This PDF file contains the front matter associated with SPIE Proceedings Volume 12191, including the Title Page, Copyright information, Table of Contents, and Conference Committee Page.

Teledyne e2v develops silicon sensors for ground and space-based Astronomy applications. Multiple new back-side illuminated (BSI) CMOS and CCD sensors are presented, such as the large area CMOS platform. Teledyne’s sensors are also supported by advances in back-thinning capabilities. Teledyne has upgraded the operation to process 8” wafers with optimised anti-reflection coatings for applications from UV to NIR. The new 8” process is enabling back-thinning of the wafer-scale large area CMOS product family and the latest AR coatings use novel technology to achieve high stable QE performance at VUV and UV wavelengths.

Microwave Kinetic Inductance Detectors (MKIDs) are a class of superconducting cryogenic detectors that simultaneously exhibit energy resolution, time resolution and spatial resolution. The pixel yield of MKID arrays is usually a critical figure of merit in the characterisation of an MKIDs array. Currently, for MKIDs intended for the detection of optical and near-infrared photons, only the best arrays exhibit a pixel yield as high as 75-80%. The uniformity of the superconducting film used for the fabrication of MKIDs arrays is often regarded as the main limiting factor to the pixel yield of an array. In this paper we will present data on the uniformity of the TiN/Ti/TiN multilayers deposited at the Tyndall National Institute and compare these results with a statistical model that evaluates how inhomogeneities affect the pixel yield of an array.

MKIDs are promising candidates for next generation optical-IR instrumentation as they combine single pixel energy resolution, photon counting and vanishing dark counts with the possibility of megapixel arrays. Ti/TiN multilayers have significant advantages for MKIDs as they allow full control of the superconducting energy gap. We will compare the performance of different Ti/TiN stacks varying in Tc, layer number and film thickness. We have already achieved Qi up to 150 000 and will demonstrate how to control energy resolution and Qi and explore the proximity effect’s limits in the Ti/TiN system.

Superconducting Microwave Kinetic Inductance Detectors (MKIDs) are superconducting, photon-counting, and energy-resolving detectors for visible to near-infrared wavelengths. We present the analysis of a hybrid Lumped Element (LEKID) design with a beta-phase Ta inductor. We show that the measured KID response matches a response model based on the complex conductivity and material parameters. The signal-to-noise is limited by the devices' microwave power handling, the very fast pulse decay, and saturation of the KID phase response. We will present our follow-up design optimized for higher power handling and with a larger inductor volume to reduce the response saturation.

Superconducting transition-edge sensors (TESs) carried by X-ray telescopes are powerful tools for the study of neutron stars and black holes. Several methods, such as optimal filtering or principal component analysis, have already been developed to analyse X-ray data from these sensors. However, these techniques may be hard to implement in space. Our goal is to develop a lower-computational-cost technique that optimizes energy and time resolution when X-ray photons are detected by a TES. TESs exhibit a non-linear response with photon energy. Therefore, at low energies we focus on the current-pulse height whereas at high energies we consider the current-pulse width, to retrieve energy and arrival time of X-ray photons. For energies between 0.1 keV and 30 keV and with a sampling rate of 195 kHz, we obtain an energy resolution (full width at half the maximum) between 1.32 eV and 2.98 eV. We also get an arrival-time resolution (full duration at half the maximum) between 163 ns and 3.85 ns. To improve the accuracy of these results it will be essential to get a thorough description of non-stationary noise in a TES, and to develop a robust on-board identification method of pile-up events.

The trap pumping technique has proven to be a powerful method of detecting and characterising single defects in the silicon lattice of radiation damaged Charge-Coupled Devices (CCDs). With the ever-increasing demand for improved accuracy of data from space telescopes, radiation damage calibration will play a big role for future space emissions. While current charge transfer inefficiency (CTI) correction algorithms are based on fitting parameters to EPER charge tails, trap pumping can provide more knowledge about the single defects creating these tails, and thus be used to improve the accuracy of the CTI calibration. Using data from an irradiated CCD monitored over a long period of time, we show which information can be gained from the trap pumping data and how the trap densities of different trap species can be used to inform the CTI calibration routines.

The CCD47-20 detector of CHEOPS (CHaracterizing ExOPlanet Satellite, ESA/Switzerland), operated at -45°C, is developing an increasing number of hot pixels in orbit, due to particle-induced radiation damage in its 700 km, sun-synchronous dawn/dusk orbit. While the satellite offers the possibility to raise the detector’s temperature to well above +20°C, it is not clear whether this could have a beneficial effect on the hot pixel distribution, and which temperature and duration would be required. To inform the mission on the potential benefits of in-orbit annealing, we irradiated CCD47-20s from the CHEOPS flight production batch at -45°C with protons. After irradiation, the hot pixels were monitored for 7 days at -45°C Subsequently, the temperature was raised step-wise (up to +80°C) for 12 hrs, each step followed by characterisation at -45°C. A significant reduction in the hot pixel count was observed at each step. A recommendation for a possible in-orbit annealing procedure was derived.

We have been developing the SOI pixel detector “INTPIX” for space use and general purpose applications such as the residual stress measurement of a rail and high energy physics experiments. INTPIX is a monolithic pixel detector composed of a high-resistivity Si sensor, a SiO₂ insulator, and CMOS pixel circuits utilizing Silicon-On- Insulator (SOI) technology. We have considered the possibility of using INTPIX to observe X-ray polarization in space. When the semiconductor detector is used in space, it is subject to radiation damage resulting from high-energy protons. Therefore, it is necessary to investigate whether INTPIX has high radiation tolerance for use in space. The INTPIX8 was irradiated with 6 MeV protons up to a total dose of 2 krad at HIMAC, National Institute of Quantum Science in Japan, and evaluated the degradation of the performance, such as energy resolution and non-uniformity of gain and readout noise between pixels. After 500 rad irradiation, which is the typical lifetime of an X-ray astronomy satellite, the degradation of energy resolution at 14.4 keV is less than 10%, and the non-uniformity of readout noise and gain between pixels is constant within 0.1%.

Over the course of a mission, Irradiation damage will compromise images obtained through CCDs as the Charge Transfer Inefficiency is altered by traps induced in such devices. To ensure that the evolution of CTI is understood throughout the lifetime of a mission a long-term study of an irradiated CCD273 device has been undertaken at the Open University (OU) Centre for Electronic Imaging. Irradiations were performed both in room temperature and cryo (153K) conditions at a variety of irradiation doses from 6x109 protons to 1.5 x109 protons at 10MeV equivalent. Following irradiation, the device was kept under Cryo-mission-like conditions for 12 months, over which the major imaging figures of merit were measured (EPER, FPR, X-ray and dark current) to track the changes through the lifetime of a detector with focus on the evolving CTI. Over the course of the study this has given insight into the temperature dependence and long-term changes in CTI that can be expected from a CCD in orbit.

CMOS detectors offer many advantages over CCDs for optical and UV astronomical applications, especially in space where high radiation tolerance is required. However, astronomical instruments are most often designed for low light-level observations demanding low dark current and read noise, good linearity and high dynamic range, characteristics that have not been widely demonstrated for CMOS imagers. We report the performance, over temperatures from 140 - 240 K, of a radiation hardened SRI 4K×2K back-side illuminated CMOS image sensor with surface treatments that make it highly sensitive in blue and UV bands. After suppressing emission from glow sites resulting from defects in the engineering grade device examined in this work, a 0.077 me⁻/s dark current floor is reached at 160 K, rising to 1 me⁻/s at 184 K, rivaling that of the best CCDs. We examine the trade-off between readout speed and read noise, finding that 1.43 e⁻ median read noise is achieved using line-wise digital correlated double sampling at 700 kpix/s/ch corresponding to a 1.5 s readout time. The 15 ke⁻ well capacity in high gain mode extends to 120 ke⁻ in dual gain mode. Continued collection of photo-generated charge during readout enables a further dynamic range extension beyond 10⁶ e⁻ effective well capacity with only 1% loss of exposure efficiency by combining short and long exposures. A quadratic fit to correct for non-linearity reduces gain correction residuals from 1.5% to 0.2% in low gain mode and to 0.4% in high gain mode. Cross-talk to adjacent pixels is only 0.4% vertically, 0.6% horizontally and 0.1% diagonally. These characteristics plus the relatively large (10μm) pixel size, quasi 4-side buttability, electronic shutter and sub-array readout make this sensor an excellent choice for wide field astronomical imaging in space, even at FUV wavelengths where sky background is very low.

CMOS image sensors traditionally have used a pinned photodiode with a transfer gate to achieve low dark signal and noise. One drawback of the pinned photodiode is the inability to achieve good Modulation Transfer Function (MTF) as the sensor thickness is increased beyond epitaxial thicknesses greater than 10μm as required for higher red response. This is due to the pinned photodiode providing only a very small voltage to deplete the silicon, which results in significant lateral charge diffusion and poor resolution. The limitation in device thickness means that the QE at longer wavelengths (>600nm) is limited for conventional CMOS pixel technologies. A way to increase the depletion depth is to apply a back bias from the rear of the device, however if one were to do this on standard CMOS image sensors then there would be significant leakage current between the back bias and components on the device causing it to not function. A new patented DDE (Deep Depletion Extension) implant helps diode depletion regions to merge laterally creating a “pinch-off” and prevent leakage from in-pixel transistors. This enables epitaxial thickness of up to 50μm to be fully depleted with negligible leakage. The CIS220 is a new ESA GSTP funded derivative of the CIS120 Capella Space Imager platform which incorporates this patented HiRho back bias structure allowing full depletion of the sensor thickness. This paper will present initial results from back-thinned CIS220 devices with 17μm and 33μm thicknesses and will explore the effect of the back bias on electro-optical test results.

