AIM has developed IR modules including the FPAs for a wide range of applications. For SWIR applications FPAs based on liquid phase epitaxy (LPE) are available. These devices having different array sizes and are usable in a wide range of hyperspectral imaging applications. Silicon readout circuits provide various integration and readout modes including specific functions for spectral imaging applications.
An important advantage of MCT based detectors is the tunable band gap. The spectral sensitivity of MCT detectors can be engineered to cover the extended SWIR spectral region up to 2.5μm without compromising in performance.
AIM developed and released the technology option to extend the spectral sensitivity of its SWIR modules also into the VIS. This has been successfully demonstrated for different FPA designs. A short overview is given in tis paper.
AIM has qualified this VIS technology option based on a 1024x256 FPA capable for extended hyperspectral applications. Within this paper the test approach and the results will be presented.
For improved long-range reconnaissance applications, a SWIR module for active imaging was developed at AIM. Using laser illumination together with gated viewing (GV) capability reduces noise, amount of background clutter and path radiance and helps e.g. to see through smoke obscuration. Based on AIM’s MCT technology a 2D SWIR electron avalanche photodiode (eAPD) array was developed. A 640×512 15μm pitch format was chosen to allow imaging with the desired resolution. The APD arrays have been designed and fabricated by liquid phase epitaxy (LPE) growth of MCT layers for a 2.5μm cut-off on lattice-matched CdZnTe substrates. Also, a specific ROIC was designed to enable the GV capability of the module. In GV operating mode, the gate can be controlled by an external trigger signal or by internal timing parameters. The gate-delay and integration can be programmed precisely. Focal Plane Arrays (FPAs) have been fabricated and integrated into a dewar/cooler assembly. A dedicated command and control electronics has been designed providing the system interface including power supply, triggering and digital video data. To demonstrate long-range reconnaissance capability of SWIR GV a field camera demonstrator was developed. The demonstrator incorporates the SWIR GV camera, a thermal camera with a wide field of view (WFOV) for detection and the laser illuminator. A user interface was implemented to operate the demonstrator in the field, having easy access to the gating capability. The paper will present the latest performance results of the SWIR GV module including results of field trials with the demonstrator.
In the recent years AIM has developed IR modules for imaging applications sensitive in the extended SWIR (eSWIR) spectral range with a cut-off wavelength of 2.5μm. The modules are based on AIM’s state-of-the-art MCT FPA technology with a dedicated ROIC integrated in a low size, weight and power (SWaP) Dewar/Cooler configuration. The different modules are either designated to combine emissive and reflective imaging in one sensor by already detecting thermal radiation in the eSWIR band or to make use of laser illumination including gating capability. Further integration including a lens, image processing electronics and power supply was done resulting in sights for targeting and reconnaissance applications. For targeting under low-light conditions a low SWaP MCT eSWIR module in a 640x512 format with 10μm pitch was developed. The module was integrated to a compact clip-on weapon sight for small arms providing medium range performance up to 1000m. For reconnaissance applications a MCT based SWIR 2D APD array in a 640x512 15μm pitch format was developed providing gated viewing capability. The device was optimized to provide a higher gain for improvement of the signal to noise ratio (SNR). The module was integrated in a camera demonstrator including a 1.5μm laser illuminator for field trials to demonstrate long range identification. The paper will present the latest performance results including field trials of MCT based eSWIR modules and sights for imaging applications.
For SWIR imaging applications, based on AIM’s state-of-the-art MCT IR technology specific detector designs for either low light level imaging or laser illuminated active imaging are under development. For imaging under low-light conditions a low-noise 640x512 15μm pitch ROIC with CTIA input stages and correlated double sampling was designed. The ROIC provides rolling shutter and snapshot integration. To reduce size, weight, power and cost (SWaP-C) a 640x512 format detector in a 10μm pitch is been realized. While LPE grown MCT FPAs with extended 2.5μm cut-off have been fabricated and integrated also MBE grown MCT on GaAs is considered for future production. The module makes use of the extended SWIR (eSWIR) spectral cut-off up to 2.5μm to allow combination of emissive and reflective imaging by already detecting thermal radiation in the eSWIR band. A demonstrator imager was built to allow field testing of this concept. A resulting product will be a small, compact clip-on weapon sight. For active imaging a detector module was designed providing gating capability. SWIR MCT avalanche photodiodes have been implemented and characterized on FPA level in a 640x512 15μm pitch format. The specific ROIC provides also the necessary functions for range gate control and triggering by the laser illumination. The FPAs are integrated in a compact dewar cooler configuration using AIM’s split linear cooler. A command and control electronics (CCE) provides supply voltages, biasing, clocks, control and video digitization for easy system interfacing. First lab and field tests of a gated viewing demonstrator have been carried out and the module has been further improved.
