Adaptive pattern recognition
First Claim
1. An optical inspection system for analyzing the object content of a field of view comprising:
- an optical system adapted to produce either from the said object content or an image thereof, a diffraction pattern;
a light level detection means on which the diffraction pattern is focussed for producing electrical signals corresponding to the light intensity at different points within the pattern;
electrical circuit means response to said electrical signals comprising means for storing a plurality of different reference signal patterns and comparison means for comparing the electrical signals from the light level detection means produced from a subsequent field of view with each of the stored reference signal patterns to facilitate the identification of the subsequent signal pattern.
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Accused Products
Abstract
A pattern recognition system which produces from any object a diffraction pattern-typically an optical Fourier transform of the object, on a high resolution detector. Different points in the detector can be addressed by a scanning device to produce an electrical signal which can be digitized if required before being processed and compared with reference signals in a processor. A reduction in the formation to be scanned and pattern matched is obtained by using an optical Fourier transform or the like of the original object. A further reduction in the information needed to classify each of a known group of objects is obtained by a method which involves the presentation of each of the group members to the apparatus, the computation from each scanning of a discriminant function by multivariate analysis of the signal produced by the scanning and the use of the discriminant function to determine the points in the scanning of subsequent unknown members of the group which are required (and the weighting to be attributed to the signal at each such point) to allow for the reliable classification of each such unknown member of the group.
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Citations
20 Claims
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1. An optical inspection system for analyzing the object content of a field of view comprising:
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an optical system adapted to produce either from the said object content or an image thereof, a diffraction pattern; a light level detection means on which the diffraction pattern is focussed for producing electrical signals corresponding to the light intensity at different points within the pattern; electrical circuit means response to said electrical signals comprising means for storing a plurality of different reference signal patterns and comparison means for comparing the electrical signals from the light level detection means produced from a subsequent field of view with each of the stored reference signal patterns to facilitate the identification of the subsequent signal pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of identifying the object content of a field of view comprising the steps of:
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i. producing a diffraction pattern of the said object; ii. imaging the diffraction pattern onto a detector adapted to generate a first electrical signal one parameter of which varies independence on the light level at different points in the diffraction pattern image, and iii. comparing the said first electrical signal with one or more stored signals, the output of the comparison determining the identity of the said object content. - View Dependent Claims (14, 15)
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16. A method of selecting regions of a detector in an optical inspection system in which a diffraction pattern of object content to be inspected is focussed on to the detector and in which an electrical signal is generated having a parameter which varies in dependence on the light level at selected points in the said diffraction pattern, comprising the steps of:
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i. presenting to the inspection system one of a plurality of objects from a group; ii. producing a diffraction pattern of the object content in the field of view as each object is presented to the system; iii. imaging the diffraction pattern onto a detector having a plurality of different light sensitive regions and generating from a scanning of the said regions a first electrical signal for each different diffraction pattern; iv. supplying the said first electrical signals to computing means programmed to produce from such electrical signals a discriminant function, the discriminant function determining the positions within the image area of the said detector, of selected ones of a plurality of regions therein, from which the said first signal is to be generated during subsequent inspection scans, and v. limiting the electrical signals from the said detector means during inspection scans to electrical signals arising from the said selected regions in the detector to thereby reduce the amount of information which must be processed during the inspection scans to permit identification of the objects of the said group when presented to the inspection system. - View Dependent Claims (17, 18, 19)
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20. In an optical inspection system comprising optical means for forming a diffraction pattern of the object content of the field of view of the system, light level detection means on which the diffraction pattern is focussed for producing electrical signals corresponding to light intensity at different points within the diffraction pattern, electrical circuit means responsive to the said electrical signals for comparing selected signals with a reference pattern, the outcome of each such comparison determining the identity of the object content of the field of view, an improved method of operation for reducing the time to identify objects of a given class, comprising the steps of:
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i. presenting to the system examples from the said group of objects so that each said object occupies the said field of view in turn, ii. forming a diffraction pattern of the object content of each said field of view and at least temporarily storing the first electrical signal obtained from the detector for each said field of view, iii. computing from the stored signals a discriminant function for the group and determining therefrom the positions of selected windows in the diffraction pattern image from which information must be derived to permit identification of the different objects within the group, iv. storing the discriminant function or signals which will allow for identification or creation of said selected windows, and v. utilising the stored function or signals to limit the information presented to the said electrical circuit means during subsequent inspections, to the electrical signals derived from the said selected windows in the diffraction pattern.
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Specification