David C. Harrison

An abuttable CCD imager for visible and X-ray focal plane arrays

A frame-transfer silicon charge-coupled-device (CCD) imager has been developed that can be closely abutted to other imagers on three sides of the imaging array. It is intended for use in multichip arrays. The device has 420*420 pixels in the imaging and frame-store regions and is constructed using a three-phase triple-polysilicon process. Particular emphasis has been placed on achieving low-noise charge detection for low-light-level imaging in the visible and maximum energy resolution for X-ray spectroscopic applications. Noise levels of 6 electrons at 1-MHz and less than 3 electrons at 100-kHz data rates have been achieved. Imagers have been fabricated on 1000- Omega cm material to maximize quantum efficiency and minimize split events in the soft X-ray regime. >

Large area focal plane comprising charge-coupled devices and fiber optics

Driven by a requirement for an 80 mm square sensor, we have combined CCD and tapered fiber optic technologies to create a large area focal plane. Seven custom low noise CCD imagers are assembled onto four tapered fiber optic bundles to match the physical characteristics of a tube camera used in an operational system. Two taper ratios are used in the focal plane to meet requirements for broad search and high accuracy measurements in a single device. The entire focal plane is cooled to -40°C to reduce dark current to insignificance at an integration time of 0.6 s. The focal plane has been integrated into a camera head that has an all-digital interface. The camera preserves the low noise characteristics of the focal plane in a multichannel assembly.

Space-based visible surveillance experiment

A small visible-band sensor, built by Lincoln Laboratory, Massachusetts Institute of Technology, will be flown as part of a sensor ensemble on the Midcourse Space Experiment (MSX) satellite, an SDIO program. This sensor, as well as the other sensors on MSX, will perform above-the-horizon surveillance experiments and acquire data on targets of interest and background phenomenology. This paper discusses the Space-Based Visible (SBV) sensor, the incorporated technologies, and the surveillance experiments to be performed.

The MIT Lincoln Laboratory optical systems test facility

The Optical Systems Test Facility was established at MIT Lincoln Laboratory to support a broad scope of program areas, encompassing tactical ground-based sensors through strategic space-based sensors. The Optical Systems Test Facility comprises several separate ranges developed as a coordinated set of test sites at MIT Lincoln Laboratory. There are currently four separate ranges in the facility, an active range (Laser Radar Test Facility), a passive range (Seeker Experimental System), an aerosol range (Standoff Aerosol Active Signature Testbed) and an optical material measurements range. The active range has optical and target facilities for evaluating elements of laser radar sensors as well as complete ladar systems. It has facilities for simulating long range wavefronts and for dynamic target motions. The passive range concentrates on evaluating passive infrared sensors, with capabilities for static and dynamic scene generation in both cryogenic and room temperature environments. The aerosol range is currently configured for the measurement of both particulate and bio-agent aerosol dispersion characteristics. The optical materials measurements range started with measurement capabilities for laser radar target materials and is currently being expanded to measure both emissivity and reflectance of materials from the visible through the infrared.

Space-based visible sensor on midcourse space experiment (MSX) satellite

Lincoln Laboratory, Massachusetts Institute of Technology has built and tested the space-based visible (SBV) sensor to be flown on the Ballistic Missile Defense Offices Midcourse Space Experiment spacecraft. SBV, one of a group of sensors on the spacecraft, is designed to perform above-the-horizon surveillance experiments and acquire visible/VNIR band data (450 to 950 nm) on targets and backgrounds. This paper describes the flight configuration of SBV and some calibration results.