AIM has developed SWIR modules including FPAs based on liquid phase epitaxy (LPE) grown MCT usable in a wide range of hyperspectral imaging applications. Silicon read-out integrated circuits (ROIC) provide various integration and readout modes including specific functions for spectral imaging applications. An important advantage of MCT based detectors is the tunable band gap. The spectral sensitivity of MCT detectors can be engineered to cover the extended SWIR spectral region up to 2.5μm without compromising in performance. AIM developed the technology to extend the spectral sensitivity of its SWIR modules also into the VIS. This has been successfully demonstrated for 384x288 and 1024x256 FPAs with 24μm pitch. Results are presented in this paper. The FPAs are integrated into compact dewar cooler configurations using different types of coolers, like rotary coolers, AIM’s long life split linear cooler MCC030 or extreme long life SF100 Pulse Tube cooler. The SWIR modules include command and control electronics (CCE) which allow easy interfacing using a digital standard interface. The development status and performance results of AIM’s latest MCT SWIR modules suitable for hyperspectral systems and applications will be presented.
Based on AIM’s state-of-the-art MCT IR technology, detector modules for the SWIR spectral range have been
developed, fabricated and characterized. While LPE grown MCT FPAs with extended 2.5μm cut-off have been
fabricated and integrated also MBE grown MCT on GaAs is considered for future production.
Two imaging applications have been in focus operating either in passive mode by making use of e.g. the night glow, or
in active mode by laser illumination for gated viewing. Dedicated readout integrated circuits (ROIC), realized in
0.18μm Si-CMOS technology providing the required functionality for passive imaging and gated imaging, have been
designed and implemented. For both designs a 640x512 15μm pitch format was chosen. The FPAs are integrated in
compact dewar cooler configurations using AIM’s split linear coolers. A command and control electronics (CCE)
provides supply voltages, biasing, clocks, control and video digitization for easy system interfacing.
For imaging under low-light conditions a low-noise 640x512 15μm pitch ROIC with CTIA input stages and correlated
double sampling was designed. The ROIC provides rolling shutter and snapshot integration. To reduce size, weight,
power and cost (SWaP-C) a 640x512 format detector in a 10μm pitch is under development. The module makes use of
the extended SWIR spectral cut-off up to 2.5μm.
To be used for active gated-viewing operation SWIR MCT avalanche photodiodes have been implemented and
characterized on FPA level in a 640x512 15μm pitch format. The specific ROIC provides also the necessary functions
for range gate control and triggering by the laser illumination. First lab and field tests of a gated viewing demonstrator
have been carried out.
The paper will present the development status and performance results of AIM’s MCT based SWIR Modules for
imaging applications.
In the framework of this paper, AIM presents the actual status of some of its currently ongoing focal plane detector
module developments for space applications covering the spectral range from the short-wavelength infrared (SWIR) to
the long-wavelength infrared (LWIR) and very-long-wavelength infrared (VLWIR), where both imaging and
spectroscopy applications will be addressed. In particular, the integrated detector cooler assemblies for a mid-wavelength
infrared (MWIR) push-broom imaging satellite mission, for the German hyperspectral satellite mission EnMAP will be
elaborated. Additionally dedicated detector modules for LWIR/VLWIR sounding, providing the possibility to have two
different PVs driven by one ROIC will be addressed.
In the framework of this paper, AIM presents the actual status of some of its currently ongoing focal plane detector
module developments for space applications covering the spectral range from the short-wavelength infrared (SWIR) to the long-wavelength infrared (LWIR) and very-long-wavelength infrared (VLWIR), where both imaging and spectroscopy applications will be addressed. In particular, the integrated detector cooler assemblies for a mid-wavelength infrared (MWIR) push-broom imaging satellite mission, for the German hyperspectral satellite mission EnMAP will be elaborated. Additionally dedicated detector modules for LWIR/VLWIR sounding, providing the possibility to have two different PVs driven by one ROIC will be addressed.
S. Hanna, A. Bauer, H. Bitterlich, M. Bruder, L.-D. Haas, M. Haiml, K. Hofmann, K.-M. Mahlein, H.-P. Nothaft, T. Schallenberg, A. Weber, J. Wendler, R. Wollrab, J. Ziegler
An increasing need for high-precision atmospheric data especially in the long wavelength infrared (LWIR) and very long
wavelength infrared (VLWIR) spectral ranges has arisen in the past years not only for the analysis of climate change and
its effect on the earth's ecosystem, but also for weather forecast and atmospheric monitoring purposes.
Spatially and spectrally resolved atmospheric emission data are advantageously gathered through limb or nadir sounding
using an imaging Fourier transform (FT) interferometer with a two-dimensional (2D) high-speed focal plane detector
array (FPA).
In this paper, AIM reports on its latest results on MCT VLWIR FPAs for Fourier transform infrared sounding
applications in the 8-15μm spectral range. The performance of a (112x112) pixel photodiode array with a 40μm pixel
pitch incorporating extrinsic p-doping for low dark current, a technique for linearity improvement at high photon fluxes,
pixel guards, pixel select/de-select, and a (2x2) super-pixel architecture is discussed. The customized read-out integrated
circuit (ROIC) supporting integrate while-read (IWR) operation has a buffered direct injection (BDI) input stage and a
full well capacity (FWC) of 143 Megaelectrons per super-pixel. It consists of two independently operating halves with
two analog video outputs each. The full frame rate is typically 4k frames/sec, making it suitable for use with rapid scan
FT infrared spectrometers.
At a 55K operating temperature and an ~14.4μm cut-off wavelength, a photo response of 12.1mV/K and a noise
equivalent temperature difference of 24.8mK at half well filling are demonstrated for a 286K reference scene. The nonlinearity
error is <0.5%.
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