Multi-spectral imaging using longitudinal chromatic aberrations
First Claim
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1. An imaging device for detecting counterfeit bills, the image device comprising:
- an objective lens having symmetry around an optical axis, the objective lens configured to disperse images of a bill in longitudinal chromatic aberrations along the optical axis;
a sensor configured to obtain multiple images of the bill, each image corresponding to a specific wavelength within a predetermined spectrum from ultraviolet to near infrared;
a processor configured to analyze the multiple images to detect features of the bill, wherein the processor is configured to process the multiple images to obtain a three-dimensional image stack comprising a plurality of images respectively corresponding to one of a plurality of different wavelengths in the spectrum, wherein the processor is configured to;
compare one or more regions of each of one or more of the plurality of images in the three-dimensional image stack, to one or more regions of a corresponding image of an original bill selected from a three-dimensional image stack comprising a plurality of images of the original bill respectively corresponding to the one of the plurality of different wavelengths in the spectrum; and
determine whether the bill is counterfeit based at least in part on the comparison.
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Abstract
Systems and methods for imaging a target object are provided. In one example, an imaging device comprises an objective lens having symmetry around an optical axis. The objective lens is configured to disperse images of a target object in longitudinal chromatic aberrations along the optical axis. The imaging device further includes a sensor configured to obtain multiple images of the target object. Each image corresponds to a specific wavelength within a predetermined spectrum.
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Citations
18 Claims
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1. An imaging device for detecting counterfeit bills, the image device comprising:
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an objective lens having symmetry around an optical axis, the objective lens configured to disperse images of a bill in longitudinal chromatic aberrations along the optical axis; a sensor configured to obtain multiple images of the bill, each image corresponding to a specific wavelength within a predetermined spectrum from ultraviolet to near infrared; a processor configured to analyze the multiple images to detect features of the bill, wherein the processor is configured to process the multiple images to obtain a three-dimensional image stack comprising a plurality of images respectively corresponding to one of a plurality of different wavelengths in the spectrum, wherein the processor is configured to; compare one or more regions of each of one or more of the plurality of images in the three-dimensional image stack, to one or more regions of a corresponding image of an original bill selected from a three-dimensional image stack comprising a plurality of images of the original bill respectively corresponding to the one of the plurality of different wavelengths in the spectrum; and determine whether the bill is counterfeit based at least in part on the comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for for detecting counterfeit bills, the method comprising the steps of:
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optically dispersing multiple wavelengths of light reflected from a bill so as to create longitudinal chromatic aberrations on an optical axis, wherein each wavelength of the light corresponds to a point on the optical axis in a range from ultraviolet to near infrared; sensing multiple in-focus images of the bill at the multiple wavelengths; creating a three-dimensional image stack comprising multiple in-focus images corresponding to a plurality of wavelengths in the range; analyzing one or more of the multiple in-focus images to detect chromatic features of the bill; comparing the chromatic features corresponding to one or more regions of each of one or more of the multiple in-focus images in the three-dimensional image stack, to one or more regions of a corresponding in-focus images of an original bill selected from a three-dimensional image stack comprising multiple in-focus images of the original bill respectively corresponding to one of the plurality of wavelengths in the range; and determining whether the bill is counterfeit based at least in part on the comparison. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification