Abstract:
A compressive imaging system and method for quickly detecting spectrally and spatially localized events (such as explosions or gun discharges) occurring within the field of view. An incident light stream is modulated with a temporal sequence of spatial patterns. The wavelength components in the modulated light stream are spatially separated, e.g., using a diffractive element. An array of photodetectors is used to convert subsets of the wavelength components into respective signals. An image representing the field of view may be reconstructed based on samples from some or all the signals. A selected subset of the signals are monitored to detect event occurrences, e.g., by detecting sudden changes in intensity. When the event is detected, sample data from the selected subset of signals may be analyzed to determine the event location within the field of view. The event location may be highlighted in an image being generated by the imaging system.
Abstract:
A mechanism for reconstructing sub-images based on measurement data acquired by an imaging system including an array of light modulating elements and an array of photodetectors. Each sub-image is reconstructed based on samples from a respective photodetector and a respective set of measurement patterns defined on a respective virtual sub-region on the modulating array. Each virtual sub-region is configured to include at least the light modulating elements that are able to send a non-trivial amount of light to the respective photodetector during a pattern application period. The virtual sub-regions overlap because many light modulating elements are capable of sending light to more than one photodetector. Whenever a measurement pattern of one virtual sub-region overlaps the measurement pattern of a neighboring virtual sub-region, the two measurement patterns agree by design. Thus, the measurement patterns for the collection of virtual sub-regions combine to form a pattern on the whole modulating array.
Abstract:
An imaging system and method that captures compressive sensing (CS) measurements of a received light stream, and also obtains samples of background light level (BGLL). The BGLL samples may be used to compensate the CS measurements for variations in the BGLL. The system includes: a light modulator to spatially modulate the received light stream with spatial patterns, and a lens to concentrate the modulated light stream onto a light detector. The samples of BGLL may be obtained in various ways: (a) injecting calibration patterns among the spatial patterns; (b) measuring complementary light reflected by digital micromirrors onto a secondary output path; (c) separating and measuring a portion of light from the optical input path; (d) low-pass filtering the CS measurements; and (e) employing a light power meter with its own separate input path. Also, the CS measurements may be high-pass filtered to attenuate background light variation.
Abstract:
An imaging system and method that captures compressive sensing (CS) measurements of a received light stream, and also obtains samples of background light level (BGLL). The BGLL samples may be used to compensate the CS measurements for variations in the BGLL. The system includes: a light modulator to spatially modulate the received light stream with spatial patterns, and a lens to concentrate the modulated light stream onto a light detector. The samples of BGLL may be obtained in various ways: (a) injecting calibration patterns among the spatial patterns; (b) measuring complementary light reflected by digital micromirrors onto a secondary output path; (c) separating and measuring a portion of light from the optical input path; (d) low-pass filtering the CS measurements; and (e) employing a light power meter with its own separate input path. Also, the CS measurements may be high-pass filtered to attenuate background light variation.
Abstract:
An imaging system and method that captures compressive sensing (CS) measurements of a received light stream, and also obtains samples of background light level (BGLL). The BGLL samples may be used to compensate the CS measurements for variations in the BGLL. The system includes: a light modulator to spatially modulate the received light stream with spatial patterns, and a lens to concentrate the modulated light stream onto a light detector. The samples of BGLL may be obtained in various ways: (a) injecting calibration patterns among the spatial patterns; (b) measuring complementary light reflected by digital micromirrors onto a secondary output path; (c) separating and measuring a portion of light from the optical input path; (d) low-pass filtering the CS measurements; and (e) employing a light power meter with its own separate input path. Also, the CS measurements may be high-pass filtered to attenuate background light variation.
Abstract:
A method for designing a spectral sensing device. The method includes: (1) performing computational operations on a computer, wherein the computational operations determine the positions of diffracted orders of an optical system model that models at least an array of light modulating elements and a diffraction grating, wherein the diffracted orders correspond to respective spectral components of input light to the optical system model, wherein the positions of the diffracted orders are determined at a target plane of the optical system model; and (2) storing the positions of the diffracted orders in a memory, wherein the positions determine corresponding locations for light detectors in the spectral sensing device. The spectral sensing device may be assembled by modifying an existing single pixel camera, i.e., by adding the diffraction grating and adding the light detectors respectively at said positions of the diffracted orders.
Abstract:
A method for designing a spectral sensing device. The method includes: (1) performing computational operations on a computer, wherein the computational operations determine the positions of diffracted orders of an optical system model that models at least an array of light modulating elements and a diffraction grating, wherein the diffracted orders correspond to respective spectral components of input light to the optical system model, wherein the positions of the diffracted orders are determined at a target plane of the optical system model; and (2) storing the positions of the diffracted orders in a memory, wherein the positions determine corresponding locations for light detectors in the spectral sensing device. The spectral sensing device may be assembled by modifying an existing single pixel camera, i.e., by adding the diffraction grating and adding the light detectors respectively at said positions of the diffracted orders.
Abstract:
An imaging system and method that captures compressive sensing (CS) measurements of a received light stream, and also obtains samples of background light level (BGLL). The BGLL samples may be used to compensate the CS measurements for variations in the BGLL. The system includes: a light modulator to spatially modulate the received light stream with spatial patterns, and a lens to concentrate the modulated light stream onto a light detector. The samples of BGLL may be obtained in various ways: (a) injecting calibration patterns among the spatial patterns; (b) measuring complementary light reflected by digital micromirrors onto a secondary output path; (c) separating and measuring a portion of light from the optical input path; (d) low-pass filtering the CS measurements; and (e) employing a light power meter with its own separate input path. Also, the CS measurements may be high-pass filtered to attenuate background light variation.
Abstract:
A mechanism for reconstructing sub-images based on measurement data acquired by an imaging system including an array of light modulating elements and an array of photodetectors. Each sub-image is reconstructed based on samples from a respective photodetector and a respective set of measurement patterns defined on a respective virtual sub-region on the modulating array. Each virtual sub-region is configured to include at least the light modulating elements that are able to send a non-trivial amount of light to the respective photodetector during a pattern application period. The virtual sub-regions overlap because many light modulating elements are capable of sending light to more than one photodetector. Whenever a measurement pattern of one virtual sub-region overlaps the measurement pattern of a neighboring virtual sub-region, the two measurement patterns agree by design. Thus, the measurement patterns for the collection of virtual sub-regions combine to form a pattern on the whole modulating array.
Abstract:
A compressive imaging system and method for quickly detecting spectrally and spatially localized events (such as explosions or gun discharges) occurring within the field of view. An incident light stream is modulated with a temporal sequence of spatial patterns. The wavelength components in the modulated light stream are spatially separated, e.g., using a diffractive element. An array of photodetectors is used to convert subsets of the wavelength components into respective signals. An image representing the field of view may be reconstructed based on samples from some or all the signals. A selected subset of the signals are monitored to detect event occurrences, e.g., by detecting sudden changes in intensity. When the event is detected, sample data from the selected subset of signals may be analyzed to determine the event location within the field of view. The event location may be highlighted in an image being generated by the imaging system.