InGaAs detector material used in near infrared focal plane arrays (NIR FPAs) has typically been limited in spectral response to a range from approximately 900 nm to 1700 nm. Through special processing techniques, the spectral response can be extended down through the visible spectrum and into the ultraviolet. Test results showing preliminary spectral response from 350nm to 1700 nm, responsivity, sensitivity, corrected uniformity and simultaneous imaging of NIR and visible signals will be presented along with a discussion of anticipated applications for this new sensor technology.
Indigo Systems Corporation has developed a family of standard readout integrated circuits (ROIC) for use in IR focal plane arrays (FPAs) imaging systems. These standard ROICs are designed to provide a compete set of operating features for camera level FPA control, while also providing high performance capability with any of several detector materials. By creating a uniform electrical interface for FPAs, these standard ROICs simplify the task of FPA integration with imaging electronics and physical packages. This paper begins with a brief description of the features of four Indigo standard ROICs and continues with a description of the features, design, and measured performance of indium antimonide, quantum well IR photo- detectors and indium gallium arsenide imaging system built using the described standard ROICs.
This paper describes the test results for the MIRAGE read- in-integrated-circuit (RIIC) designed by Indigo Systems Corporation. This RIIC, when mated with suspended membrane, micro-machined resistive elements, forms a highly advanced emitter array. This emitter array is used by Indigo and Santa Barbara Infrared Incorporated in a jointly developed product for infrared scene generation, called MIRAGE. The MIRAGE RIIC is a 512 X 512 pixel design which incorporates a number of features that extend the state of the art for emitter array RIIC devices. These innovations include an all-digital interface for scene data, snapshot image updates (all pixels show the new frame simultaneously), frame rates up to 200 Hz, operating modes that control the device output, power consumption, and diagnostic configuration. Tests measuring operating speed, RIIC functionality and D/A converter performance were completed. At 2.1 X 2.3 cm, this die is also the largest nonstitched device ever made by Indigo's foundry, American Microsystems Incorporated. As with any IC design, die yield is a critical factor that typically scales with the size and complexity. Die yield, and a statistical breakdown of the failures observed will be discussed.
The MIRAGE Dynamic IR Scene Projector is a standard product being developed jointly by Santa Barbara Infrared, Inc. and Indigo Systems Corporation. MIRAGE is a complete IR scene projection system, accepting digital or analog scene data as the input and providing all other electronics, optics and mechanics to project high fidelity dynamic IR scenes to the unit under test. At the heart of the MIRAGE system is the 512 X 512 microemitter array that incorporates many state-of-the-art features previously not available. The Read-In-Integrated-Circuit (RIIC) leverages technology from IR Focal Plane electronics to provide a system with advanced capability with low risk. The RIIC incorporates on chip DACs, snap-shot frame updating, constant current mode, voltage drive emitters and substrate ground plane providing high resolution and low noise performance in a very small package. The first 512 X 512 microemitter assembly has been received and was imaged on 2 APR 99. The complete MIRAGE system is currently in integration with the first deliverable unit scheduled for June 1999.
Thermal imaging equipment utilizing microbolometer detectors operating at room temperature has found widespread acceptance in both military and commercial applications. Uncooled camera products are becoming effective solutions to applications currently using traditional, photonic infrared sensors. The reduced power consumption and decreased mechanical complexity offered by uncooled cameras have realized highly reliable, low-cost, hand-held instruments. Initially these instruments displayed only relative temperature differences which limited their usefulness in applications such as Thermography. Radiometrically calibrated microbolometer instruments are now available. The ExplorIR Thermography camera leverages the technology developed for Raytheon Systems Company's first production microbolometer imaging camera, the Sentinel. The ExplorIR camera has a demonstrated temperature measurement accuracy of 4 degrees Celsius or 4% of the measured value (whichever is greater) over scene temperatures ranges of minus 20 degrees Celsius to 300 degrees Celsius (minus 20 degrees Celsius to 900 degrees Celsius for extended range models) and camera environmental temperatures of minus 10 degrees Celsius to 40 degrees Celsius. Direct temperature measurement with high resolution video imaging creates some unique challenges when using uncooled detectors. A temperature controlled, field-of-view limiting aperture (cold shield) is not typically included in the small volume dewars used for uncooled detector packages. The lack of a field-of-view shield allows a significant amount of extraneous radiation from the dewar walls and lens body to affect the sensor operation. In addition, the transmission of the Germanium lens elements is a function of ambient temperature. The ExplorIR camera design compensates for these environmental effects while maintaining the accuracy and dynamic range required by today's predictive maintenance and condition monitoring markets.
One of the simplest device realizations of the classic particle-in-a-box problem of basic quantum mechanics is the quantum well infrared photodetector (QWIP). Optimization of the detector design and material growth and processing have culminated in the realization of a 15 micrometer cutoff 128 by 128 focal plane array camera and a camera with large (256 by 256 pixel) focal plane array of QWIPs which can see at 8.5 micrometer, holding forth great promise for a variety of applications in the 6 - 25 micrometer wavelength range. This paper discusses the physics of the QWIP and QWIP technology development at Jet Propulsion Laboratory.
In this paper, we discuss the development of very sensitive long wavelength infrared GaAs/AlxGa1-xAs quantum well infrared photodetectors (QWIPs), fabrication of random reflectors for efficient light coupling, and the demonstration of first hand-held long-wavelength 256 X 256 QWIP focal plane array camera. Excellent imagery, with a noise equivalent differential temperature of 25 mK has been achieved.