This PDF file contains the front matter associated with SPIE Proceedings Volume 13103, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Teledyne Imaging Sensors (TIS) is the leading supplier of infrared focal plane arrays (FPAs) to astronomy and TIS plays a strong role in providing image sensors for Earth and Planetary Science. This paper starts with a brief introduction to TIS’ technologies and image sensor products. We then present some of TIS’ deliveries to space missions and ground-based telescopes. The space missions include ESA’s Euclid Dark Universe mission and several NASA missions (James Webb Space Telescope, Roman Space Telescope, SPHEREx). TIS continues to serve ground-based astronomy by providing the H2RG and the world’s largest high performance astronomy FPA, the H4RG-15, to several ground-based observatories. Active programs include NASA’s NEO Surveyor asteroid surveillance mission, ESA’s Ariel exo-planet spectroscopy mission, and deliveries to the European Southern Observatory’s Extremely Large Telescope.

This paper presents a new infrared imaging system, SIRIS (Short InfraRed Imaging System) that was entirely developed in LPENS of ENS Paris. It is designed around a hybrid CMOS InGaAs FPA from NIT (New Imaging Technologies). This detector was originally intended for industrial high dynamic applications, however through innovative controls and new readout methods, it became fully exploitable for low noise scientific applications. The SIRIS camera is aimed at cutting-edge applications, like astronomy ones, that can take advantage of all of its improved characteristics to gain in signal to noise ratio, dynamic, resolution and optimization of acquisition times. We took advantage of the availability of the 1 m telescope at the Pic du Midi Observatory to test the camera and develop it for astronomical applications with demanding requirements in terms of both detection and dynamic range. This system, with its specific SWIR sensor, will be presented, illustrated through its recent observational results.

We demonstrate a 64-pixel single-photon imager based on superconducting nanowire single-photon detectors (SNSPDs) capable of counting single photons up to a wavelength of 10μm. This technology could be useful in future space telescopes in applications such as exoplanet transit spectroscopy.

A Medium Wave Infrared (MWIR) image sensor developed by Teledyne e2v UK is studied for potential use in the International Mars Ice Mapper mission (I-MIM). Featuring a 640×512 array with a 15μm pixel pitch and a cutoff wavelength of 5μm, the sensor employs Ga-free InAsSb/InAs Type 2 Super Lattice (T2SL) and bariode (XBn) technologies. The study focuses on characterizing the sensor’s quantum efficiency (QE), dark current (DC), and radiation hardness under cryogenic conditions down to 130K. A system allowing in situ measurements pre- and post-irradiation was developed. The first QE measurements were conducted before and after irradiation with a 10MeV proton (p⁺) equivalent end-of-life fluence of 5×10⁹ p⁺cm⁻² and a double end-of-life fluence of 1×10¹⁰ p⁺cm⁻² into the absorber layer, while the device was kept cryogenically cooled.

High-performance large-format infrared (IR) detectors for astronomy will be in high demand for the next generation of ground- and space-based IR observatories. We present advances in previously published characterization results of HgCdTe-on-Silicon (MCT/Si) IR detectors developed by the RIT Center for Detectors (CfD) and Raytheon Vision Systems (RVS) through the SWIR Advanced Technology Instruments for NSF and NASA (SATIN) development program. The program successfully demonstrates the feasibility of MCT/Si detectors as a competitive architecture for astronomy applications, and we believe that future MCT/Si detectors will lower the cost of IR focal plane arrays by approximately a factor of five. We analyze the correlation between p-n junction size and quantum efficiency and full well depth, and present initial results from an observing program carried out with the best detector of the SATIN project. Finally, we outline a plan to conduct proton and heavy ion radiation testing of the devices to evaluate the radiation tolerance of the MCT/Si technology for space-based applications.

Scientific applications, such as, astronomy or Earth observation from low-Earth orbits, often involve extreme operating conditions, requiring state-of-the-art performance parameters with very low photon arrival rates. These present a technical challenge for infrared sensor manufacturers, in particular dark current. The infrared detector technology at Leonardo UK is well suited to these challenges due to bandgap-engineered HgCdTe, grown by Metal Organic Vapour Phase Epitaxy (MOVPE). By widening the bandgap in critical parts of the sensor the dark current can be effectively switched off. Each diode is physically separated in a mesa process giving market-leading resolution, crosstalk and inter-pixel capacitance. The structure also provides 100% fill-factor and 100% internal QE. This paper focusses on astronomy because this field has the most extreme low photon flux levels (less than 0.01 photons /pixel/second). In particular, linear-mode avalanche photodiode arrays (LmAPDs) are vital for astronomy to amplify the single-photon response above the noise floor. The design and performance of the detectors for astronomy is a particularly good example of bandgap-engineering using MOVPE. Progress in two other fields are reported. Firstly, for future adaptive optics (AO) systems, a new 512×512/24 μm sensor with frame-rates over 2000 frames/s is described, aimed initially at the Extremely Large Telescope (ELT). Secondly, the progress on high speed (GHz) APDs mainly for free-space optical communications and LIDAR is summarised.

The sounding rocket experiment FOXSI-4, successfully launched in April 2024, conducted the world's first focusing imaging spectroscopic observation of a solar flare in x-rays. It aims to investigate the magnetic energy release and the magnetic to other forms of energy conversion mechanism caused by magnetic reconnection in solar flares. For soft x-ray observations, a non-dispersive type imaging-spectroscopy, that is, photon counting, was performed using back-illuminated CMOS sensors. The sensor has a sensitive layer of fully depleted silicon which is 25μm-thick and can achieve a high-speed continuous exposure at a rate of ~250fps. To evaluate the sensor's performance, we irradiated the sensor with monochromatic x-rays from 0.8 to 10keV at synchrotron facilities. Based on this data set, we evaluated the relationship between incident x-ray photon energy and the output signals from the sensor, known as a response matrix for use in analyzing flight data. We confirmed that the sensor outputs signals mainly proportional to the incident photon energy with little charge loss. We also analyzed charge sharing, which refers to the spread of electrons produced by a single photon across multiple pixels. The energy resolution is better than 400eV FWHM for the energy range of up to 10keV, which is sufficient to diagnose the spectrum of a solar flare.

The Auroral x-ray Imaging Spectrometer (AXIS) instrument proposed by the Indian Space Research Organisation’s (ISRO) Space Astronomy Group plans to gather spectral information of the Earth’s aurorae in the 0.3 to 3keV band from a low Earth polar orbit for the first time. A trade-off study comparing possible Teledyne e2v (Te2v) detectors to meet preliminary instrument requirements previously concluded that the backside-illuminated (BI) CIS221-X, a prototype CMOS image sensor (CIS) optimised for soft x-ray detection, was a viable option. This paper introduces the current preliminary instrument requirements for AXIS and the compact Nuscis camera electronics from XCAM Ltd that will be used with the CIS221-X to produce an engineering model of the instrument. Continued studies on the CIS221-X for AXIS will include the optimisation of operating conditions in particular for the less well-studied pixel variants of the detector, and calibration with soft x-rays.

X-ray interferometry (XRI) was first demonstrated in the early 2000’s, and many early mission concepts followed which exploited the significant improvement in spatial resolution that XRI offered. Unfortunately, optical technology was not mature enough to meet the requirements, and the idea remained dormant. ESA’s voyage 2050 programme, in combination with optical and pointing accuracy technology developments, has reignited interest in the concept, but large technological challenges still remain to realise such a groundbreaking telescope. Given the spectral and now spatial requirements of a XRI, the next generation of detector technologies must be developed which can meet those requirements to enable such a telescope. For the proposed ESA THESEUS x-ray astronomy mission, strict requirements on instrument operating temperature (-40°C) have necessitated developments of new detectors technologies, namely CMOS image sensors (CIS). The CEI, in collaboration with Te2v, have designed, manufactured, and characterised a monolithic fully depleted CIS specifically optimised for soft x-ray astronomy. The prototype detector currently meets the THESEUS soft x-ray imager requirements and boasts a near Fano-limited energy resolution of 130eV (@5.9keV) at -40°C. Although the new technology can perform well, the specific detector requirements of XRI need to balance opposing parameters of spatial and energy resolution. This paper will outline the current performance of the CIS221-X for soft x-ray astronomy (as well as other competing technologies) and describe future plans for developing CIS to meet the challenging requirements of XRI.

Detectors are very often a performance-limiting component for space instrumentation – the better the detector, the better the instrument performance. Consequently, the European Space Agency (ESA) invests significant resources into the development of high-performance detector solutions for current and future missions. While technology developments span the full electromagnetic spectrum, infrared (and visible) wavebands are of particular interest and this paper presents a detailed overview of infrared detector development activities currently being undertaken by ESA in collaboration with European industrial partners.

The Cassiopée project aims to develop the key technologies that will be used to deploy very high-performance Adaptive Optics for future ELTs. The ultimate challenge is to detect earth-like planets and characterize the composition of their atmosphere. For this, imaging contrasts of the order of 109 are required, implying a leap forward in adaptive optics performance, with high density deformable mirrors (120x120 actuators), low-noise cameras and the control of the loop at few kHz. The project brings together 2 industrial partners: First Light Imaging and ALPAO, and 2 academic partners: ONERA and LAM, who will work together to develop a new camera for wavefront sensing, a new deformable mirror and their implementation in an adaptive optics loop. This paper will present the development of the fast large infrared e-APD camera which will be used in the wavefront sensor of the system. The camera will integrate the latest 512x512 Leonardo e-APD array and will benefit from the heritage of the first-light imaging's C-RED One camera. The most important challenges for the application are the autonomous operation, vibration control, background limitation, compactness, acquisition speed and latency.

