Director, Lincoln Laboratory
Lincoln Laboratory is a mission-oriented laboratory operated by MIT for the Department of Defense (DoD) carrying out research and development in surveillance, identification, and communications. The laboratory continued a celebration during the academic year of its establishment fifty years ago, in 1951, as Project Lincoln by MIT in response to a request from the Army, Navy, and Air Force. During the past year, agencies of the DoD—namely, the Air Force, the Army, the Navy, the Defense Advanced Research Projects Agency, the Ballistic Missile Defense Office, and the National Reconnaissance Office—supplied approximately 86 percent of the laboratory's budgetary support. The Federal Aviation Administration provided most of the non-DoD support, which additionally includes work for the National Aeronautics and Space Administration and the National Oceanographic and Atmospheric Agency . Lincoln Laboratory also carries out pre-competitive research with industry under approved Cooperative Research and Development Agreements. For the federal fiscal year 2001, Lincoln Laboratory received $380.3 million, supporting the efforts of 1,200 professional technical staff.
The following administrative changes occurred at the Laboratory Steering Committee level. Associate Provost Claude L. Caniares was appointed to the Laboratory Steering Committee and serves as the campus liaison. Professor David H. Staelin, who had served on the Steering Committee and part-time as assistant director, has returned full time to the Department of Electrical Engineering and Computer Science. Dr. Kenneth D. Senne was appointed technology investment officer. Mr. Lee O. Upton, assistant director, was also named head of the Sensor Technology Division, formerly the Air Defense Division.
Activity at the laboratory focuses on DoD tasks in surveillance, missile defense and air defense, information extraction, and communications and information technology, supported by advanced electronic technology and on air traffic control technology for the Federal Aviation Administration. Technical work areas include radar and optical sensors, measurements, and systems; communications; signal design and processing; identification algorithms; lasers; solid-state devices; digital technology, circuitry, and data systems; and tactical control systems. Unclassified summaries of several accomplishments during the past year are presented below.
Urban Biological Defense
The Defense Threat Reduction Agency (DTRA) selected Lincoln Laboratory to lead a nine-month study on a proposed means of dealing with a bioterrorist attack on US cities. This follows a study done for DTRA in 2001 on "Health Surveillance and Biodefense," described in last year's report. The new study expands a health-surveillance-only system into a much broader-based detection and reporting system that includes environmental sensors and considers implications of connecting into an already existing consequence management network. The current study includes participation from MIT, Harvard, and consultants, including medical, public health, and urban specialists. The goal is to develop a realistic architecture for an urban system based on technology that could be available today or in the near future.
The Lincoln Near Earth Asteroid Research (LINEAR) project continues to operate a wide-area asteroid search program employing an advanced electro-optics search system originally developed for Air Force-sponsored space surveillance applications. A third telescope using the same advanced technology has been recently added to the program. This newest telescope is dedicated to following up and improving the orbit accuracy of the asteroids found with the two search systems. The LINEAR system has generated over 9 million observations during the period of March 1998 to July 2002. These observations account for over half of all observations in the Minor Planet Center archives, and 70 percent of all new asteroid discoveries since 1998. LINEAR has discovered 995 near-Earth asteroids (1,940 total known), 87 comets, and over 165,000 main belt asteroids.
Lincoln Laboratory joined with the nonprofit Science Service to begin the Ceres Connection activity that honors students in fifth through twelfth grades and their teachers in the naming of minor planets. The students and teachers are selected through the Science Service competitions, the Discovery Youth Science Challenge, Intel Science Talent Search, Intel International Science and Engineering Fair, and Intel Excellence in Teaching Award. The Ceres Connection has honored 264 students and teachers with minor planets so far this year.
Imaging Radar Technology Study
Lincoln Laboratory conducted a six-month study to investigate the feasibility of developing a millimeter-wave satellite imaging radar at Haystack and to develop a preliminary system design. The objective is to demonstrate imaging of small satellites at ranges out to geosynchronous orbits. The combination of short wavelength, wide bandwidth, and sensitivity (signal-to-noise ratio) needed for this task has never been demonstrated and will require a very significant advancement in radar technology. The proposed radar, named Deep View, will be built upon the infrastructure of the Haystack radar at the Lincoln Space Surveillance Complex in Westford, Massachusetts. The radar will operate in the W frequency band (96 GHz). The 37-m-diameter Haystack antenna would require resurfacing to <100-µm tolerance to efficiently transmit and receive at W-band. To simultaneously achieve the high power and wide bandwidth, the Deep View radar will combine an innovative sparse-band multiplexed gyrotron transmitter architecture and signal processing. The sparse-band design removes the bandwidth limitations of individual high-power amplifiers and has potential applications in other military high-resolution radar systems.