We present an approach for improving the effective well depth of a CMOS detector for use on a UV space telescope by using a combination of two techniques: a dual-gain readout mode and the use of a multi-exposure HDR algorithm. Non-destructive readout of the detector in a high-gain and a low-gain mode optimizes the dynamic range of a single exposure by taking advantage of the low read noise of the first mode and the high well depth of the second. The dynamic range can be further extended by the addition of a second, shorter exposure to probe the saturated regions of the initial exposure. We find that, for simulations of an SRI CMOS imager we are testing, its initial sensitivity to ~3 orders of magnitude in flux can be improved to a dynamic range of over 5.5 orders of magnitude (equivalent to a difference of ~14 AB magnitudes) by the combination of a 300 second dual-gain exposure and a 3 second low-gain exposure, with a low overhead in additional read time and computational complexity.

Curved imaging sensors bring significant size, weight and cost reduction to imaging systems while mitigating their off-axis optical aberrations. Unlocking these key features has captured the interest of major players of the imaging and semiconductor industry for the last two decades. Curved CMOS image sensors help to create compact imagers, telescopes and spectrographs. Recent research programs have demonstrated a reduction by a factor 2 of optical elements for wide field ultra-violet and visible Earth imagers, enhancing instrument image quality and signal to noise ratio. We illustrate the benefits brought by curved sensors for various applications, and present our on-going developments and technological roadmap.

Teledyne Digital Imaging has a long history of providing state-of-the-art sensors for both ground and space astronomy applications spanning visible to mid-infrared wavelengths. This paper provides an overview on recent technical developments of the COSMOS large format 8k x 8k deeply cooled CMOS camera for ground-based astronomy. Salient features of the custom back illuminated sensor developed for this camera are presented, including having a 10μm pixel pitch with dual conversion gain HDR (>100dB), very low temporal noise (< 1 e- rms) and dark current (<0.05 e-/p/s at - 25°C), greater than 90% quantum efficiency, as well as excellent linearity and response uniformity required for astronomy applications.

The readout channel in the 64Mpixel sensor utilized in COSMOS consists of column-parallel two-stage oversampled analog-to-digital converters with programmable resolution from 14-to-16 bit output with 5 us row conversion time in 14- bit. While internal on-chip CDS is utilized to achieve nominal temporal noise values of 1.8e_rms with rolling shutter, external CDS with multi-sampling (CMS) further reduces temporal noise to sub-electron levels and when combined with dual conversion gain HDR readout, dynamic range of over 100dB is realized in a single exposure.

The sensor and accompanied ceramic package having a 24 cm diagonal dimension are situated inside a permanently sealed light-weighted high-vacuum chamber thermally connected in parallel to 4 multi-stage TE coolers which are capable of cooling the sensor to < -40 °C in low power mode.

Sharjah-Sat-1 is currently being developed as a collaborative research project between the Sharjah Academy for Astronomy, Space Sciences, and Technology (SAASST), the University of Sharjah, Istanbul Technical University, and Sabanci University. A 3U CubeSat design has been adopted with a dual payload onboard: (i) the improved X-ray Detector (iXRD) and (ii) a system of two optical cameras. The mission's primary scientific target is the observation of bright, hard X-ray sources in our Galaxy and the solar coronal holes. The paper discusses a high-level design, testing, and validation of the mission's primary science payload. The iXRD (Improved X-ray Detector) is equipped with a pixelated CdZnTe-based crystal as the active detection material and a Tungsten collimator with a field of view of 4.26 degrees. The detection range is from 20 to 200 keV with a target spectral resolution of 6 keV at 60 keV. The paper will cover a high-level design of the iXRD, environmental testing performed on the detector such as thermal-vacuum and vibration testing, anSharjah-Sat-1 is currently being developed as a collaborative research project between the Sharjah Academy for Astronomy, Space Sciences, and Technology (SAASST), the University of Sharjah, Istanbul Technical University, and Sabanci University. A 3U CubeSat design has been adopted with a dual payload onboard: (i) the improved X-ray Detector (iXRD) and (ii) a system of two optical cameras. The mission's primary scientific target is the observation of bright, hard X-ray sources in our Galaxy and the solar coronal holes. The paper discusses a high-level design, testing, and validation of the mission's primary science payload. The iXRD (Improved X-ray Detector) is equipped with a pixelated CdZnTe-based crystal as the active detection material and a Tungsten collimator with a field of view of 4.26 degrees. The detection range is from 20 to 200 keV with a target spectral resolution of 6 keV at 60 keV. The paper will cover a high-level design of the iXRD, environmental testing performed on the detector such as thermal-vacuum and vibration testing, and calibrating the detector.

We have been developing monolithic active pixel sensors, X-ray SOIPIXs based on a Silicon-On-Insulator CMOS technology. Its event trigger output function offers a high time resolution better than ~10 usec. (1) We report the device structure optimized to achieve both low noise, a thick depletion layer, and to non-punch-through. (2) We succeeded in achieving an energy resolution of ~300 eV (FWHM) at 6 keV with a depletion layer of 300 um at room temperature by operating frequent reset to reduce the shot noise. (3) We present the development of "Digital X-ray SOIPIXs" having on-chip ADCs, DACs and readout sequencers.

In recent years, scientific CMOS (sCMOS) sensors have found increasing applications to X-ray detection, including Xray astronomical observations. In order to examine the performance of sCMOS sensors, we have developed X-ray cameras based on sCMOS sensors. Two cameras, CNX22 and CNX 66, have been developed using sCMOS sensors with a photosensitive area of 2 cm × 2 cm and 6 cm × 6 cm, respectively. The designs of the cameras are presented in this paper. The CNX22 camera has a frame rate of 48 fps, whereas CNX66 has a frame rate of currently 20 fps, that can be boosted to 100 fps in the future. The operating temperature of the sCMOS sensor can reach to -20°C for CNX22 and - 30°C for CNX66 with a peltier cooler device. In addition to the commonly used mode of saving original images, the cameras provide a mode of real-time extraction of X-ray events and storage their information, which significantly reduces the requirement for data storage and offline analysis work. For both cameras, the energy resolutions can reach less than 200 eV at 5.9 keV using single-pixel events. These cameras are suitable for X-ray spectroscopy applications in laboratories and calibration for the space X-ray telescopes.

A monolithic CMOS image sensor based on the pinned photodiode (PPD) and optimized for X-ray imaging in the 300 eV to 5 keV energy range is described. Featuring 40 μm square pixels and 40 μm thick, high resistivity epitaxial silicon, the sensor is fully depleted by reverse substrate bias. Backside illumination (BSI) processing has been used to achieve high X-ray QE, and a dedicated pixel design has been developed for low image lag and high conversion gain. The sensor, called CIS221-X, is manufactured in a 180 nm CMOS process and has three different 512×128-pixel arrays on 40 μm pitch, as well as a 2048×512 array of 10 μm pixels. CIS221-X also features per-column 12-bit ADCs, digital readout via four highspeed LVDS outputs, and can be read out at 45 frames per second. CIS221-X achieves readout noise of 2.6 e- RMS and full width at half maximum (FWHM) at the Mn-K_α 5.9 keV characteristic X-ray line of 153 eV at -40 °C. This paper presents the characterization results of the first backside illuminated CIS221-X, including X-ray response and readout noise. The newly developed sensor and the technology underpinning it is intended for diverse applications, including Xray astronomy, synchrotron, and X-ray free electron laser light sources.

Infrared focal plane arrays are widely used for astronomical observations and are constantly optimized to provide higher-quality images. The knowledge of the pixel spatial response becomes critical to extract ever more data from scientific missions. A specific cryogenic spot scan objective with an f-number of 1.2 has been developed in order to finely characterize 15 μm (or smaller) pixel pitch cooled infrared focal plane arrays in the spectral band between 3-5 μm. It will be operated in the MIRCOS test bench with different narrow-band filters. We present the first optical characterization of this objective obtained with a cryogenic wavefront analyzer – a quadrilateral shearing interferometer. The measured wavefront indicates a peak-to-valley amplitude of 2 μm, which corresponds to an optical quality of about λ/2 at 3.75 μm working wavelength. This value higher than expected might be due to a non-uniform cooling of the objective.

We describe progress developing infrared detectors with HgCdTe grown on silicon substrates using Molecular Beam Epitaxial growth. The project is a collaboration between the RIT Center for Detectors and Raytheon Vision Systems (RVS). NASA and NSF jointly funded the program, known as SATIN (Short-wave infrared Advanced Technologies and Instrumentation program funded by NASA and NSF). We present detector characterization results for detectors made in the final lot of devices made by RVS. A full suite of characterization results, including for dark current, read noise, spectral response, persistence, linearity, full well, and crosstalk probability, are presented. The performance satisfies requirements for astronomy imaging applications. We plan to use the design to make HELLSTAR (HgCdTe Extremely Large Layout Sensor Technology for Astrophysics Research), a 4K×6K infrared detector with the highest number of pixels ever made for infrared astronomy.

