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High-performance InAs/GaSb type-II superlattice infrared detectors and focal plane arrays (FPAs) are normally grown by molecular beam epitaxy (MBE). In this work, we demonstrate the first long-wavelength infrared InAs/GaSb superlattice FPA grown by metalorganic chemical vapor deposition (MOCVD) with clear image. High-quality superlattice material was obtained evidenced by sharp X-ray diffraction peaks and atomic flat surface. Electrical and optical measurements performed on single element detectors showed a 50% cut-off wavelength of $\sim 10.1~\mu \text{m}$ , a dark current density of $2.5\times 10^{-5}$ A/cm2, a peak responsivity of 0.88 A/W and a peak detectivity of $1.7\times 10^{11}$ cm $\cdot $ Hz1/2/W at 80 K. A $320\times256$ FPA with $30~\mu \text{m}$ pixel pitch was then fabricated. With an integration time of 1.9 ms and an applied bias of -0.1 V, the FPA shows an average operability of 96.96%, a non-uniformity of 4.97%, a noise equivalent temperature difference of 51.1 mK and a peak detectivity of $2.3\times 10^{10}$ cm $\cdot $ Hz1/2/W at 80 K without thinning down the substrate.

In a traditional spaceborne microwave radiometer system with a scanning antenna there is often a conflict between spatial and radiometric resolution. Integration over many beams per frequency might be necessary to improve radiometric resolution. Many beams may be generated using many classical feed horns or by a Focal Plane Array (FPA) system. At C-band horns are bulky and replacing several such horns with a FPA is an interesting option. The FPA concept uses many small antenna elements, many receivers, and powerful on-line digital processing. A focal plane array system that can replace 4 horns is evaluated, especially concerning power consumption.

We report the high performance of Mid-wave Infrared Region (MWIR) InAs/GaSb Type-II Superlattice (T2SL) sensors with $640\times512$ format and 15- $\mu \text{m}$ pixel pitch at both Focal Plane Array (FPA) and pixel level. The p-intrinsic-Barrier-n epilayer structure is adopted for this study, which is grown on 620 ± $30~ \mu \text{m}$ thick GaSb substrate and highly-doped GaSb cap layer at the top structure. The mesa type pixels with sizes of $220\,\,\mu \text{m}\,\,\times 220\,\,\mu \text{m}$ have dark currents $7.8\times10$ −12 A at 77 K both of which are equivalent to state-of-the-art values for Type-II Superlattice sensors. The various passivation techniques to lower the dark current are applied and the results are given in terms of dark current. Electro-optical measurements yielded comparable results to literature. After gathering data and optimizing the fabrication conditions, the FPA of 15- $\mu \text{m}$ pitch having $4.92~ \mu \text{m}$ cut-off wavelength ( $\lambda _{\mathrm {c}}$ ) shows 1.6 A/W peak responsivity, Noise Equivalent Temperature Difference (NETD) of 22.6 mK with optics of f/2.3, quantum efficiency larger than 65% and 99.75% operability. The acquired images by using aforementioned FPA device is presented in this paper. With the reduction of dark current, an encouraging imaging performance is obtained which shows the potential of the Type-II Superlattice detectors in 3 rd generation infrared sensors.

International audience; Infrared applications remain too often a niche market due to their prohibitive cost. Nanocrystals offer an interesting alternative to reach cost disruption especially in the shortwave infrared (SWIR, λ

For the first time, the characteristics of an evolving commercial camera technology that can operate at millimeter-wave frequencies has been independently investigated. In this work, we benchmark the TeraSense camera against a custom-built single-pixel camera at W-band, for image quality and aperture reflectance. It is found that the Tera-1024 TeraSense camera exhibits limited image resolution and fidelity, with significant levels of systematic spatial noise. In a poor signal-to-noise ratio scenario, the addition of random noise exacerbates these problems. Possible causes of both beam and image distortion have been identified in quasi-optical applications, which gives important insight into the best use of (sub-)THz cameras and interpretation of their images. Inherent standing waves caused by the significant power reflectance of the camera aperture is investigated in detail. A simple W-band one-port quasi-optical scalar network analyzer is developed, to determine the levels of reflectance for both cameras, with its bespoke calibration routine derived from first principles - providing a low-cost solution for many non-destructive testing applications. It is found that the TeraSense camera (with additional RAM) and single-pixel camera (having default RAM) have measured reflectance values of 27% and 3%, respectively, over a corresponding aperture area ratio of approximately 714:1. While our single-pixel camera provides excellent image resolution and fidelity, it inherently suffers from very slow raster-scanning speeds and operational bandwidth limitations. For this reason, the TeraSense camera technology is excellent for performing qualitative measurements in real time, with the caveats outlined in this paper.

Reflector antennas are utilized in a lot of applications that require a high gain antenna system. Conventionally, the reflector antenna is fed by a single radiating element, making the direction of the beam fixed. Using a focal plane array (FPA) as feeding mechanism, the magnitude and direction of the resulting beam can be controlled electronically. Using an in-house developed tool, the amplitude and phase settings for a 28 GHz active phased array antenna are determined in order to mimic the ideal feeding pattern for a certain reflector. The far-field of the FPA in combination with the reflector antenna is determined for a scan angle of 0° and 3°.

In this presentation, we will discuss the advantages of using an in-pixel digital read out integrated circuit and type-II strained layer superlattice detector array technology to elevate the operating temperature of the focal plane array for Earth remote sensing instruments.

Passive imaging cameras at sub-millimeter wavelengths with large format focal plane arrays are being developed as the next generation of security screening systems. In this contribution, a dual-band focal plane array (FPA) for security imagers at submillimeter wave frequencies is presented. The detectors are based on bolometric superconducting kinetic inductance resonators, which allows the development of large FPAs at medium cooled temperatures. Two frequency selective absorber (FSA) sets coupled to superconductive resonator lines are designed to implement a dual color security imager. The performance of the dual band imager is evaluated using spectral analysis approach that combines Fourier optics with a Floquet mode field representation. The geometry of the unit cells is based on a Jerusalem cross configuration and the designed FSAs show a stable angular response and a rejection 1 to 3 of the undesired bandwidth. The detectors in the dual band FPA are distributed over a hexagonal grid to maximize their physical size and then improve their sensitivity. The effective point spread function of the imager coupled to a black body point source over a wide frequency band (1:6) was demonstrated experimentally with excellent agreement to the one estimated by using the proposed spectral technique.

Performance enhancement of a very inexpensive millimeter-wave (MMW)/terahertz (THz) sensor for MMW/THz imaging systems is experimentally demonstrated in this study. The MMW sensor is composed of a glow discharge detector (GDD) and a light-to-frequency (LTF) converter combination. The experimental results given in this study show an improvement in the performance parameters of the detector element, such as the minimum detectable signal, as well as the signal to noise ratio (SNR) and the noise equivalent power (NEP), when a NIR long-pass filter was inserted between the GDD and the LTF combination. A detailed derivation of the NEP of this unique sensor is presented in this work. Based on this derivation and the experimental measurements, the NEP value was calculated.

International audience; Short‐wave infrared (IR) detection is currently driven by InGaAs technology which has limited the perspective of cost effectiveness and consequently slows the development of IR sensors. Since organic electronics are ineffective in this wavelength range, an alternative to conductive polymers is the use of colloidal quantum dots (CQDs) which exhibit strongly tunable IR absorption. In this paper, the extended short‐wave IR (2.5 µm cut‐off) is focused on to expand the capabilities of InGaAs, while using HgTe nanocrystals as the active material. Previous devices based on this material suffer from a low responsivity due to weak absorption (few percents). The integration of HgTe nanocrystals is presented in ink form to build thick (up to 600 nm), strongly absorbing nanoparticle films. This ink is integrated into a diode, allowing one to boost the responsivity by two orders of magnitude and the detectivity by one order of magnitude compared to previous HgTe devices at the same wavelength. Detectivity reaches 3 × 109 Jones, while the time response is found to be 370 ns for room temperature and 0 V bias operation. Finally, the material is integrated into a focal plane array which is used to determine laser beam profile.

