Duke University

Xiaobai Sun

David Brady

Prasant Potuluri

Nikos P Pitsianis

Nikos Pitslanis

An optical wavemeter includes a slit, a diffraction grating, a mask, a complementary grating, and a detector. A monochromatic source is incident on the slit. The diffraction grating produces an image of the slit in an image plane at a horizontal position that is wavelength dependent. The mask has a two-dimensional pattern of transmission variations and produces different vertical intensity channels for different spectral channels. The complementary grating produces a stationary image of the slit independent of wavelength. The detector measures vertical variations in intensity of the stationary image, and the mask is created so that the number of measurements made by the detector is less than the number of spectral channels sampled.

Compressive sampling and signal inference

An optical signal is compressively sampled. An optical component with a plurality of transmissive elements and a plurality of opaque elements is created. The location of the plurality of transmissive elements and the plurality of opaque elements is determined by a transmission function. A spectrum of the optical signal is dispersed across the optical component. Signals transmitted by the plurality of transmissive elements are detected in a single time step at each sensor of a plurality of sensors dispersed spatially with respect to the optical component. Each sensor of the plurality of sensors produces a measurement resulting in a number of measurements for the single time step. A number of estimated optical signal values is calculated from the number of measurements and the transmission function. The transmission function is selected so that the number of measurements is less than the number of estimated optical signal values.

An optical signal is compressively sampled using an optical component to encode multiplex measurements. A mapping from the optical signal to a detector array is created using spatial and/or spectral dispersion. Signals transmitted by a plurality of transmissive elements of the optical component are detected at each sensor of a plurality of sensors of the detector array dispersed spatially with respect to the optical component. Each sensor of a plurality of sensors produces a measurement resulting in a number of measurements. A number of estimated optical signal values is calculated from the number of measurements and a transmission function. The transmission function is selected so that the number of measurements is less than the number of estimated optical signal values.

A signal is temporally compressively sampled. A plurality of analog to digital converters are assembled to sample the signal. Each analog to digital converter of the plurality of analog to digital converters is configured to sample the signal at a time step determined by a temporal sampling function. The signal is sampled over a period of time using the plurality of analog to digital converters. Each analog to digital converter of the plurality of analog to digital converters produces a measurement resulting in a number of measurements for the period of time. A number of estimated signal values are calculated from the number of measurements and the temporal sampling function. The temporal sampling function is selected so that the number of measurements is less than the number of estimated signal values.

An optical signal is copressively sampled using an imaging system. The imaging system is created from a plurality of subimaging systems. Each subimaging system comprises a subaperture and a plurality of sensors. The optical signal is collected at each subaperture of the plurality of subimaging systems at a single time step. The optical signal is transformed into a subimage at each subimaging system of plurality of subimaging systems. The subimage includes at least one measurement from a plurality of sensors of each subimaging systems. An image of the optical signal is calculated from the sampling function and each subimage, spatial location, pixel sampling function, and point spread function of each subimaging system of the plurality of subimaging systems. The sampling function is selected so that the number of measurements from a plurality of subimages is less than a number of estimated optical signal values in the image.

A transmission mask or cooled aperture is used in spectroscopy to compressively sample an optical signal. The locations of transmissive and opaque elements of the mask are determined by a transmission function. The optical signal transmitted by the mask is detected at each sensor of a plurality of sensors dispersed spatially with respect to the mask. A number of estimated optical signal values is calculated from sensor measurements and the transmission function. The optical signal is compressed by selecting the transmission function so that the number of measurements is less than the number of estimated optical signal values. A reconstructed optical signal is further calculated using signal inference. An imaging system created from plurality of encoded subimaging systems compressively samples an optical signal. Encoding methods include but are not limited to pixel shift coding, birefringent shift coding, transmission mask coding, micro-optic coding, diffractive coding, interferometric coding, and focal plane coding.

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Durham, NC, United States of America

Xiaobai Sun