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The Soft X-ray Imager instrument on the ESA THESEUS mission will provide high-energy imaging and spectroscopy observations of fast transients, providing significant steps forward in our understanding and characterisation of the early Universe. The instrument will utilise high performance microchannel plate optics (MPOs) and some of the first X-ray optimised CMOS devices to be used for space applications. The instrument team are currently developing a flight-like prototype instrument in order to enable full and appropriate characterisation of the instrument, and in particular the performance of candidate detectors. Here we present early results from the focal plane requirement study programme (including performance modelling and trade-off studies).

The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper, we present the concept, design, and pre-launch performance of this facility instrument on the ESA/NASA Solar Orbiter mission. The goal of this paper is to give prospective users a better understanding of the possible types of observations, the data acquisition, and the sources that contribute to the instrument's signal. The paper discusses the science objectives, with a focus on the SPICE-specific aspects, before presenting the instrument's design, including optical, mechanical, thermal, and electronics aspects. This is followed by a characterisation and calibration of the instrument's performance. The paper concludes with descriptions of the operations concept and data processing. The performance measurements of the various instrument parameters meet the requirements derived from the mission's science objectives. The SPICE instrument is ready to perform measurements that will provide vital contributions to the scientific success of the Solar Orbiter mission., Comment: A&A, accepted 19 August 2019; 26 pages, 25 figures

The CCD remains the pre-eminent visible and UV wavelength image sensor in space science, Earth and planetary remote sensing. However, the design of space-qualified CCD readout electronics is a significant challenge with requirements for low-volume, low-mass, low-power, high-reliability and tolerance to space radiation. Space-qualified components are frequently unavailable and up-screened commercial components seldom meet project or international space agency requirements. In this paper, we describe an alternative approach of designing and space-qualifying a series of low- and high-voltage mixed-signal application-specific integrated circuits (ASICs), the ongoing development of two low-voltage ASICs with successful flight heritage, and two new high-voltage designs. A challenging sub-system of any CCD camera is the video processing and digitisation electronics. We describe recent developments to improve performance and tolerance to radiation-induced single event latchup of a CCD video processing ASIC originally developed for NASA’s Solar Terrestrial Relations Observatory and Solar Dynamics Observatory. We also describe a programme to develop two high-voltage ASICs to address the challenges presented with generating a CCD’s bias voltages and drive clocks. A 0.35 μm, 50 V tolerant, CMOS process has been used to combine standard low-voltage 3.3 V transistors with high-voltage 50 V diffused MOSFET transistors that enable output buffers to drive CCD bias drains, gates and clock electrodes directly. We describe a CCD bias voltage generator ASIC that provides 24 independent and programmable 0–32 V outputs. Each channel incorporates a 10-bit digital-to-analogue converter, provides current drive of up to 20 mA into loads of 10 μF, and includes current-limiting and short-circuit protection. An on-chip telemetry system with a 12-bit analogue-to-digital converter enables the outputs and multiple off-chip camera voltages to be monitored. The ASIC can drive one or more CCDs and replaces the many discrete components required in current cameras. We also describe a CCD clock driver ASIC that provides six independent and programmable drivers with high-current capacity. The device enables various CCD clock parameters to be programmed independently, for example the clock-low and clock-high voltage levels, and the clock-rise and clock-fall times, allowing configuration for serial clock frequencies in the range 0.1–2 MHz and image clock frequencies in the range 10–100 kHz. Finally, we demonstrate the impact and importance of this technology for the development of compact, high-performance and low-power integrated focal plane electronics.

