvature wavefront sensor using back illuminated CCID-35 detectors developed by J. Beletic et al. instead of 104 APDs, which are prohibitively expensive under the present budget conditions. The CCID-35 detectors, developed at ESO and MIT/LL, were specifically designed to serve as direct replacements for APDs in curvature sensing. The first step in the upgrade is to build and test a system using two CCID-35 detectors, dubbed FlyEyes. These new detectors were successfully tested and integrated in the lab by R. Dorn at ESO but have yet to see sky time. FlyEyes will be their first opportunity. They will directly replace the 19 APDs in PUEO temporarily for a few engineering nights in January of 2005.

The PanSTARRS project has undertaken an ambitious effort to develop a completely new array controller architecture that is fundamentally driven by the large 1gigapixel, low noise, high speed OTCCD mosaic requirements as well as the size, power and weight restrictions of the PanSTARRS telescope. The result is a very small form factor next generation controller scalar building block with 1 Gigabit Ethernet interfaces that will be assembled into a system that will readout 512 outputs at ~1 Megapixel sample rates on each output. The paper will also discuss critical technology and fabrication techniques such as greater than 1MHz analog to digital converters (ADCs), multiple fast sampling and digital calculation of multiple correlated samples (DMCS), ball grid array (BGA) packaged circuits, LINUX running on embedded field programmable gate arrays (FPGAs) with hard core microprocessors for the prototype currently being developed.

The University of Hawaii Wide-Field Imager (UHWFI) is a focal compressor designed to project the full half-degree field of the UH 2.2m telescope onto the refurbished 8K×8K CCD camera. The optics use Ohara glasses and are mounted in an oil-filled cell to minimize light losses and ghost images from the large number of internal surfaces. The UHWFI is equipped with a six-position filter wheel and a rotating sector shutter, both driven by stepper motors. The instrument is currently in the design phase and will be commissioned early in 2003.

The Institute for Astronomy has developed and recently installed a high-resolution cross-dispersed echelle spectrograph for use at one of the coude foci of the AEOS 3.7-meter telescope, operated by the Air Force Space Command atop Mt. Haleakala on the island of Maui. The spectrograph features an optical arm for the wavelength range 0.5 - 1.0 μm and an infrared arm for the range 1.0 - 2.5 μm. We review the spectrograph design and present commissioning results obtained with both the visible and infrared arms. Both channels use a white-pupil collimator design to maximize grating efficiency and to limit the size of the camera optics. The visible arm of the spectrograph uses deep-depletion CCDs optimized for operation near 1.0 μm. The infrared detector is a 2048 x 2048 HgCdTe array (HAWAII-2) that has been developed by the Rockwell Science Center for this project. Both channels are equipped with slit-viewing cameras for object acquisition and control of a fast guiding tip-tilt mirror located at a pupil image in the spectrograph fore optics.

Until now, only avalanche photodiodes (APD) have been used as the detectors in curvature wavefront sensors in astronomy. This is due to the strict requirements of very short integration time and very low readout noise. In 1999, Beletic et al. invented a new CCD design which should achieve the same performance as APDs but with higher reliability and lower cost. In addition, this CCD has higher quantum efficiency than APD modules and larger dynamic range, eliminating the need for neutral density filters on bright objects. The CCD was designed and fabricated by MIT Lincoln Laboratory in collaboration with ESO and IfA. R. Dorn extensively tested the CCD in laboratory at ESO and proved that it achieves the predicted performance. CFHT is currently implementing this CCD on PUEO, CFHT’s Adaptive Optics system, to assess its performance for the first time in real conditions on the sky for a direct comparison with the current 19 APD detector system. In this article we present the current implementation scheme and discuss the upgrade we foresee for PUEO NUI, a 104-element high-order curvature AO system envisaged to replace the current AO system at Canada-France-Hawaii Telescope.

The WIYN One Degree Imager (ODI) will be a well-sampled (0.11” per pixel) imager that provides a full one degree square field of view (32K×32K pixels). ODI will utilize high resistivity, red sensitive, orthogonal transfer (OT) CCDs to provide rapid correction for image motion arising from telescope shake, guider errors, and atmospheric effects. ODI will correct the full field of view by deploying 64 array packages having a total of 4096 independently controllable OTCCDs that can correct individually for local (2 arcmin) image motion. Each array package is an orthogonal transfer array (OTA) of 64 CCDs arranged in an 8×8 grid. Each CCD has 512×512 pixels. We expect the median image quality at the WIYN 3.5m telescope in RIZ to be 0.52”, 0.43”, and 0.35” FWHM. ODI makes optimal use of the WIYN telescope, which has superb optics, excellent seeing characteristics, a natural 1.4 degree field of view (with a new corrector), and can serve as a pathfinder for LSST in terms of detectors, data pipelines, operations strategies, and scientific motivation.

We describe progress in removing image motion over large fields of view. A camera using a new type of CCD has been commissioned and we report first results which are very promising for wide field imaging. We are embarking on a project to build a new type of astronomical CCD which should provide image motion compensation over arbitrarily large fields of view, very fast readout, autoguiding capability, good red sensitivity, and should be significantly less expensive than the present generation of CCDs.

CFH12K is a 12,228 by 8,192 pixel wide-field imaging camera in operation at the 3.6m Canada-France-Hawaii Telescope (CFHT) since January 1999. It still remains the largest close-packed array in use in astronomy today. The mosaic consists of twelve MIT Lincoln laboratories 2K by 4K thinned backside illuminated CCID-20 devices. The camera is used in broad-band and narrow-band filter direct imaging mode which constrains the devices' operating parameters to ensure the best data quality. Adaptation to the 20-year old CFHT prime focus environment included modifications to reduce the scattered light seen by the camera. Computer facilities have been upgraded and new software has been developed to handle the large amount of data generated. The two terabytes of scientific data taken by the camera in 1999 has proven the success of CFHT's new capability for 42 by 28 square arcminute imaging with high resolution subarcsecond seeing.

We review the state-of-the-art in large area mosaic CCD camera designs and discuss the technical challenges and future evolution of these instruments. Many of these mosaic cameras are being used as wide-field optical imagers, and toward this end we present a new approach for achieving enhanced resolution (FWHM ≈ O”.12) deep images over large fields of view (l°×l°) using an array of modest telescopes (D ∼ 1.5-1.8m) equipped with mosaics of independently-addressable orthogoral transfer CCD (OTCCD) arrays.

CFH12K is a 12Kx8K wide field imaging camera for the CFHT prime focus. The mosaic consists of twelve MIT Lincoln Laboratory 2Kx4k thinned backside illuminated CCID-20 devices. The devices’ operating parameters have been optimised to ensure the best data quality for use in broad and narrow band filter imaging mode. Adaptation to the CFHT prime focus environment included modifications to reduce the scattered light seen by the CFH12K. Science data taken by the camera has proven the success of CFHT’s new capability for 42×28 square arcminute imaging with high-resolution subarcsecond seeing.

We propose a new strategy for obtaining enhanced resolution (FWHM = 0.12 arcsec) deep optical images over a wide field of view. As is well known, this type of image quality can be obtained in principle simply by fast guiding on a small (D = 1.5m) telescope at a good site, but only for target objects which lie within a limited angular distance of a suitably bright guide star. For high altitude turbulence this 'isokinetic angle' is approximately 1 arcminute. With a 1 degree field say one would need to track and correct the motions of thousands of isokinetic patches, yet there are typically too few sufficiently bright guide stars to provide the necessary guiding information. Our proposed solution to these problems has two novel features. The first is to use orthogonal transfer charge-coupled device (OTCCD) technology to effectively implement a wide field 'rubber focal plane' detector composed of an array of cells which can be guided independently. The second is to combine measured motions of a set of guide stars made with an array of telescopes to provide the extra information needed to fully determine the deflection field. We discuss the performance, feasibility and design constraints on a system which would provide the collecting area equivalent to a single 9m telescope, a 1 degree square field and 0.12 arcsec FWHM image quality., 46 pages, 22 figures, submitted to PASP, a version with higher resolution images and other supplementary material can be found at http://www.ifa.hawaii.edu/~kaiser/wfhri