CAGIRE is the near infrared camera of the Colibrí robotic telescope, designed for the follow-up of SVOM alerts, mainly Gamma Ray Bursts (GRBs), and the quick imaging of sky regions where transient sources are detected by the SVOM satellite. CAGIRE is based on the Astronomical Large Format Array (ALFA) 2k x 2k SWIR sensor from the French consortium CEA-LYNRED. In the context of CAGIRE the sensor is operated in “Up the Ramp” mode to observe the sky in a square field of view of 21.7 arcmin on a side, in the range of wavelengths from 1.1 to 1.8 μm. An observation with CAGIRE consists of a series of short (1-2 minutes) exposures during which the pixels are read out every 1.3 second, continuously accumulating charges proportionally to the received flux, building a ramp.

The main challenge is to quickly process and analyse these ramps, in order to identify and study the near infrared counterparts of the bursts, within 5 minutes of the reception of an alert. Our preprocessing, which is under development, aims at providing reliable flux maps for the astronomy pipeline. It is based on a sequence of operations. First, calibration maps are used to identify saturated pixels, and for each pixel, the usable (non saturated) range of the ramp. Then, the ramps are corrected for the electronic common mode noise, and differential ramps are constructed. Finally, the flux is calculated from the differential ramps, using a previously calibrated map of pixel non-linearities. We present here the sequence of operations performed by the preprocessing, which are based on previous calibrations of the sensor response. These operations lead to the production of a flux map corrected from cosmic-rays hits, a map depicting the quality of the fit, a map of saturated pixels and a map of pixels hit by cosmic-rays, before the acquisition of the next ramp. These maps will be used by the astronomy pipeline to quickly extract the scientific results of the observations, like the identification of uncatalogued or quickly variable sources that could be GRB afterglows.

Future Extremely Large Telescopes (ELTs) will require advances in Adaptive Optics (AO) systems to fully realize their potential. In addition to separate, dedicated wavefront sensors, it is recognized that wavefront sensing within the science focal plane itself will also be needed for many new instruments. One approach is to use On-Detector Guide Windows (ODGWs), whereby a small sub-window of a science detector is read-out continuously (~10s-100s of Hz) in parallel with slower reads of the full chip (>10 s). Guide star centroids from these windows can be used to correct for vibrations and flexure. Another potential use for these windows is to perform localized resets at high cadence to prevent saturation and to minimize persistence from bright sources. We have prototyped an ODGW system using a 5-μm cutoff Teledyne HAWAII-2RG infrared detector, and the new Astronomical Research Cameras Gen-4 controller. We describe our implementation of an ODGW mode, and science image artifacts that were observed.

The HAWAII-4RG-15 infrared detector arrays were developed by Teledyne Imaging Systems under a contract from the University of Hawaii with funding from the National Science Foundation. The development program produced three devices of near science-grade quality. This paper summarizes the characterization of these devices. The best detector, using “PV1” passivation, shows very low dark currents except for the edges of the detector, and very low levels of persistence.

Single-photon sensing and photon-number resolving image sensors are key to enabling projects that are not possible today. We present detector characterization results for four single-photon sensing and photon-number resolving backside illuminated complementary metal-oxide semiconductor (CMOS) image sensors. Eric R. Fossum and his team at Dartmouth College led early detector development and continues through Gigajot Technology Inc. The CMOS image sensors have pixels (1.1 μm pitch) that use small-capacitance floating diffusions to achieve deep sub-electron read noise (<0.5 e⁻ RMS). Characterization results include dark current, read noise, quantum efficiency, persistence, linearity, well depth. We also report on our ongoing work to use the image sensors for astronomical observations. We compare the performance of the four CMOS image sensors to that of state-of-the-art detectors, particularly with respect to the large UV/O/IR space telescope recommended by the 2020 Decadal Survey on Astronomy and Astrophysics.

We present the development of a Skipper Charge-Coupled Device (CCD) focal plane prototype for the SOAR Telescope Integral Field Spectrograph (SIFS). This mosaic focal plane consists of four 6k × 1k, 15 μm pixel Skipper CCDs mounted inside a vacuum dewar. We describe the process of packaging the CCDs so that they can be easily tested, transported, and installed in a mosaic focal plane. We characterize the performance of ∼ 650μm thick, fully-depleted engineering-grade Skipper CCDs in preparation for performing similar characterization tests on science-grade Skipper CCDs which will be thinned to 250μm and backside processed with an antireflective coating. We achieve a single-sample readout noise of 4.5 e− rms/pix for the best performing amplifiers and subelectron resolution (photon counting capabilities) with readout noise σ ∼ 0.16 e− rms/pix from 800 measurements of the charge in each pixel. We describe the design and construction of the Skipper CCD focal plane and provide details about the synchronized readout electronics system that will be implemented to simultaneously read 16 amplifiers from the four Skipper CCDs (4-amplifiers per detector). Finally, we outline future plans for laboratory testing, installation, commissioning, and science verification of our Skipper CCD focal plane.

The Skipper is a special type of charge-coupled device (CCD) that allows pixel measurements with sub-electron noise levels due to its non-destructive readout operation. Over the last decade, these sensors have been used as particle detectors on a variety of experiments, such as the direct detection of galactic dark matter and neutrino experiments. Skipper CCD achieves low-noise by reading multiple times, and sequentially, the pixel charge packet, which translates to longer readout times. This becomes a limiting factor for those applications that require sub-electron detection and faster readout speeds. A novel analysis method for reducing the total pixel readout time is presented in this work. The method relies on analyzing the time-domain properties of the video signal including the clock feedthroughs and their shapes to optimize the clock transitions that define the pixel. The analysis technique is experimentally demonstrated using a standard scientific detector and also with a Skipper CCD with single photon sensitivity. In both cases the sensors are operated and readout using the Low Threshold Acquisition (LTA) controller with an updated firmware for faster clock sequencing. A good compromise between noise performance and total readout time was achieved. This will allows the use of the Skipper CCD and/or the LTA for astronomy, quantum imaging, and other applications that require faster readout times than previous uses of the sensor and the controller.

Single electron Sensitive Read Out (SiSeRO) is a novel on-chip charge detector output stage for charge-coupled device (CCD) image sensors. Developed at MIT Lincoln Laboratory, this technology uses a p-MOSFET transistor with a depleted internal gate beneath the transistor channel. The transistor source-drain current is modulated by the transfer of charge into the internal gate. At Stanford, we have developed a readout module based on the drain current of the on-chip transistor to characterize the device. Characterization was performed for a number of prototype sensors with different device architectures, e.g. location of the internal gate, MOSFET polysilicon gate structure, and location of the trough in the internal gate with respect to the source and drain of the MOSFET (the trough is introduced to confine the charge in the internal gate). Using a buried-channel SiSeRO, we have achieved a charge/current conversion gain of >700 pA per electron, an equivalent noise charge (ENC) of around 6 electrons root mean square (RMS), and a full width half maximum (FWHM) of approximately 140 eV at 5.9 keV at a readout speed of 625 Kpixel/s. In this paper, we discuss the SiSeRO working principle, the readout module developed at Stanford, and the characterization test results of the SiSeRO prototypes. We also discuss the potential to implement Repetitive Non-Destructive Readout (RNDR) with these devices and the preliminary results which can in principle yield sub-electron ENC performance. Additional measurements and detailed device simulations will be essential to mature the SiSeRO technology. However, this new device class presents an exciting technology for next generation astronomical X-ray telescopes requiring fast, low-noise, radiation hard megapixel imagers with moderate spectroscopic resolution.

The ASTRI Mini-Array is an international project led by the Italian National Institute for Astrophysics (INAF) aiming at building and operating an array of nine Imaging Atmospheric Cherenkov Telescopes (IACTs) at the Observatorio del Teide in Tenerife (Canary Islands, Spain). UVSiPM, a calibrated small photon counter working in the 280-900 nm wavelength range, is one of the auxiliary instruments of the ASTRI Mini-Array.

UVSiPM is mainly devoted to measure the level of night sky background during the ASTRI Mini-Array observations in the same energy range of the ASTRI cameras. It is composed of one single multi-pixel SiPM sensor (the same model adopted in the ASTRI Mini-Array Cherenkov cameras) coupled to an electronic chain working in single photon counting mode. The design of the optical system foresees a pin-hole mask equipped with a collimator to regulate the UVSiPM field of view. UVSiPM will be mounted on the external structure of one of the ASTRI Mini-Array telescopes and co-aligned with its camera. In addition, it will be used as a support instrument for the absolute end-to-end calibration of the ASTRI Mini-Array telescopes performed with the illuminator, a further auxiliary device devoted to perform the optical throughput calibration of each telescope of the array. Last but not least, UVSiPM can be used as diagnostic tool for the camera functionalities. In this contribution we present the overall design of the UVSiPM instrument and some preliminary results of its performance based on simulations.

Traditional optical astronomy is limited to the measurement of transient signals at time scales greater than ∼ 1ms due to the readout speed of detectors and read noise limitations to sensitivity in short exposures. The Ultra-Fast Astronomy Project (UFA)1, 2 explores much faster events in the sub-millisecond domain. We designed a single-photon imaging camera based on position-sensitive silicon photomultiplier (PS-SiPM) with a low-cost FPGA readout system to observe such events. The sensor operates in a photon-counting mode with time resolution on the order of 10ns and a spatial resolution of around 200μm. We present our camera’s electronic and mechanical design, the algorithm for data handling, and testing and calibration data.

