Massachusetts Institute of Technology

Other

Brian M Tyrrell

Michael W Kelly

Curtis Colonero

Lawrence M Candell

Daniel Allan Mooney

Kenneth I Schultz

Michael Fritze

Robert P Berger

Christy Fernandez Cull

James Wey

Andrew K Bolstad

Robert K Reich

Joseph H Lin

Jonathan P Frechette

Ralph Hamilton Shepard, Iii

Peter J Grossmann

Matthew Stamplis

Kate Thurmer

Conventional methods for imaging transient targets are constrained by a trade-off between resolution and frame rate, and transient targets moving faster than the detector frame typically result in image blurring. Imagers using digital-pixel focal plane arrays ('DFPAs') have on-chip global pixel operation capability for extracting a single transient-feature (i.e., single-frequency discrimination) in a snapshot that depends on the number of counters implemented per pixel. However, these DFPA systems are not capable of multi-target and multi-frequency discrimination. Imagers described herein achieve multi-target transient signature discrimination orders of magnitude faster than the readout frame rate using in-pixel electronic shuttering with a known time-encoded modulation. Three-dimensional (x,y,t) data cube reconstruction is performed using compressive sensing algorithms.

Method and apparatus for on-chip per-pixel pseudo-random time coded exposure

A digital focal plane array includes an all-digital readout integrated circuit in combination with a detector array. The readout circuit includes unit cell electronics, orthogonal transfer structures, and data handling structures. The unit cell electronics include an analog to digital converter. Orthogonal transfer structures enable the orthogonal transfer of data among the unit cells. Data handling structures may be configured to operate the digital focal plane array as a data encryptor/decipherer. Data encrypted and deciphered by the digital focal plane array need not be image data.

Focal plane array processing method and apparatus

An imaging device is often paired with a readout integrated circuit (ROIC), which provides processing and data transfer functionality. The circuitry of a ROIC is typically specialized to meet the requirements of an application, which limits the ROIC to a few modes of operation and restricts compatibility to only certain types of imaging devices and applications. Furthermore, the circuitry supporting the processing functionality is limited due to size constraints on the ROIC. These shortcomings can be overcome with a field programmable imaging array (FPIA), which can be implemented as an integrated circuit combining customized ROIC sensor interface circuitry with field programmable gate array (FPGA) circuitry to enable post-fabrication definition of ROIC operational modes. An FPIA chip may form part of a three-chip stack that also includes an analog sensor interface chip for analog-to-digital conversion and an imaging device.

Methods for enabling in-field selection of near-sensor digital imaging functions

An imaging system uses a dynamically varying coded mask, such as a spatial light modulator (SLM), to time-encode multiple degrees of freedom of a light field in parallel and a detector and processor to decode the encoded information. The encoded information may be decoded at the pixel level (e.g., with independently modulated counters in each pixel), on a read-out integrated circuit coupled to the detector, or on a circuit external to the detector. For example, the SLM, detector, and processor may create modulation sequences representing a system of linear equations where the variables represent a degree of freedom of the light field that is being sensed. If the number of equations and variables form a fully determined or overdetermined system of linear equations, the system of linear equations' solution can be determined through a matrix inverse. Otherwise, a solution can be determined with compressed sensing reconstruction techniques with the constraint that the signal is sparse in the frequency domain.

Methods and systems for time-encoded multiplexed imaging

Digital focal plane arrays (DFPAs) with multiple counters per unit cell can be used to convert analog signals to digital data and to filter the digital data. Exemplary DFPAs include two-dimensional arrays of unit cells, where each unit cell is coupled to a corresponding photodetector in a photodetector array. Each unit cell converts photocurrent from its photodetector to a digital pulse train that is coupled to multiple counters in the unit cell. Each counter in each unit cell can be independently controlled to filter the pulse train by counting up or down and/or by transferring data as desired. For example, a unit cell may perform in-phase/quadrature filtering of homodyne- or heterodyne-detected photocurrent with two counters: a first counter toggled between increment and decrement modes with an in-phase signal and a second counter toggled between increment and decrement modes with a quadrature signal.

Methods and apparatus for counting pulses representing an analog signal

Methods and apparatus for in-pixel filtering in focal plane arrays including apparatus and method for counting pulses representing an analog signal

Methods and apparatus for in-pixel filtering in focal plane arrays

A method forms patterns on a substrate by exposing the substrate a first time and exposing 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 implemented as sub-resolution features formed by pixellation. The gray-tone features may also be realized by the local size bias of trim features on the trim mask that have dimensions near the resolution limit of the exposure system. The trim mask containing gray-tone features may have regions with different transmissivities or generate varying illumination intensities.

Method and system of lithography using masks having gray-tone features

A method forms a feature pattern on a substrate by exposing the substrate, using a mask having a pattern of features thereon, with illumination having a first set of settings. The substrate is exposed a second time, using the same mask having the pattern of features thereon, with illumination having a second set of settings. The mask having the pattern of features thereon remains stationary between the two illumination exposures of the substrate.

Method for photolithography using multiple illuminations and a single fine feature mask

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Brookline, NH, United States of America

Brian M Tyrrell