We are developing a high-resolution cross-dispersed echelle spectrograph for installation at one of the coude foci of the new AEOS 3.67 meter telescope, operated by the Air Force Space Command on Haleakala, Maui, Hawaii. The spectrograph will consist of two major subsystems, an optical arm for the wavelength range 0.5-1.0 microns and a SWIR arm for the range 1.0-2.5 microns. The optical arm will include a mosaic 4096 by 4096 thinned CCD array, providing coverage of the wavelength range in two settings at a resolving power of 50,000. The CCD camera will be operated in frame-transfer mode. The IR arm will consist of a compact, folded cross- dispersed cryogenic echelle spectrography. The SWIR detector will be a 2048 by 2048 HgCdTe array, based on the existing HAWAII 1024 by 1024 devices. The large-format detector will permit coverage of the entire J or H band in a single grating setting with a resolving power of 60,000, and the K band in two settings. The high resolution, coupled with careful attention to scattering and stray light in the optical system, will permit exploitation of the low sky background between the strong OH airflow lines. Adequate order separation will be maintained to permit work on moderately extended objects while still retaining sky subtraction capability. The spectrography is expected to be available for use in early 2000.

The Institute for Astronomy at the University of Hawaii has an active program in detector development, both in optical CCDs and Infrared Arrays. Below, I briefly describe the optical detector program and the existing scientific CCD cameras in place on UH facilities on Mauna Kea. I also list present and future development efforts.

We describe recent work in the area of large, back-illuminated CCD imagers at M.I.T. Lincoln Laboratory as well as new technology applicable to astronomy. We completed in 1995 the development of a 2560 x 1960-pixel frame-transfer imager that filled a 100-mm wafer and several back-illuminated versions of this device were completed. More recently we have begun the development, in collaboration with the U. of Hawaii, of a three-side abuttable 2k x 4k CCD for a multi-chip focal plane. In the unused chord area of the wafer layout, we added test imagers as development vehicles for blooming control and for the demonstration of a CCD that is capable of charge transfer in all four directions. We expect the latter to find application as an electronic means of performing tip-tilt correction to compensate for atmospheric turbulence.

At the University of Hawaii, Institute for Astronomy, we are carrying out several activities to develop CCDs for astronomical observation. In this paper, we report the test results of devices from three CCD manufacturers: Loral, Hamamatsu Photonics and MIT/Lincoln Laboratory.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The MegaCam is a multi-purpose, wide-field, two-color camera being designed for use at the UH 2.2m telescope. The camera will utilize a Rockwell 1024 x 1024 HgCdTe detector array for 1-2.5 micrometers imaging, and a 2048 x 4096 frame-store CCD (2048 x 2048 active area) for optical imaging. The optics are based on a modified Offner relay design with additional lenses to give a 2:1 magnification in the infrared channel for a field of view of 5'.8 x 5'.8 (0.34 arcsec/pixel) using the f/10 telescope secondary, or a scale of 1'.9 x 1'.9 (0.15 arcsec/pixel) at f/31. This design provides a simple, high-throughput, and compact optical layout. A beamsplitter is placed in front of the IR optics at a low angle of incidence to form the optical image at 1:1 magnification on the CCD, for a field of view of 4'.7 x 4'.7 and 1'.5 x 1'.5 at f/10 and f/31, respectively. The optics and filters are to be housed in a LN2-cooled dewar. The CCD and IR arrays will be operated with modified SDSU-design controllers. The user interface will have several modes to make simultaneous optical/IR imaging simple to configure and perform at the telescope.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We describe the design of an ultra-format, 8192 x 8192 pixel CCD mosaic imager under construction for the Mauna Kea Observatory. The mosaic will be built from a 4 x 2 array of 3-edge-buttable 2048 x 4096 15 micrometers pixel CCDs fabricated by Loral Fairchild. We outline the scientific justification for such a mosaic and the technical details of the 3-edge-buttable 2048 x 4096 CCD design. We also present our strategy for imager packaging and subsequent mosaic construction which will result in a mosaic with individual elements that can easily be installed and removed. This particular CCD mosaic is intended for two existing MKO telescopes: the UH 2.2 m and the CFHT 3.6m. In either configuration, the imager will offer an enormous field of view with excellent spatial sampling.

A fast tip-tilt secondary is being implemented on the University of Hawaii 2.2-m telescope, to provide image quality to match the site characteristics of Mauna Kea, and complement the existing wide-field RC secondary.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

CCDs having circular rather than rectilinear symmetry offer some advantages for low-order wavefront sensing. A series of imagers having 24 sectors and 12 radial zones (plus frame store) has been developed. Three different output structures have been utilized in order to investigate low-noise operational limits.