One of the primary goals of HgCdTe linear-mode avalanche photodiode arrays is to provide a 1kx1k pixels format, @15 μm pitch, near-infrared (0.9 to 2.5 μm) detector suitable for ultra-low background astronomical applications and long integration times. Such science goals impose very strict detector requirements, namely a dark current <0.001 [e⁻/pix/sec] and a sub-electron read noise. The Institute for Astronomy (IfA), University of Hawaii has partnered with Leonardo Company to develop such devices, using fine control of the photodiode process to enable noise-free amplification of the charge carriers and a readout circuit optimized for minimal glow. We discuss the first results of the tests conducted at the IfA on this new device operated in our cryogenic testbed. We report the values of dark current, read noise and conversion gain, as well as its cosmetic qualities that we have measured at a temperature of 50K. The measured dark current of these devices at low bias voltages is of ∼3 [e-/pix/ksec] (ksec=1000 seconds). We show that this dark current is dominated by the glow emitted by the ROIC of the detector when it is being read out. The intrinsic dark current of these devices is consistent with zero, with a best estimate of ∼0.1 [e-/pix/ksec]. The glow coming from the ROIC is measured to be ∼0.08 [e-/pix/frame], or 1 [e-/pix] every ∼12 frames. The read noise of these devices starts around ∼10 [e-/pix/frame] at a bias voltage of 3V, and decreases by a factor of 1.3 with each +1V increment of the bias voltage, in agreement with theory. It is reduced to ∼2 [e-/pix/frame] at a bias voltage of 8V.

This conference presentation was prepared for the X-Ray, Optical, and Infrared Detectors for Astronomy X conference at SPIE Astronomical Telescopes + Instrumentation, 2022.

Over de past decade, conventional superconductors (like Al), have been replaced by disordered superconductors (like beta-Ta, PtSi, Hf and TiN) in visible/near-infrared MKIDs, improving the responsivity and quantum efficiency. However, important detector characteristics, such as the single photon pulse decay time and generation-recombination (GR) noise levels, of disordered MKIDs are presently not understood. We present temperature dependent GR noise and single photon (1545 – 402 nm) pulse measurements in MKIDs made from beta-Ta (Tc=1.0 K, ρ=240 μΩcm) and show that it does not follow theory. We hypothesize that quasiparticle trapping causes this deviation.

Microwave Kinetic Inductance Detectors (MKIDs) are cryogenic photon detectors and are attractive because they permit simultaneous time, energy and spatial resolution of faint astronomical sources. We present a cost-effective alternative to dedicated (e.g. analogue) electronics for prototyping readout of single-pixel Optical/NIR MKIDs by repurposing existing and well-known ROACH-1 boards. We also present a pipeline that modernises previously-developed software and data frameworks to allow for extensibility to new applications and portability to new hardware (e.g. Xilinx ZCU111 or 2x2 RFSoC boards).

In this paper we review the physics and performance of back-illuminated CCDs. Models of back-illuminated CCDs are used to derive requirements for stable, strong surface passivation in space-relevant environments. Models and data are used to compare state-of-the-art surface passivation methods with 2D-doped surfaces. MBE growth of 2D-doped silicon on back-illuminated CCDs and CMOS image sensors enables near 100% charge collection efficiency with exceptional stability in space and other harsh environments. Lifetime tests performed on 2D-doped CMOS image sensors using pulsed DUV lasers have demonstrated the unique stability of 2D-doped detectors against high levels of radiation-induced surface damage. The insensitivity of 2D-doped detectors to Si-SiO₂ traps has facilitated the development of a variety of coatings and filters with science-enabling capabilities for NASA instruments and missions in the far and near ultraviolet spectral range. We discuss the status and goals of a strategic partnership between JPL and Teledyne e2v for the certification of 2Ddoping processes, and report initial results from our collaboration.

We present a low-cost ultraviolet to infrared absolute quantum efficiency detector characterization system developed using commercial off-the-shelf components. The key components of the experiment include a light source, a regulated power supply, a monochromator, an integrating sphere, and a calibrated photodiode. We provide a step-by-step procedure to construct the photon and quantum efficiency transfer curves of imaging sensors. We present results for the GSENSE 2020 BSI CMOS sensor and the Sony IMX 455 BSI CMOS sensor. As a reference for similar characterizations, we provide a list of parts and associated costs along with images of our setup.

The Off-plane Grating Rocket Experiment (OGRE) is a sounding rocket mission which aims to raise the technology readiness levels of three new technologies for soft X-ray astronomy, as well as produce the highest resolution spectrum of Capella yet. This paper focusses on the focal plane camera of the telescope which employs four electron-multiplying CCDs – three for spectral observations and one for imaging observations. The camera and its detectors will switch between two different operating modes during the observation window to maximise the scientific return of the mission, all while transmitting live telemetry and a limited amount of imagery data to the ground in real time. The energy resolution of the detectors has been modelled across the intended operational energy range to confirm whether diffraction orders can be separated, and the dependency of the multiplication gain on voltage and temperature has been characterised for each detector.

The Pixelated silicon Drift Detector (PixDD) is a two-dimensional multi-pixel X-ray sensor based on the technology of Silicon Drift Detectors, designed to solve the dead time and pile-up issues of photon-integrating imaging detectors. Read out by a two-dimensional self-triggering Application-Specific Integrated Circuit named RIGEL, to which the sensor is bump-bonded, it operates in the 0:5 — 15 keV energy range and is designed to achieve single-photon sensitivity and good spectroscopic capabilities even at room temperature or with mild cooling (< 150 eV resolution at 6 keV at 0 °C). The paper reports on the design and performance tests of the 128-pixel prototype of the fully integrated system.

Current, state-of-the-art CCDs are close to being able to deliver all key performance figures for future strategic X-ray missions except for the required frame rates. Our Stanford group is seeking to close this technology gap through a multi-pronged approach of microelectronics, signal processing and novel detector devices, developed in collaboration with the Massachusetts Institute of Technology (MIT) and MIT Lincoln Laboratory (MIT-LL). Here we report results from our (integrated) readout electronics development, digital signal processing and novel SiSeRO (Single electron Sensitive Read Out) device characterization.

Energy-dispersive imaging spectroscopy of X-ray emission from the Earth’s aurorae promises to further knowledge in the field of aeronomy. Time- and spatially-resolved observations of fluorescence from the dominant atmospheric components require the detection of X-rays as soft as 390 eV with a resolution of no more than 100 eV at these energies. The Auroral X-ray Imaging Spectrometer (AXIS) instrument of the Disturbed and quiet time Ionosphere-thermosphere System at High Altitudes (DISHA) mission is expected to perform these observations.

The baseline instrument design has suggested the use of an electron-multiplying charge-coupled device (EMCCD). The EMCCD’s electron-multiplying register can reduce the effective readout noise and enable the detection of signals as small as a single photoelectron. For the detection of soft X-rays, however, the noise penalty from the EM register’s stochastic process degrades energy resolution.

Emerging CMOS image sensors (CIS), particularly the Teledyne e2v CIS221-X test device, with back illumination, full depletion (with 36 μm thickness), large pixel sizes (40 μm), and low readout noise (3 e- rms effective) are expected to achieve the required performance without the effects of the EM register. Simple models for X-ray event sensitivity, detectability, and resolution, indicate that candidate CIS equal or better EMCCD performance. Furthermore, CIS offer other advantages including lower power consumption, higher operating temperature, and increased radiation hardness. However, these sensors introduce other behaviors that may impact their apparent benefits, which initial experimental testing and analyses are working to understand.

The combined storage and amplifier structure of a Depleted P-channel Field-Effect Transistor provides the capability to collect, store and read out charge carriers. In combination with an efficient charge transfer between two storage regions, this enables a statistically independent repetitive non-destructive readout of active pixels integrated on a fully depleted, high purity silicon bulk. Averaging the repetitions allows for deep sub-electron noise levels. After the working principle of those sensors was demonstrated on single pixel devices, a 64×64 pixel detector has been operated for the first time. The sensor achieved a single electron sensitivity by recording the spectrum of a light emitting diode. A mean sub-electron noise below 0.2 e⁻ENC at a readout time below 230 ms/frame are demonstrated.

The Next Generation Transit Survey (NGTS) has now been operating for six years, discovering and characterizing transiting exoplanets around bright stars. We outline the NGTS project, including the Andor CCD cameras used to perform high-precision time-series photometry. We quantify the photometric precision for a sample of over 20,000 bright star observations. We find for single NGTS telescope observations we achieve a 30-minute photometric precision of 400 ppm at low airmass. This is in good agreement with the photometric noise predicted using a four-component noise model. We find that the photometric noise for bright stars (G < 12) is dominated by atmospheric scintillation. We also present details of the NGTS multi-telescope observing mode, whereby 12 telescopes can be used simultaneously on a single target star to achieve a 30-minute photometric precision of 100 ppm. Finally, we describe a new generation scientific CMOS camera that we will be testing on-sky at the NGTS facility to determine if it can compete with state-of-the-art CCD cameras used for high precision bright star photometry.