The Standoff Aerosol Active Signature Testbed (SAAST) at MIT Lincoln Laboratory

The Standoff Aerosol Active Signature Testbed (SAAST) is the aerosol range within the MIT Lincoln Laboratorys Optical System Test Facility (OSTF). Ladar and Lidar are promising tools for precise target acquisition, identification, and ranging. Solid rocket effluent has a strong Lidar signature. Currently, calculations of the Lidar signature from effluent are in disagreement from measurements. This discrepancy can be addressed through relatively inexpensive laboratory measurements. The SAAST is specifically designed for measuring the polarization-dependent optical scattering cross sections of laboratory-generated particulate samples at multiple wavelengths and angles. Measurements made at oblique angles are highly sensitive to particle morphology, including complex index of refraction and sample shape distribution. With existing hardware it is possible to re-aerosolize previously collected effluent samples and, with online and offline diagnostics, ensure that these samples closely represent those found in situ. Through comparison of calculations and measurements at multiple angles it is possible to create a realistic model of solid rocket effluent that can be used to extrapolate to a variety of conditions. The SAAST has recently undergone a dramatic upgrade, improving sensitivity, flexibility, sample generation, sample verification, and level of automation. Several measurements have been made of terrestrial dust and other samples.

Spectral Radiant Emission of Dynamic Resistive Arrays

A persistent question in the infrared scene projection community has been the spectral characteristics of resistive array emission. This paper describes the results of a comprehensive study performed on two resistive array technologies; the Nuclear Optical Dynamic Display System (NODDS) and the Santa Barbara Infrared (SBIR) Large Format Resistive Array (LFRA) product lines. A Fourier Transform Infrared (FTIR) spectral radiometer is used to measure the spectral radiant emission of both resistive array technologies at multiple drive levels and substrate temperatures. Application of the results to scene projection and cross spectral non-uniformity correction is discussed.

The seeker experimental system at MIT Lincoln Laboratory

The Seeker Experimental System (SES) is the passive range within MIT Lincoln Laboratorys Optical System Test Facility (OSTF). The SES laboratory focuses on the characterization of passive infrared sensors. Capable of projecting static and dynamic scenes in both cryogenic and room temperature environments, SES supports sensors that range from tactical ground based systems through strategic space-based architectures. Optical infrared sensors are a major component of military systems, having been used to acquire, track, and discriminate between potential targets and improve our understanding of the physics and phenomenology of objects. This paper delineates the capabilities of the SES laboratory and describes how they are used to characterize infrared sensors and develop new algorithms and hardware in the support of future sensor technology. The SES Cryogenic Scene Projection System vacuum chamber has recently been upgraded to allow dynamic projection of radiometrically accurate two-color infrared imagery. Additional capabilities include the ability to combine imagery from multiple sources, NIST traceable radiometric calibration, and dynamic scene projection in an ambient environment using a combination of high speed mirrors, point source blackbodies, and resistive array based dynamic infrared scene projectors.

Active Range of the Optical Systems Test Facility at MIT Lincoln Laboratory

The Active Range of the Optical Systems Test Facility was established in 2003 to allow for rapid development and demonstration of active electro-optic technology in a system context, investigate critical phenomenology issues in a repeatable environment, and enhance expertise in electro-optic technology. The test facility consists of four major parts: a control room, a 50-m range with installed ladar systems, a far-field emulator comprising of a 1-m primary mirror and zoom optics, and a dynamic target manipulator for full-scale (1-m) targets. This paper will focus on the capabilities of the Optical Systems Test Facility and present some examples of laser radar experiments and data taken in the range.

Characterization and comparison of 128x128 element nuclear optical dynamic display system resistive arrays

Dynamic infrared scene projection is a common technology used to provide end to end testing and characterization of infrared sensor systems. Scene projection technology will play an increasing role in infrared system evaluation and development as the cost and risk of flight testing increases and new display technologies begin to emerge. This paper describes a series of tests performed in the Seeker Experimental System (SES) at MIT Lincoln Laboratory (MIT LL). A small collection of 128×128 element Nuclear Optical Dynamic Display System (NODDS) resistive arrays were tested and compared using FIESTA drive electronics developed by ATK Mission Research. The residual spatial nonuniformity of the NODDS arrays were calculated after applying a sparse grid based nonuniformity correction algorithm developed at MIT LL. The nonuniformity correction algorithm is a slightly modified version of the industry standard sparse grid technique and is outlined in this paper. Additional metrics used to compare the arrays include emitter temporal response, raw nonuniformity, transfer function smoothness, dynamic range, and bad display pixel characteristics.