Sensors in a networked environment which are used for security applications could be jeopardized by man-in-the-middle or address spoofing attacks. By authentication and secure data transmission of the sensor's data stream, this can be thwart by fusing the image sensor with the necessary digital encryption and authentication circuit, which fulfils the three standard requirements of cryptography: data integrity, confidentiality and non-repudiation. This paper presents the development done by AIM, which led to the unique sensor SECVGA, a high performance monochrome (B/W) CMOS active pixel image sensor. The device captures still and motion images with a resolution of 800x600 active pixels and converts them into a digital data stream. Additional to a standard imaging sensor there is the capability of the on-chip cryptographic engine to provide the authentication of the sensor to the host, based on a one-way challenge/response protocol. The protocol that has been realized uses the exchange of a session key to secure the following video data transmission. To achieve this, we calculate a cryptographic checksum derived from a message authentication code (MAC) for a complete image frame. The imager is equipped with an EEPROM to give it the capability to personalize it with a unique and unchangeable identity. A two-wire <i>I<sup>2</sup>C</i> compatible serial interface allows to program the functions of the imager, i.e. various operating modes, including the authentication procedure, the control of the integration time, sub-frames and the frame rate.
Security applications of sensors in a networking environment has a
strong demand of sensor authentication and secure data transmission
due to the possibility of man-in-the-middle and address spoofing
attacks. Therefore a secure sensor system should fulfil the three
standard requirements of cryptography, namely data integrity,
authentication and non-repudiation. This paper is intended to
present the unique sensor development by AIM, the so called SecVGA,
which is a high performance, monochrome (B/W) CMOS active pixel
image sensor. The device is capable of capturing still and motion
images with a resolution of 800x600 active pixels and converting the
image into a digital data stream. The distinguishing feature of this development in comparison to standard imaging sensors is the on-chip cryptographic engine which provides the sensor authentication, based on a one-way challenge/response protocol. The implemented protocol results in the exchange of a session-key which will secure the following video data transmission. This is achieved by calculating a cryptographic checksum derived from a stateful hash value of the complete image frame. Every sensor contains an EEPROM memory cell for the non-volatile storage of a unique identifier. The imager is
programmable via a two-wire <i>I<sup>2</sup>C</i> compatible interface which controls the integration time, the active window size of the pixel array, the frame rate and various operating modes including the authentication procedure.
The 3rd generation of infrared (IR) detection modules is expected to provide advanced features like higher resolution 1024x1024 or 1280x720 pixels and/or new functionalities like multicolor or multi band capability, higher frame rates and better thermal resolution. This paper is intended to present the current status at AIM on the Mercury Cadmium Telluride (MCT), quantum well (QWIP) and antimonide superlattices (SL) detection modules for ground and airborne applications in the high performance range. For high resolution a 1280x720 MCT device in the 3-5μm range (MWIR) is presently under development. For spectral selective detection, a QWIP detector combining MWIR and 8-10μm (LWIR) detection in each pixel has been developed in a 384x288x2 format with 40 μm pitch, NETD < 35mK @ F/2, 6,8 ms for both peak wavelengths (4.8 μm and 8.0 μm). The device provides synchronous integration of both bands for temporal and spatial coincidence of the events observed. QWIP dual band or dual color detectors provide good resolution as long as integration times in the order of 5-10ms can be tolerated. This is acceptable for all applications where no fast motions of the platform or the targets are to be expected. For rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - a material system with higher quantum efficiency is required to limit integration times to typically 1ms. For this case, several companies work on molecular beam epitaxy (MBE) of MCT to have access to double or multi layer structures. AIM and IAF selected antimonide based type II superlattices (SL) for such kind of applications. The SL technology provides -- similar to QWIP's -- an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. While promising results on single SL pixels have been reported since many years, so far no SL based detection module could be realized. Just recently, IAF and AIM managed to realize first most promising SL based detectors. Fully integrated IDCAs with a MWIR SL device with 256 x 256 pixels in 40 μm pitch have been integrated and tested. The modules exhibit excellent thermal resolution of NETD > 12 mk @ F/2 and 5 ms. The next step will now be to stabilize the technology and to start the development of a dual color MWIR device based on SL technology and the existing 384 x 288 read out circuit (ROIC) used in the dual band QWIP device.
Full video format focal plane array (FPA) modules with up to 640 x 512 for high resolution imaging applications in either mercury cadmium telluride (MCT) mid wave (MWIR) infrared (IR) or platinum silicide (PtSi) and quantum well infrared photodetector (QWIP) technology as low cost alternatives to MCT for high performance IR imaging in the MWIR or long wave spectral band (LWIR) have been presented in several earlier publications. MCT units provide fast frame rates >100Hz together with state of the art thermal resolution NETD <20mK for short snapshot integration times of typically 2ms. PtSi and QWIP modules need longer integration times and are usually operated at frame rates of 30-60Hz to provide thermal resolutions of NETD <80mK for PtSi and NETD <20mK for QWIP, respectively. Presently, 2 new MCT detection modules are under development to provide lower geometrical resolution but much faster frame rates and dual color capability. The modules are specifically useful for missile seeker and ir search and track (IRST) applications where fast frame rates are needed or where dual color capability helps to suppress clutter, detect specific ir signatures or discriminates camouflaged targets. A high speed device with 256x256 pixels in a 40micrometers pitch is designed to provide up to 800Hz full frame rate with pixel rates as high as 80Mpixels/s.
To meet the demands for high performance infrared imaging systems AIM had developed a family of CMT detector modules with linear focal plane arrays, integrated detector cooler assemblies (IDCA), and command and control electronics (CCE). Common features of these modules are focal plane multiplexers with time delay and integration (TDI) function, pixel deselect, programmable gain for each line, bidirectional scan capability, partitioning and global gain select. The family of IDCA's consists either of single chip focal plane arrays (FPA) directly linked to a read out integrated multiplexer (ROIC) by solder bump technique, or one clip infrared detectors connected to one or more ROIC's using a multichip module (MCM) technique, dewars with optimized thermal heat load, coolers with integrated control electronics, and command and control electronics (CCE). The general design of these modules is outlined. Test results are shown.
Full video format focal plane array (FPA) modules with up to 640 X 512 pixels have been developed for high resolution imaging applications in either mercury cadmium telluride (MCT) mid wave (MWIR) infrared (IR) or platinum silicide (PtSi) and quantum well infrared photodetector (QWIP) technology as low cost alternatives to MCT for high performance IR imaging in the MWIR or long wave spectral band (LWIR). For the QWIP's, a new photovoltaic technology was introduced for improved NETD performance and higher dynamic range. MCT units provide fast frame rates > 100 Hz together with state of the art thermal resolution NETD < 20 mK for short snapshot integration times of typically 2 ms. PtSi and QWIP modules are usually operated in a rolling frame integration mode with frame rates of 30 - 60 Hz and provide thermal resolutions of NETD < 80 mK for PtSi and NETD < 20 mK for QWIP, respectively. Due to the lower quantum efficiency compared to MCT, however, the integration time is typically chosen to be as long 10 - 20 ms. The heat load of the integrated detector cooler assemblies (IDCAs) could be reduced to an amount as low, that a 1 W split liner cooler provides sufficient cooling power to operate the modules -- including the QWIP with 60 K operation temperature -- at ambient temperatures up to 65 degrees Celsius. Miniaturized command/control electronics (CCE) available for all modules provide a standardized digital interface, with 14 bit analogue to digital conversion for state to the art correctability, access to highly dynamic scenes without any loss of information and simplified exchangeability of the units. New modular image processing hardware platforms and software for image visualization and nonuniformity correction including scene based self learning algorithms had to be developed to accomplish for the high data rates of up to 18 M pixels/s with 14-bit deep data, allowing to take into account nonlinear effects to access the full NETD by accurate reduction of residual fixed pattern noise. The main features of these modules are summarized together with measured performance data for long range detection systems with moderately fast to slow F-numbers like F/2.0 - F/3.5. An outlook shows most recent activities at AIM, heading for multicolor and faster frame rate detector modules based on MCT devices.
The family of 2D detection modules at AEG Infrarot-Module GmbH (AIM) based on platinum silicide (PtSi) GaAs/AlGaAs quantum well (QWIP) devices or mercury cadmium telluride (MCT) focal planes for applications in either the 3.5 micrometers (MWIR) or 8.10 micrometers (LWIR) range was recently extended. Two new devices have been realized in the configurations 640 X 512 in a 24 micrometers pitch for mid and long wave applications using either a MCT photovoltaic (PV) array for the MWIR or a QWIP device for the LWIR, respectively. The existing 256 X 256 MCT MWIR was redesigned in a new configuration with increased fill factor of > 80 percent for improved NETD performance. The MCT units provide fast full frame rates up to > 100 Hz for the 640 X 512 units and 200Hz for the 256 X 256 units. The modules achieve with short snapshot integration times of typically 1ms excellent thermal resolution with an average NETD < 25 mK for the 640 X 512 NETD < 9mK for the 256 X 256 modules. The QWIP units are operated in either a rolling frame or snapshot integration mode with typical frame rates of 60Hz and reach a thermal resolution NETD < 25mK for full frame integration times. The FPAs are integrated up to modules using AIM's standard dewar cooler and command/control electronics (CCE) family. The package is basically identical to the existing large FA modules like the PtSi640 X 486 or the QWIP or MCT 256 X 256 in 40 micrometers pitch and is cooled by AIMs 1W split linear cooler. The CCE of the modules provides the common exclusively digital interface, using 14 Bit analog to digital conversion to provide state of the art correctability, access to highly dynamic scenes without any loss of information and simplified interchangeability of the units.