The photon counting imaging paradigm in the visible and the infrared comes from the very small energy carried by a single photon at these wavelengths. Usually to detect photons the photoelectric effect is used. It converts a photon to a single electron making it very difficult to detect because of the readout noise of the electronics. To overcome this there are two strategies, either to amplify the signal to make it larger than the readout noise (used in the so called gain or amplified detectors), or to lower the readout noise in a standard image sensor. For a long time, only amplified detectors were able to do some photon counting. Since the first photon counting systems in the visible, developed by Boksenberg and his collaborators in 1972, many groups around the world improved photon counting techniques. In the 2000's in the visible, EMCCDs (electron multiplying charge coupled devices) allowed to replace the classical image intensifier photon counting systems by solid state devices and improved a lot the QE. But EMCCDs suffer from several issues, and the most important of them is the excess noise factor which prevents to know the exact incoming number of photons in the case of multiple photons per pixel. In the infrared there was no equivalent to EMCCDs up to the development of e-APD sensors and cameras made with HgCdTe material (electron initiated avalanche photo diode). With an excess noise factor near 1 at low temperatures, photon counting is possible with these devices but only in the infrared. We will show that having excess noise factor prevents from being able to do multiple photon counting (quanta imaging) and the only solution is to lower the readout noise.

We have been studying fast low noise CCDs with a readout circuit based on pJFET transistors developed by MIT Lincoln Laboratory as a candidate technology for X-ray detectors for future strategic missions. We have already achieved significant progress, running the serial register of the device at a frequency of 2 MHz with readout noise of 2.6 electrons rms. Accurate measurements of responsivity produced a value of 60 microV/electron, very high for a CCD. By exploring the temperature dependencies of readout noise we found substantial improvement of noise at lower temperatures, with resonant-like features at medium temperatures. We attribute those resonant features to bulk traps with discrete energy levels inside transistor channel. We studied noise power spectra at different operating voltages and device temperatures and present results of such measurements with the goal of further optimizing noise and readout frequency of the sensor.

The Focusing Optics X-ray Solar Imager (FOXSI ) sounding rockets are the first solar-dedicated direct-focusing hard X-ray (HXR) instruments. FOXSI rockets use Wolter-1 style HXR optics and solid state double-sided strip detectors. FOXSI images of solar HXR sources are influenced by the point spread function of the optics, the 2D segmentation of the detector into strip intersections, and noise in the detector readout. For FOXSI-4, new high-resolution optics will cause the instrument angular resolution to be limited by the minimum strip pitch of its CdTe detectors (60 μm).

FOXSI images are also affected by charge sharing in the detector, when one incident photon causes signals in multiple adjacent strips. Charge sharing is more likely the closer a photon is incident to a strip boundary, making it a sub-strip-position-dependent effect. Tests of a FOXSI-3 CdTe detector (with 60 μm strip pitch) at a synchrotron beamline (the Advanced Light Source) have allowed for characterization of charge shared events. This knowledge is used to develop new methods for achieving sub-strip resolution in FOXSI detectors (0.6-3", depending on incident photon position), applicable in the future to the FOXSI-4 detectors (or other similar systems).

To evaluate the performance of these methods, a model has been developed combining the FOXSI-3 optical and detector response, the latter incorporating lab-measured properties of charge sharing in the system. Using this model, generated sources are convolved with the FOXSI-3 system to simulate FOXSI data. A corresponding deconvolution process then extracts a reconstructed source from the simulated data using the new imaging methods, and the original and reconstructed sources can be compared. We show that the reconstructed source approximates the original with higher spatial resolution than that which results from using strip-based position knowledge only. Notably, we demonstrate a new ability to resolve independent sources located only one strip pitch apart.

To tackle the ever-more demanding requirements of upcoming astronomical instruments, emphasis is being put on accurate, reliable, and reusable models to simulate detector effects on images. The open-source python package Pyxel aims at solving these issues by providing a simulation framework where detector effects models can be easily implemented, pipelined and calibrated or validated against test data. In this contribution, we detail how by using the Pyxel framework, it is possible to calibrate ArCTIC – a model for simulating and correcting Charge Transfer Inefficiency in CCDs – and check its correction efficiency for realistic galaxy images acquired using an irradiated Teledyne e2v CCD273.

The European Space Agency’s Gaia spacecraft was launched in 2013 with the aim of making the largest and most precise map of the Milky Way by taking measurements of almost one billion astronomical objects. It has a focal plane that consists of 106 Charge-Coupled Devices (CCDs), custom designed by Teledyne e2v to help fulfil its objectives. These detectors make measurements of positions, velocities, parallaxes, and other physical properties of any objects, with a sufficiently bright enough magnitude, that pass through their field of view. Operating in space means that the Gaia CCDs have been subjected to radiation damage, both ionizing and non-ionizing in nature, in orbit from predominantly solar radiation. This radiation-induced damage leads to the formation of trap defects in the CCD silicon lattice which can trap electrons during readout leading to the increase of charge transfer inefficiency (CTI) and a reduction in the quality of the returned science data. From previous analysis of in-flight data, the degradation of the CCDs, measured from an increase in CTI, has been calculated to be less that that predicted from pre-flight models and on-ground tests. In this study, in-flight and on-ground data is modelled so that the trap landscapes can be further investigated. This was achieved using a charge transfer model, the Charge Distortion Model (CDM), integrated in the Pyxel detector simulation toolkit. Other simulations, namely C3TM, are used in conjunction with the results from Pyxel to obtain a more thorough understanding of the trap landscape causing the observed CTI effects.

ESA’s Science Payload Validation section (SCI-FIV) is developing a new detector test bench to expand its existing suite of test facilities and enable the characterisation of larger detectors (4k x 4k 15 μm pitch devices), sensitive over the visible to mid-wave infrared wavelengths (300-4000 nm) and at colder temperatures (down to 20 K). In this contribution we describe the main requirements of the bench, the novel mechanical and thermal concepts of the modular cryostat, as well as the requirements of the readout electronics chain, including a new detector controller. We also present ESA’s package and flex design for Leonardo’s LAPD (Large-format Avalanche Photo Diode array) device, the first detector to be tested with this new bench.

Complementary Metal Oxide Semiconductor (CMOS) detectors have attracted more and more interests as appropriate imaging instruments, because their performance is close to that of CCD with low power consumption and low noise level. Yangwang-1 is a commercial satellite in China that has two telescopes on board. An optical telescope and a ultra-violet telescope are installed in the satellite to observe near earth objects and bright stars in optical and ultra-violet band for space mining. Yangwang-1 uses CMOS as its camera for optical and UV-band. However, CMOS detectors have different response for different pixels and there is no independent cooling system for the CMOS in the Yangwang-1, which would make dark current control and modelling hard. In this paper, we propose an unsupervised dark current modelling and bad pixel recognition method for CMOS detectors in Yangwang-1 UV camera. Our method obtains several dark current calibration frames on the ground when the CMOS is in different temperatures. Then vectors of dark current in each pixel will be clustered with Gaussian Mixture Model to identify bad pixels and pixels that have the same trends in dark current and temperature relations. We would fit different dark-current and temperature relations for pixels that belong to the same cluster as templates for dark current estimation. Then we could quickly estimate dark current for real observation data with pixels that have no sources nearby. With estimated dark current and bad pixel mask, we find that our source detection pipeline could achieve higher accuracy for UV band observation images.

Charge-coupled devices have been the detector of choice for soft X-ray astronomy missions for many decades due to excellent energy resolution, noise performance, and longevity in space. Newer CCD-based missions require everincreasing performance which is made challenging by radiation damage inherent to the space environment. Missions such as ESA’s upcoming EUCLID observatory is aiming to measure tiny changes in the shape of distant galaxies, created by the presence of dark matter. Such high precision (not only specific to EUCLID) necessitates significant mitigation against radiation damage effects, one of which is utilising different detector operation modes such as multilevel clocking. Multi-level clocking uses three electrode voltage levels (compared to the standard two) to encourage traps within the damaged silicon to emit their charge such that they do not contribute to charge transfer losses, improving charge transfer efficiency and overall detector performance. However, multi-level clocking requires bespoke hardware to implement, followed by significant amount of testing to show that the benefit is significant.

A recent CCD optimisation technique, called the Active Trap Model, utilises knowledge of the radiation-induced defects within a CCD to optimise charge transfer performance across a wide range of variables including temperature, clocking speeds and device operation modes. This paper presents development of the Active Trap Model to predict the performance of multi-level clocking in CCDs. The performance of the model is compared to the experimental data available, namely from ESA’s PLATO¹ mission, and shows good agreement between model and experimental data. The results show the versatility of the Active Trap Model and uses of the technique in potential future CCD-based space missions such as HabEx² and LUVIOR³.

The next UV/O/IR flagship observatory mission recommended by the 2020 Decadal Survey on Astronomy and Astrophysics requires detector performance beyond what many devices deliver; i.e., lower dark current, lower read noise, higher QE, photon counting capability, etc. We evaluate how detector performance parameters affect the ability of an instrument to satisfy the science goals described in the LUVOIR concept study. We compare the requirements to performance in relevant metrics for current state-of-the-art devices. Current UV/O devices (specifically photon-counting CMOS ones) already perform at a level that meet most of the requirements of the upcoming flagship mission. We find that CMOS devices provide performance characteristics that exceed the requirements and exist in formats that demonstrate scalability beyond tens of mega-pixels. EMCCDs have demonstrated scalability to this size as well, though the excess noise factor introduced by the gain mechanism presents significant issues. MKIDs can resolve photon energy, but have yet to demonstrate scalability to mega-pixel formats. SNSPDs do not currently have readout architectures beyond the kilo-pixel level.

