Method and apparatus for providing enhanced resolution in photodetectors
First Claim
1. A method for increasing resolution in a photodetector array comprising:
- setting all pixels in the photodetector array to a low input impedance level;
measuring a first set of signals from the pixels in a first pass;
setting selected pixels in the photodetector array to a high input impedance level and remaining pixels to a low input impedance level;
measuring a second set of signals from low input impedance pixels in a second pass; and
calculating partial pixel values for pixels in the array using the first set of signals and the second set of signals, the partial pixel values corresponding to light received by a portions of pixels of the array.
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Abstract
A method and apparatus for providing enhanced resolution in photodetector arrays is provided. A suitable photodetector array, such as a charged coupled device (CCD), a focal plane array (FPA), an active pixel sensor (APS), a CMOS imager, or other detector, is provided. In a first pass, pixels of the array are set to low input impedance values, and measurements of each pixel value are taken. In a second pass, selected pixels are set to high input impedance levels and remaining pixels set to low input impedance level, and measurements are taken at the low input impedance pixels. In a third pass, input impedance levels are reversed (i.e., low input impedance level pixels are set to high input impedance levels, and vice versa), and measurements are taken at the low input impedance pixels. A sequence of mathematical calculations are then performed on the measurements taken in the first, second, and third passes to produce half-pixel values for each of the pixels of the array, thereby doubling the resolution of the array without requiring additional circuitry or modification thereto. The invention can be practiced with two-dimensional arrays, and resolutions enhancement factors of up to eight times can be achieved.
8 Citations
26 Claims
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1. A method for increasing resolution in a photodetector array comprising:
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setting all pixels in the photodetector array to a low input impedance level;
measuring a first set of signals from the pixels in a first pass;
setting selected pixels in the photodetector array to a high input impedance level and remaining pixels to a low input impedance level;
measuring a second set of signals from low input impedance pixels in a second pass; and
calculating partial pixel values for pixels in the array using the first set of signals and the second set of signals, the partial pixel values corresponding to light received by a portions of pixels of the array. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for increasing resolution in a two-dimensional photodetector array comprising:
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establishing a horizontal bin area in the array;
measuring pixel intensities in horizontal bin area;
determining a first set of half-pixel values from measurements taken from the horizontal bin area;
establishing a vertical bin area in the array;
measuring pixel intensities in a vertical bin area;
determining a second set of half-pixel values from measurements taken from the vertical bin area; and
calculating partial pixel values for pixels in the array using the first set of half-pixel values and the second set of half-pixel values. - View Dependent Claims (8, 9, 10, 11)
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12. An apparatus for increasing resolution of a photodetector comprising:
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a photodetector;
means for individually controlling input impedance levels of pixels in the photodetector;
means for scanning detector areas within the photodetector; and
means for calculating partial pixel values using outputs from the means for scanning detector areas. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification