Readout integrated circuits (ROICs) to support space-based infrared detection applications often have severe radiation tolerance requirements. Radiation hardness-by-design (RHBD) significantly enhances the radiation tolerance of commercially available CMOS and custom radiation hardened fabrication techniques are not required. The combination of application specific design techniques, enclosed gate architecture nFETs and intrinsic thin oxide radiation hardness of 180 nm process node commercial CMOS allows realization of high performance mixed signal circuits. Black Forest Engineering has used RHBD techniques to develop ROICs with integrated A/D conversion that operate over a wide range of temperatures (40K-300K) to support infrared detection. ROIC radiation tolerance capability for 256x256 LWIR area arrays and 1x128 thermopile linear arrays is presented. The use of 130 nm CMOS for future ROIC RHBD applications is discussed.
We report on progress to develop and demonstrate CZT and Si hybrid detector arrays for future NASA missions in X-ray
and Gamma-ray astronomy. The primary goal for these detectors is consistent with the design concept for the EXIST
mission1 and will also be appropriate for other NASA applications and ground-based projects. In particular we target
science instruments that have large aperture (multiple square meters) and therefore require a low power ROIC (readout
integrated circuits) design (< 10 microwatt per pixel in quiescent mode). The design also must achieve good energy
resolution for single photon detection for X rays in the range 5-600 keV with a CZT sense layer and 2-30 keV with a Si
sense layer. The target CZT arrays are 2 cm × 2 cm with 600 micron square-shaped pixels. The low power smart pixel
detects rare X-ray hits with an adjustable threshold setting. A test array of 7 × 5 pixels with a 5 mm thick CZT sense
layer demonstrates that the low power pixel can successfully detect X-rays with ~50 readout noise electrons RMS.
The NASA Jupiter Europa Orbiter (JEO) conceptual payload contains a thermal instrument with six different spectral
bands ranging from 8μm to 100μm. The thermal instrument is based on multiple linear arrays of thermopile detectors
that are intrinsically radiation hard; however, the thermopile CMOS readout needs to be hardened to tolerate the
radiation sources of the JEO mission. Black Forest Engineering is developing a thermopile readout to tolerate the JEO
mission radiation sources. The thermal instrument and ROIC process/design techniques are described to meet the JEO
A series of tests were conducted to assess the feasibility and performance of a fixed-field, infrared landing monitor system, located on the runway. The resultant images are used to provide enhanced vision for ground personal, in contrast to the more traditional enhanced vision for the flight crew. This paper describes the architecture and design of a dithered 320 by 240 MWIR InSb infrared camera, along with qualitative performance and test results. Issues associated with SWIR/MWIR bandpass selection, FPA type and atmospheric penetration are discussed as well as resolution requirements. Images of aircraft landing on an aircraft carrier are included for illustrative purposes.
Recent advances in multiple disciplines have lead to the development of low cost, portable radiometers with outstanding thermal sensitivity, resolution, range and true 'point and shoot' capabilities. These new systems use technologies such as: infrared focal plane array (FPA), integral dewar/cooler, hybrid optics, embedded processor, digital processing/storage and thermal image analysis. The integration of these new technologies into a camera system is described and related to imaging and radiometric performance. Specific applications in traditionally difficult radiometric areas are discussed such as low temperature sensitivity and variable integration times for high temperature radiometric capability. A camera system is broken down into specific technology blocks. Discussion of these technologies shows how each was chosen to produce a system which covers a broad temperature range while maintaining ease of use in many different radiometric applications. These choices include FPA selection criteria (readout architecture and detector material), optical design (f/# and bandpass), dynamic range management and radiometric analysis/display features.
In 1993, FLIR SYStems, Inc. developed and established production of an MWIR staring sensor based upon affordable and reliable platinum silicide staring focal plane array technology. This sensor incorporates many new features in addition to the FPA technology that makes it well suited for a wide variety of applications. The FPA is a 240 X 320 area array of Schottky detectors read out in a snap shot progressive scan mode. The FPA architecture is a hybrid bump bonded detector to a CCD readout for high sensitivity and uniformity. The sensor uses a new miniature linear cooler with an integral dewar; this approach provides unsurpassed reliability and low power at affordable cost. The sensor electronics contain electronically programmable logic to read out the FPA and format the detector gain and offset nonuniformity correction circuitry. The video output can be controlled by manual gain/level or by automatic mode. The optics are designed to be low cost, light weight and easily interchangeable to serve a wide variety of applications. The sensor is designed to support all video formats and be user friendly. The compact size and low power is well suited for portable applications.
High performance thermal imagers, such a serial and parallel scanned FLIRs are now readily available. In these sensors an array of photo-conductive HgCdTe detectors is scanned over the infrared scene, using a combination of opto-mechanical components to generate a two dimensional display. The replacement of mechanically scanning with electronically addressed 'staring arrays' is very attractive since the all electronic approach allows the fabrication of small light-weight imagers. The performance of staring imagers is determined more by FPA charge handling capacity and residual nonuniformity after compensation and less by choice of detector material or spectral bands. Our analysis and measurements indicate that a 244 X 320 FPA based upon platinum silicide detectors is well suited to meet the requirements of small high performance thermal imagers.
Infrared imaging systems have increased in number rapidly since the early 1960's; however, system insertion has been almost entirely in military and paramilitaryapplications. In the future, infraredimaging systems wilifind increasedacceptance in commercial applications provided that system costs are reduced. FLIR Systems, Inc. was founded in response to a recognized world wide need for high quality, affordable infrared systems. In this paper we present the salient features of a serial scan forward looking infrared (FUR) system which has been developed to achieve high sensitivity and resolution in systems which are less complex and are inherently less expensive to manufacture, operate and maintain. Specifically our systems utilize an 8 to 12 micron band HgCdTe detector array consisting of two or more rows of detectors in parallel with four to six detector elements in series summed in Time Delay and Integration (TDI). The serial scan approach greatly reduces the complexity and cost of the amplification and scan conversion when compared to parallel scanned systems while a small amount ofparallel scanning reduces the scan rate to a practical level. Design considerations and manufacturing methods are reviewed with emphasis on high performance and system affordability.
A medium wavelength infrared (MWIR) staring focal plane array (FPA) technology using Schottky barrier detectors with arrays consisting of 20-micron pixel spacings in a 488 x 640 array format is described. The new 488 x 640 hybrid FPA is a result of an ongoing developmental process that has evolved from a 62 x 58 array to a 488 x 640 array over the past nine years. Reported are the performance goals, design, fabrication, and test results of this high-density hybrid FPA based on PtSi infrared detector technology. The advantages of the hybrid approach include the ease of fabrication, high optical fill factor, compatibility with existing multiplexer technology, and excellent imaging performance. We review past Schottky FPA development and discuss the technical trade-offs of our approach. Also discussed are the design, fabrication, and test results of our most recent Schottky FPA.
This paper describes a staring Platinum Silicide (PtSi) medium wave infrared (MWIR) camera. The sensor is configured with a 244 x 400 hybrid focal plane array (HFPA), which has a 24 x 24 sq micron unit cell and an 84-percent fill factor. The PtSi HFPA exhibits high sensitivity with a single pixel NE-Delta-T less than 0.09 C at F/2.0 at 60 Hz. The HFPA performance characteristics, such as dc uniformity, signal responsivity, noise, and NE-Delta-T, are reviewed. The camera containing the HFPA is divided into two units: a camera head and camera processor. The camera head operates at a 60 Hz frame rate generating two 3.6 MHz video outputs. The camera processor converts these two outputs into RS-170 video. Nonuniformity correction and video reformatting are performed in the processor. The system architecture, operation, and system performance are described.
The requirements, design, fabrication, and test results are presented for a high-density hybrid FPA based on platinum silicide IR detector technology. The hybrid Schottky FPA is intended to optimize detector and readout design and processing, achieve optimal fill factors, and reduce cell size. Schottky barrier detectors are employed in arrays of 24 micron pixel spacings, in a 244 by 400 array format. The readout and detector structure are detailed, as well as the fast-settling circuitry, and a fill factor of 84 percent is shown. The modeling used to predict optical performance is set forth, indicating detector response and noise level for specified conditions. The preamplified output of each detector was sampled in a performance test consisting of irradiation by an extended blackbody IR source. Results are presented for responsivity, RMS noise, dc uniformity and noise equivalent temperature distance. Sensitivity levels in low background conditions are shown to be suitable. The design permits low-cost readout fabrication and extension to larger arrays.