MICADO, a Multi-AO Imaging Camera for Deep Observations, is a first light imager for the European Large Telescope (ELT). It is being designed and built by a consortium of partners from 6 different countries across Europe and led by the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching. The European Southern Observatory (ESO) is responsible for delivering the near infrared detector subsystem to the instrument. This subsystem includes nine Hawaii-4RG-15 (H4RG-15) near infrared detectors (2.5μm cut-off) mounted in a compact 3x3 mosaic at the heart of the instrument. They will operate at a nominal temperature of 82K using an array of cryogenic preamplifiers located at the back of the focal plane plate, close to the detectors. This paper presents an overview of this detector subsystem, including the measured performance of two of the H4RG-15 science detectors already characterised in a custom-built test facility at ESO. Special readout modes have been developed for the instrument and for AO corrections to one of the ELT mirrors and these are described. The design of the focal plane, its thermal analysis and the focal plane flatness measurement system being setup at ESO is also presented. This paper also provides a brief description of the new detector controllers (NGCII) being developed at ESO for all the ELT and future VLT (Very Large Telescope) science detector systems and presents the specific controller configuration which must be implemented for the MICADO detectors.

The SMILE mission, a collaborative effort between the European Space Agency and the Chinese Academy of Sciences, seeks to enhance our comprehension of the interplay between solar phenomena and the Earth's magnetosphere-ionosphere system on a global scale. Among its instrumental arsenal is the Soft X-ray Imager (SXI), designed to capture photons generated within the 200eV to 2000eV energy spectrum through the solar wind charge exchange process. This imaging tool employs two large CCD370s, each with 4510 x 4510 18μm pitch pixels, as its focal plane. SMILE will orbit Earth in an elliptical trajectory, traversing the radiation belts approximately every 52 hours. Over the course of its anticipated 3-year mission, the CCDs onboard will endure progressive deterioration from the persistent presence of trapped and solar protons. To gauge the extent of this damage and its effect on the devices' functionality, a sequence of proton radiation campaigns is underway. The final cryogenic irradiation campaign has now been completed using a fully functioning engineering model of the SXI CCD370s that will be used in flight and irradiating up to the expected end of life total non-ionising dose. The results show that the measured parallel charge transfer inefficiency (pCTI) varies with temperature both before and after irradiation, however the trend changes from decreasing with temperature to increasing. This is thought to be due to a change in the dominant effective trap species. The impact of multiple charge injection lines and 6x6 binned frame transfer is also assessed and shows that between -130 to -100°C the pCTI, when both measures are utilized, is independent of temperature. This suggests potential for more flexible thermal controls in future missions that use similar devices.

We present the first on-sky results from an ultra-low-readout-noise Skipper CCD focal plane prototype for the SOAR Integral Field Spectrograph (SIFS). The Skipper CCD focal plane consists of four 6k×1k, 15μm pixel, fully-depleted, p-channel devices that have been thinned to ∼250μm, backside processed, and treated with an anti-reflective coating. These Skipper CCDs were configured for astronomical spectroscopy, i.e., a single-sample readout noise <4.3 e⁻ rms/pixel, the ability to achieve multi-sample readout noise ≪ 1 e⁻ rms/pixel, full-well capacities ∼40,000 to 65,000 e⁻, low dark current and charge transfer inefficiency (∼2×10⁻⁴ e⁻/pixel/s and 3.44×10⁻⁷, respectively), and an absolute quantum efficiency of ≳80% between 450nm and 980nm (≳90% between 600nm and 900nm). We optimized the readout sequence timing to achieve sub-electron noise (∼ 0.5 e⁻ rms/pixel) in a region of 2k×4k pixels and photon-counting noise (∼0.22 e⁻ rms/pixel) in a region of 220×4k pixels, each with a readout time of ≲17 min. We observed two Lyman-α emitting quasars (HB89 1159+123 and QSOJ1621–0042) at redshift z∼3.5, two moderate redshift galaxy clusters (CL J1001+0220 and SPT-CL J2040−4451), an emission line galaxy at z=0.3239, a candidate member star of the Boötes II ultra-faint dwarf galaxy, and five CALSPEC spectrophotometric standard stars (HD074000, HD60753, HD106252, HD101452, HD200654). We present charge-quantized, photon-counting observation of the quasar HB89 1159+123 and show the detector sensitivity increase for faint spectral features. We demonstrate signal-to-noise performance improvements for SIFS observations in the low-background, readout-noise-dominated regime. We outline future scientific studies that will leverage these SIFS-Skipper CCD data, as well as new detector architectures that utilize the Skipper floating gate amplifier with faster readout times.

Skipper CCDs are a mature detector technology that has been suggested for future space telescope instruments requiring sub-electron readout noise in the near-ultraviolet to the near-infrared. While modern skipper CCDs inherit from the radiation-tolerant p-channel detectors developed by LBNL, the effects of high doses of ionizing radiation on skipper CCDs (such as those expected in space) remains largely unmeasured. We report preliminary results on the performance of p-channel skipper CCDs following irradiation with 217-MeV protons at the Northwestern Medicine Proton Center. The total nonionizing energy loss (NIEL) experienced by the detectors exceeds 6 years at the Sun-Earth Lagrange Point 2 (L2). We demonstrate that the skipper amplifier continues to function as expected following this irradiation. Owing to the low readout noise of these detectors, controlled irradiation tests can be used to sensitively characterize the charge transfer inefficiency, dark current, and the density and time constants of charge traps as a function of proton fluence. We conclude with a brief outlook toward future tests of these detectors at other proton and gamma-ray facilities.

We study the amplifier light emission of a set of MOSFET transistors with different Drain-Source to Gate (DS-G) distances using a dedicated Skipper-CCD sensor with single photon resolution. This light emission comes in the form of near-infrared photons produced on the Skipper’s readout stage by "hot electrons" generated in the output transistor. Depending on the applied voltages, this effect can be very faint generating only a few photons or produce a noticeable glow that can greatly impact the quality of the CCD images. A dedicated sensor with four output transistors and a different Drain-Source to Gate distance in each of them was specifically designed and fabricated at Teledyne/DALSA in order to study this phenomenon. Two different methods to characterize photons from the amplifier were explored. The first one takes advantage of the Skipper’s spatial resolution to study the total number of photons being emitted and how they propagate through silicon in the active area. The second one uses the single-electron counting mode of the device to measure the rate at which photons are emitted only in the readout stage.

The 4-Metre Multi-Object Spectrograph Telescope (4MOST) is a second-generation instrument build for ESO’s VISTA telescope in Chile, enabling large-scale spectroscopic surveys of the night sky. 4MOST will complement several European space-based observatories and future ground-based survey facilities, furthering our understanding of the universe. The instrument uses over 2 400 science optical fibres to collect and transmit light simultaneously from various astronomical targets to three spectrographs. Two thirds of the fibres will go to low-resolutions spectrographs and the remaining to a high-resolution spectrograph. Each spectrograph has three channels. Each channel uses a charge-coupled device (CCD) 231-C6 from Teledyne e2v, which gives a total of 9 science detectors. The detectors have a resolution of 6k × 6k with a pixel size of 15 μm which accounts for a total image area of 92.2mm × 92.4 mm. The image area has four separately connected sections that allow the read-out to be conducted through four output circuits. The data acquisition and signal processing unit of each detector is a new general detector controller (NGC), which is a versatile platform for infrared and optical detectors developed by ESO that is already employed in several state-of-the-art instruments. During the testing phase of the different spectrographs, flat frames were acquired that showed an unidentified image structure manifesting mostly as diagonal lines across all quadrants with central-to-edge preferential pathways. The observed fingerprint showed a slightly elevated charge amount over a few pixels wide when compared to the rest of the array. Due to the dynamic variation of the affected pixels across successive frames, the feasibility of mitigating the described phenomenon through calibration was impractical. While large format CCDs of this nature find extensive application, and the NGC is a prevalent choice for ESO instrumentation, the observation of this particular artifact appears to be previously undocumented, although it shows some similarities with the tearing patterns observed in other deep-depletion devices which are associated with field distortions in thick silicon. In this work, we describe, evaluate, and present a removal technique for the undefined image structure observed in the science detectors of the 4MOST instrument.

The Advanced x-ray Imaging Satellite (AXIS) is a NASA probe class mission concept designed to deliver arcsecond resolution with an effective area ten times that of Chandra (at launch). The AXIS focal plane features an MIT Lincoln Laboratory (MIT-LL) x-ray charge-coupled device (CCD) detector working in conjunction with an application specific integrated circuit (ASIC), denoted the Multi-Channel Readout Chip (MCRC). While this readout ASIC targets the AXIS mission, it is applicable to a range of potential x-ray missions with comparable readout requirements. Designed by the x-ray astronomy and Observational Cosmology (XOC) group at Stanford University, the MCRC ASIC prototype (MCRC-V1.0) uses a 350nm technology node and provides 8 channels of high speed, low noise, low power consumption readout electronics. Each channel implements a current source to bias the detector output driver, a preamplifier to provide gain, and an output buffer to interface directly to an analog-to-digital (ADC) converter. The MCRC-V1 ASIC exhibits comparable performance to our best discrete electronics implementations, but with ten times less power consumption and a fraction of the footprint area. In a total ionizing dose (TID) test, the chip demonstrated a radiation hardness equal or greater to 25krad, confirming the suitability of the process technology and layout techniques used in its design. The next iteration of the ASIC (MCRC-V2) will expand the channel count and extend the interfaces to external circuits, advancing its readiness as a readout-on-a-chip solution for next generation x-ray CCD-like detectors. This paper summarizes our most recent characterization efforts, including the TID radiation campaign and results from the first operation of the MCRC ASIC in combination with a representative MIT-LL CCD.