First Demonstration of an Integrated Solid-State 3-D Laser Radar Detector Array
Lincoln Laboratory successfully demonstrated the first operation of an integrated solid-state detector array for three-dimensional (3-D) laser radar during DARPA-sponsored field trials at Eglin Air Force Base, Florida, in December 2001. The detector consisted of a 32-by-32 array of single-photon-sensitive avalanche photodiodes bonded to a commensurate array of CMOS timing circuitry. The 3-D laser radar operated with a 532-nm frequency-doubled Nd:YAG laser transmitter with at a 5-kHz pulse repetition rate. This system measured three-dimensional shapes of objects by performing a laser ranging measurement for every pixel.
Geosynchronous Satellite Encounters
In January 1997 Telstar 401, a geosynchronous communications satellite, failed on-orbit with no ability to be boosted from the populous geosynchronous belt. Without station-keeping capability, Telstar 401 will oscillate indefinitely from 97 to 113 degrees west longitude in a geopotential well centered at 105 west, posing a long-term threat to numerous active satellites. Another geosynchronous satellite, Solidaridad 1, failed on-orbit in August 2000 and also became a threatening drifter. Lincoln Laboratory has monitored nearly one hundred encounters of these two drifters with active satellites in the past five years. This work is performed under a Cooperative Research and Development Agreement (CRDA) with four commercial satellite operators. There are numerous other drifting, inactive satellites besides Telstar 401 and Solidaridad 1 that pose a threat to the active geosynchronous population. Lincoln Laboratory has developed an automated system to predict and monitor all such encounters of the drifting population with the CRDA-partner active satellites.
Meteor Radar Data Analysis
Lincoln Laboratory was selected to lead a multi-year effort, sponsored by NASA, to assess the meteoroid threat to orbiting spacecraft. High-power radar data indicate that there is a high probability of damage to an orbiting satellite, due to the unexpectedly large number of microgram-class meteoroids moving with high velocities. Meteor data were collected by the ALTAIR radar located on the Kwajalein Atoll during the Perseid 1998 shower and the Leonid 1998 and 1999 showers with an average detection rate of one meteor every two seconds. ALTAIR collected data at approximately 100-km altitude, where meteoroids entering the Earth's atmosphere form plasmas. These data were analyzed to determine meteoroid radius, density and mass. Accurate mass and density distributions can now be employed in environment models, which will have a significant impact upon spacecraft meteoroid risk analyses.
Monitoring Space Weather with GPS
Lincoln Laboratory has computed Global Positioning System (GPS) maps of total electron content at various locations using data from approximately 150 GPS receivers across the North American continent for several large geomagnetic storms. These maps have been used to monitor the time evolution of ionospheric-storm-enhanced density, a known "space weather phenomenon." During the storms studied, plasma is transported to higher latitudes and to earlier local times—approaching the noon meridian. The storm-enhanced-density total-electron-content plumes, seen in the GPS data, map directly into the dramatic plasmaspheric tails observed in the images collected by NASA's IMAGE satellite. This is one of the first proven observations of a magnetospheric phenomenon measured by a ground-based system.
Earth Observing 1 Mission: Advanced Land Imager
Advanced Land Imager (ALI) has been operating successfully on orbit for twenty months, well over the originally planned mission duration of one year. Currently, sixteen images per day, on average, are being collected for a variety of government and commercial interests. The success of ALI has lead NASA to select ALI as the benchmark design for the Landsat Data Continuity Mission, currently in the formulation phase by two contractor teams selected competitively. Lincoln Laboratory is supporting NASA in these procurement activities and helping the contractors understand the ALI technology.
Missile Defense Changes
The nation's approach to ballistic missile defense (BMD) is going through significant change. The Anti Ballistic Missile Treaty with Russia has ended, and options such as mobile sensors and interceptors for missile defense can now be utilized. There is no longer a requirement to carefully delineate between national and theater missile defense, and a single system of integrated elements can be developed. A capability-based development concept is being utilized, with the initial capability available in late 2004 and future improvements planned in subsequent two-year increments. A collaborative government-FFRDC-industry national team has been formed to focus on the critical system-architecture trades. The laboratory is a major participant in laying out the future architecture for the BMD system. A BMD system test bed that can be deployed with contingency capability in the event of an emergency is being considered.