The spectral resolution of a spectrograph depends on the input slit width, the diffraction grating grooves and the number of imaging sensor/detector pixels. Due to the proprietary nature of spectrograph designs, recalibration by end-users can be challenging. Most calibration procedures currently published are applicable to in-house instruments or spectrographs with access to the internal specifications. Narrowing the input slit improves the resolution but also reduces the throughput of the imaging system. We attempted to recalibrate an Offner-based spectrograph by using a larger detector plane (an imaging system with a larger sensor), to vary the distance along the focal plane; and by utilising lens optics. Basic experiments were conducted by varying the distance from the exit window and inserting a lens to magnify the spectrograph output onto the larger detector plane. We concluded that the calibration could not be achieved using simple optics within the scope of our experiments. This article addresses a gap in literature that does not present the research community with the unsuccessful steps that are not applicable to similar problem statements. The alternative would be to rely on reflective optics, but this approach may reduce portability.

We present the fabrication of large format $640\times512$ , 15- ${\mu }\text{m}$ pitch, mid-wave infrared region (MWIR) InAs/GaSb type-II superlattice (T2SL) focal plane array (FPA). In this report, the details of device design and fabrication processes are withheld adhering to the common practice of most of the manufactures and developers because of the strategic importance; however, information about fabrication processes of T2SLs FPA is presented to a certain extent. Comparison of etching techniques, passivation materials and methods, and substrate thinning (mechanical and chemical) is given besides of details regarding the standard ohmic contact and indium (In) bump formations. Morphological investigations of fabrication step are included. Large area pixels, $220\,\,{\mu }\text{m}\,\,\times 220\,\,{\mu }\text{m}$ , fabricated by different etching methods and passivation materials/methods are compared in terms of dark current levels. Wet passivation with (NH4)2S is discussed in terms of morphological investigations, and dark current results are compared with untreated samples. Large area pixel level characterizations as well as image level benchmarking of mechanical and chemical substrate thinning are reported. Effect of GaSb substrate on device performance and the way of reducing stress of In bumps are revealed. The importance of complete substrate removal is demonstrated through FPA images.

Short-wavelength infrared (SWIR) detection systems are increasingly in demand for surveillance, reconnaissance, and remote sensing applications. Eye-safe SWIR lasers can be utilized for active imaging systems with high image contrast and long detection range. The gated-viewing (GV) technique using short-pulse lasers and fast-gated cameras in the nanosecond range enables utilizing the distance information in addition to the signal intensity of the acquired images. The InGaAs material system is very well suited for the fabrication of high-performance SWIR photodetectors providing a typical cutoff wavelength of 1.7 μm, which covers the emission lines of available laser sources at typical telecom wavelengths around 1.55 μm. However, the usually short integration times needed for GV leads to very small photosignals. We report on the development of SWIR avalanche photodetector (APD) arrays with 640 × 512 pixels and 15 μm pixel pitch based on the InGaAs material system. The InGaAs-APD focal plane arrays have been successfully integrated into SWIR cameras which yield gain values of M ≈ 10 on camera level at a reverse bias voltage around 21 V and are the first InGaAs-based SWIR cameras worldwide providing a 640 × 512 image format and utilizing avalanche gain for signal amplification. The camera performance is demonstrated by SWIR laser GV sample images.

CCAT-prime will be a 6-meter aperture telescope operating from sub-mm to mm wavelengths, located at 5600 meters elevation on Cerro Chajnantor in the Atacama Desert in Chile. Its novel crossed-Dragone optical design will deliver a high throughput, wide field of view capable of illuminating much larger arrays of sub-mm and mm detectors than can existing telescopes. We present an overview of the motivation and design of Prime-Cam, a first-light instrument for CCAT-prime. Prime-Cam will house seven instrument modules in a 1.8 meter diameter cryostat, cooled by a dilution refrigerator. The optical elements will consist of silicon lenses, and the instrument modules can be individually optimized for particular science goals. The current design enables both broadband, dual-polarization measurements and narrow-band, Fabry-Perot spectroscopic imaging using multichroic transition-edge sensor (TES) bolometers operating between 190 and 450 GHz. It also includes broadband kinetic induction detectors (KIDs) operating at 860 GHz. This wide range of frequencies will allow excellent characterization and removal of galactic foregrounds, which will enable precision measurements of the sub-mm and mm sky. Prime-Cam will be used to constrain cosmology via the Sunyaev-Zeldovich effects, map the intensity of [CII] 158 $\mu$m emission from the Epoch of Reionization, measure Cosmic Microwave Background polarization and foregrounds, and characterize the star formation history over a wide range of redshifts. More information about CCAT-prime can be found at www.ccatobservatory.org., Comment: Presented at SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, June 15th, 2018

Polariscopy is demonstrated using hyperspectral imaging with a focal plane array (FPA) detector in the infrared (IR) spectral region under illumination by thermal and synchrotron light sources. FPA Fourier-transform IR (FTIR) imaging microspectroscopy is useful for monitoring real time changes at specific absorption bands when combined with a high brightness synchrotron source. In this study, several types of samples with unique structural motifs were selected and used for assessing the capability of polariscopy under this FPA-FTIR imaging technique. It was shown that the time required for polariscopy at IR wavelengths can be substantially reduced by the FPA-FTIR imaging approach. By using natural and laser fabricated polymers with sub-wavelength features, alignment of absorbing molecular dipoles and higher order patterns (laser fabricated structures) were revealed. Spectral polariscopy at the absorption peaks can reveal the orientation of sub-wavelength patterns (even when they are not spatially resolved) or the orientation of the absorbing dipoles.

Short-wave infrared (SWIR) photon detection has become an essential technology in the modern world. Sensitive SWIR detector arrays with high pixel density, low noise levels, and high signal-to-noise-ratios are highly desirable for a variety of applications including biophotonics, light detection and ranging, optical tomography, and astronomical imaging. As such many efforts in infrared detector research are directed toward improving the performance of the photon detectors operating in this wavelength range. We review the history, principle of operation, present status, and possible future developments of a sensitive SWIR detector technology, which has demonstrated to be one of the most promising paths to high pixel density focal plane arrays (FPAs) for low flux applications. The so-called electron-injection (EI) detector was demonstrated for the first time in 2007. It offers an overall system-level sensitivity enhancement compared to the p–i–n diode due to a stable internal avalanche-free gain. The amplification method is inherently low noise, and devices exhibit an excess noise of unity. The detector operates in linear-mode and requires only bias voltage of a few volts. This together with the feedback stabilized gain mechanism, makes formation of large-format high pixel density electron-injection FPAs less challenging compared to other detector technologies such as avalanche photodetectors. Detector is based on the mature InP material system and has a cutoff wavelength of 1700 nm. The layer structure consists of 500 nm InP injector/50 nm InAlAs etch stop/50 nm GaAsSb electron barrier (and hole trap)/1 μm InGaAs absorber. The epitaxial layers are grown on InP substrates. Electron-injection detector takes advantage of a unique three-dimensional geometry and combines the efficiency of a large absorbing volume with the sensitivity of a low-dimensional switch (injector) to sense and amplify signals. EI detectors have been designed, fabricated, and tested during two generations of development and optimization cycles. We review our imager results using the first-generation detectors. In the second-generation devices, the dark current is reduced by two orders of magnitude, and bandwidth is improved by four orders of magnitude. The dark current density of the second-generation EI detector is shown to outperform the state-of-the-art technology, the SWIR HgCdTe eAPD by more than one order of magnitude. We demonstrate a performance comparison with other SWIR detector technologies with internal amplification and show that the electron-injection detectors offer more than three orders of magnitude better noise-equivalent sensitivity compared with state-of-the-art phototransistors operating at similar temperature. Second-generation devices provide high-speed response ~6 ns rise time, low jitter ~12 ps, high amplification of more than 1000, unity excess noise factor, and operate at bias voltage of –3 V, at room temperature. The internal dark current density is ~1 μA/cm2 at room temperature decreasing to 1 nA/cm2 at 210 K. These improvements have opened up many applications for these detectors in the medical field, remote sensing, and exoplanet detection.