Future mega-pixel imaging x-ray detectors will require excellent spectral response at soft (E<1keV) x-ray energies while operating at fast frame-rates. We have characterized the sub-keV spectral resolution of two low-noise MIT Lincoln Laboratory CCDs in detail. These devices are identical in format but differ in gate structure and output stage design. We report measurements of the shape of the spectral redistribution function as a function of energy for each of these sensor types and compare our measurements with theoretical expectations. We also assess the implications of the observed response functions for scientific performance in deep x-ray imaging and high-resolution spectroscopy applications.

Current x-ray astronomical satellites carry CCD cameras that have moderate performance in imaging, spectroscopy and timing. Future x-ray telescopes with large effective areas and sharp point spread functions require quick readout of focal plane sensors to realize imaging spectroscopy without photon pile-up nor intermittency of exposure time. To fulfill the requirements we are developing a hybrid sensor of CCD and CMOS. The former has readout nodes for every columns and the latter equips corresponding readout ICs including analog-to-digital converters. Both parts are implemented in the same package. Vertical transfer frequency of 100kHz enables us to readout the whole frame within 10ms even with 1k by 1k pixel format. Our first test device with pixel format of 128×1024 and pixel size of 11μm square has been evaluated with monochromatic x-rays from ¹⁰⁹Cd. X-ray events are successfully detected and the energy resolution is 1.43keV (full width at half maximum) at 22keV for the events whose signal charges are concentrated in a single pixel. Approximately 30% of charges are lost for the multi-pixel events, which implies that there might exist non-depleted region in the wafer. Pulse height comparison among the split pattern of the events indicated non-uniformity of the electric field in horizontal axis. As a next step We will adopt the CCD wafer that has been used for XRISM/Xtend in order to realize the optimum electric field.

The Pennsylvania State University High-Energy Astrophysics Detector and Instrumentation (HEADI) Lab, in collaboration with Teledyne Imaging Sensors (TIS), has continued its efforts to improve soft x-ray Hybrid CMOS detectors (HCDs) on several fronts. We report on the read noise and energy resolution for the H1RG and the H2RG using a cryogenic SIDECAR^TM, which gained TRL 9 and flight heritage through the Water Recovery x-ray Rocket Mission in 2018. We also describe the 40-μm event-driven Speedster-EXD HCD, which has been scaled up from a 64×64 array to an 550×550 array. The readout circuitry within the ROIC for the Speedster-EXD contains a high-gain capacitive transimpedance amplifier (CTIA) to negate pixel cross-talk, in-pixel correlated double sampling (CDS) for correction of reset noise variations, and an in-pixel comparator enabling event-driven readout. Here we report on read noise and energy resolution measurements for the Speedster-EXD and discuss the upcoming BlackCAT CubeSAT, on which the Speedster-EXD550 will fly, raising the TRL of these HCDs. Further, to meet the requirements of future high-throughput and high spatial resolution Lynx-like x-ray observatories, HCDs with fast readout and small pixel sizes have been developed. Here we report on the energy resolution and the lowest measured read noise of any x-ray HCD to-date for the 12.5-μm 128×128 prototype Small-pixel HCD, as well as present the current results for the newest x-ray HCD, the Small-pixel1024. The Small-pixel1024 is a 12.5μm 1024×1024 HCD utilizing a high-gain CTIA and in-pixel CDS. Finally, we report on the development efforts between Penn State and Teledyne on a new event-driven HCD, which will retain the low read noise of the Small-pixel HCD while having event-driven capabilities like the Speedster-EXD.

Current-generation solar observatories employ CCD image sensors to observe the Sun in the soft x-ray (SXR) and extreme ultraviolet (EUV) regimes. However, these observations are often compromised by pixel saturation and charge blooming in the CCD image sensors when observing large solar flares. To address these limitations, the Swift Solar Activity x-ray Imager Rocket (SSAXI-Rocket) program is developing CMOS image sensors (CIS) with low noise and high-speed readout (greater than 5Hz) for next-generation solar observatories. These CIS aim to enable the observation of large solar flares while significantly reducing the effects of pixel saturation and charge blooming. As a part of NASA’s 2024 solar flare sounding rocket campaign, the SSAXI-Rocket program demonstrated delta-doped CIS technology in a space environment by operating a novel camera as a sub-payload on board the High-Resolution Coronal Imager (Hi-C) sounding rocket. This paper describes the pre-launch laboratory tests performed with the SSAXI-Rocket CIS to characterize its linearity and soft x-ray spectral resolution.

Teledyne e2v is continuing to invest in CCD and CMOS sensors innovation for ground and space-based astronomy applications. The new upgraded 8 inch process is enabling back-thinning of wafer-scale large area CMOS detectors such as the CIS300 product family. New world class broadband anti-reflecting coatings using novel technology enable high stable QE performance at VUV and UV wavelengths. Teledyne e2v has also developed a solution to increase drastically QE in near-infrared without losing on MTF nor centroiding. Building on the recent successful launch and first images of Euclid, latest information on large area CCDs from Plato, JPAS and Flyeye are provided, including details on Plato flight level focal plane assembly at Teledyne e2v. Details for CMOS imagers and their measured performance are described with a focus on noise performance, high QE in ultra-violet and near-infrared and low temperature testing. The CIS300 is a large area 9k x 8.6k 10 micron pixel pitch detector featuring high speed, high dynamic range and ultra-low noise technology enabling sub electron performance. The CIS220 is a HiRho version of CIS120 (selected for ESA’s CO2M Copernicus mission) with a significant improvement in QE and MTF in Near-Infra-Red with a QE of 60% at 950nm and an MTF of 0.55. Ultraviolet response below 200nm from CIS120 detectors is also reported. In a last part the benefits of this combination of large format imagers and wide range of wavelength sensitivity is discussed.

We present a project aiming at evaluating a novel hybrid imaging/timing detector concept comprising a photocathode, a chevron-stack micro-channel plate, and a TimePix3 readout ASIC for the detection of visible photons with high time resolution and good quantum efficiency and spatial resolution. Due to these attributes, this detector holds significant promise for time-domain astronomy. The evaluation and data collection for this project will primarily occur at the OARPAF observatory (80cm primary mirror) with the objective of pioneering this technology in the astronomical domain and gathering essential information to advance toward developing an instrument based on this technology for the Telescopio Nazionale Galileo at a later stage.

This paper discusses the further development of JPL’s n-type superlattice doping (2D doping) process for sensitivity and stability enhancement of backside illuminated (BSI), p-channel CCDs and PMOS pixel CMOS imaging arrays. We discuss the results of the n-type 2D-doping of SRI’s backside illuminated PMOS pixel 4k×4k and 8k×8k CMOS imagers. We briefly describe the backside processing parameters for the optimization of the 2D-doping process and antireflection coating design. Performance characterization, including quantum efficiency (QE), dark signal, and modulation transfer function (MTF) as a function of silicon epitaxial thickness and operating temperature will be discussed. These will be compared with the performance of devices produced using SRI’s standard BSI processes.

Modern scientific complementary metal-oxide semiconductor (sCMOS) detectors provide a highly competitive alternative to charge-coupled devices (CCDs), the latter of which have historically been dominant in optical imaging. sCMOS boast comparable performances to CCDs with faster frame rates, lower read noise, and a higher dynamic range. Furthermore, their lower production costs are shifting the industry to abandon CCD support and production in favour of CMOS, making their characterization urgent. In this work, we characterized a variety of high-end commercially available sCMOS detectors to gauge the state of this technology in the context of applications in optical astronomy. We evaluated a range of sCMOS detectors, including larger pixel models such as the Teledyne Prime 95B and the Andor Sona-11, which are similar to CCDs in pixel size and suitable for wide-field astronomy. Additionally, we assessed smaller pixel detectors like the Ximea xiJ and Andor Sona-6, which are better suited for deep-sky imaging. Furthermore, high-sensitivity quantitative sCMOS detectors such as the Hamamatsu Orca-Quest C15550-20UP, capable of resolving individual photoelectrons, were also tested. In-lab testing showed low levels of dark current, read noise, faulty pixels, and fixed pattern noise, as well as linearity levels above 98% across all detectors. The Orca-Quest had particularly low noise levels with a dark current of 0.0067 ± 0.0003 e⁻/s (at −20◦C with air cooling) and a read noise of 0.37 ± 0.09 e⁻ using its standard readout mode. Our tests revealed that the latest generation of sCMOS detectors excels in optical imaging performance, offering a more accessible alternative to CCDs for future optical astronomy instruments.

NASA seeks to identify habitable exoplanets and explore signatures of life with the Habitable Worlds Observatory and through a series of missions to Europa. The former requires single photon sensing detectors that measure fluxes as low as one photon per hour, while the latter requires detectors that maintain performance after exposure to intense high-energy space radiation. Single-photon sensing and photon-number resolving CMOS image sensors are promising for these missions. One such sensor, the Quanta Image Sensor (QIS), has deep sub-electron read noise (DSERN) that remains unchanged even after exposure equivalent to that experienced over ten 11-year mission lifetimes. The dark current increases modestly after one mission lifetime and can be returned to beginning-of-life values with cooling of ~4 to 6K. In this paper, we present pre-irradiation results obtained from another DSERN sensor, the BAE HWK4123 in the Hamamatsu ORCA-QUEST camera. We find the read noise, photon transfer, and full well depth agree with reported values for the camera, while the dark current is 2.8× higher than the reported value. We also present a radiation test program plan, including simulations of the environment at L2 and around Jupiter.

In this work, we investigate a mechanism of dark current generation under the transfer gate (TRA) in pinned photodiode (PPD) image sensors for science and space applications. It was established that the dark current could change by an order of magnitude depending on the biasing conditions of the TRA and the sense node during integration. This was observed in three sensors with different pixel sizes, made by two different foundries. The results from the characterization work to investigate the source of the dark current are presented. It was discovered that the effect strongly depends on the interplay between the timing and the biasing of the transfer gate and the sense node during reset. Two methods for the reduction of this dark current are proposed and evaluated. The results could help to find the optimal operating conditions of PPD image sensors used in applications where the dark current performance is paramount.

Astronomers are always looking to image fainter and farther objects in the night sky. Recent improvements in signal to noise ratio in solid-state detector technology have the potential to provide researchers with the ability to determine photon-number including single photons, allowing them to sense at the limit of physics. The quanta image sensor (QIS), the electron-multiplying charge-coupled device (EMCCD), and the single-photon avalanche diode (SPAD) are three types of next-generation silicon detectors that can capture images with high sensitivity and low input-referred read noise that can result in the ability to count photons. QIS uses a unique CMOS pixel topology that increases conversion gain without impact ionization, reducing readout noise to deep-sub-electron levels and enabling photon-number resolution, high dynamic range, and high spatial resolution. The EMCCD uses a CCD sensor design that amplifies the signal a small amount but very high number of times during readout using impact ionization, reducing readout noise to deep-sub-electron levels and a degree of photon-number resolution. SPAD uses fast in-pixel signal amplification using impact ionization and positive feedback to achieve negligible read noise and is capable of measuring the precise time-of-arrival of photons, enabling high-precision distance measurement and photon-counting. A representative device of each technology was characterized and evaluated with space flight missions in mind. Additionally, a variety of CCD and CMOS image sensors with “Skipper” readout are being explored for photon-number-resolving applications by several groups, including parts of our team, and we will also briefly discuss the Skipper approach in this report. Additionally, recommendations for potential improvements of the technology to better support the astronomical community are made.

The Wide Field Survey Telescope (WFST) is a dedicated photometric surveying facility equipped with a 2.5-meter diameter primary mirror, an active optics system, and a mosaic CCD camera with 0.765 gigapixels on the primary focal plane for high quality image capture over a 6.5-square-degree field of view. The mosaic CCD camera is the key device for high precision photometric and high frequency observation and the ‘eye’ of the telescope for deep survey with wide field. The focal plane consists of three kinds of CCD including scientific imaging sensors, wavefront sensors and guiding sensors. In the scientific imaging area, there are 9 back-illuminated full frame scientific CCDs –CCD290-99 from E2V company with pixels of 9K by 9K and pixel size of 10um, which is mosaicked by 3 by 3 with flatness of 20μm PV. The R&D of the camera including the high precision large-scale mosaicking of detectors, detectors’ cryocooling and vacuum sealing, readout and driving with low noise and low power, data acquisition, imaging control, data storage and distribution. Furthermore a camera control system (CCS) was developed at same time.

The LSST Camera for the Vera C. Rubin Observatory has been constructed at SLAC National Accelerator Laboratory. The Camera covers a 3.5-degree field of view with 3.2 gigapixels. The goal of the LSST survey is to provide a well-understood astronomical source catalog to the community. The LSST Camera’s focal plane is populated by 189 sensors on the science focal plane that are a combination of E2V CCD250 and ITL STA3800 deep-depletion, back-illuminated devices, accompanying eight guide sensors, and four wavefront sensors. Nine science sensors are grouped as a ”Raft” with three identical electronics boards (REBs), each operating three sensors. The REB can change the operating voltages and CCD clock, allowing operation of sensors from two different vendors in the same focal plane. We conducted phased electro-optical testing campaigns to characterize and optimize the sensor performance in the construction phase. We collected images with the focal plane illuminated by flat illuminators and some specialty projectors to produce structured images. During these tests, we found some performance issues in noise, bias stability, gain stability, image persistence, and distortion in flat images, including ”tearing”. To mitigate those non-idealities, we attempted different clocking and operation voltages and switching from unipolar voltages to bipolar voltages in parallel clock rails for E2V devices. We describe the details and the results of the optimizations.

Like many telescopes around the world, JWST was tasked to observe the double asteroid system Didymos / Dimorphos during the impact of NASA’s Double Asteroid Rendezvous Test (DART) spacecraft on Dimorphos on Sept 28, 2022. At the date of the test, the target asteroids were moving with a rate of ~110 milli-arcseconds per second across the JWST field of view, almost four times the nominal design rate for JWST’s moving target tracking mode. To help ensure that some data was acquired, eleven different observations were acquired with different guide stars, seven with Guider 1 and four with Guider 2. The large number of observations and the high motion rate provided an unprecedented opportunity to evaluate FGS performance across approximately half the field of view of both guiders. The DART tracking data provides an opportunity to examine guider performance across a wide area of the 5μm cutoff H2RG HgCdTe arrays employed in the guiders, providing a means to measure the systematic offset in the centroid as the PSF moves across, and is sampled by, the pixel grid. Systematic offsets in the centroid are of interest because they could create undesirable offsets in the pointing of the science instruments. An FFT analysis of the centroid time-series was used to identify the spatial scales and magnitudes of these centroid offsets. The expected systematic offset magnitude in the centroid due to the pixel sampling scale should be on the order of ~2 milli-arcseconds, with a corresponding variation in the count rate of 6 to 8%. The observed Guider 2 performance meets both expectations, while the results for Guider 1 show significantly larger variations in the reported count rate, likely due to the greater degree of ‘cross-hatching’ on the Guider 1 detector array. Despite these significantly larger count rate variations, the systematic offset variations observed on Guider 1 were found to be similar Guider 2 and thus consistent with expectations. This somewhat surprising result may be due to charge migration effectively blurring the detected point spread function.

For infrared detectors a new nondestructive multiple sampling technique of the detector integration ramp has been developed. It improves the duty cycle of observations by a factor of two if the integration ramp is sampled with the maximum possible number of nondestructive readouts, and several exposures are averaged to improve the sensitivity. The sampling method has been tested with the bare ROIC of the large SAPHIRA detector at room temperature, but this mode can also be applied to Hawaii-2RG, Hawaii-4RG and other infrared detectors. If the frame rate permits multiple nondestructive readouts, it is also well suited for near-infrared eAPD arrays used for NIR adaptive optics and fringe tracking. A paradigm change of detector testing is proposed: Instead of optimizing single parameters, such as the read noise, the signal-to-noise ratio of a faint image pattern should be optimized, as presented here by an experiment. For a given exposure time the signal-to-noise ratios of the new readout mode and conventional Fowler sampling are compared.

In the past few years, CEA LETI demonstrated MCT P on N photodiodes arrays achieving high level of detection for very low flux astronomy in the short wave infrared (SWIR), with dark currents values as low as 3 10⁻³ e-/s/pixel at 100K and high quantum efficiency. Persistence was also a key element to monitor for the development of this technology, and significant improvements were demonstrated in the frame of ALFA program. From this reference technology, LETI developed a brand new P on N process, focused on decreasing defectiveness and improving low frequency stability for MWIR high operating temperature (>130K) detectors for tactical application. In this spectral range, low noise stability is characterized by Random Telegraph Signal (RTS) and noise distribution tail. In the SWIR range, persistence would be the best signature to probe this low frequency stability. Declining this new generation process for the SWIR range, we present and discuss on dark current and persistence characterization on TV format 15μm pixel pitch study array designed for SWIR low flux application.

Detectors with sub-electron noise open new possibilities for the spectroscopy of Earth-like exoplanets, probing the faintest signatures of dark energy and dark matter with high-redshift galaxies, and observing fast-evolving transients. Multi-amplifier sensing (MAS) charge-coupled devices (CCDs) offer the capability to achieve ultra-low readout noise floors together with a readout rate comparable to current CCDs employed in observatories. This is achieved by distributing a chain of Skipper floating-gate amplifiers along the serial register, allowing charge to be read repeatedly, non-destructively, and independently. We show recent progress in optimizing the MAS CCD for use in astronomy. These include reducing noise to sub-electron levels with faster read times than Skipper CCDs, optical characterization results, and a discussion of the range of astronomical science cases and facilities that would be enabled by MAS CCDs.

The non-destructive readout capability of the Skipper Charge Coupled Device (CCD) has been demonstrated to reduce the noise limitation of conventional silicon devices to levels that allow single-photon or single-electron counting. The noise reduction is achieved by taking multiple measurements of the charge in each pixel. These multiple measurements come at the cost of extra readout time, which has been a limitation for the broader adoption of this technology in particle physics, quantum imaging, and astronomy applications. This work presents recent results of a novel sensor architecture that uses multiple non-destructive floating-gate amplifiers in series to achieve sub-electron readout noise in a thick, fully-depleted silicon detector to overcome the readout time overhead of the Skipper-CCD. This sensor is called the Multiple-Amplifier Sensing Charge-Coupled Device (MAS-CCD) can perform multiple independent charge measurements with each amplifier, and the measurements from multiple amplifiers can be combined to further reduce the readout noise. We will show results obtained for sensors with 8 and 16 amplifiers per readout stage in new readout operations modes to optimize its readout speed. The noise reduction capability of the new techniques will be demonstrated in terms of its ability to reduce the noise by combining the information from the different amplifiers, and to resolve signals in the order of a single photon per pixel. The first readout operation explored here avoids the extra readout time needed in the MAS-CCD to read a line of the sensor associated with the extra extent of the serial register. The second technique explore the capability of the MAS-CCD device to perform a region of interest readout increasing the number of multiple samples per amplifier in a targeted region of the active area of the device.