A pair of radiation hardened high-voltage mixed signal Application Specific Integrated Circuits (ASICs) are described that provide the biasing and clocking functions required to drive large format CCDs used for space-borne cameras and focal planes. The use of these ASICs allows the CCD drive electronics to be realised in a compact and energy efficient manner saving volume, mass, and power when compared with traditional space-qualified discrete implementations. The STAR ASIC provides 24 independent voltage outputs with a 32.736V range at 10 bit resolution and with

Solar Dynamics Observatory (SDO) is imaging the Sun in many wavelengths near simultaneously and with a resolution ten times higher than the average high-definition television. In this paper we describe our innovative systems approach to the design of the CCD cameras for two of SDO’s remote sensing instruments, the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI). Both instruments share use of a custom-designed 16 million pixel science-grade CCD and common camera readout electronics. A prime requirement was for the CCD to operate with significantly lower drive voltages than before, motivated by our wish to simplify the design of the camera readout electronics. Here, the challenge lies in the design of circuitry to drive the CCD's highly capacitive electrodes and to digitize its analogue video output signal with low noise and to high precision. The challenge is greatly exacerbated when forced to work with only fully space-qualified, radiation-tolerant components. We describe our systems approach to the design of the AIA and HMI CCD and camera electronics, and the engineering solutions that enabled us to comply with both mission and instrument science requirements.

Digital correlated double sampling (DCDS) is an emerging technology for CCD imaging systems in space-based applications. DCDS technology not only provides the low readout noise electronics required by many applications but also offers a range of flexible readout modes that allows the readout noise and pixel frequency to be dynamically adjusted even in operation.

The WUVS (WSO-UV Ultra Violet Spectrographs) consists of two high resolution spectrographs (R=50000) covering the Far-UV range of 115–176 nm and the Near-UV range of 174–310 nm, and a long-slit spectrograph (R=1000) covering the wavelength range of 115–305 nm. Significant progress in the CCD development gives a possibility to use back-illuminated CCD detectors with anti-reflection coating for observations in the UV. These detectors are under construction by e2v company (UK) based on their heritage of detectors production for numerous space missions including those for UV- and far-UV. The main parameters of WUVS detector subsystems are described.

The Solar Mass Ejection Imager (SMEI) was the first of a new class of helio- spheric and astronomical white-light imager. A heliospheric imager operates in a fashion similar to coronagraphs, in that it observes solar photospheric white light that has been Thomson scattered by free electrons in the solar wind plasma. Compared with traditional

A high voltage mixed signal ASIC is described that provides multiple fully programmable clock outputs capable of driving large format CCD capacitive electrodes. The COMET ASIC provides 6 independent clock buffering channels each with individually programmable rising/falling current drive and high/low voltage levels. Output voltage levels are controlled with integrated fast response regulators that operate over a 16.368V range without the need for external decoupling capacitors. Clock drive currents can be adjusted for the load capacitance and voltage swing required over a 409.6mA range, with edge speeds

World Space Observatory Ultraviolet (WSO-UV) is a major international collaboration led by Russia and will study the universe at ultraviolet wavelengths between 115 nm and 320 nm. The WSO Ultraviolet Spectrograph (WUVS) subsystem is led by a consortium of Russian institutes and consists of three spectrographs. RAL Space is contracted by e2v technologies Ltd to provide the CCD readout electronics for each of the three WUVS channels. The programme involves the design, manufacturing, assembly and testing of each Camera Electronics Box (CEB), its associated Interconnection Module (ICM), Electrical Ground Support Equipment (EGSE) and harness. An overview of the programme will be presented, from the initial design phase culminating in the development of an Engineering Model (EM) through qualification whereby an Engineering Qualification Model (EQM) will undergo environmental testing to characterize the performance of the CEB against the space environment, to the delivery of the Flight Models (FMs). The paper will discuss the challenges faced managing a large, dynamic project. This includes managing significant changes in fundamental requirements mid-programme as a result of external political issues which forced a complete re-design of an existing CEB with extensive space heritage but containing many ITAR controlled electronic components to a new, more efficient solution, free of ITAR controlled parts. The methodology and processes used to ensure the demanding schedule is maintained through each stage of the project will be presented including an insight into planning, decision-making, communication, risk management, and resource management; all essential to the continued success of the programme.