Sea Based Midcourse Defense Program
Lincoln Laboratory has been helping develop a theater ballistic missile defense capability as part of the Sea Based Midcourse Defense Program. The challenges associated with detection, discrimination, and handover of hostile targets within a missile complex are an area of active laboratory work. The laboratory has developed a midcourse discrimination architecture including algorithms for synthetic wideband radar measurements and algorithms to improve two-color infrared focal-plane performance. Two intercept flight tests have been attempted to date, both of which successfully hit the incoming missile.
Advanced Air and Missile Defense Technologies
Multiple applications demand large-aperture radars and advanced missile systems to counter emerging threats and new missions. Large-aperture radars stress technology by requiring large dynamic range, multiple electronic beams formed on receive using high-performance digital signal processors, and on-board jamming resistance. We are working for the Navy on demonstrating a digital array radar to sample the RF signals close to the antenna phase. Once the signals are digitized, we will implement a system based on an open system architecture to permit easy transfer of the innovative algorithms to new systems as computing technology evolves. This effort is synergistic with advances in signal processing technologies for missile seekers. In both cases, large antenna arrays and missile seekers, the architecture and algorithms are implemented in a processor-independent signal processing software architecture. We have successfully demonstrated portability from a network of workstations to embedded systems, thus achieving the predicted improved performance for a new class of missile discrimination algorithms.
High Energy Laser Beam Control Technology
As a result of renewed DoD interest in tactical high-energy lasers, Lincoln Laboratory has expanded its efforts in high-energy laser beam control technology. Research programs are focusing on several technologies critical to the success of tactical high energy laser systems. To study beam-control concepts, Lincoln Laboratory operates the Advanced Concepts Laboratory under Air Force sponsorship. This laboratory is designed to explore unconventional and innovative techniques for adaptive-optics compensation and tracking.
Under sponsorship from the Joint Technology Office, Lincoln Laboratory is integrating another beam-control laboratory to investigate the effects of thermal blooming, a phenomenon resulting from laser heating of the atmosphere. In a related measurements program, Lincoln Laboratory is leading an effort to identify candidate atmospheric transmission windows in order to reduce the effects of thermal blooming.
A 3-D laser radar system is being developed for installation on the SeaLite beam director at White Sands Missile Range, New Mexico. The 3-D laser radar and associated track algorithms will enable target tracking in cluttered environments where conventional image-tracking techniques fail.
Airborne Seeker Test Bed
The Airborne Seeker Test Bed, in a Gulfstream II aircraft, has participated this year in two major test campaigns and infrastructure upgrades. One of the test campaigns was conducted in Nevada to evaluate the effectiveness of electronic countermeasures against a modern surface-to-air missile system and to measure bistatic radar cross sections. The second test utilized the seeker test bed's IR focal-plane arrays and IR seekers to test flare countermeasures.
Knowledge-Aided Sensor Signal Processing and Expert Reasoning
The challenge of accurately geo-locating, identifying, and engaging enemy mobile air defense systems is considered a high priority for our force structure, due to the demonstrated ability of these threats to shoot and move on a very short timeline. To address this problem, we have begun a new effort for DARPA to improve the performance of ground moving-target indicators and synthetic aperture radars in detecting and tracking ground mobile threats by exploiting a priori knowledge. The techniques rely on delimited terrain maps, information from other cooperative sensors, and aggregated knowledge from previous measurements. These techniques are highly computational intensive. However, with the advances in computing technology, the practicality of these techniques is within reach. The laboratory is working jointly with industry to develop a high-performance digital signal processor system that can be embedded in experimental aircraft.
Undersea Warfare Systems
Lincoln Laboratory has provided algorithm capability for sonar classification to the Los Angeles–class submarine fleet. Operator feedback from the testing of the Lincoln Interactive Passive Acoustic Classifier has established confidence in the promise of automated aids to classification. This technology has been successfully transitioned to the submarine fleet for different classes of towed arrays. The application of this technology is expanding to new sensors and additional threats.
GPS Pseudolite System
Lincoln Laboratory is working with industry to demonstrate a phase array instrumented in an airborne platform to serve as a relay of GPS coordinates. The approach would permit suppression of jamming interference while maintaining enough signal-to-interference ratios for airborne users. A demonstration of a seven-element array in an anechoic chamber has been completed with a series of flight tests planned for next year.
Multi-Sensor Fusion and Exploitation
Over the past two years, an integrated visualization and target recognition system that supports the intelligence community was developed and deployed. This system provides a capability to visualize color-fused three-dimensional scenes of areas of interest. Automatic search algorithms for detecting terrain features within these scenes can be trained using a simple graphical user interface. This same system was also integrated into an automatic target recognition system that was deployed to a ground station. This automatic target recognition system screens incoming data for significant targets such as surface-to-air missile systems. This work is now focused on integrating the fusion and target recognition system and designing a user interface. Also work has started to address the integration of passive data sources for improved detection and false alarm performance.
Optical Communications Technology
Optical logic gates are potential building blocks for all optical routers and would permit the routing of optical packets without the need for optical signal to electrical signal conversion, then back to optical signal. The laboratory has demonstrated switching of optical packets based on decoding the packet address optically at a line rate of 112.5 Gbps. In related work, the laboratory demonstrated the world's fastest all-optical-exclusive OR (XOR) function. The XOR operates at 50 Gbps. The laboratory and campus researchers are now examining ways to reduce the physical size of all-optical logic gates to make these circuits practical in future optical networks.
The Lincoln Laboratory Satellite Communications On The Move effort completed the test-bed-equipped vehicle and demonstrated the initial concept. The test bed incorporated an antenna positioner that can compensate for the vehicle-motion and blockage-mitigation protocols that compensate for the loss of signal.
Tools for FAA Cyber-Security Analysts
Lincoln Laboratory has been working with the Federal Aviation Administration (FAA) to improve the efficiency and effectiveness of FAA cyber-security analysts. These analysts have the responsibility for detecting computer attacks against FAA networks. Working with the FAA and the government inter-agency Technical Support Working Group, prototype tools were developed and demonstrated by using real FAA network data. These tools are currently in the alpha and beta testing phases.
Lincoln Laboratory is working with the FAA and NASA to enhance air safety, reduce controller workload, and increase airport capacity by developing planning aids for air traffic controllers. A NASA-sponsored effort is underway to integrate advanced weather products developed by Lincoln Laboratory into the Center Terminal Automation System developed by NASA. This activity helps coordinate activities between arrival controllers located at en route centers and final-approach controllers located at radar control facilities. The focus of initial work is on integrating wind field products from the Integrated Terminal Weather System in order to improve aircraft trajectory estimates. Additional work is being carried out to determine the delay-reduction potential of automated traffic spacing advisories for air traffic controllers.
Air Traffic Surveillance Technology Improvements
The laboratory has undertaken an FAA program to perform flight-test validation of Automatic Dependent Surveillance Broadcast in the US and Europe. The technology, developed at the laboratory, uses the Mode S secondary radar frequency and data formats to broadcast aircraft-derived position and state information. It enables air-to-air and air-to-ground exchange of more precise and timely information in support of improving the efficiency of air traffic management. The FAA is also sponsoring the laboratory 's effort to assist with the development of time-difference multilateration, a technique for surveillance of the airport surface that will form the basis for improved management of surface traffic and the prevention of runway incursions.
Aviation Weather Surveillance and Forecasting
The laboratory has made significant progress in automated thunderstorm forecasting and is demonstrating this operationally at key terminal and en route air traffic control facilities. The time horizon for the forecasts has been extended to two hours and their accuracy improved through identification of storm type and through detection of storm initiation, growth, and decay. The laboratory's automated forecast of ceiling and visibility changes at San Francisco is in its second year of operational demonstration, and will be transferred to the National Weather Service for long-term operations.
The laboratory-developed and industry-produced Integrated Terminal Weather System is now operational at Kansas City, Houston, and Atlanta, and will be deployed to thirty additional large airports during 2003. The laboratory continues to operate prototypes covering six airports and is assisting the FAA in deployment and enhancement of the production Integrated Terminal Weather System. A Corridor Integrated Weather System extends high-resolution Integrated Terminal Weather System weather products and thunderstorm forecasts to the congested airspace over the eastern seaboard and upper Midwest. This system is used by FAA traffic management specialists at five en route centers, six large terminal radar control facilities, and the FAA command center outside Washington.
Liquid Immersion Lithography
The semiconductor industry's roadmap anticipates that by the year 2010 the smallest features in an integrated circuit will be 45 nm. Within the next four to six years, as the dimensions shrink to 65 nm, optical projection will be performed with 157-nm radiation, a technology that was first developed at Lincoln Laboratory. However, even 157-nm lithography will encounter difficulties in patterning the 45-nm structures needed by the end of the decade. To meet this need, Lincoln Laboratory is exploring the incorporation of transparent liquids between the optical system and the resist-coated silicon wafer. This approach, which in effect increases the numerical aperture of the optical system, is well known in the visible and near-ultraviolet wavelengths as "oil immersion microscopy." For its application to the specific requirements of lithography at very short wavelengths, Lincoln Laboratory has identified a class of suitable transparent liquids, and has demonstrated their effectiveness by printing 30-nm lines and spaces in a 157-nm liquid-immersion interference configuration. These are the smallest dense features printed to date with optical methods.