Single electron Sensitive Read Out (SiSeRO) is a novel on-chip charge detection technology that can, in principle, provide significantly greater responsivity and improved noise performance than traditional charge coupled device (CCD) readout circuitry. The SiSeRO, developed by MIT Lincoln Laboratory, uses a p-MOSFET transistor with a depleted back-gate region under the transistor channel; as charge is transferred into the back gate region, the transistor current is modulated. With our first generation SiSeRO devices, we previously achieved a responsivity of around 800pA per electron, an equivalent noise charge (ENC) of 4.5 electrons root mean square (RMS), and a full width at half maximum (FWHM) spectral resolution of 130eV at 5.9keV, at a readout speed of 625Kpixel/s and for a detector temperature of 250K. Importantly, since the charge signal remains unaffected by the SiSeRO readout process, we have also been able to implement Repetitive Non-Destructive Readout (RNDR), achieving an improved ENC performance. In this paper, we demonstrate sub-electron noise sensitivity with these devices, utilizing an enhanced test setup optimized for RNDR measurements, with excellent temperature control, improved readout circuitry, and advanced digital filtering techniques. We are currently fabricating new SiSeRO detectors with more sensitive and RNDR-optimized amplifier designs, which will help mature the SiSeRO technology in the future and eventually lead to the pathway to develop active pixel sensor (APS) arrays using sensitive SiSeRO amplifiers on each pixel. Active pixel devices with sub-electron sensitivity and fast readout present an exciting option for next generation, large area astronomical x-ray telescopes requiring fast, low-noise megapixel imagers.

In recent years, CCD-in-CMOS time delayed integration (TDI) image sensors are becoming increasingly popular for many small satellite missions to assure fast and affordable access to space for Low Earth Observation. Imec first introduced its monolithic CCD-in-CMOS technology at IEDM 2014. It combines the benefits of a classical CCD TDI with the advantages of CMOS System-On-a-Chip (SoC) design. Imec’s CCD-in-CMOS technology is continuously being tuned to reach high pixel performance. This paper presents Technology Computer Aided Design (TCAD)-based design methodology of a CCD-in-CMOS imager pixel. This pixel design methodology includes test structure based TCAD simulation approach to design CCD-in-CMOS pixel by extracting design conditions and criteria to achieve CCD performance specifications. In this methodology, the proposed design technique discloses a way to realize CCD functionality integration in the charge domain with a view to optimizing the critical parameters such as full well capacity (FWC) and charge transfer efficiency (CTE). As a part of this design consideration, we studied transient behavior of charge transfer efficiency (CTE). As the charge transfer process within pixels differs from the conditions when charge is being dumped from the output summing well (OSW) to the floating diffusion (FD), these two cases are considered separately. Ideal clocks with different slews are used for the pixel-to-pixel transfer study, whereas they have been replaced with more realistic exponential curves for the output charge drain simulations, allowing a further refinement of the results. Although this work was originally done for CCD-in-CMOS TDI pixel design, this is in no way specific to the only TDI CCD-in-CMOS. Rather, the proposed methodology is applicable to all types of CCD pixel-design.

We have developed the 100 ns high-time resolution optical camera based on the Multi-Pixel Photon Counter (MPPC) called ”Imager of MPPC-based Optical photoN counter from Yamagata (IMONY)”. IMONY has three important parts: the customized sensor, the front-end board, and the Field Programmable Gate Array (FPGA) with the Global Navigation Satellite System (GNSS). The sensor is made with the MPPC composed of a monolithic Geiger-mode Avalanche PhotoDiodes (GAPD) array. The photon detection efficiency is more than 60% at 450nm. The feature that GAPD can detect a single photon has cons in terms of dynamic range, while has pros in terms of nothing readout noise. A detected photon is converted to a photo-electron, and it is multiplied ∼106 times larger via avalanche amplification. The front-end board has a comparator and the amplified signal is recognized as a single photon when the pulse height exceeds a threshold. The output signal is sent to the FPGA and given a timestamp of 100ns accuracy. In January 2023 and October 2023, we mounted IMONY for two Japanese optical telescopes. One is the 1.5m Kanata telescope, Hiroshima, Japan. The other is the 3.8m Seimei telescope, Okayama, Japan. We observed the Crab pulsar and detected pulses for all rotations (one pulse per single rotation) more than 5σ for the main pulse phase.

Large-format infrared detectors are at the heart of major ground and space-based astronomical instruments, and the HgCdTe HxRG is the most widely used. The Near Infrared Spectrometer and Photometer (NISP) of the ESA’s Euclid mission launched in July 2023 hosts 16 H2RG detectors in the focal plane. Their performance relies heavily on the effect of image persistence, which results in residual images that can remain in the detector for a long time contaminating any subsequent observations. Deriving a precise model of image persistence is challenging due to the sensitivity of this effect to observation history going back hours or even days. Nevertheless, persistence removal is a critical part of image processing because it limits the accuracy of the derived cosmological parameters. We will present the empirical model of image persistence derived from ground characterization data, adapted to the Euclid observation sequence and compared with the data obtained during the in-orbit calibrations of the satellite.

The MIT x-ray Polarimetry Beamline is a facility that we developed for testing components for possible use in x-ray polarimetry. Over the past few years, we have demonstrated that the x-ray source can generate nearly 100% polarized x-rays at various energies from 183eV (Boron Kα) to 705eV (Fe Lα) using a laterally graded multilayer coated mirror (LGML) oriented at 45 degrees to the source. The position angle of the polarization can be rotated through a range of roughly 150°. In a downstream chamber, we can orient a Princeton Instruments MTE1300B CCD camera to observe the polarized light either directly or after reflection at 45° by a second LGML. In support of the REDSoX Polarimeter project, we have tested four other detectors by directly comparing them to the PI camera. Two were CCD cameras: a Raptor Eagle XV and a CCID94 produced by MIT Lincoln Laboratories, and two had sCMOS sensors: the Sydor Wraith with a GSENSE 400BSI sensor and a custom Sony IMX290 sensor. We will show results comparing quantum efficiencies and event images in the soft x-ray band.

Charge coupled devices remain the scientific tool of choice for x-ray imaging spectrometers for astrophysics applications due to their deep depletion depths, low noise, and uniform Gaussian energy response. These qualities provide advantages over both monolithic and hybridized CMOS sensors in this application space, but relative to these alternatives come most significantly at the cost of frame rate. This work at MIT’s Lincoln Laboratory in collaboration with MIT’s Kavli Institute and Stanford’s KIPAC presents current directions of pursuit in design, fabrication, and architecture towards the end of improved CCD performance at elevated data rates. Advanced sense nodes designed for low noise, high speed operation requires pushing towards high conversion gain and high transconductance sense transistors both through enhancement of current generation JFETs and refinement of design for future generation SiSeRO nodes [single electron sensitive readout]. Larger devices require lower capacitance parallel gates to support charge transfer towards output nodes at the requisite pixel rates. Transition from triple-poly to single poly gate structures reduces this capacitance while maintaining high charge transfer efficiency to high transfer rates across many cm² devices. Architecturally, enhanced parallelization with increased port counts and densities supports elevated data rates for any given pixel rate. Close integration to support ASICs handles this elevated data rate without undue multiplication of support electronics.

We present the development of a large-volume, increased field-of-view Time Projection Chamber (TPC) for x-ray polarimetry, utilizing a triple-GEM detector with optical readout. Initially optimized for directional Dark Matter searches, this system employs a scientific CMOS (sCMOS) camera and a PMT to detect secondary scintillation light produced during the TPC amplification stage. A prototype TPC with a cylindrical active volume of radius 3.7 cm and height 5 cm was tested at the INAF-IAPS calibration facility in Rome, Tor Vergata to establish the instrument’s sensitivity to low-energy electron direction. Complete reconstruction of electrons in the 10-60 keV range with angular resolution down to 15° was measured, resulting in inferred modulation factors up to 0.9. We will present the initial results from our test campaign, which confirm effective photoelectron tracking in the tens of keV range with a strong modulation factor. This innovative approach could extend x-ray polarimetry sensitivity to higher energies and possibly enable the observation of rapid transient phenomena, such as Gamma Ray Bursts (GRBs) and solar flares, thus contributing significantly to x-ray astronomy.

In recent years, an interest in the detection of the ShortWave Infra-Red (SWIR) band has grown. On the ground, the development of telescopes (ELTs) requires the construction of large focal planes in the SWIR for imaging, spectroscopy, or wavefront sensing applications. In space, the SWIR band can have many applications whether for communications or for imaging space and earth. The state-of-the-art III-V detectors in the SWIR are InGaAs photodiodes on InP substrate that are limited by a 1.7μm cut-off wavelength. Superlattice (SL) based detectors, that have been increasingly studied in recent years, make it possible to reach new cut-off wavelengths. Starting from the InGaAs on InP detector technology that has been mastered for more than ten years by THALES, the III-V Lab we propose to extend the detection range beyond 1.7μm by introducing a SL in the active region of an InGaAs photodiode. We will present the results obtained up to 2.6μm, as well as the solutions implemented to limit the carrier localization in the superlattice and the associated QE degradation. We will also discuss the consequence of minority carrier lifetime on the performance and the consequence of localization on MTF.

Space targets are mainly divided into spacecraft and space debris working in orbit. Important near-Earth objects can be accurately detected and tracked, and their threats to the planet security can be predicted by monitoring their orbit and volume parameters. Optical telescope is one of the most important astronomical telescopes, science-grade image sensors were used to collects optical information about stars. In modern times, with the rapid development of semiconductor technology, CMOS (Complementary Metal Oxide Semiconductor) image sensor has high data transmission rate and high integration, CMOS image sensors have become the main optical imaging image sensors used in astronomical telescopes. In this presentation, the imaging principle and firmware design of a scientific CMOS camera named PX400 are introduced and tested. The PX400 uses a scientific image sensor called GSENSE400BSI (hereinafter referred to as GS400) produced by GPIXEL, which has a high data readout rate and a variety of operating modes.