A new family of 2 dimensional detection modules based on GaAs quantum well (QWIP) photoconductors was recently developed by AEG Infrarot-Module GmbH (AIM). The QWIP material was developed by the Fraunhofer Institute for Applied Physics (IAF) in Freiburg, Germany. Details of the QWIP chip will be presented in a separate paper. This paper will concentrate on the features of the QWIP detection module i.e. the integration of this specific focal plane array (FPA) into an integrated detector cooler assembly (IDCA), the driving and readout electronics and the necessary non uniformity correction (NUC) hardware and algorithms for achieving the best performance. The paper shows how the new 256 X 256 QWIP module is integrated in AIM's modular family of detectors. Measured results are shown for the thermal resolution and the correctability of the device. The results are compared with results of recently developed detection modules based on mercury cadmium telluride (MCT) as discussed in a separate paper. The correctability results show, that the full performance of the QWIP module with a thermal resolution as low as NETD less than 10 mK can only be used in systems by highly sophisticated NUC algorithms. AIM has introduced a new self adaptive algorithm (SAICA) which allows a dynamical optimization of the correction coefficients of high performance detection modules. Features of this algorithm will shortly be discussed. AIM contemporarily develops a new 640 X 512 QWIP module in cooperation with IAF. The device is available starting mid 1998. Basic features of the new device will be given as an outlook.
The family of two dimensional detection modules at AEG Infrared-Modules GmbH (AIM) based on platinum silicide (PtSi) or mercury cadmium telluride (MCT) focal plane arrays for applications in either the 3..5 micrometer (MWIR) or 8..10 micrometer (LWIR) range was recently extended. Two new MCT devices have been realized in the configurations 384 X 288 elements in a 24 micrometer pitch for mid wave applications and 256 X 256 elements in a 40 micrometer pitch for long wave applications. Also a quantum well infrared photodetector (QWIP) device with 256 X 256 elements for long wave applications was introduced. The MCT devices provide extremely fast frame rates like 2200 Hz with snapshot integration times below 350 microseconds and noise equivalent temperature differences (NETD's) less than 20 mK for the LWIR modules while the QWIP device provides a NETD about 10 mK for a rolling frame integration with 20 ms integration time and 50 Hz frame rate. Besides the thermal resolution given by the NETD also a measurement of the correctability of the devices is introduced which is an important characteristic for the system design. The main features of these modules are summarized together with measured performance data of the new MCT devices. The performance data of the QWIP detection module is discussed in reference 1.
AEG has successfully developed a family of PtSi detection modules to cover various applications. The development was performed in a cooperation with Daimler Benz Research and Technology F2M and Telefunken Microelectronic TEMIC EZIS. The modules are designed around 2 staring PtSi focal plane arrays (FPA) having 256 X 256 pixels or 640 X 486 pixels, respectively. Both arrays are identical in their basic features like 24 micrometers pitch, > 60% fillfactor, variable integration time, optional interlaced and non interlaced rolling frame readout, subframe capability and excellent thermal resolution with measured values for the NETD < 70 mK (300 K, 20 ms, F/1.4). The FPA's are integrated either in integrated dewar cooler assemblies with a 1/3 W split linear compressor for the 256 X 256 FPA or a 1 W split linear compressor for the 640 X 486 FPA, respectively, or designed for the use in seeker applications with a Joule Thomson cryocooler (640 X 486 FPA only). The modules are completed by different miniaturized types of electronics, providing all DC and clock supplies to drive the FPA's and providing the customer with either a buffered analog or a 14 Bit resolution digital interface. Digital signal processor (DSP) based image correction units were developed for testing the units. The DSP boards provide the ability for freely programmable real-time functions like 2 point correction or other data manipulations in camera applications. The modules and their key features are reviewed together with their performance data.