Euclid is a major ESA mission scheduled for launch in 2023-2024 to map the geometry of the dark Universe using two primary probes, weak gravitational lensing and galaxy clustering. Euclid’s instruments, a visible imager (VIS) and an infrared spectrometer and photometer (NISP) have both been designed and built by Euclid Consortium teams. The NISP instrument will hold a large focal plane array of 16 near-infrared H2RG detectors, which are key elements to the performance of the NISP, and therefore to the science return of the mission.

Euclid NISP H2RG flight detectors have been individually and thoroughly characterized at Centre de Physique des Particules de Marseille (CPPM) during a whole year with a view to producing a reference database of performance pixel maps. Analyses have been ongoing and have shown the relevance of taking into account spatial variations in deriving performance parameters. This paper will concentrate on interpixel capacitance (IPC) and conversion gain. First, per pixel IPC coefficient maps will be derived thanks to single pixel reset (SPR) measurements and a new IPC correction method will be defined and validated. Then, the paper will look into correlation effects of IPC and their impact on the derivation of per super-pixel IPC-free conversion gain maps. Eventually, several conversion gain values will be defined over clearly distinguishable regions.

The program Astronomy European Infrared Detector (ASTEROID), funded by the European Union through H2020 (under Grant Agreement n°730161), aims at enabling Europe to acquire the technology and knowledge necessary to manufacture 2k² high performance IR detectors. To reach these goals 9 detectors have been manufactured at Lynred and characterized at the Astrophysics Department of CEA. ASTEROID detectors are 640×512 pixels arrays with a pixel pitch of 15 μm. The detectors are p-on-n technology, with 15 μm pixel pitch, with a cut-off wavelength of 2.1 μm. In the detector architecture, the MCT light-sensitive layer is hybridized on a Source Follower Detector (SFD) Read Out Integrated Circuit (ROIC) via indium bumps. In this paper, the characterization results of ASTEROID detectors will be presented. The best detectors show extremely low dark current around 0.001 e-/s/pix, which is equivalent to standard H2RG IR detector (widely used in the IR domain for astrophysics applications). The quantum efficiency (QE) of these detectors has also been measured on a dedicated test bench and will be presented. ASTEROID detectors demonstrated a QE of 70 %.

When a HgCdTe IR detector is used for low flux astronomy mission, persistence is one of the main characteristic to calibrate. However, it is not yet a true figure of merit since no generic persistence characterization protocol exist. Indeed, a protocol is usually developed for each mission in order to calibrate this parameter according to the specific needs and specific operating point of the detectors (Integration time, temperature, flux dynamics ...). It is consequently not possible to compare persistence performance of two detectors if the characterization protocol differs and no definitive calibration scheme exist.

In the frame of ALFA and ASTEROID programs, we started characterizing persistence at CEA LETI, CEA IRFU and Lynred a few years ago. The objective was to improve the performance of our built in house detectors in terms of persistence. The goal of this paper is to present our approach to identify which protocol is best suited to compare persistence between two detectors manufactured with different technological steps. With a dedicated instrument, we compare systematically persistence protocols in a controlled environment and on a single detector. Electrical and optical stimulation are compared as well as several stimulation parameters (amplitude and stimulation duration, ie soak time).

With the best-suited protocol for detector comparison, we show technological improvements on persistence comparing detectors manufactured at CEA Leti and Lynred in the frame of ASTEROID and NIRLFSA, a program prior to ALFA.

The fourth medium class ESA mission Atmospheric Remote-Sensing Infrared Exoplanet Large-survey also known as ARIEL is dedicated to the study of exoplanets. The goal of this mission is to characterize the atmosphere of exoplanets to find out what they are made of, how they form and evolve. The satellite is composed of two instruments: AIRS, for ARIEL Infrared Spectrometer, and a Fine Guidance System (FGS) which is used both to monitor the satellite position and as a near infrared spectrometer and photometer. AIRS instrument is made of two channels; one covers the spectral range 1.95 μm – 3.9 μm (called CH0) and the other 3.9 μm – 7.8 μm (called CH1). Both detectors are H1RG IR detectors based on MCT (Mercury Cadmium Telluride) technology. During AIRS’ operations, the detectors will be operated in window mode. On CH1, the targeted window size is set to 64 columns over 130 lines. We will present the first results of characterization of early engineering model of CH1 detector performed on a dedicated test bench at the Astrophysics department of the French Alternative Energies and Atomic Energy Commission (CEA). The detector control electronics is based on home developed electronics which is very similar to the one which will be used onboard of the AIRS instrument. The detector is operated in differential mode using the separate reference output available on the H1RG detectors. First the AIRS acquisition chain will be presented and then we will present he characterization results acquired with the detector operated in window mode.

The inherent nonlinear response of infrared detectors limits the ultimate photometric accuracy that can be obtained. In this paper we show that, by limiting the observations to a fraction of the full dynamic range, we can decrease the variance of the corrected residuals. This improvement is due both to a more accurate nonlinearity correction solution and to a reduction in the number of pixels affected by saturation in neighboring pixels.

We compare several metrics of goodness-of-fit for non-linearity corrected integrations over a range of full well fractions. We show that, by limiting the operational dynamic, we can improve the quality of the non-linearity corrections and increase the number of science-grade pixels. We find that when we limit the dynamic range to 80% of the full well, the variance of the residuals decreases by a factor of two and that other metrics of slope consistency show even larger improvements.

There have been no significant breakthroughs in infrared imagery since the hybridization of III-V or II-VI narrow-bandgap semiconductors on complementary metal-oxide semiconductor (CMOS) read-out integrated circuits (ROICs). The development of third-generation, linear-mode avalanche photodiode arrays (LmAPDs) using mercury cadmium telluride (MCT) has resulted in a significant sensitivity improvement for short-wave infrared (SWIR) imaging. The first dedicated LmAPD device, called SAPHIRA (320x256/24μm), was designed by Leonardo UK Ltd specifically for SWIR astronomical applications requiring speed and sensitivity. In the past decade there has been a significant development effort to make larger LmAPD arrays for low-background astronomy and advance adaptive optics.

Larger LmAPD formats for ultra-low noise/flux SWIR imaging, currently under development at Leonardo include a 512 x 512 LmAPD array funded by ESO, MPE and NRC Herzberg, a 1k x 1k array funded by NASA and a 2K x 2K device funded by ESA for general scientific imaging applications. The 2048x2048 pixel ROIC has a pitch of 15 microns, 4/8/16 outputs and a maximum frame rate of 10 Hz.

The ROIC characterization is scheduled in the third quarter of 2022, while the first arrays will be fabricated by end-2022. The hybridized arrays will be characterized during end-2022. At this time, First Light Imaging will start the development of an autonomous camera integrating this 2Kx2K LmAPD array, based on the unique experience from the C-RED One camera, the only commercial camera integrating the SAPHIRA SWIR LmAPD array. The main features of this camera is presented. The detector will be embedded in a compact high vacuum cryostat cooled with low vibration pulse at 50-80K which does not require external pumping. If necessary, an active vibration damping system can be added for reducing the array vibrations down to 0.01 micron. Sub-electron readout noise is expected to be achieved with high multiplication gain. Custom cold filters and beam aperture cold baffling will be integrated in the camera.

The large format 2Kx2K ROIC for APD array is funded by ESA under a TDE program with the contract number 000130154/20/NL/AR.

The new 512x512 pixel large SAPHIRA infrared eAPD array is an extension of the earlier 320x256 pixel small SAPHIRA device, using the same 24 micron pixel design mated to a larger format readout integrated circuit. It was developed by Leonardo, in partnership with MPE, NRC and ESO. The first packaged test devices were completed in 2021. The bare ME1120 ROIC has been tested in the 64-channel mode at MPE with the ESO NGC controller. The possibilities and adaptations of e-APD technology to provide noiseless large format science grade arrays for long integration times are also discussed.

Large MCT FPA (≥ 2k²) are demanded to satisfy the current scientific needs to cover large portions of the sky in the range of near- and shortwave-infrared wavelength. The European Union has founded the ASTEROID project, a consortium of key research institutions and industrial partners to develop an European MCT FPA of 2k² class in the state of the art of this technology. In order to validate the hybridization reliability of the resulting ASTEROID detector, several setups were developed at IFAE with capabilities to perform thermal cycles while the detector is capturing images. Since the detector prototypes were built with a special pixel configuration forming a "chessboard" with pixels at two levels, the damaged pixels by thermal stress were identified based on their position and signal level using machine vision algorithms. After 30 thermal cycles performed in the range from room temperature (293K) up to 50K, just few damaged pixels were found out before any thermal stress, thus likely damaged during the manufacturing process, being the number of damaged pixels by thermal stress negligible.