CIS221-X is a prototype monolithic CMOS image sensor, optimised for soft x-ray astronomy and developed for the proposed European Space Agency THESEUS mission. One significant advantage of CMOS technology is its resistance to radiation damage. To assess this resistance, three backside-illuminated CIS221-X detectors have been irradiated with 10MeV protons using the MC40 cyclotron facility at the University of Birmingham, UK. Each detector received ½, 1 and 2 THESEUS end-of-life proton fluences (6.65 × 10⁸ p⁺/cm²). One had already been exposed to ionising radiation (up to 59.04krad TID) during a previous radiation campaign. Using unirradiated readout electronics, the electro-optical performance of each device has been measured before and after proton irradiation. No significant change was observed in the readout noise and image lag. An increase in mean dark current was recorded, as was an increase in the number of hot pixels. The degradation of CIS221-X performance due to non-ionising radiation effects is similar to that of comparable CMOS image sensors.

Observations in the near-infrared using large ground-based telescopes are limited by bright atmospheric emission lines, particularly OH lines, which can saturate a spectrograph on the order of minutes. Longer exposures will not contain useful information about the emission lines and also run the risk of detector effects such as bleeding and persistence. By using guide windows on a HAWAII-2RG infrared detector, we demonstrate on-detector suppression of these bright lines in long exposures. This is achieved by periodically resetting detector regions which contain bright emission lines before they have the chance to saturate, while the rest of the detector continues integrating. Used with extended exposure lengths, this could allow for significant reduction of the read noise overhead required for stacking shorter exposures. In addition, through non-destructive reading we are able to monitor the lines which are being reset, allowing us to retain information about the characteristics and variability of these lines. We present the results of a first demonstration of this technique using controlled observations of arc lamps with the 1.2-m McKellar Spectrograph at the Dominion Astrophysical Observatory in Victoria, Canada. We find promising results for the potential future use of this technique.

Future strategic x-ray satellite telescopes, such as the probe-class Advanced x-ray Imaging Satellite (AXIS), will require excellent soft energy response in their imaging detectors to enable maximum discovery potential. In order to characterize Charge-Coupled Device (CCD) and Single Electron Sensitive Read Output (SiSeRO) detectors in the soft x-ray region, the x-ray Astronomy and Observational Cosmology (XOC) group at Stanford has developed, assembled, and commissioned a 2.5-meter-long x-ray beamline test system. The beamline is designed to efficiently produce monoenergetic x-ray fluorescence lines in the 0.3 to 10keV energy range and achieve detector temperatures as low as 173K. We present design and simulation details of the beamline, and discuss the vacuum, cooling, and X-ray fluorescence performance achieved. As a workhorse for future detector characterization at Stanford, the XOC beamline will support detector development for a broad range of x-ray astronomy instruments.

The conventional response band of Indium Gallium Arsenide (InGaAs) detectors ranges from 0.9 to 1.7μm. The J atmospheric window (1.25μm) in infrared astronomy falls at the center of the response band of InGaAs detectors, making them widely used in this spectral region for infrared astronomy. Three representative Chinese-made Indium Gallium Arsenide focal plane arrays (InGaAs FPAs) were selected, and corresponding interface circuits were designed to match the testing system. Key performance indicators such as dark current, gain, and readout noise were tested.

The Mid-Infrared Instrument (MIRI), on-board the James Webb Space Telescope (JWST), was designed to produce a diffraction-limited Point Spread Function (PSF) at the detector image plane in the 5 to 28 micron wavelength range. For the MIRI Medium-Resolution Spectrometer (MRS), a PSF broadening of 60% down to 10% is observed in the 5 to 28 micron range. Additionally, 20% of the light is scattered into the wings as an extended component on the detector. The same PSF systematics manifest in the MIRI Imager and Low-Resolution Spectrometer (LRS) data. We use physical optics propagation to propagate a uniform wavefront from the JWST pupil to the MIRI Imager detector plane. The camera F-number and variation of incidence angle across the detector allow us to reproduce the detailed features of the cruciform, as well as an observed bending in the cruciform arms that changes across the detector. This presents a significant leap for PSF-weighted photometry. The model can be extended to the LRS and potentially to the MRS, although the optical path of the latter is much more complex to model.

We conducted the evaluation testing of the InGaAs image sensor for the future JASMINE mission. The InGaAs image sensor, which is manufactured by Hamamatsu Photonics K.K., has been updated with substrate removal to avoid fluorescence caused by cosmic rays. We introduce preliminary performance reports of the 128×128 arrayed small prototype at 170K, assuming space use, including dark current and relative quantum efficiency in the near-infrared. Notably, we confirmed that fluorescence is significantly mitigated with an exposure of about 10 minutes. Furthermore, the relative quantum efficiency in the visible wavelength is enhanced compared to previous evaluations in the literature. These results provide a good configuration for the test of the sensor for deployment and play an important role in the future development of infrared astronomical instruments.

Future strategic x-ray astronomy missions will require unprecedentedly sensitive wide-field imagers providing high frame rates, low readout noise and excellent soft energy response. To meet these needs, our team is employing a multi-pronged approach to advance several key areas of technology. Our first focus is on advanced readout electronics, specifically integrated electronics, where we are collaborating on the VERITAS readout chip for the Athena Wide Field Imager, and have developed the Multi-Channel Readout Chip (MCRC), which enables fast readout and high frame rates for MIT-LL JFET (junction field effect transistor) CCDs. Second, we are contributing to novel detector development, specifically the SiSeRO (Single electron Sensitive Read Out) devices fabricated at MIT Lincoln Laboratory, and their advanced readout, to achieve sub-electron noise performance. Hardware components set the stage for performance, but their efficient utilization relies on software and algorithms for signal and event processing. Our group is developing digital waveform filtering and AI methods to augment detector performance, including enhanced particle background screening and improved event characterization. All of these efforts make use of an efficient, new x-ray beamline facility at Stanford, where components and concepts can be tested and characterized.

With CMOS sensors starting to be utilised in astronomical telescopes, new uses for them are being explored. One such use is the possibility of observing distant, dim objects, which requires long integration times, and therefore low dark current. This work focuses on the dark current characterisation of the CIS220, a sensor made by Teledyne e2v for future space missions, at very long integration times at a range of temperatures, from +20 to –60 °C, before and after proton and gamma irradiation.

Under an ESA contract, Leonardo UK developed the IBEX detector also referred to as LAPD for Large-format Avalanche Photo Diode array. Leonardo’s packaging solution relied on a chip-on-board solution incompatible with technical and performance requirements of ESA characterization campaign and experimental setup. An in-house solution has been developed, with ESA responsible for the design, manufacture, and test. And Leonardo responsible for gluing the device to the carrier and the wire bonding. ESA’s packaging solution relies on molybdenum carrier and two flexible PCB cables. The design, manufacturing, testing, and assembling of the various components of the LAPD package assembly entailed a variety of design iterations, tests, and trials. The material choice was a compromise between optimal CTE mismatch of Invar 36 and excellent thermal conductivity of TZM molybdenum (TZM = 0.5% titanium, 0.08% zirconium, 0.02% carbon). TZM molybdenum was chosen, and it was decided to verify the behavior by test. A thermal-vacuum test campaign showed that a mounted ROIC survives test representative conditions i.e., various thermal cycles between 20 and 200K. The gold coating of the molybdenum carrier is a real challenge, we will report on lessons learned. Similarly, the flexible PCB cables gluing to the carrier performed in-house is a delicate exercise. The flex cables are bonded to molybdenum blocks which are permanently mounted in a recess in the back of the carrier. Several trials were done for the mounting until successful result was reached. A sequence of thermal cycles between 20 and 200K were performed and showed no evidence of failure throughout the bond line between the block and flex cable. A handling jig was designed to fit Leonardo’s bonding setups for the die mounting and wire bonding. The handling jig is also used to safely mount the device in an in-house designed transportation and storage container.

National Astronomical Observatory of Japan and Hamamatsu Photonics K.K. have been developing large format and high-speed readout CMOS sensors. It is designed to be 2,560 × 10,000 pixels with 7.5μm and three-side buttable in order to cover a wide field of view. The CMOS sensors is designed to be back-illuminated to achieve higher filling factor than front-illuminated CMOS sensors and to improve the sensitivity by avoiding photon absorption by the poly-silicon circuit. Each pixel row is equipped with an ADC to achieve the frame rate of 10Hz. The evaluation in the laboratory shows that the sensor has excellent performance; the quantum efficiency is 80% at maximum at 600nm and readout noise is 3 e⁻ rms at 2fps. We are developing a wide field camera using these CMOS sensors.

We are developing x-ray Silicon-On-Insulator (SOI) pixel sensors, called "XRPIX" for the next generation x-ray astronomy satellites. The XRPIX has the unique function of event trigger and hit address outputs allowing us to read out signals only from the x-ray detected pixels. In order to use the XRPIX for the x-ray observatories, the sufficient time resolution is required to discriminate non x-ray events using the anti-coincidence method. For this method, a hit trigger of the XRPIX with a short delay and jitter time (~10μs) is required since the typical hitting rate of the high-energy background events on active shields is ~10kHz. Therefore, we have evaluated the trigger performance using the laser-generated pseudo-x-ray instead of x-ray sources. This allows us to easily control the timing, the position, and the energy of the hit events on the XRPIX. We estimated trigger's delay and jitter time to be ≲1μs. Here, we will report on the results of the trigger evaluation.