Readout noise is a key factor in the performance of optical systems based on charge coupled devices (CCDs). Recent developments have shown that digital correlated double sampling (DCDS) using weighted averaging may provide a further reduction in the system readout noise. This paper describes recent advances in noise filtering using DCDS. Particular emphasis is placed on optimising weighted averaging filters to reduce 1/f noise and the characterisation of system performance when using the unsettled samples within the pixel period. Experimental results are presented and compared with theoretical predictions based on the extracted noise spectrum. The analysis provides a detailed study of the relationship between the 1/f corner frequency, the pixel frequency and weighted averaging technique in comparison with the theory of matched filters. Furthermore, the results include a comparison of the noise profile with measured and simulated noise patterns. Key system metrics, including linearity and gain stability, have been characterised and are presented to confirm the suitability of this technique for high-performance scientific applications.

In this paper we demonstrate a magnetically guided Cesium (Cs) atom interferometer in the Talbot-Lau regime for inertial sensing with two interferometer schemes, Mach-Zenhder and Ramsey-Borde. The recoil frequency of the Cs atoms and the acceleration along the waveguide symmetry axis is measured. An acceleration measurement uncertainty of $7\times10^{-5}$ m/s$^{2}$ is achieved. We also realize an enclosed area of $0.018$ mm$^{2}$ for rotation measurement. As the first reported magnetically guided Cs atom interferometer, the system limitation and its advantages are discussed.

Mounted on the sides of two widely separated spacecraft, the two Heliospheric Imager (HI) instruments onboard NASA’s STEREO mission view, for the first time, the space between the Sun and Earth. These instruments are wide-angle visible-light imagers that incorporate sufficient baffling to eliminate scattered light to the extent that the passage of solar coronal mass ejections (CMEs) through the heliosphere can be detected. Each HI instrument comprises two cameras, HI-1 and HI-2, which have 20° and 70° fields of view and are off-pointed from the Sun direction by 14.0° and 53.7°, respectively, with their optical axes aligned in the ecliptic plane. This arrangement provides coverage over solar elongation angles from 4.0° to 88.7° at the viewpoints of the two spacecraft, thereby allowing the observation of Earth-directed CMEs along the Sun – Earth line to the vicinity of the Earth and beyond. Given the two separated platforms, this also presents the first opportunity to view the structure and evolution of CMEs in three dimensions. The STEREO spacecraft were launched from Cape Canaveral Air Force Base in late October 2006, and the HI instruments have been performing scientific observations since early 2007. The design, development, manufacture, and calibration of these unique instruments are reviewed in this paper. Mission operations, including the initial commissioning phase and the science operations phase, are described. Data processing and analysis procedures are briefly discussed, and ground-test results and in-orbit observations are used to demonstrate that the performance of the instruments meets the original scientific requirements.

As part of a strategy to provide increasingly complex systems to customers, e2v is currently developing the sensor solution for focal plane array for the WSO-UV (World Space Observatory – Ultraviolet) programme, a Russian led 170 cm space astronomical telescope. This is a fully integrated sensor system for the detection of UV light across 3 channels: 2 high resolution spectrometers covering wavelengths of 115 – 176 nm and 174 – 310 nm and a Long-Slit Spectrometer covering 115 nm – 310 nm. This paper will describe the systematic approach and technical solution that has been developed based on e2v’s long heritage, CCD experience and expertise. It will show how this approach is consistent with the key performance requirements and the overall environment requirements that the delivered system will experience through ground test, integration, storage and flight.

Flavocytochrome P450 (cytochrome P450) BM3 is an intensively studied model system within the P450 enzyme superfamily, and is a natural fusion of a P450 to its P450 reductase redox partner. The fusion arrangement enables efficient electron transfer within the enzyme and a catalytic efficiency that cannot be matched in P450 systems from higher organisms. P450 BM3's potential for industrially relevant chemical transformations is now recognized, and variants with biotechnological applications have been constructed. Simultaneously, structural and mechanistic studies continue to reveal the intricate mechanistic details of this enzyme, including its dimeric organization and the relevance of this quaternary structure to catalysis. Homologues of BM3 have been found in several bacteria and fungi, indicating important physiological functions in these microbes and enabling first insights into evolution of the enzyme family. This short paper deals with recent developments in our understanding of structure, function, evolution and biotechnological applications of this important P450 system.

