Coded aperture imaging using successive imaging of a reference object at different positions
First Claim
1. A method of coded aperture imaging (CAI) using CAI apparatus having a coded aperture mask in a fixed relation to a detector array which outputs image data in response to illumination by radiation passing from a scene via the coded aperture mask, the method comprising the steps of:
- successively imaging each of a plurality of reference objects at a plurality of different reference object positions with respect to the CAI apparatus such that radiation from the plurality of reference objects reaches the detector array via different parts of the coded aperture mask, wherein, at each of the plurality of the different reference object positions, the plurality of reference objects are each disposed at different parts of the scene, and each of the plurality of reference objects is imaged using the CAI apparatus to form a reference intensity pattern upon the detector array,obtaining reference image data output from the detector array for each reference object position,using the reference image data to derive a decoding pattern for each different reference object, andmonitoring a scene with the CAI apparatus to produce scene image data output from the detector array and using the decoding patterns to reconstruct an image of the scene from the scene image data.
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Abstract
In coded aperture imaging knowledge of the coded array pattern and its positional relation to the detector array is needed in order to be able to reconstruct the scene image. Usually a theoretical model of the coded array is used and the actual array needs to be aligned accurately with respect to the detector. The present invention uses a coded aperture imager to image a reference object in the scene and uses the intensity pattern on the detector array to determine the decoding pattern corresponding to the coded aperture array. The reference object may be a point source in which case the pattern on the detector array may be used directly as the decoding pattern or it may be used to correct a theoretical pattern for any misalignment.
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Citations
20 Claims
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1. A method of coded aperture imaging (CAI) using CAI apparatus having a coded aperture mask in a fixed relation to a detector array which outputs image data in response to illumination by radiation passing from a scene via the coded aperture mask, the method comprising the steps of:
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successively imaging each of a plurality of reference objects at a plurality of different reference object positions with respect to the CAI apparatus such that radiation from the plurality of reference objects reaches the detector array via different parts of the coded aperture mask, wherein, at each of the plurality of the different reference object positions, the plurality of reference objects are each disposed at different parts of the scene, and each of the plurality of reference objects is imaged using the CAI apparatus to form a reference intensity pattern upon the detector array, obtaining reference image data output from the detector array for each reference object position, using the reference image data to derive a decoding pattern for each different reference object, and monitoring a scene with the CAI apparatus to produce scene image data output from the detector array and using the decoding patterns to reconstruct an image of the scene from the scene image data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of coded aperture imaging (CAI) comprising:
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monitoring a scene using a CAI apparatus having a detector array arranged to receive radiation from the scene through a coded aperture mask such that the radiation produces an intensity pattern on the detector array, and the detector array responds by output of image data, and processing the image data using decoding patterns determined by reference image data, wherein the reference image data is derived by; successively imaging each of a plurality of reference objects at a plurality of different reference object positions with respect to the CAI apparatus such that radiation from the plurality of reference objects reaches the detector array via different parts of the coded aperture mask, wherein, at each of the plurality of the different reference object positions, the plurality of reference objects are each disposed at different parts of the scene, and each of the plurality of reference objects is imaged using the CAI apparatus to form a reference intensity pattern upon the detector array, and obtaining reference image data output from the detector array for each reference object position. - View Dependent Claims (17)
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18. A coded aperture imager comprising:
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a detector array for receiving an intensity pattern of radiation passing from a scene through a coded aperture mask and for output of image data in response, a processor for decoding the image data to produce an image, the processor having a memory storing a decoding pattern derived from a radiation intensity pattern received at the detector array by successively imaging each of a plurality of reference objects at a plurality of different reference object positions with respect to the coded aperture imager such that radiation from the plurality of reference objects reaches the detector array via different parts of the coded aperture mask, wherein, at each of the plurality of the different reference object positions, the plurality of reference objects are each disposed at different parts of the scene, and each of the plurality of reference objects is imaged using the coded aperture imager to form a reference intensity pattern upon the detector array, and obtaining reference image data output from the detector array for each reference object position. - View Dependent Claims (19)
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20. A coded aperture imaging (CAI) apparatus comprising:
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a coded aperture mask, a detector array providing image data output in response to illumination by radiation passing from a scene via the coded aperture mask, a plurality of reference objects for imaging by the CAI apparatus to form a reference intensity pattern upon the detector array and thereby to obtain output of reference image data from the detector array, wherein the reference objects are disposed at different parts of the scene, and a processor for processing the reference image data to derive a decoding pattern using each reference object and for using the decoding patterns to reconstruct an image of a scene from image data output by the detector array in response to illumination by radiation when the CAI apparatus monitors a scene, wherein the CAI apparatus is configured to (1) successively image each of the plurality of reference objects at a plurality of different reference object positions with respect to the CAI apparatus such that radiation from the plurality of reference objects reaches the detector array via different parts of the coded aperture mask, wherein, at each of the plurality of the different reference object positions, the plurality of reference objects are each disposed at different parts of the scene, and each of the plurality of reference objects is imaged using the CAI apparatus to form a reference intensity pattern upon the detector array, and (2) obtain reference image data output from the detector array for each reference object position.
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Specification