Recently, InGaAs cameras have been utilized in time domain astronomical observations in the infrared bands, taking advantage of their improved performance. However, the noise levels of InGaAs cameras remain high compared to Charge coupled device (CCD) in optical bands, thereby limiting the signal-to-noise ratio for photometry. We characterize noise of Ninox 640 SU InGaAs camera. We test the noise components originating from bias, dark current, and flat, and analyze the readout noise, dark current, non-linearity, and the variation in responses between pixels. Bias and readout noise of CCD in optical band are stable. The frame with the minimum integration time of camera is generally considered as bias, and the readout noise is calculated based on it. However, count and noise of InGaAs camera are still unstable during a short period of integration time, prompting a detailed discussion on bias selection and readout noise calculation methods. The photon transfer curve (PTC), which represents the variance as a function of signal, is commonly employed to determine gain of camera from the slope. However, our PTCs exhibit varying slopes corresponding to different levels of brightness in the light source, indicating a non-constant slope. Consequently, we maintain a fixed integration time while increasing the signal level by intensifying the light source. This adjustment yields constant PTC slopes, consistent with the expectation, thereby suggesting the presence of additional noise that increases with integration time. Therefore, when measuring the gain of InGaAs cameras via PTC, it is imperative to opt for fixing exposure time and changing light brightness. Following the characterization of the noise components, we will develop correction methods for each noise and apply these methods to frames obtained from astronomical time domain observations. Finally, we will discuss the potential of InGaAs cameras in infrared time domain observations.

Electron Multiplying Charge Coupled Devices (EMCCDs) are used in several astronomical applications thanks to their low noise at high frame rates. Depending on the application, it can be important to estimate the sensor gain, especially since the gain can change over time or depend on operating conditions. In this article we compare five techniques that have been proposed to estimate EMCCD gain using simulated, laboratory and data collected on-sky.

This paper will show a very precise and easier concept to align CCD sensor packages out of an extremely stiff and precise machined SiC based composite material called HB-Cesic to assemble numerous sensors on a focal plane with micron precision. The focal plane structure will be from the same ceramic material therefore, the complete focal plane assembly will be manufactured out of a single material having a very low CTE with high thermal conductivity. Such assembly can be scaled from Cubesats like 6U up to very large scaled focal plane assemblies (FPA) like 1 x 1m for ground-based applications to allow super precise alignments and high camera resolution.

Future space observatories dedicated to direct imaging and spectroscopy of extra-solar planets will require ultra-low-noise detectors that are sensitive over a broad range of wavelengths. Silicon charge-coupled devices (CCDs), such as EMCCDs, Skipper CCDs, and Multi-Amplifier Sensing CCDs, have demonstrated the ability to detect and measure single photons from ultra-violet to near-infrared wavelengths, making them candidate technologies for this application. In this context, we study a relatively unexplored source of low-energy background coming from Cherenkov radiation produced by energetic charged particles traversing a silicon detector. In the intense radiation environment of space, energetic cosmic rays produce high-energy tracks and more extended halos of low-energy Cherenkov photons, which are detectable with ultra-low-noise detectors. We present a model of this effect that is calibrated to laboratory data, and we use this model to characterize the residual background rate for ultra-low noise silicon detectors in space. We find that the rate of cosmic-ray-induced Cherenkov photon production is comparable to other detector and astrophysical backgrounds that have previously been considered.

The Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission is a four-spacecraft observatory designed for low earth orbit observations of the Sun to understand better the solar wind. Each of the four observatories carries a Teledyne e2V 230-82 CCD controlled by a Rutherford Appleton Laboratories (RAL) detector controller and a filter wheel that allows for the selection of different polarization vectors and a blank off to monitor detector health. The CCD is 2kx4k pixels and has a store shield covering half the device to serve as a charge storage region. The CCDs are operated in pseudo frame transfer mode. We present here the laboratory optical calibration data for the four flight detector systems.

Persistence effects in HgCdTe infrared detectors cause significant artifacts that can impact the quality of science observations for up to many hours after exposure to bright/saturating sources. This problem will have a substantially greater impact on viable observing modes for infrared cameras on future ELTs due to the leap in sensitivities that is expected. In this paper we present new results from an updated test system that was previously used to prototype “on-detector guide windows” to provide fast T/T feedback to AO systems, interleaved with simultaneous (slow) full-frame readouts for science. We now explore the possibility of continuously resetting these small regions of the detector that are illuminated with a compact source as a strategy for mitigating persistence, using two different detectors. While our results generally show promise for this observing strategy, we found for one of our detectors that the combination of fast localized resets with intense illumination can introduce a potentially problematic persistent change in local reset levels.

We report recent progress on microchannel plate (MCP) sealed, high-vacuum devices and open-face architectures. These can be configured with UV transmissive windows, bi-alkali or alkali-halide opaque photocathodes and atomic layer deposited (ALD) MCPs. Detectors with 100cm² cross-strip (XS) readouts are currently under development, and we discuss our results with newly fabricated hermetic, high temperature co-fired ceramic XS anodes. We employ event driven electronics and make initial performance assessment of these new sensing elements. We also discuss the implementation of a first-generation GRAPH ASIC that couples charge sensitive amplification and digitization for XS signal conversion in a low power, small format. The approaches shared serve as candidates for creating large focal planes that can meet the requirements of future flagship UV missions. They also constitute a tailorable option for the community and can support smaller missions with a variety of detector formats.

This paper details the development of the Adiabatic Demagnetization Refrigerator (ADR) control electronics for X-IFU instrument, of ESA’s newAthena observatory. The ADR operates in a closed loop using a PID system, where the voltage bias is regulated based on the temperature measurements. The core of this work details the design and development of two electronics board prototypes, a differential low noise amplifier and a power supply board, addressing the unique space constraints and operational requirements. The ultra-low noise amplifier is designed to readout a 50mK resistive sensor. We have achieved a noise level of 2nV/√Hz which is critical for addressing the challenges of thermal stability (0.8μK RMS at 50mK), essential to achieve the instrument’s target resolution of 2.5eV. Preliminary results of the ADR cooler’s performance and its control electronics will be presented, emphasizing the temperature regulation achievements during the observation phase.

The METIS instrument (Mid-infrared ELT Imager and Spectrograph) is one of the three first-light instruments for the ELT. It will work in the mid-infrared with a set of four different focal planes, grouped in three different subsystems: the imager (IMG) and the spectrograph (LMS) are the two scientific focal planes, and the last one, SCAO, is the dedicated adaptive optics system. In total, this instrument requires five H2RG detectors (5.3μm cutoff), one SAPHIRA detector (2.5μm) and one GEOSNAP (13.5μm). All of these detectors will be controlled by the New General Controller, second generation (NGCII). These three separate subsystems require specific tests and development : the IMG needs a fast readout for both N and LM channels, the LMS requires a mosaic of four detectors and SCAO works with one single detector operated fast for AO corrections. In this paper, we will present the challenges for the development of the detector systems of the three detector subunits in METIS. This includes the design, tests and preparations for the AIT/AIV phases that each subsystem has to go through. First, we describe the detector-specifics of all the instruments. In a second part, we go over the design challenges for these detector subunits. In the end, we will report on the current testing.

The second generation of ELT instruments includes an optical-infrared high-resolution spectrograph, ANDES, ArmazoNes high Dispersion Echelle Spectrograph. It covers a wide spectral range that goes from 0.4 to 1.8μm (goal 0.35 to 2.4μm). A common model of detector is planned for the two visible spectrographs RIZ and UBV. A total of five detectors will cover the latter spectral range. A common detector unit design has been developed based on ELT's standard components and inspired by the previous successful detector units designed for HARPS and ESPRESSO. It consists of a 9k x 9k CCD detector, a differential vacuum cryostat that keeps the detector in its dedicated vacuum chamber and a cryocooler that cools down the detector to minimize the dark noise. The required temperature, mechanical and pressure stabilities drive the design of the detector unit.

With the expanding integration of infrared instruments in astronomical missions, accurate per-pixel flux estimation for near-infrared hybrid detectors has become critical to the success of these missions. Based on CPPM’s involvement in both SVOM/Colibri and Euclid missions, this study introduces universally applicable methods and framework for characterizing IR hybrid detectors and decorrelating their intrinsic properties. The characterization framework, applied to the ALFA detector and Euclid’s H2RG, not only validates the proposed methods but also points out subtle behaviors inherent to each detector.

ESA’s Science Payload Validation laboratory is responsible for the characterization of detectors (CCDs, CMOS, MCT hybridised arrays, etc.) under technology development or foreseen to be used in ESA’s science missions. In this context, the ESA’s Science Payload Validation laboratory has developed COMODOR (ESA’s COntroller for cMOs DetectOR), a new modular CMOS controller focused on controlling and reading out new and future large format infrared and visible CMOS imaging sensors. A prototype for COMODOR has been developed and is currently in use to characterize Leonardo’s IBEX 2k x 2k pixels MCT-hybridised detector. To achieve such a goal, COMODOR is based on a modular architecture which contains a Xilinx PCIe FPGA Video card to readout the detector and to reconstruct the images, a PCIe Timing Card to drive the timing clocks and control the detector, an in-house Front End-Electronic Video board which accommodates ADCs to sample analogue video channels and Power Supply boards to provide low-noise power supplies for the analogue chain and to the detector. The entire system is under the control of a dedicated Linux computer. In this contribution we give an overview of the architecture, a description of key elements, and provide a first report on functionality and performance testing activities. We also provide an outlook of the next improvements and corresponding challenges.

