About
Selected Patents
A list of selected patents issued to Lincoln Laboratory–developed inventions is published below. Each patent is linked to its entry on the U.S. Patent and Trademark Office website. An archive of past featured inventions can be found at the patents archive.
For further information on the availability of these technologies for license, contact Jack Turner of the MIT Technology Licensing Office, at http://web.mit.edu/tlo/www/, 617-253-6966, or mailto:jht@mit.edu.
Patents from July 2006 through December 2007
Method and System of Lithography Using Masks Having Gray-Tone Features
Inventors: Michael Fritze and Brian M. Tyrrell
Date issued: 11 December 2007
U.S. Patent No.: 7,306,881
A method of forming patterns on a substrate exposes the substrate a first time and then exposes the substrate a second time using a mask containing gray-tone features. The gray-tone features locally adjust an exposure dose in regions corresponding to features defined in the primary exposure. Moreover, the gray-tone features enable the forming of features having different critical dimensions on a substrate. The gray-tone features may be subresolution features and formed by pixellation. The trim mask containing gray-tone features may have regions with different transmissivities.
Incremental Reduced Error Pruning
Inventors: Robert K. Cunningham and Oliver Dain
Date issued: 4 December 2007
U.S. Patent No.: 7,305,373
This patent describes techniques for the automatic generation of classification rules used in machine learning. A single rule is formed of one or more logical expressions and an associated target. Using a set of training data, rules are formed one logical expression at a time using special data structures that require each feature to be sorted only once per rule formation. The FOIL gain metric is used in determining optimal splits for categorical features. Rule formation ceases with the production of five bad rules in which a bad rule is one in which there are more negative than positive examples in the training data set.
Apparatus and Methods for Surface Contour Measurement
Inventor: Lyle G. Shirley
Date issued: 10 July 2007
U.S. Patent No.: 7,242,484
The apparatus and methods for measuring three-dimensional position information of a point on a surface of an object include two sources of radiation separated by a distance, each source having a spectral distribution and being coherent with respect to the other of the sources, a control system moving each of the sources relative to the other of the sources, and a detector positioned to receive radiation scattered from the point on the surface of the object. In another embodiment, the two sources of radiation include an initial source of a beam of radiation having a spectral width, a beam separator in optical communication with the initial source of a beam of radiation generating a first optical beam and a second optical beam, and an imaging system optically connected to the beam separator.
Micro-electromechanical Switch Designs
Inventors: Carl O. Bozler, Shaun R. Berry, Jeremy Muldavin, and Craig L. Keast
Date issued: 15 May 2007
U.S. Patent No.: 7,218,191
A capacitive RF switch and dc RF switch include a fixed electrode having a thin layer of metal and at least one pull-down electrode. A moving plate has a plurality of corrugations and a selective finger design. The capacitive switch includes a selective finger that comes into contact with the fixed electrode so as to minimize the stiction between the moving plate and the fixed electrode when the switch is closed. The dc switch comprises a plurality of dimples that are formed on the selective portion of the moving plate and are positioned to come into contact with the fixed electrode when the switch is closed in order to increase the contact force and lower the resistance between the moving plate and the fixed electrode.
Interferometric Communication System and Method
Inventor: Sumanth Kaushik
Date issued: 6 March 2007
U.S. Patent No.: 7,187,871
High-bandwidth angle-modulated communications may be obtained using an incoherent/broadband "white light" source. The light is passed through interferometer arms before and after a communication link. The light is modulated in a transmitter signal optical angle modulator and in a reference optical angle modulator. By locating an interferometer and light source at a receiver, the light passes through the interferometer both before and after the optical link to the transmitter. A balanced detector implements subtraction of noninterfering light.
Inventor: David O. Caplan
Date issued: 19 June 2007
U.S. Patent No.: 7,233,430
Differential-phase-shift keying (DPSK) provides increased sensitivity over commonly used on-off keying in optical communications, making it particularly useful for free-space and telecom applications with many wavelength-division-multiplexed (WDM) channels. This patent presents a method of demodulating optical channels by using a single delay-line interferometer (DI). The benefits of DPSK come at the cost of increased complexity, requiring (among other things) a DI demodulator in the receiver. The DI must be stable to a small fraction of a wavelength, requiring careful thermomechanical packaging or stabilization techniques that add to size, weight, power, and cost. Conventional approaches use a separate DI for each WDM channel so that costs and complexity grow with the channel count.
This invention leverages the DI’s periodic transfer function and constrains the wavelength spacing to enable simultaneous demodulation of multiple WDM channels by using a single DI. It also provides the framework for achieving stable, near-theoretical DPSK performance while maintaining compatibility with existing data-rate and channel spacing standards. The resulting hardware simplification has the potential to reduce the cost of deploying and scaling future wideband optical-communication networks.
Apparatus and Method for Isolating a Nucleic Acid from a Sample
Inventors: Lalitha Parameswaran, Albert Young, Laura Bortolin, Mark Hollis, James Harper, and Johanna Bobrow
Date issued: 15 May 2007
U.S. Patent No.: 7,217,513
The Department of Defense and Department of Homeland Security have a growing need for rapid collection, processing, and analysis of samples for the presence of biological warfare agents. Such agents are commonly analyzed by using the polymerase chain reaction (PCR), a process that repeatedly replicates specific nucleic-acid sequences in the sample, allowing the identification of extremely small quantities of the organisms present. PCR inhibitors, which hinder the reaction, are often present in samples collected for medical diagnosis, during forensic investigations, or in defense applications. It is difficult, for example, to extract amplifiable DNA from soil or slurry samples—particularly from samples that include clays or other soils that have high organic content. Conventional techniques for extracting nucleic acids from samples are labor intensive and require laboratory facilities. Many existing protocols also require toxic reagents, such as phenol and chloroform.
This patent describes a procedure to separate nucleic-acid inhibitors from a raw liquid or solid sample by using a chemically treated paper that binds PCR inhibitors and uses only water to release clean DNA. This chemically treated paper archives and preserves the DNA in a dry state such that it can be extracted and analyzed after months or even years of room-temperature storage. The patent also describes a self-contained, portable plastic device that incorporates the paper into a compact, easy-to-use cartridge that can be used to collect a wipe or liquid sample and process it to produce PCR-ready DNA in minutes, with no external power or vacuum source required. (For more detail on the work that produced this patent, see "Recovery of Organisms and Nucleic Acids from Complex Samples" (pdf), Lincoln Laboratory Journal, vol. 17, no. 1, pp. 167–186, 2007.
High-Yield Single-Level Gate Charge-Coupled Device Design and Fabrication
Inventors: Barry E. Burke and Vyshnavi Suntharalingam
Date issued: 15 May 2007
U.S. Patent No.: 7,217,601
Charge-coupled devices (CCDs) consist of an array of gates that hand charge off to each other much like the fire-fighting bucket brigades of long ago. Efficient charge transfer requires that the gates be separated by extremely narrow (<0.3 µm) gaps. For the large CCDs used in scientific and military applications, the need for such small gaps lowers device yield: a single defect that closes that gap creates a short circuit and can render the device useless.
CCD gates are fabricated from thin films of polycrystalline silicon or polysilicon that have been doped with impurities to make them conductive. This patent describes techniques for reducing the likelihood of short circuits between gates to nearly zero. The polysilicon layer is deposited undoped (and hence nonconducting), and the layer is selectively doped by using the gate pattern design. This process essentially yields the desired gate pattern but with the gaps filled with nonconducting polysilicon. Because a manufacturing defect that dopes the gaps would result in a short, in the next step the narrow gaps are etched into the film. Thus the gates are defined by two separate process steps with independent random defect locations. If the process has a reasonably low defect rate, then the odds of spatially coincident defects from the two process steps should be extremely low.
Optoelectronic Detection System
Inventors: James D. Harper, Richard H. Mathews, Bernadette Johnson, Martha S. Petrovick, Ann Rundell, Frances E. Nargi, Timothy Stephens, Linda M. Mendenhall, Mark A. Hollis, Albert M. Young, Todd H. Rider, Eric D. Schwoebel, and Trina R. Vian Date Issued: 8 May 2007
U.S. Patent No.: 7,214,346
Cells derived from the mammalian immune system have been genetically modified to respond to specific pathogens and to emit measurable light within seconds. This biosensor technology, called CANARY, harnesses nature’s optimized pathogen identification system to provide the best known combination of speed and sensitivity for pathogen identification. This patent describes methods and devices for creating and using CANARY cell-based biosensors for the rapid identification of bacteria, viruses, proteins, and DNA/RNA sequences from liquid and aerosol samples. This invention provides substantial improvement in combined speed and sensitivity for identification of biological pathogens compared to conventional technologies and has utility for a broad range of medical, environmental, and defense applications. Automated sensors combining CANARY analysis with dry aerosol collection methods, as described in the patent, provide the first detect-to-protect biological identification capability: response time is less than three minutes. (For more detail on the work that produced this patent, see "Rapid Sensors for Biological-Agent Identification"(pdf), Lincoln Laboratory Journal, vol. 17, no. 1, pp. 63–84, 2007).
Device for Subtracting or Adding Charge in a Charge-Coupled Device
Inventor: Michael Anthony
Date issued: 3 April 2007
U.S. Patent No.: 7,199,409
Existing methods of moving charge along in a charge-coupled device (CCD) rely on balancing charge between CCD wells. This patent describes a compact device that performs this task faster and more accurately. The method permits a pipelined, charge-domain analog-to-digital converter to process decreasing amounts of charge in successive stages, thus reducing power consumption in downstream stages and also increasing effective charge resolution.
Network Security Planning Architecture
Inventors: Richard Lippmann, Chris Scott, Kendra Kratkiewicz, Michael Artz,
and Kyle Ingols
Date issued: 20 March 2007
Patent No.: 7,194,769
Current tools for assessing enterprise computer networks measure the security of individual hosts but not of the overall network. Attack graphs have been proposed as a way to model network security by showing how an attacker can progress through a network by exploiting vulnerabilities and trust relationships to progressively compromise more hosts. This patent describes a new type of attack graph, called a predictive graph, that is created by using firewall rules, vulnerability scans, and subnet interconnect information. Unlike past approaches, predictive graphs can be computed efficiently for large enterprise networks, yielding recommendations that improve security by changing firewall rules or patching applications on specific hosts. These recommendations can help prioritize protective actions when new vulnerabilities are announced, when new hosts or services are added, or when a network’s topology changes.
Methods of Achieving Optimal Communications Performance
Inventors: David O. Caplan and Walid A. Atia
Date issued: 20 February 2007
U.S. Patent No.: 7,181,097
In optical communications, the filter shape needed to maximize signal-to-noise ratio (SNR) for a given signal waveform is known as the matched filter. Imperfections in pulse shape or filter bandwidth can degrade SNR for commonly used matched pairs, such as the square waveform and corresponding matched filter. For these waveforms, SNR is susceptible to further degradation by effects such as timing jitter and limited sample speed.
This invention overcomes these and other performance impairments by using mismatch- and jitter-tolerant Gaussian-like waveforms and matched receiver filters. This combination could cost-effectively achieve nearly ideal communication performance with a system composed of imperfect elements. These features, coupled with a narrow time-bandwidth product, make the Gaussian an efficient waveform for densely packed time- and wavelength-multiplexed communications, especially high-rate fiber-optic networking and long-haul free-space laser-communications applications. Better matching in the optical domain can reduce the need for high-performance wideband electronics, and improved SNR can extend link distances and repeater spacing, or reduce system size, weight, power, and cost.
Self-Assembled Quantum Dot Superlattice Thermoelectric Materials and Devices
Inventors: Theodore C. Harman, Patrick J. Taylor, Michael P. Walsh, and
Brian E. LaForge
Date issued: 20 February 2007
U.S. Patent No.: 7,179,986
The key to the use of thermoelectric technologies for cooling applications is the development of materials with increased thermoelectric efficiency. Quantum-dot-superlattice (QDSL) structures of lead selenide and lead telluride grown by molecular beam epitaxy can be twice as efficient as conventional bismuth telluride alloys. Because of the lattice mismatch between PbTe and PbSe, heterostructures of a very thin layer of PbSe sandwiched between two PbTe layers results in an array of PbSe quantum dot structures. Struc-tures with thousands of periods are grown to produce bulk-like QDSL structures, with quantum dots of PbSe0.98Te0.02 in a matrix of PbTe. The quantum-dot material’s high efficiency comes primarily from reducing the thermal conductivity because of phonon scattering at the interfaces between the dissimilar materials.
Adjustable CCD Charge Splitter
Inventor: Michael Anthony
Date issued: 26 December 2006
U.S. Patent No.: 7,154,134
A charge-coupled-device (CCD) charge splitter receives an incoming charge packet and splits it into two outgoing packets. The sum of the outgoing packets equals the incoming one; the ratio between the outgoing packets is set mainly by the geometry of the splitter. This invention provides a means of applying an electrical control signal to adjust the splitting ratio, fine-tuning it to exactly the targeted value. The ability to adjust the splitting ratio makes possible CCD-based analog-to-digital converters with much higher linearity than otherwise obtainable.
Resist with Reduced Line Edge Roughness
Inventor: Theodore H. Fedynyshyn
Date issued: 26 December 2006
U.S. Patent No.: 7,153,630
As transistor gate dimensions shrink to 65 nm and below, the high level of line edge roughness (LER) exhibited by chemically amplified resists can cause both inter- and intra-transistor gate length variations. The result is decreased process latitude, poorer device performance, and, ultimately, lower wafer yield. The patent describes a way to modify the composition of resist compounds with the addition of a base having a molar concentration ratio of about 0.2 to less than 1 relative to the photoacid generator. This invention allows for high-resolution and high-sensitivity resists while significantly reducing LER and consequently transistor gate length variation. Importantly, the invention is polymer platform independent: resists have significantly lower LER than do other resists based on similar polymer platforms with lower base levels. Because of its simplicity, this approach can be employed to reduce LER at several exposure wavelengths, including 193 nm, 157 nm, and 14 nm.
Efficient Subband Channelizer and Subband Combiner with Oversampled Subbands
Inventor: William S. Song
Date issued: 28 November 2006
U.S. Patent No.: 7,142,607
A subband channelizer efficiently generates oversampled subbands with lower oversampling ratios than a conventional channelizer. A low oversampling ratio reduces the subband sampling rate, which in turn reduces the computational load on subsequent data processing. The architecture relies on clocking and routing schemes that reduce the number of registers and the routing lengths. Use of highly regular structures allows the architecture to easily be implemented in integrated circuits.
Inventor: Jerry Chen
Date issued: 24 October 2006
U.S. Patent No.: 7,127,172
Optical filters allow the transmission (or, equivalently, reflection) of selective frequencies (or colors) of light. In sensors, such filters can help analyze spectral content emitted by light sources ranging from lamps to lasers to stars.
Spectroscopists use filters to figure out what frequencies are absorbed; these absorption lines give clues to a material’s composition. Modern communication links send information in predefined frequency bands. Here optical filters let the information pass through and suppress the noise present in the other frequencies. Unfortunately, it is not always easy to design and fabricate a filter with the proper shape.
This patent presents a method to synthesize such a filter. How does this work? Different frequencies are sent to different places. A prism is one way to effect this "dispersive" process. Another "disperser" is a chirped fiber grating in which different frequencies travel different distances into the fiber. The amount that the light is absorbed (or amplified) depends on its new spatial position. The advantage is this absorption (or amplification) can be applied without much consideration to the underlying color of the light. This absorption does have to be spatially specific. Then the light is collected or undispersed, but the light is now filtered.
Inventors: Robert K. Reich, Bernard B. Kosicki, Jonathan C. Twichell, and Dennis D. Rathman
Date Issued: 15 August 2006
U.S. Patent No.: 7,091,530
Imaging devices such as the ones used in camcorders and digital still cameras can take 30 to 60 pictures per second and have exposure times of milliseconds. The technology described in the patent gives a method for making a sensitive imaging detector [a charge-coupled device (CCD)] that can take pictures with submicrosecond exposure times. The imager will be used to take very fast pictures of explosions or implosions of subcritical events at Los Alamos National Laboratory. The unique feature of this new imager architecture is the ability to quickly capture and store four pictures in a single chip while having good sensitivity. Almost all other imagers capture a single picture that must be read off the chip before another exposure can be taken. Other fast imaging technologies are available that can take single pictures, so multiple cameras could be used to take sequential images. However, having the pictures co-located was very important for the Los Alamos application.
Inventors: Todd H. Rider and Laura Bortolin
Date issued: 15 August 2006
U.S. Patent No.: 7,090,988
The CANARY (Cellular Analysis and Notification of Antigen Risks and Yields) pathogen sensing system uses genetically engineered cells that glow in response to intracellular signaling. Within seconds of exposure to even a few particles of a pathogen they have been designed to detect, the cells emit photons. This patent covers the use of B cells, fibroblast cells, and other cell types for CANARY. This technology is faster and more sensitive than competing approaches such as polymerase chain reaction (PCR), which could take up to an hour, and immunoassays, which take several minutes and may require thousands of particles for detection. CANARY could warn of biological warfare agents, diagnose illnesses on the spot, detect pathogens in agricultural products, or monitor the quality of air and water. (For more detail on the work that produced this patent, see "Rapid Sensors for Biological-Agent Identification"(pdf), Lincoln Laboratory Journal, vol. 17, no. 1, pp. 63–84, 2007).
Fabrication of a High-Precision Blooming Control Structure for an Image Sensor
Inventors: Barry E. Burke and Eugene D. Savoye
Date issued: 11 July 2006
U.S. Patent No.: 7,074,639
Overloading the pixels of an image sensor by a bright source causes an uncontrolled lateral spreading of signal charge known as blooming: a bright point source of light expands to produce a large region of signal, obscuring imagery in the region affected. In conventional image sensors, such excess charge is expelled into the bulk of the chip. High-performance charge-coupled-device (CCD) imagers, however, are illuminated through the back of the chip, so such an arrangement is not an option. Instead, a sink for such charge must be created within the pixel circuitry on the front. Such blooming-control features can add complexity to the process and occupy space that can be at a premium in small pixels. This patent describes a process for implementing blooming control in a CCD. The process occupies less space and requires fewer steps than do competing approaches. The key is creating very narrow regions of precisely defined doping in the silicon; these regions serve as overflow barriers separating the charge collected in the pixel from a charge sink or blooming drain. Doping is accomplished by using ion implantation into the wafer by way of an open region in a photomasking layer or photoresist. First, an implant normal to the wafer surface creates the blooming drain within the opening. Then an implant performed at an angle (typically about 45˚) penetrates the sidewall edge of the masking layer and produces a narrow doped region adjacent to the drain for the overflow barrier.
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