Re-invented in the early 1990s on both sides of the Atlantic, Monolithic Active Pixel Sensors (MAPS) in a CMOS technology have slowly invaded the world of consumer imaging and are now on the edge of becoming the first technology in this field, previously dominated by Charge-Coupled Devices (CCD). Thanks to the advantages brought by the use of standard CMOS technology, MAPS have great potential in many areas including function integration, leading to the concept of a camera-on-a-chip, pixel size, random access to selected region-of-interest, low power, higher speed and radiation resistance. In many ways, MAPS have introduced a new way of doing imaging. Despite their success in the consumer arena, MAPS are still to make a definitive impact in the world of scientific imaging. This paper first briefly reviews the way radiation is detected by a CMOS sensor, before analysing the main noise source and its relationship with the full well capacity and the dynamic range. This paper will also show first examples of scientific results, obtained in the detection of low-energy electrons.

Monolithic Active Pixel Sensors (MAPS) take advantage of recent developments in deep sub-micron VLSI technology. CMOS sensors now enjoy widespread commercial applications as inexpensive visible light-imaging devices. These are also being utilised and developed for an increasing number of scientific fields due to advantages which include: low power consumption, radiation hardness, small pixel size and on-chip or even in-pixel processing capabilities. We have designed, characterised and evaluated a number of prototype CMOS MAPS devices as position-sensitive detectors for ionising radiation. This development was primarily driven by the requirements of the Linear Collider vertex detector but a broader spectrum of applications, including several outside particle physics, has been explored and some of these are also briefly presented here.

著者人数：48名, Accepted: 2002-12-31, 資料番号: SA1002070000

The X-ray solar monitor (XSM) is a calibration instrument of the demonstration of compact imaging X-ray spectrometer (D-CIXS) experiment, with a separate Silicon detector unit on the SMART-1 spacecraft. The non-imaging HPSi PIN sensor has a wide field-of-view (FOV) to enable Sun visibility during a significant fraction of the mission lifetime, which is essential for obtaining calibration spectra for the X-ray fluorescence measurements by the imaging D-CIXS spectrometer. The energy range (1– 20 keV ), spectral resolution (about 250 eV at 6 keV ), and sensitivity (about 7000 cps at flux level of 10 −4 W m −2 in the range 1– 8 A ) are tuned to provide optimal knowledge about the Solar X-ray flux on the Lunar surface, matching well with the activating energy range for the fluorescence measured by D-CIXS. The independent science of the XSM will also be valuable, since the XSM energy range is very sensitive to solar flares. The countrate during the top of an X1 flare will be about 35 times higher than the average quiescent countrate at solar maximum. The relative increase will be the same for an M1 flare during the SMART-1 mission, which will be closer to the next solar minimum. Since the XSM will observe the Sun as a star, and the energy range and spectral resolution are close to those of present astronomical X-ray satellites (e.g., XMM-Newton, ASCA, Chandra), we will obtain an X-ray database of the Sun which can be related with the stellar X-ray observations more easily than the data from present solar X-ray instruments. In this publication we give a detailed description of the design, performance, and tasks of the XSM instrument, and view the science perspectives.

The purpose of the D-CIXS (Demonstration of a Compact Imaging X-ray Spectrometer) instrument on the ESA SMART-1 mission is to provide high quality spectroscopic mapping of the Moon by imaging fluorescence X-rays emitted from the lunar surface. In order to obtain adequate statistics for what can be very weak sources, it is essential to have a large effective area, while maintaining a low mass. The solution is to make a thin, low profile detector, essentially a modern version of “X-ray detecting paper”. D-CIXS will achieve a spatial resolution on the ground of 42km from a spacecraft at 300 km altitude, with a spectral resolution of 200 eV or better. The instrument is based around the use of advanced dual microstructure collimator and Swept Charge Device X-ray detector technologies. Swept Charge Device X-ray detectors, a novel architecture based on proven CCD technology, have the virtue of providing superior X-ray detection and spectroscopic measurement capabilities, while also operating at room temperature. Thus we avoid the need for the large passive cooling radiator that was previously required to cool large X-ray focal plane CCDs. The advanced low profile microstructure collimation and filter design builds on expertise developed in solid state and microwave technology to enable us to dramatically reduce the instrument mass. The total mass of D-CIXS, including an X-ray solar monitor is ∼4.6 kg. D-CIXS will provide the first global map of the Moon in X-rays. During normal solar conditions, it will be able to detect absolute elemental abundances of Fe, Mg, Al and Si on the lunar surface, using the on-board solar monitor to obtain a continuous measurement of the input solar spectrum. During solar flare events, it will also be possible to detect other elements such as Ca, Ti, V, Cr, Mn, Co, K, P and Na. The global mapping of Mg, Al and Si, and in particular deriving Mg#, the magnesium number (MgO/[MgO+FeO]), represents the prime goal of the D-CIXS experiment.

We report the first absolute effective quantum efficiency (e-h pairs collected/predicted) measurements of a monolithic thinned back-illuminated CMOS active pixel sensor (APS) in the extreme ultraviolet and soft X-ray region (13-600 Å). The sensor was designed and fabricated under a joint Rutherford Appleton Laboratory/e2v research program and characterized in the Lockheed Martin Solar and Astrophysics calibration facility. We compare our QE results to the data and models developed for thinned CCDs with similar back surface passivation. Our results demonstrate that CMOS APS arrays show significant promise for use in space-based solar physics and astrophysics missions.

We describe our programme to develop a large-format, science-grade, monolithic CMOS active pixel sensor for future space science missions, and in particular an extreme ultraviolet (EUV) spectrograph for solar physics studies on ESA's Solar Orbiter. Our route to EUV sensitivity relies on adapting the back-thinning and rear-illumination techniques first developed for CCD sensors. Our first large-format sensor consists of 4k×3k 5 μm pixels fabricated on a 0.25 μm CMOS imager process. Wafer samples of these sensors have been thinned by e2v technologies with the aim of obtaining good sensitivity at EUV wavelengths. We present results from both front- and back-illuminated versions of this sensor. We also present our plans to develop a new sensor of 2k×2k 10 μm pixels, which will be fabricated on a 0.35 μm CMOS process. In progress towards this goal, we have designed a test-structure consisting of six arrays of 512×512 10 μm pixels. Each of the arrays has been given a different pixel design to allow verification of our models, and our progress towards optimizing a design for minimal system readout noise and maximum dynamic range. These sensors will also be back-thinned for characterization at EUV wavelengths.

SPICE is a high resolution imaging spectrometer operating at extreme ultraviolet wavelengths, 70.4 – 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the Solar Orbiter mission. SPICE will address the key science goals of Solar Orbiter by providing the quantitative knowledge of the physical state and composition of the plasmas in the solar atmosphere, in particular investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. By observing the intensities of selected spectral lines and line profiles, SPICE will derive temperature, density, flow and composition information for the plasmas in the temperature range from 10,000 K to 10MK. The instrument optics consists of a single-mirror telescope (off-axis paraboloid operating at near-normal incidence), feeding an imaging spectrometer. The spectrometer is also using just one optical element, a Toroidal Variable Line Space grating, which images the entrance slit from the telescope focal plane onto a pair of detector arrays, with a magnification of approximately x5. Each detector consists of a photocathode coated microchannel plate image intensifier, coupled to active-pixel-sensor (APS). Particular features of the instrument needed due to proximity to the Sun include: use of dichroic coating on the mirror to transmit and reject the majority of the solar spectrum, particle-deflector to protect the optics from the solar wind, and use of data compression due to telemetry limitations.