Within a very few years, InAs/GaSb superlattice technology has proven its suitability for high-performance infrared imaging detector arrays. At the Fraunhofer Institute for Applied Solid State Physics (IAF) and AIM Infrarot-Module GmbH, efforts have been focused on developing mature fabrication technology for dual-color InAs/GaSb superlattice focal-plane arrays for simultaneous, colocated detection at 3 µm to 4 µm and 4 µm to 5 µm in the mid-wavelength infrared atmospheric transmission window. Integrated into a wide-field-of-view missile approach warning system for an airborne platform, a very low number of pixel outages and cluster defects is mandatory for bispectral detector arrays. Process refinements, intense root-cause analysis, and specific test methodologies employed at various stages during the process have proven to be the key for yield enhancements.

© 2015 Lupoi et al. Background: Slow-degrading, fossil fuel-derived plastics can have deleterious effects on the environment, especially marine ecosystems. The production of bio-based, biodegradable plastics from or in plants can assist in supplanting those manufactured using fossil fuels. Polyhydroxybutyrate (PHB) is one such biodegradable polyester that has been evaluated as a possible candidate for relinquishing the use of environmentally harmful plastics. Results: PHB, possessing similar properties to polyesters produced from non-renewable sources, has been previously engineered in sugarcane, thereby creating a high-value co-product in addition to the high biomass yield. This manuscript illustrates the coupling of a Fourier-transform infrared microspectrometer, equipped with a focal plane array (FPA) detector, with multivariate imaging to successfully identify and localize PHB aggregates. Principal component analysis imaging facilitated the mining of the abundant quantity of spectral data acquired using the FPA for distinct PHB vibrational modes. PHB was measured in the chloroplasts of mesophyll and bundle sheath cells, acquiescent with previously evaluated plant samples. Conclusion: This study demonstrates the power of IR microspectroscopy to rapidly image plant sections to provide a snapshot of the chemical composition of the cell. While PHB was localized in sugarcane, this method is readily transferable to other value-added co-products in different plants.

In many undersampled imaging systems, spatial integration from the individual detector elements is the dominant component of the system point spread function (PSF). Conventional focal plane arrays (FPAs) utilize square detector elements with a nearly 100% fill factor, where fill factor is defined as the fraction of the detector element area that is active in light detection. A large fill factor is generally considered to be desirable because more photons are collected for a given pitch, and this leads to a higher signal-to-noise-ratio (SNR). However, the large active area works against super-resolution (SR) image restoration by acting as an additional low pass filter in the overall PSF when modeled on the SR sampling grid. A high fill factor also tends to increase blurring from pixel cross-talk. In this paper, we study the impact of FPA detector-element shape and fill factor on SR. A detailed modulation transfer function analysis is provided along with a number of experimental results with both simulated data and real data acquired with a midwave infrared (MWIR) imaging system. We demonstrate the potential advantage of low fill factor detector elements when combined with SR image restoration. Our results suggest that low fill factor circular detector elements may be the best choice. New video results are presented using robust adaptive Wiener filter SR processing applied to data from a commercial MWIR imaging system with both high and low detector element fill factors.

Radiometric sub-millimeter imaging is a candidate technology especially in security screening applications utilizing the property of radiation in the band of 0.2 - 1.0 THz to penetrate through dielectric substances such as clothing. The challenge of the passive technology is the fact that the irradiance corresponding to the blackbody radiation is very weak in this spectral band: about two orders of magnitude below that of the infrared band. Therefore the role of the detector technology is of ultimate importance to achieve sufficient sensitivity. In this paper we present results related to our technology relying on superconducting kinetic inductance detectors operating in a thermal (bolometric) mode. The detector technology is motivated by the fact that it is naturally suitable for scalable multiplexed readout systems, and operates with relatively simple cryogenics. We will review the basic concepts of the detectors, and provide experimental figures of merit. Furthermore, we will discuss the issues related to the scale-up of our detector technology into large 2D focal plane arrays.