This paper describes a low cost adaptive optics (AO) instrument that is being built for the f/31 focus of the UH 2.2m telescope. While operating within the low cost constraint, we have tried to maximize the flexibility and usefulness of the instrument, and minimize the impact of the necessary performance compromises. We have used off-the-shelf optical and electronic components wherever possible, and have emphasized simplicity of design throughout the instrument. The UH prototype AO system, on which the 2.2m AO system is based, is described elsewhere, thus the principles of operation of the UH 2.2m instrument will not be described in detail here.

We present the first results from the University of Hawaii Institute for Astronomy project to develop largeformat optical CCD mosaics for the telescopes on Manna Kea. We have constructed two 4096 x 4096 mosaics: both are 2 x 2 arrays of 2-edge abuttable 2048 x 2048 15tm pixel imagers built by Loral Aeronutronics. The first mosaic is constructed using an abuttable package design yielding an array that can be assembled and disassembled using the bestavailable separatelytested quadrants. The second mosaic is formed by packaging a monolithic quad die consisting of four functioning 2048 x 2048 devices from a single wafer. In addition to the mechanical design of the focal plane and dewar we describe the system used to operate the CCDs including the programmable DSP-based CCD controller and our high-speed serial interface into the DSP port of a NeXT computer workstation. We present our initial x-ray and optical test results from the " monolithic mosaic" and our first data from the telescope. 1

A large-format CCD imager to be used in a 2 X 2 mosaic array has been designed and fabricated. Each quadrant is an independent imager of 2048 X 2048 15 micrometers pixels, designed to be edge-butted on two sides. After sawing and mounting the individual dice in custom, buttable packages, the authors assembled a 4096 X 4096 mosaic array measuring more than 61 mm on a side with just 400 microns dead space between imaging areas. With this buttable package design, each quadrant of the mosaic can be separately tested, optimized, and, if necessary, replaced. Also described are smaller 2688 X 512 15 micrometers pixel CCD imagers designed for spectrographic applications that were fabricated using space in the chords of the same 100 mm silicon wafer containing the 2048 X 2048 edge-buttable devices.

In general, attention to a multitude of details is essential when designing low noise CCD cameras. This paper describes some of the critical details of the MIT X-ray CCD camera design. Special attention is given to those portions of the system which are different from conventional practice in the design of CCD cameras. Furthermore, an attempt has been made to generalize the design so that both optical and X-ray requirements can be satisfied wherever possible. Currently, noise levels of

This paper describes the design and performance of a laboratory instrument for imaging and nondispersive spectroscopy of soft X-rays (300 eV to 10 keV) utilizing a virtual-phase CCD. This instrument has achieved a spatial resolution of 22 microns (limited by pixel size) with an overall array area of 584 x 390 pixels. It has achieved an energy resolution of about 140 eV FWHM for single-pixel Fe-55 X-ray events (5.9 keV) with the CCD operated at -30 C. The CCD has been operated in photon-counting mode at room temperature, and X-ray spectra with an energy resolution of about 450 eV at 5.9 keV have been obtained. The low energy X-ray sensitivity of the CCD also has been demonstrated by detecting carbon K-alpha X-rays (277eV).

This paper describes some of the critical details of the MIT X-ray CCD camera design. Special attention is given to those portions of the system that deviate from conventional practice in the design of CCD cameras. Furthermore, an attempt has been made to generalize the design so that both optical and X-ray requirements can be satisfied whenever possible. Currently, noise levels of less than 8 electrons rms are routinely achieved with this design, and even lower levels (less than 5 electrons) should be realizable.

The use of charge-coupled devices (CCDs) as single photon X-ray detectors has been documented by several research groups. In this paper we describe the design and performance of a powerful laboratory instrument for imaging and non-dispersive spectroscopy of soft X-rays (200 eV to 10 keV) utilizing Texas Instruments TI-4849 virtual-phase CCDs. With this instrument we have achieved a spatial resolution of 22 microns (limited by pixel size) with an overall array area of 584x390 pixels.We have achieved an energy-resolution of -140 eV FWHM for single-pixel Fe55 X-ray events (5.9 keV) with the CCD operated at only -30°C. We have operated the CCD in photon-counting mode at room-temperature and have obtained X-ray spectra with an energy resolution of -450 eV at 5.9 keV. We also have demonstrated the low-energy X-ray sensitivity of the CCD by detecting Carbon K-alpha X-rays (277 eV).