The charge-coupled device (CCD) has been developed primarily as a compact image sensor for consumer and industrial markets, but is now also the preeminent visible and ultraviolet wavelength image sensor in many fields of scientific research including space-science and both Earth and planetary remote sensing. Today’s scientific or science-grade CCD will typically maximise pixel count, focal plane coverage, photon detection efficiency over the broadest spectral range and signal dynamic range whilst maintaining the lowest possible readout noise. The relatively recent re-emergence of complementary metal oxide semiconductor (CMOS) image sensor technology is arguably the most important development in solid-state imaging since the invention of the CCD. Current sub-micron CMOS technology now enables the integration on a single silicon chip of a large array of photodiode pixels alongside all of the ancillary electronics needed to address the array and digitise the resulting analogue video signal. Compared to the CCD, CMOS promises a more compact, lower mass, lower power and potentially more radiation tolerant camera.

The J-PAS (Javalambre Physics-of-the-Accelerating-Universe Astrophysical Survey) project will perform a five-year survey of the northern sky from a new 2.5m telescope in Teruel, Spain. We describe the design concept of a complete cryogenic camera with a mosaic focal plane and 1.2 gigapixel science array which is to be commercially supplied. The focal plane is contained within a novel liquid-nitrogen-cooled vacuum cryostat, with proximity drive electronics designed to achieve a 4 e- readout noise from the 224-channel CCD system.

Bacillus megaterium flavocytochrome P450 BM3 (BM3) is a high activity fatty acid hydroxylase, formed by the fusion of soluble cytochrome P450 and cytochrome P450 reductase modules. Short chain (C6, C8) alkynes were shown to be substrates for BM3, with productive outcomes (i.e. alkyne hydroxylation) dependent on position of the carbon-carbon triple bond in the molecule. Wild-type P450 BM3 catalyses ω-3 hydroxylation of both 1-hexyne and 1-octyne, but is suicidally inactivated in NADPH-dependent turnover with non-terminal alkynes. A F87G mutant of P450 BM3 also undergoes turnover-dependent heme destruction with the terminal alkynes, pointing to a key role for Phe87 in controlling regioselectivity of alkyne oxidation. The terminal alkynes access the BM3 heme active site led by the acetylene functional group, since hydroxylated products are not observed near the opposite end of the molecules. For both 1-hexyne and 1-octyne, the predominant enantiomeric product formed (up to ∼90%) is the (S)-(-)-1-alkyn-3-ol form. Wild-type P450 BM3 is shown to be an effective oxidase catalyst of terminal alkynes, with strict regioselectivity of oxidation and potential biotechnological applications. The absence of measurable octanoic or hexanoic acid products from oxidation of the relevant 1-alkynes is also consistent with previous studies suggesting that removal of the phenyl group in the F87G mutant does not lead to significant levels of ω-oxidation of alkyl chain substrates.

This paper discusses the Topsat satellite, currently being built by a partnership between DERA Space, Rutherford Appleton Laboratory, Surrey Satellite Technology Ltd and InfoTerra Ltd (Formerly NRSC). Topsat will have the capability to provide imagery at 25m panchromatic and 5m colour resolution, direct to the user at a mobile ground station, from a 125kg microsatellite in low Earth orbit. Its low‐cost philosophy includes wide use of commercial off‐the‐shelf components and the goal of a one‐year mission life.

Bacillus megaterium P450 BM3 (BM3) is a P450/P450 reductase fusion enzyme, where the dimer is considered the active form in NADPH-dependent fatty acid hydroxylation. The BM3 W1046A mutant was generated, removing an aromatic "shield" from its FAD isoalloxazine ring. W1046A BM3 is a catalytically active NADH-dependent lauric acid hydroxylase, with product formation slightly superior to the NADPH-driven enzyme. The W1046A BM3 K(m) for NADH is 20-fold lower than wild-type BM3, and catalytic efficiency of W1046A BM3 with NADH and NADPH are similar in lauric acid oxidation. Wild-type BM3 also catalyzes NADH-dependent lauric acid hydroxylation, but less efficiently than W1046A BM3. A hypothesis that W1046A BM3 is inactive [15] helped underpin a model of electron transfer from FAD in one BM3 monomer to FMN in the other in order to drive fatty acid hydroxylation in native BM3. Our data showing W1046A BM3 is a functional fatty acid hydroxylase are consistent instead with a BM3 catalytic model involving electron transfer within a reductase monomer, and from FMN of one monomer to heme of the other [12]. W1046A BM3 is an efficient NADH-utilizing fatty acid hydroxylase with potential biotechnological applications.

We describe a centroiding image photon counting detector intended for photon counting applications in both ground-based and space astronomy. The detector uses a 40 mm diameter proximity focussed microchannel place intensifier and a rapid-scanned CCD readout system with a transputer based electronic processing system for the on-line data processing. An interesting result has been that this system resolves the pore structure in the front microchannel plate of the intensifier, showing that the system can work to the maximum possible resolution using the MCP intensifiers.

We describe our programme to develop science-grade CMOS active pixel sensors for future space science missions, and in particular an extreme ultra-violet spectrograph for solar physics studies on the ESA Solar Orbiter. Our goal is the development of a large format 4k x 4k pixel CMOS sensor with useful sensitivity in the extreme ultra-violet (EUV) for solar physics spectroscopy and imaging. Our route to EUV sensitivity relies primarily in adapting the back-thinning and rear-illumination techniques first developed for CCD sensors; however we are also exploring the alternative approach of using a front-etch to expose the CMOS photodiodes. We have successfully back-thinned several 525 x 525 prototype CMOS sensors and proved that the devices survived the process both structurally and functionally. We have also been successful in removing the oxide from the front side of a small array of pixels, using focused ion beam etching. Preliminary results from these pixels show they are sensitive in the Ultra Violet. We have also designed a working large format 4k x 3k prototype on a 0.25 micron CMOS imager process.

A visible wavelength linear photosensor featuring a pixel size of 3µm has been designed for fabrication using commercial 0.25µm CMOS technology. For the photo-sensing element, the design uses a special "deep N-well" in P-epi diode offered by the foundry for imaging devices. Pixel reset is via an adjacent p-FET, thus allowing high reset voltages for a wide pixel voltage swing. The pixel voltage is buffered using a voltage-follower op-amp and a sampling scheme is used to allow correlated double sampling (CDS) for removal of reset noise. Reset and signal levels are buffered through a 16:1 multiplexer to a switched capacitor amplifier which performs the CDS function. Incorporated in the CDS circuit is a programmable gain of 1-8 for increased signal-to-noise ratio at low signal levels. Data output is via 4 analogue output drivers for off-chip conversion. Each driver supplies a differential output voltage with a ± 1V swing for 6.25kHz. This gives a peak data rate at each output driver of 10M sample/s. The device will operate on a 3.3V supply and will dissipate approximately 950mW. Simulations indicate an equivalent noise charge at the pixel of 66.3e- for a full well capacity of 255,000e-, giving a dynamic range of 71.7dB.

Description du spectrometre a objets faibles (FOS-2) destine au telescope William Herschell de l'Observatoire del Roque de Los Muchachos, La Palma

Although current interest is focussed on the emergence of large CCDs from Tektronix, for many applications smaller devices based on the TV imaging format are still relevant. Several manufacturers produce CCDs of this size, and deciding which to use for a particular application is of some importance. Over the past three years, the general purpose CCD camera system developed at' the Royal Greenwich Observatory (RGO) has been used to test, optimise and compare various types of CCD with further work being carried out on a variety of telescopes. The results of this work are described, dealing not only with the obvious features such as noise and quantum efficiency, but the more subtle aspects such as low light level performance and temperature dependence. The astronomical relevance of the various factors is considered and suggestions made as to the suitability of each type of chip for various types of observation. Finally, the future of these TV format CCDs is considered in the light of the likely availability of much larger alternatives.