The third generation of infrared detection modules is characterized by advanced functionalities like more pixels (array size⩾640×512), higher frame rates (⩾800 Hz at an array size of 256×256), multicolor or multiband capability, and better thermal resolution. This paper focuses on the present status of such technologies at AIM, based on HgCdTe and quantum well focal plane array detectors.

In this study, fabricated 320 × 256 infrared focal plane arrays (FPAs) were realised using a GaSb/InAs-based type-II superlattice heterostructure for midwave infrared (MWIR) imaging. We report here the optimized fabrication and characterization of single-pixel infrared detectors and FPAs. MWIR spectral response up to 5 μm of these single-pixel detectors was evident up to 250 K. Responsivity was measured to be 1.62 A/W at 0.8 V and 80 K. Current–voltage characteristics at room temperature (300 K) and at low temperature (18 K) revealed the resistance and dark current variation of the device in the operating bias region. Moreover, good thermal images were obtained at device temperatures up to 150 K for low-temperature targets. Low noise equivalent difference in temperature was measured to be 58 mK at 50 K and 117 mK at 120 K.

System properties of focal plane array (FPA) cameras based on GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) operating in the long-wavelength infrared are analyzed. Due to the limited charge storage capacity of available readout circuits, a small photoconductive gain improves the noise-equivalent temperature difference (NEΔT) of the sensor. We have demonstrated several camera systems based on conventional photoconductive QWIPs with NEΔT mK and NEΔT mK for FPAs with 256×256 and 640×512 pixels, respectively. A small photoconductive gain is obtained by operating the QWIP at very small electric fields ( kV / cm ). Finally, we discuss the possibility of reducing the NEΔT even further by using QWIP structures in which the photoexcited carrier mean free path is controlled by the incorporation of additional epitaxial layers. We thus obtain a high detectivity at very small signal and noise currents, which is useful in particular for large arrays with reduced pixel sizes. In addition, these detectors are shot-noise limited since the recombination noise is suppressed. The performance of FPA sensors based on these detectors will be addressed.

We demonstrate a method for infrared tomographic imaging of the initial three-dimensional (3-D) temperature increase of in vivo blood vessels following pulsed laser exposure. Using a time-sequence of infrared images recorded by a fast focal plane array camera as input data, a reconstruction algorithm is used to compute the initial 3-D temperature increases in the chick chorioallantoic membrane and port wine stain in human skin. The noncontact tomographic imaging method is relevant to various laser therapies that rely on a photothermal mechanism for selective modification of tissue and may find diagnostic application to determine optimal laser dosimetry, position, and size of targeted subsurface chromophores.

Passive microwave (MW) remote sensing (radiometry) relies on the thermal radiation of objects having a temperature higher than 0 K within the frequency range of 1–300 GHz. The intensity of this radiation depends on the surface characteristics, the chemical and physical composition, and the temperature of the material. So it is possible to discriminate and to image objects having different material characteristics and hence different brightness temperatures compared to their surrounding. The range of applications of microwave remote sensing systems is spread out widely. For example, in Earth observation missions it is possible to estimate the salinity of oceans, the soil moisture of landscapes or to extract atmospheric parameters like the liquid water content of clouds or the oxygen content [1,4]. Due to the penetration capabilities of electromagnetic waves through dielectric materials, and the purely passive character of this kind of remote sensing technique, it nowadays is used as well in many security and reconnaissance applications. Examples here are the observation of sensitive areas or the detection of hidden objects like weapons or explosives during security checks. Presently different imaging principles for MW radiometry are in use. Most of them still perform pure mechanical scanning as well as a combination with electronic scanning by using parts of a focal plane array, for instance, as known from modern optical cameras. In principle, there are two main problems with mechanical scanning systems, on one hand the antenna aperture dimension has to be large for a given wavelength in order to get a sufficient spatial resolution. On the other hand it is important to record an image in a reasonable period of time. Most of the mechanical scanning systems are working with a rotating antenna structure. The velocity of this rotation cannot be increased arbitrarily due to inertia problems caused by the antenna size and mass. Hence, the trend is going towards fully electronic and quick beam steering or two-dimensional focal plane arrays. These systems are able to achieve high frame rates, but they still are very expensive, because they require a significantly higher number of receiver modules compared to a mechanical scanning system. Furthermore one has to handle a rising complexity by the integration of such a high number of receiver modules, all consisting of many discrete components following the antenna frontend. Also the weight is an important factor with respect to airborne/spaceborne platforms. Consequently, in order to minimize the weight and the costs, the whole receiver components have to be realized in a considerably integrated design by using MMIC (Monolithic Microwave Integrated Circuit) technology as far as possible.