The Little Ultraviolet Camera (LUVCamera) is a low-cost, high-performance UV/optical camera system designed to support a range of space-based astronomical facilities. At the heart of LUVCamera is a GSENSE 4040-BSI scientific CMOS (sCMOS) sensor, similar to those found in commercial-off-the-shelf (COTS) cameras. Given the intended use of LUVCamera in space-based missions, it is crucial to understand not only the performance of the sensor, but also the degradation of that performance due to effects from radiation in space environments. In this work, we report our characterization results of a SBIG Aluma AC4040 which utilizes this sensor, as well as those of a SBIG Aluma AC2020 (based on the smaller GSENSE 2020-BSI) which has been exposed to radiation. Specifically, we detail the methods used to characterize the sensors along with measurements of the read noise (RN), dark current (DC), and absolute quantum efficiency (QE). Additionally, we report changes in those quantities after radiation exposure for the AC2020. We conclude that COTS sCMOS sensors such as these are sufficiently suited for applications in space-based missions.

The Rubin Observatory LSST Camera exhibits novel crosstalk between CCD amplifier segments that does not scale linearly with intensity as we would expect from capacitive coupling alone. Illuminating with images of satellite streaks and stars, we create realistic crosstalk sources and images in science-grade LSST CCDs. We use a custom-made electronics board that simulates the load of a CCD to inject proxy video signals directly into Rubin LSST Camera readout electronics board to isolate the sources and shape of crosstalk and its nonlinearity. We discuss possible mechanisms for the origin of this nonlinear crosstalk in the camera and how it may be partially corrected in the main survey by making changes to the correlated double sampler timing in the camera readout. We show that crosstalk nonlinearity originates at least in part from the readout electronics and the correlated double sampler (CDS) in particular. We show that increasing CDS ramp time will decrease crosstalk nonlinearity.

Spectroscopy and direct-imaging of ultra-faint targets such as Earth-like exoplanets and high redshift galaxies are among the primary goals of upcoming large scale astronomy projects like the Habitable World Observatory (HWO). Such objectives pose extreme instrumental challenges, in particular on detectors where dark currents lower than 1 e-/pixel/kilosecond and read noise less than 1 e-/pixel/frame will have to be achieved on large format arrays. Some technologies meet these requirements at optical wavelengths, but none do in the infrared. With this goal in mind, the University of Hawaii has partnered with Leonardo to develop linear-mode avalanche photodiodes (LmAPDs). In this paper, we report recent tests performed on LmAPDs, where we measure a ROIC glow of ∼0.01 e-/pixel/frame, without which the intrinsic dark current is essentially zero (<0.1 e-/pixel/kilosecond). We show that at high gain, these devices are capable of detecting single photons.

In this study we present the characterization and optimization of the Rubin Observatory’s LSST Camera CCDs that was done using the LSST Beam Simulator, a wide field 1:1 re-imaging system that recreates the f/1.2 optical beam of the LSST Camera. We describe the software and hardware upgrades to the imaging system to replace our previous commercial SAO electronics controller with the custom-built Readout Electronics Board (REB5) and Data Acquisition system (DAQ) used by the LSST Camera, to more accurately replicate the on-sky operation of the CCDs. Basic characterization was carried out using bias, dark, and flat images to calculate electro-optical properties including read noise, gain, and dark current. We used images of spots and streaks to simulate realistic astronomical objects such as stars and satellites to study non-linear electronic crosstalk and image persistence and to test changes to the CCD operating conditions to reduce the impact of these sensor effects. The results showed the crosstalk for each source-target pair may be fit with a 3-parameter function that includes higher order non-linear terms and that increasing clocking buffer time can reduce the linear and first-order non-linear crosstalk terms. It was determined that image persistence that occurs only in the LSST Camera CCDs manufactured by Teledyne E2V can be partially mitigated but not eliminated by modifying the parallel transfer clocking from the nominal to a scheme that does not use over-lapping parallel phases, but this improvement may also degrade other aspects of the CCD performance.

We present the design and initial tests of the HIgh-speed Array Controller (HIAC) developed at NRC to operate high frame rate multi-channel imaging detectors. The development of HIAC was prompted by the need for a controller to operate the SaphiraQM infrared APD array, which has 64 output channels running at up to 10Mpx/s each. No available controller had this capability. The controller is based around a Xilinx Zynq system-on-chip (SoC) module with multiple processor cores and programmable logic, which provides plenty of computing resources and real-time sequencing capability, as well as sufficient high-speed transceivers for handling the data communication. The highly flexible nature of the Zynq device allows the system to be reprogrammed to operate many types of detectors. Two compact prototype systems have been built from a Zynq development board and some custom analog circuit boards. One is designed to operate the SaphiraQM and the other to operate a large format CMOS imager with a digital interface (CIS120). Initial tests demonstrate the system's ability to handle high-speed data acquisition and processing effectively, achieving synchronization and accurate signal capture across all channels.

Microchannel plates-based detectors have been for a long time the detectors of choice for astronomical applications in the FUV/EUV, due to their photon counting capability and the possibility of solar blindness. In the framework of technological R&D for a future astronomical FUV/EUV spectrograph, we are developing a new readout system to allow unprecedented dynamic range. The goal is to realize a photon counting, solar blind, UV detector, based on a MCP read out with a 2D anode array integrated in a custom designed Read Out Integrated Circuit (MIRA: Microchannel plate Readout ASIC), able to reach unprecedented performance in terms of dynamic range combined with spatial resolution close to 30μm. Each pixel contains an anode to collect the electrons emitted by the MCP, a low noise amplifier and filter to maximize the SNR, a comparator to recognize and count single photon events, logic to correct for charge sharing among pixels (CSCL) and two counters. Some preliminary characterization of the first prototype, based on a demonstrator of the MIRA ASIC, 32×32 pixels, 35×35μm² size, for a total chip area of 2×2mm², integrated into a standard demountable MCP intensifier, have been carried out.

Metis, one of the instruments of the ESA mission Solar Orbiter (launched on 10 February 2020, from Cape Canaveral), is a coronagraph with 2 channels, capable of performing broadband polarization imaging in the visible range (580 to 640nm), and narrow-band imaging in UV (HI Lyman-α 121.6nm). It is equipped with two detectors based on CMOS APS sensors: the visible channel includes a custom CMOS sensor with direct illumination, while the UV channel is provided with an intensified camera, based on a Star-1000 rad-hard CMOS APS coupled via a 2:1 fiber optic taper to a single-stage Microchannel Plate intensifier coated with an opaque KBr photocathode and sealed with an entrance MgF2 window. Dark subtraction is a crucial step in the data reduction pipeline, thus requiring careful in-flight monitoring and characterization of the dark signal. Since it is not possible to directly acquire dark images with the visible detector, as the door of the instrument is not light-tight, an ad hoc procedure has been designed to estimate the correction to be applied. In the case of the UV detector, however, it is possible to acquire dark frames by turning off the intensifier. Due to small fluctuations occurring on the bias signal level even on short timescales, an algorithm has been developed to correct the dark matrix frame by frame.

New longwave HgCdTe detectors are critical to upcoming plans for ground-based infrared astronomy. These detectors, with fast-readouts and deep well-depths, will be key components of extremely large telescope instruments and therefore must be well understood prior to deployment. We analyze one such HgCdTe detector, a Teledyne Imaging Sensors GeoSnap, at the University of Michigan. We find that the properties of the GeoSnap are consistent with expectations from analysis of past devices. The GeoSnap has a well-depth of 2.75 million electrons per pixel, a read noise of 360e-/pix, and a dark current of 330,000 e-/s/pix at 45K. The device experiences 1/f noise which can be mitigated relative to half-well shot noise with modest frequency image differencing. The GeoSnap’s quantum efficiency is calculated to be 79.7 ± 8.3% at 10.6 microns. Although the GeoSnap’s bad pixel fraction, on the order of 3%, is consistent with other GeoSnap devices, close to a third of the bad pixels in this detector are clustered in a series of 31 ”leopard” spots spread across the detector plane. We report these properties and identify additional analyses that will be performed on future GeoSnap detectors.

Pseudothermal light exhibits photon bunching, like thermal light, but it does not originate from randomly phased emission. As photon bunching is common in both pseudothermal and thermal light, the analysis of photon bunching is insufficient to differentiate pseudothermal light and thermal light. However, thermal light obeys the Siegert relation, which connects the interferometric visibility ∥g⁽¹⁾(τ )∥ and second-order photon correlation g⁽²⁾(τ ). In this work, we present a direct test test for Siegert relation by a single-shot measurement. Using our technique, we demonstrate that laser light scattered off a rotating ground glass, violates the Siegert relation, which provides further evidence that it is a pseudothermal light source.

The PRime-focus Infrared Microlensing Experiments (PRIME) camera is part of the joint NASA-JAXA project supporting the Nancy Grace Roman Space Telescope engineering and science studies. It is installed on the 1.8m PRIME telescope with a ≈1.5 square degree FOV dedicated to the project. The instrument is equipped with multiple broad band and narrow band filters between 0.9μm to 1.8μm. The instrument is installed at the South African Astronomical Observatory and has been in continuous operation since October 2022. PRIME is currently surveying the Galactic bulge for microlensing events, GW and GRB studies and other science objectives, in advance of the Roman Space Telescope (RST) mission. After 1.5 years of on-sky operation, we present the use, performance and lessons learned operating RST’s yield demonstration lot H4RG-10 detectors as part of the PRIME camera based on the data processing and analysis tools that we have developed. With the large field of view in the near infrared bands this instrument is a powerful tool in the Southern hemisphere and a compliment to the instruments in the North and in the visible.