We describe the design of the cryogenic packaging and testing of the Sensor Chip Electronics (SCE) delivered to the Near-Infrared Spectro-Photometer (NISP) instrument for the ESA Euclid mission. The Euclid mission will observe 15 000 deg² of extragalactic sky¹ from the Sun{Earth Lagrange point L2. The payload of the Euclid spacecraft consists of a telescope with 1.2m SiC primary mirror, passively cooled to ~ 125 K, and two focal plane instruments, the visible instrument (VIS) and NISP. At the heart of the NISP instrument is a 4 x 4 mosaic focal plane of Teledyne H2RG infrared detector arrays held at 100K linked using a cryogenic ex cable (CFC) to the SCE at as low as 130 K. The SCE uses the Teledyne SIDECAR Application Specific Integrated Circuit (ASIC) to provide timing, biases, communications, and data conversion for operation of the HAWAII 2 RG (H2RG) Sensor Chip Assembly (SCA) and interfaces to the NISP warm electronics. The SIDECAR ASIC is mounted onto a Silicon Fanout (SiFO) and Invar table support structure and then wirebonded to a printed wiring board assembly (PWB) with passive components and 91-pin nanoconnectors. The PWB is housed within an enclosure which serves as the mechanical and thermal interface to the NISP Support Structure. The qualification and flight SCE were assembled and subjected to environmental testing at the Jet Propulsion Laboratory and then calibrated and tested with the flight lot SCA and CFC at Goddard Space Flight Centers Detector Characterization Lab. The results of the qualification and reliability tests as well as the measured characteristics of the flight SCE will be summarized.

NEO Surveyor is a NASA Planetary Defense Coordination Office mission designed to detect and track >2/3 of potentially hazardous asteroids >140 m in diameter during its 5-year prime mission. NEO Surveyor entered Phase B in June 2021 and is scheduled to launch in 2026 to survey the sky in two infrared bands. The infrared detectors are a key technology for the mission and have been the subject of focused development for more than a decade. In this paper, we report test results for recently produced detectors and describe design elements of the focal plane module relevant to operations for NEO Surveyor.

SYSU (Sun Yat-sen University) 1.2 Meter Telescope is a R-C Cassegrain optical Alt-Az telescope, the Cassegrain instrument unit is mounted on the telescope’s mechanical derotator, which is required to feed more than five terminal instruments by a central switching mirror with a switching accuracy less than 1 arcsec. It is a great challenge to design, accommodate and align so many instruments in such limited focus space and realize so high switching accuracy between different instruments under different observation modes at the same time. This paper explores design process problem and find the way in detail for the Cassegrain instrument unit.

We present an ASIC dedicated to the CCD controller. The SPA (Signal Processing ASIC, SPA) process one CCD output channel: amplified the CCD output analog signal, correlated double sampling, converted into differential signal. This chip is highly configurable, with both readout speed and gain adjustable, in order to fulfill the various read-out requirements of astronomical CCD, such as fast readout for wide-field imaging, high-gain and low-speed readout for spectroscopy imaging, etc. At present, the chip has obtained three performance standard models available for mass production: SPA-1ch, SPA-2ch, SPA-4ch, respectively to provide 1,2,4 CCD output signal processing. The SPA chips are encapsulated by the SIP process. The size and operating temperature allow to integrate the SPA chips in-cryostat, very close to the CCD sensor. The SPA can help to form a more compact CCD control circuit. Design process and the results of performance tests of the SPA-4ch chip are reported in detail.

Some astronomical telescopes require very small and light CCD camera. To satisfy this requirement, we develop a minimal electronics system for CCD controllers based on the two ASICs: SPA-2ch and CDA which are developed by the CCD Laboratory of NAOC. Layout the circuit that most affects the CCD noise index into a circuit board with the same area as the CCD sensor, pressing closely behind the CCD sensor. This circuit can be used in a low environment with CCD sensors, minimizing the overall volume of the camera. This system can support any full-frame CCD work with no more than 16 channels. In order to verify the solution, we designed a camera test system using CCD42-40. We report here on the design and performance of the minimal electronics system in details.

The High-speed Array Controller (HIAC) was developed at NRC to operate high-speed multi-channel imaging detectors. Originally developed to operate the large (512x512 pixel) SAPHIRA infrared APD array, which requires 64 channels at 10 Mpx/s each, it is also being used in other projects, including tests of a large format CMOS imager for the CASTOR space telescope. The design is based around a Xilinx Zynq Ultrascale+ system on chip (SoC) device, which makes the system very powerful and flexible.

The Wide Field Survey Telescope (WFST) is a large optical image survey telescope. In order to verify some technologies used in development of camera of WFST, a scientific imaging prototype camera using CCD290-99 is designed. CCD has to work at a low temperature to reduce its dark current. Aiming at the low temperature request of the scientific CCD detector, a high precision temperature control system is designed. The system includes a refrigerator, cooling strips, temperature control electronics and its cooling scheme. Based on the thermal simulation, the temperature control system with high stability is designed and established. The test shows the system can cool the CCD to -100℃ in 3 hours and the temperature stability is less than 0.1℃, which meets requirements of the WFST camera.

The X-ray Astronomy and Observational Cosmology (XOC) group at Stanford University, in collaboration with the Massachusetts Institute of Technology (MIT) and MIT Lincoln Laboratory (MIT-LL), is developing next generation X-ray detector and readout technologies. Specifically, the XOC group is developing a fast, low noise readout application specific integrated circuit (ASIC) that is intended to be paired with X-ray charge-coupled device (CCD) detectors in development at MIT-LL. This readout ASIC is denoted as the MIT CCD Readout Chip or MCRC. The MCRC prototype is designed in a 350 nm technology node featuring 8 channels. Each channel is composed of two inputs. One is dedicated to read out the proven source follower-based (SF) CCD architecture with two selectable gain settings, an input referred noise of 1.63 e⁻_RMS, an input dynamic range of ±160 mV, channel to channel crosstalk less than -75 dBc, a power consumption of roughly 30 mW/channel, and a bandwidth of approximately 50 MHz, translating to an effective rise time of around 5 ns. Such a response can comfortably support readout speeds for large CCD pixel matrices in excess of 5 Mpixel/s/channel. The chip also features a second input which is an experimental drain-current readout (DR) topology to support Single electron Sensitive Read Out (SiSeRO) CCD stages currently in development at MIT-LL. The MCRC excels in speed while its input noise and bandwidth are on par with commercial discrete offerings, but with smaller power and real-estate footprints. Here we present the latest measurement results for this state-of-the-art prototype readout ASIC.

The performance of the camera is a decisive factor in astronomical observations. The scientific CCD fits this need. In order to realize remote control of CCD camera and obtain its performance parameters, a test platform of a scientific CCD camera is built. The test parameters include gain, noise, linearity, full well capacity test, crosstalk test, dark current test. At present, our test platform has carried out multi-group tests of gain, noise, full well and linearity by connecting with a CCD scientific camera. In this paper, a remote control system of the test platform is designed using WEB technology and EPICS, which is convenient for test operators.

With the development of astronomy, more requirements of low noise and high frame rate are put forward for observation instruments. With the advancement of CMOS technology, scientific CMOS camera can provide excellent quantum efficiency, noise performance, and higher frame rate compared to CCD camera. Based on this, we have designed a scientific CMOS camera with 2K*2K pixels and 11um pixel size. The frame rate of the camera could reach 48fps, with very low readout noise. The structural design, electronic design, cooling method and data processing of the camera will be introduced in this paper.

Near-Earth Object (NEO) Surveyor, a NASA planetary defense space mission, is currently in Phase B with a launch date in 2026. NEO Surveyor is an infrared telescope designed to detect and characterize Potentially Hazardous Asteroids (PHAs). The required sensors leverage the space flight heritage and further development over the last 15 years of HgCdTe arrays to detect infrared light spanning from 4 to 10 μm. NEO Surveyor will employ eight passively cooled HgCdTe Sensor Chip Assemblies (SCAs) across two bands, each band consisting of a 1x4 SCA mosaic to cover a wide field of view. Four of these SCAs have a >5.5 μm cutoff wavelength and cover the shorter 4-5.2 μm (NC1) band, while four SCAs will have a >10.5 μm cutoff wavelength and span the longer 6-10 μm (NC2) band. We present calibration and performance results from two recently produced pathfinder SCAs, one for each band, manufactured by Teledyne Imaging Sensors with development guidance from the University of Arizona, the University of Rochester, and JPL. Both devices demonstrate the requisite low dark current, high well depth, and high quantum efficiency, exceeding mission requirements.

Scientific grade Charge Coupled Device(CCD) is widely used in astronomical telescope as imaging sensor at present. A CCD camera based on CCD driving and readout ASIC is designed using CCD47-20 in this paper. The CCD driving and readout ASIC chips include CCD drive chip BCDA2(Second Edition Bias Clock Driver ASIC) and CVRA2（Second Edition CCD Video Readout ASIC). BCDA2 provides multichannel clock and bias voltage for CCD. CVRA2 processes the output signal of CCD by correlated double sampling double slope integral. The processed signals will be sampled by external ADC. Based on the BCDA2 and CVRA2, the electronics system of the camera is designed including a Connecting Board, a pre-amp board and a master control board with CCD driver and CCD readout. The test result shows it’s working well.

The Resolve instrument onboard the XRISM satellite is equipped with 6 × 6 x-ray microcalorimeter detectors aiming at an energy resolution of 7 eV (FWHM) at 5.9 keV. It is currently under development by an international collaboration and will be launched in 2023. The detectors are operated at 50 mK, which is achieved by a combination of four Stirling coolers (STC), one Joule-Thomson cooler (JTC), three-stage adiabatic demagnetization refrigerators, and superfluid helium inside the dewar. The cryocoolers (STC and JTC) are significant sources of microphonic noise against the detector performance. To understand and characterize the microphonic propagation, we monitored the level of vibration throughout the ground instrument-level tests in 2019–2022, yielding a rich and unique data set of the accelerometers and the detector at 50 mK amounting to 1720 hours (6.2 Ms). In this article, we report the result of classifying thermal and non-thermal microcalorimeter noise, distinguishing the origin of the noise, and the method for optimizing the cooler drive frequency that minimizes the effect of the noise originating from the cooler.

Leonardo partnered with the Institute for Astronomy (IfA), University of Hawaii to develop a 1K x 1K infrared avalanche photo diode suitable for low background science applications. Presented here is the design and thermal modeling for the Kovar carrier for mounting the detector as well as the challenges faced in designing and manufacturing the complex flex cable. The flex cable provides the 68 bond pads necessary to service the detector in a width of just over 17mm as well as providing filtering for the bias supplies. The final package is a compact, three side buttable package that has been successfully tested at an operating temperature of 80K.

Imaging polarimetry is an essential diagnostic tool in astronomy and solar physics. Standard instruments, other than being generally expensive, complex and/or with moving parts (all of which are problematic features for space applications), provide measurements of the components of the polarized light sampled at different points of time and/or space (depending on the scheme adopted), thus introducing artefacts difficult to eliminate, especially when the subjects are moving or the illumination is variable.

Development of compact on-chip polarization sensitive detectors is therefore of great interest and, recently, polarimetric image sensors based on a pattern of wire-grid polarizers directly deposited on chip have been introduced in the market. In order to obtain compact imaging detectors able to simultaneously detect the polarization state of the light at each pixel, to minimize and control the systematic errors of the polarimetric measures, we investigated a different approach based on the use of organic conjugated systems possessing both high extinction coefficients and emi ssion efficiencies in selected bands, combined with intrinsic anisotropy originating from the 1D molecular structure, which makes them intrinsically sensitive to the polarization of the incoming light.

As a proof of concept, we developed films able to convert the polarization components of the incoming light into different colors, and coupled them to standard color image sensor. Preliminary tests with commercial color cameras are described.

The Athena observatory is the second large class ESA mission to be launched in early 2030's. One of its two instruments on board is the X-ray Integral Field Unit (X-IFU). X-IFU will provide a high energy resolution of 2.5eV at 7keV thanks to cryogenic micro-calorimeter of Transition Edge Sensor (TES). In this paper, we will describe the architecture of the ADR control electronics designed following space constraint rules. In particular, two prototypes have been developed. The first one is a differential low noise amplifier with an equivalent input noise density close to 2nV/√Hz at 1kHz. Together with ruthenium oxide thermometer from Lakeshore are dedicated to 50mK measurement. A goal of a noise below 0.4μK/√(Hz) RMS, twice thermal stability requirement is targeted. The second board uses DC/DC converter followed by a fully integrated low dropout voltage regulator (LDO) to supply the ADR superconducting coil. It will control precisely the voltage applied to the ADR cooler during regulation phase and provide up to 2A current during the recycling phase. Complementary approach regarding ADR regulation using simulation with a simplified model of the ADR in Matlab-Simulink will be presented herein.

Absolute Quantum Efficiency (QE) measurements are very demanding. To measure the QE of detectors from 0.8μm to 12.5μm a dedicated test bench has been built. The Quantix test bench relies on an optical design ensuring a uniform flat-field illumination of the detector. The illumination uniformity was measured with photodiodes built and calibrated at CEA/LETI. While performing QE measurements, the calibrated photodiode is placed in the vicinity of the detector to measure the incident flux. The Quantix test bench has been validated with a detector whose QE has been measured at the European Space Agency. In this paper, the test bench will be described in details and QE measurements performed on near infrared, MCT-based detectors will be presented. The intra-pixel response is also an important parameter to know as it can affect the accuracy of photometric and shape measurements. The Intrapix test bench has been specifically designed for this measurement, using the Talbot effect to simultaneously measure the intra-pixel response in a large number of subareas of a given detector, from 0.5 μm to 12 μm. The paper will give a brief status of the test bench development.

This conference presentation was prepared for the X-Ray, Optical, and Infrared Detectors for Astronomy X conference at SPIE Astronomical Telescopes + Instrumentation, 2022.

We are characterizing high-frame-rate, low-power X-ray CCDs developed at MIT Lincoln Laboratory for future strategic missions. These devices incorporate a novel, single-level polysilicon gate structure enabling fast, low-power charge transfer. We report and compare charge transfer efficiency measurements on devices from two prototype fabrication lots at row (parallel) transfer rates up to 1 MHz and over a range of device temperatures. We find that devices from the second lot have substantially improved charge transfer efficiency, especially at low temperatures, with charge transfer inefficiency (CTI) as low as 10⁻⁶ per pixel at 1 MHz with 3 V clock swings. This performance is comparable to that of the best legacy triple-poly MIT Lincoln Laboratory devices operating at much lower transfer rates with significantly larger clock swings.

This paper assesses the response to radiation effects of the RIGEL, the Application Specific Integrated Circuit developed within the framework of the PixDD project, to be coupled with a multi-pixel sensor based on Silicon Drift Detectors for operation at the focal plane of X-ray optics on board space-borne astronomy missions. The campaign was conducted at the heavy ion beam line of the Radiation Effects Facility of the University of Jyvӓskylӓ (Finland): both the response to Single Event Effects (latch-ups and bit flips) and to Total Ionising Dose was evaluated. Experimental data were combined with simulations of the in-orbit environment for two scenarios: an equatorial and a Sun-synchronous orbit. The study demonstrated that the device can be safely operated on an equatorial orbit without any dedicated circuitry to mitigate Single Event Effects, although this precaution is instead advisable in the case of a Sun-synchronous orbit. Spectroscopic degradation resulting from Total Ionising Dose stays below 10% up to 34 krad, a manageable value for both orbital configurations.

MCT-based cameras are very competitive when it comes to ultra-low light imaging, however it is crucial for less demanding applications to have a non-cryogenic and cost-effective solution. Progress in band-gap engineering has enabled to shift the detection cut-off wavelength of InGaAs by tuning the indium composition of the In_xGa_1-xAs compound. Operating with a double TEC coupled to air and water cooling, the C-RED 2 Extended Range cameras are an alternative to MCT for specific applications in astronomy and free space optics. We will present the performances of these new VGA extended range InGaAs cameras with sensitivity from 1.1 μm to 1.9 μm and from 1.2 μm to 2.2 μm.

The Wide-Field Infrared Transient Explorer (WINTER) is a new time-domain instrument which will perform a seeing-limited survey of the near-infrared sky. Deployed on a dedicated 1-meter robotic telescope at Palomar Observatory, WINTER is designed to study transients of particular interest in the near-infrared including kilo-novae from gravitational-wave sources, supernovae, tidal disruption events, and transiting exoplanets around low mass stars with surveys to a depth of J=21 magnitudes. WINTER’s custom camera combines six commercial large-format Indium Gallium Arsenide (InGaAs) sensors, observing in Y, J, and a short-H (Hs) band filters (0.9-1.7 microns), and employs a novel tiled optical design to cover a >1 degree squared field of view with 90% fill factor. Each wide-format (1920 x 1080 pixels) InGaAs sensor operates at T = -50°C with a thermoelectric cooler, achieving background-limited photometry without cryogenic cooling. The tiled InGaAs sensors result in a wide field-of-view instrument with significant cost savings when compared to HgCdTe sensors. We present WINTER’s novel readout scheme, which includes custom electronics, firmware, and software for low-noise, real-time readout of the InGaAs sensors, including up to a 30x speed up of data reduction using GPUs. This work also outlines the cooling design for warm (T = -50°C) operation of the sensors with a two-stage thermometric cooler, copper heat pipes, and liquid cooling. We conclude with updates on the alignment, integration, and test of the WINTER instrument with a projected first light in Fall 2022.

Spectroscopic observations in the far and extreme ultraviolet (FUV/EUV, 40-200nm) is of great interest in various scientific fields, such as in Solar Physics, in physics of interstellar medium and in planetary exospheres studies. Microchannel plates-based detectors have been for a long time the detectors of choice for astronomical applications in this range of wavelength, due to their photon counting capability (since the expected photon flux are low) and the possibility of solar blindness (photon flux in the visible range are order of magnitudes higher and filtering may be an issue).

However, the spectral features observed in the targets are characterized by a high range of intensities, which can cover several orders of magnitude. Response of MCP detectors at high flux is limited ultimately by the MCP itself, but generally the readout system introduces further restrictions, thus the technique of lowering the efficiency in the area interested by the most intense lines is often adopted.

In the framework of technological R&D for future astronomical FUV/EUV spectrograph, we are developing a photon counting, solar blind, UV detector with readout system based on a 2D anode array integrated in a custom designed Read Out Integrated Circuit (MIRA - Microchannel plate Readout ASIC), with the aim of achieving high performances characteristics, in particular unprecedented performance in terms of dynamic range combined with spatial resolution close to 30 μm. This detector will allow to measure, simultaneously and without the necessity of filters, spectral lines with different intensities of orders of magnitude, exploiting the maximum Signal to Noise Ratio provided by the statistical limit.

A first prototype has been realized, based on a demonstrator of the MIRA ASIC, 32×32 pixels, 35×35 μm² size, for a total chip area of 2×2 mm², to be integrated with a standard demountable MCP intensifier.