In this paper we describe a focal plane array (FPA) prototype, based on Vivaldi elements, developed for the Westerbork Synthesis Radio Telescope (WSRT) to increase its instantaneous field of view by a factor 25 and double its current bandwidth. This prototype is the first step in a project that has the ambition to equip most of the WSRT antennas with FPAs to improve the survey speed of the telescope. Examples of scientific applications are surveys of the northern sky in polarised continuum and HI emission, and efficient searches for pulsars and transients., 7 pages, 6 figures. Presented at "The Evolution of Galaxies through the Neutral Hydrogen Window", Feb 1-3, 2008, Arecibo Observatory, Puerto Rico. High resolution versions of figures available in jpg-format

The first fully operational mid-IR (3–5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement.

In recent years the XEUS mission concept has evolved and has been the subject of several industrial studies. The mission concept has now matured to the point that it could be proposed for a Phase A study and subsequent flight programme. The key feature of XEUS will be its X-ray optic with collecting area ~30-100x that of XMM. The mission is envisaged at an orbit around the L2 point in space, and is formed from two spacecraft; one for the mirrors, and the other for the focal plane detectors. With a focal length of 50m, the plate scale of the optic is 6.5x that of XMM, which using existing focal plane technology will reduce the effective field of view to a few arc minutes. Cryogenic instrumentation, with detector sizes of a few mm can only be used for narrow field studies of target objects, and a wide field instrument is under consideration using a DEPFET pixel array to image out to a diameter of 5 arcminutes, requiring an array of dimension 70mm. It is envisaged to extend this field of view possibly out to 15 arcminutes through the use of an outer detection ring comprised of MOS CCDs

Voor een hypothetische warmtebeeldcamera werden 3 doelacquisitiemodellen gedraaid, waarbij de sensorparameters systematisch werden gevarieerd. De verschillen in uitkomst zijn zorgwekkend.

Metamaterials, Metadevices, and Metasystems (2018: San Diego; United States), Focal plane arrays (FPAs) as a two-dimensional detector pixel matrix positioned in the focal plane of an optical system have been developed continuously for obtaining higher resolution. On the other hand, for developing highresolution, compact-size FPAs, used methods such as the miniaturization of pixel size leads to serious problems such as increased optical crosstalk. In this study, we proposed highly efficient all-dielectric metasurface lens arraybased FPA at mid-wave infrared spectrum. All-dielectric metasurface lens arrays were numerically demonstrated to achieve high optical efficiency above 85%. Moreover, our design compared with conventional and earlier metasurface-based studies has exhibited much superior optical crosstalk performance. While standing the high efficiency, optical crosstalk is decreased to low level of ? 2.8%. A figure-of-merit (FoM) is also defined for the device performance, which is designated as the focusing efficiency per optical crosstalk times the f-number. The results show that a FOM of approximately 90 is achieved. These proposed all-dielectric metasurface lens arrays demonstrate great potential for increasing the signal to noise ratio and sensitivity thus paving the way for compactsize and high-resolution FPAs to be deployed in various applications including thermal cameras, imaging devices and bolometers. © 2018 SPIE.