Method and apparatus for calibration of indirect measurement systems
First Claim
1. An indirect measurement system for determining an estimated value of a parameter of interest of an object, comprising:
- a sensor that produces a raw measurement that is indirectly representative of said parameter of interest of said object;
a correction function that corrects said raw measurement to a corrected measurement to minimize measurement differences between said indirect measurement system and a reference indirect measurement system;
a reference map function that estimates said estimated value of said parameter of interest of said object based on said corrected measurement; and
a correction function fitting procedure that fits said correction function based on reference values for one or more calibration samples measured on or simulated for said reference indirect measurement system and corresponding values measured on said indirect measurement system.
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Abstract
A calibration technique is presented for calibrating one or more non-reference indirect measurement systems with respect to a reference indirect measurement system. A reference map function fitting procedure fits a reference map function based on known values of a parameter of interest associated with each of one or more reference calibration samples and corresponding reference values associated with the one or more reference calibration samples measured on or simulated for the reference indirect measurement system. A correction function fitting procedure fits a correction function based on reference values for one or more calibration samples measured on or simulated for the reference indirect measurement system and corresponding values measured on the non-reference indirect measurement system. During normal use, the non-reference indirect measurement system obtains measurements that are indirectly representative of a parameter of interest of an object, corrects the raw measurements using the correction function to corresponding corrected measurements in order to minimize measurement differences between the indirect measurement system and the reference indirect measurement system, and estimates the parameter of interest of the object using the reference map function based on the corrected measurement. Reference map function fitting is typically performed only once, while correction function fitting is updated periodically and independently of the reference map function fitting to account for drift due to systemic, environmental, or other variations.
9 Citations
43 Claims
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1. An indirect measurement system for determining an estimated value of a parameter of interest of an object, comprising:
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a sensor that produces a raw measurement that is indirectly representative of said parameter of interest of said object;
a correction function that corrects said raw measurement to a corrected measurement to minimize measurement differences between said indirect measurement system and a reference indirect measurement system;
a reference map function that estimates said estimated value of said parameter of interest of said object based on said corrected measurement; and
a correction function fitting procedure that fits said correction function based on reference values for one or more calibration samples measured on or simulated for said reference indirect measurement system and corresponding values measured on said indirect measurement system. - View Dependent Claims (2, 3, 4)
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5. A system for calibrating a first indirect measurement system with respect to a second indirect measurement system, said first indirect measurement system comprising a sensor that produces a raw measurement that is indirectly representative of a parameter of interest of an object sensed by said sensor, a correction function that corrects said raw measurement to a corrected measurement to minimize measurement differences between said first indirect measurement system and said second indirect measurement system, and a reference map function that estimates an estimated value of said parameter of interest of said object based on said corrected measurement, said system comprising:
a correction function fitting procedure that fits said correction function based on reference values for one or more calibration samples measured on or simulated for said second indirect measurement system and corresponding values measured on said first indirect measurement system. - View Dependent Claims (6, 7, 8)
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9. A method for calibrating a first indirect measurement system with respect to a second indirect measurement system, said first indirect measurement system comprising a sensor that produces a raw measurement that is indirectly representative of a parameter of interest of an object sensed by said sensor, a correction function that corrects said raw measurement to a corrected measurement to minimize measurement differences between said first indirect measurement system and said second indirect measurement system, and a reference map function that estimates an estimated value of said parameter of interest of said object based on said corrected measurement, said method comprising the steps of:
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obtaining measurement values of one or more calibration samples measured on said first indirect measurement system; and
fitting said correction function based on said obtained measurement values of said one or more calibration samples and corresponding known reference values measured on or simulated for said second indirect measurement system. - View Dependent Claims (10, 11, 12, 13)
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14. A computer readable storage medium tangibly embodying program instructions implementing a method for calibrating a first indirect measurement system with respect to a second indirect measurement system, said first indirect measurement system comprising a sensor that produces a raw measurement that is indirectly representative of a parameter of interest of an object sensed by said sensor, a correction function that corrects said raw measurement to a corrected measurement to minimize measurement differences between said first indirect measurement system and said second indirect measurement system, and a reference map function that estimates an estimated value of said parameter of interest of said object based on said corrected measurement, the method comprising the steps of:
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obtaining measurement values of one or more calibration samples measured on said first indirect measurement system; and
fitting said correction function based on said obtained measurement values of said one or more calibration samples and corresponding known reference values measured on or simulated for said second indirect measurement system. - View Dependent Claims (15, 16, 17, 18)
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19. An automated inspection system, comprising:
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an imaging system utilizing a source of penetrating radiation and one or more sensors to detect said penetrating radiation reflected by, scattered by, transmitted through, or emitted from an object and to generate an image of said object from which is derived one or more features of said object that are representative of a parameter of interest of said object;
a correction function that corrects said one or more features derived from said image of said object to one or more corresponding corrected features to minimize differences between said automated inspection system and a reference automated inspection system; and
a reference map function that estimates an estimated value of said parameter of interest of said object based on said one or more corresponding corrected features; and
a correction function fitting procedure that fits said correction function based on one or more features derived from one or more images of one or more calibration samples imaged on said automated inspection system and corresponding reference features derived from one or more reference images imaged on said reference automated inspection system. - View Dependent Claims (20, 21, 22, 23)
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24. A system for calibrating a first automated inspection system with respect to a second automated inspection system, said first automated inspection system comprising an imaging system utilizing a source of penetrating radiation and one or more sensors to detect said penetrating radiation reflected by, scattered by, transmitted through, or emitted from an object and to generate an image of said object from which is derived one or more features of said object that are representative of a parameter of interest of said object, a correction function that corrects said one or more features derived from said image of said object to one or more corresponding corrected features to minimize differences between said first automated inspection system and said second automated inspection system, and a reference map function that estimates an estimated value of said parameter of interest of said object based on said one or more corresponding corrected features, said system comprising:
a correction function fitting procedure that fits said correction function based on one or more features derived from one or more images of one or more calibration samples imaged on said first automated inspection system and corresponding reference features derived from one or more reference images imaged on said second automated inspection system. - View Dependent Claims (25, 26, 27, 28, 29)
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30. A method for calibrating a first automated inspection system with respect to a second automated inspection system, said first automated inspection system comprising an imaging system utilizing a source of penetrating radiation and one or more sensors to detect said penetrating radiation reflected by, scattered by, transmitted through, or emitted from an object and to generate an image of said object from which is derived one or more features of said object that are representative of a parameter of interest of said object, a correction function that corrects said one or more features derived from said image of said object to one or more corresponding corrected features to minimize differences between said first automated inspection system and said second automated inspection system, and a reference map function that estimates an estimated value of said parameter of interest of said object based on said one or more corresponding corrected features, said method comprising:
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obtaining one or more features derived from one or more images of one or more calibration samples imaged on said first automated inspection system; and
fitting said correction function based on said one or more features derived from said one or more images of said one or more calibration samples and corresponding reference features derived from one or more reference images imaged on said second automated inspection system. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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37. A computer readable storage medium tangibly embodying program instructions implementing a method for calibrating a first automated inspection system with respect to a second automated inspection system, said first automated inspection system comprising an imaging system utilizing a source of penetrating radiation and one or more sensors to detect said penetrating radiation reflected by, scattered by, transmitted through, or emitted from an object and to generate an image of said object from which is derived one or more features of said object that are representative of a parameter of interest of said object, a correction function that corrects said one or more features derived from said image of said object to one or more corresponding corrected features to minimize differences between said first automated inspection system and said second automated inspection system, and a reference map function that estimates an estimated value of said parameter of interest of said object based on said one or more corresponding corrected features, the method comprising the steps of:
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obtaining one or more features derived from one or more images of one or more calibration samples imaged on said first automated inspection system; and
fitting said correction function based on said one or more features derived from said one or more images of said one or more calibration samples and corresponding reference features derived from one or more reference images imaged on said second automated inspection system. - View Dependent Claims (38, 39, 40, 41, 42, 43)
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Specification