Fiber-Laser Beam Combining
Lincoln Laboratory has recently demonstrated that the beams from five fiber lasers can be "wavelength-combined" so that the output appears as a nearly diffraction-limited ideal laser beam. This is made possible by operation of each laser at a slightly different wavelength, which then enables the lasers' output beams to be combined by spatially overlapping the beams so that they all propagate coaxially. This new approach is applicable to other types of laser arrays, such as diode laser arrays, and experiments show scalability of the wavelength-beam-combining technique to arrays containing hundreds of lasers.
Aluminum-Free, Mid-Infrared Semiconductor Lasers
Lincoln Laboratory has recently developed a GaSb-based, ~4-µm-wavelength semiconductor laser design that is free of aluminum. This was accomplished by replacing the typically used AlAsSb optical cladding layers with GaSb in quantum-well laser design. A careful analysis of previously published data indicated that GaSb would have a refractive index less than that of the GaInAsSb waveguiding layer by ~0.06. This small refractive index step resulted in the laser-beam far-field divergence being reduced by a factor of three from ~80° to ~25°. The collected power efficiencies were measured to be up to two times greater than the best previous devices. To date, the highest output power measured from a single facet is 5 Wpeak. The aluminum-free structure also simplifies material growth and device fabrication, thus enabling new device structures.
Slab-Coupled Semiconductor Lasers with Single-Spatial, Large-Diameter Mode
High-power single-mode semiconductor diode lasers, with outputs that can easily be coupled into single-mode fibers, are of interest for a variety of applications. Conventional single-mode diode lasers are typically restricted to modest output powers and feature elliptical beams that require expensive packaging schemes with external lenses to achieve efficient optical coupling to single-mode fibers. A new approach to this problem has now been demonstrated in the slab-coupled optical waveguide laser (SCOWL). The SCOWL combines modern quantum-well gain regions with low-loss passive slab-coupled rib waveguide concepts. This design permits single-mode lasers with larger, nearly circular modes permitting easy coupling into fibers. The large mode size also results in reduced power density at the facets. Other features enable efficient, high-power operation. To date, 980-nm SCOWLs with continuous-wave output powers greater than 1.2 W, electrical-to-optical efficiency greater than 35 percent, average brightness of greater than 100 MW/cm2-str, and butt-coupled (no lenses) efficiency of greater than 84 percent into a single-mode fiber have been demonstrated.
Superconducting Circuits for Quantum Computation
In collaboration with MIT's Department of Electrical Engineering and Computer Science, and the Harvard University Physics Department, Lincoln Laboratory is developing superconductive quantum devices for application to quantum computation. This collaboration has designed, fabricated, and measured the amount of stored flux in a micrometer‑scale superconductive circuit as a function of the applied magnetic field and has observed two states in the circuit, as well as evidence for resonant transitions induced by quantum-mechanical tunneling between these states. This result is a first step towards developing a useful superconductive gate for quantum computation.
Scientific Charge-Couple Imagers
Lincoln Laboratory has developed wide-spectral-bandwidth, large-format charge-coupled imagers for astronomy applications. Over the past year, processes have been developed that give near reflection-limited detector quantum efficiency from the ultraviolet to the near infrared. To improve the ultraviolet response, where the silicon absorption length is a few nanometers, a high-boron-doped, thin single-crystal silicon layer was grown on the device surface to create an electric field that efficiently accelerates the photoelectrons into the charge detection well. A process was developed that uses molecular beam epitaxy to grow a few-monolayers-thick layer on 150-mm wafers. Multilayer antireflection coatings were used to maximize broadband response and reduce Fabry-Perot interference effects. Atop Mauna Kea on the island of Hawaii, the Canada-France-Hawaii observatory recently discovered 30 new moons orbiting Jupiter, Saturn, and Neptune by using a 2-by-6 array of Lincoln Laboratory 2048-by-4096-pixel CCD imagers (>100 million pixels). These observations doubled the number of such moons known to orbit the planet and is the largest number of satellites ever discovered at one time.
More information about Lincoln Laboratory can be found on the web at http://www.ll.mit.edu/.