Massachusetts Institute of Technology

Other

Kenneth I Schultz

Michael W Kelly

Curtis Colonero

Lawrence M Candell

Brian M Tyrrell

Daniel Allan Mooney

Robert P Berger

James Wey

Amplitude-modulated (AM) signals spanning a spatial wide area can be efficiently detected using a slowly scanning optical system. The system decouples the AM carrier from the AM signal bandwidth (or carrier uncertainty), enabling Nyquist sampling of only the information-bearing AM signal (or the known frequency bandwidth). The system includes a staring sensor with N pixels (e.g., N&#x3e;10) that searches for a sinusoidal frequency of unknown phase and frequency, perhaps constrained to a particular band by a priori information about the signal. Counters in the sensor pixels mix the detected signals with local oscillators to down-convert the signal of interest, e.g., to a baseband frequency. The counters store the down-converted signal for read out at a rate lower than the Nyquist rate of AM signal. The counts can be shifted among pixels synchronously with the optical line-of-sight for scanning operation.

Wide-area sensing of amplitude modulated signals

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

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 system for optically imaging a specimen is provided, which system amplitude modulates an optical signal with a longer wavelength signal, and in particular a signal having a wavelength which is much longer than any dispersive phase shift in the sample. The modulated optical signal is passed through the specimen. Scattered radiation in the optical output from the sample is filtered out and the resulting optical signal is detected and processed to obtain amplitude/absorption and phase/dispersion information, which information may be used in imaging. Optical signals at different frequencies may be passed through the same sample of the specimen to obtain additional information.

Optical imaging for specimens having dispersive properties

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Somerville, MA, United States of America

Kenneth I Schultz