Multi-imaging automated inspection methods and systems for wet ophthalmic lenses
First Claim
Patent Images
1. A method of inspecting an ophthalmic lens for defects, comprising;
- providing an ophthalmic lens in a volume of liquid in a cavity of a container;
obtaining a first image of the ophthalmic lens at a first position in the container, the first image comprising a first image of a center of the ophthalmic lens and a first image of a lens edge of the entire ophthalmic lens, the lens edge including an outer peripheral edge of the ophthalmic lens, or an inner edge of the ophthalmic lens, or a distance between the outer peripheral edge and the inner edge of the ophthalmic lens, or combinations thereof;
causing the ophthalmic lens to move from the first position in the container to a second position in the container;
obtaining a second image of the ophthalmic lens at the second position, the second image comprising a second image of the center of the ophthalmic lens and a second image of the lens edge of the entire ophthalmic lens, the lens edge including the outer peripheral edge of the ophthalmic lens, or the inner edge of the ophthalmic lens, or the distance between the outer peripheral edge and the inner edge of the ophthalmic lens, or combinations thereof;
processing the first image and second image with a computer algorithm to locate features in the images;
generating a first lens edge profile from the first image by measuring first image linear radial distances around a perimeter of the first image of the lens, each first image linear radial distance being measured from the first image of the center of the ophthalmic lens to the first image of the lens edge, wherein the lens edge used for the measuring is one of the outer peripheral edge of the ophthalmic lens, or the inner edge of the ophthalmic lens, or both, all of the first image linear radial distances are measured using the same lens edge, and the first image linear radial distances so measured vary around the perimeter of the lens;
generating a second lens edge profile from the second image by measuring second image lens linear radial distances around a perimeter of the second image of the lens, each second image linear radial distance being measured from the second image of the center of the ophthalmic lens to the second image of the lens edge, wherein the lens edge used for the measuring is one of the outer peripheral edge of the ophthalmic lens, or the inner edge of the ophthalmic lens, or both, all of the second image linear radial distances are measured using the same lens edge, the second image linear radial distances are measured using the same lens edge as the first image linear radial distances, and the second image linear radial distances so measured vary around the perimeter of the lens;
determining an amount of rotational, movement of the lens from the first position to the second position by calculating a first and second image lens angular shift between the first lens edge profile and the second lens edge profile;
calculating a first and second image feature angular shift between a corresponding feature located in the first and second images;
distinguishing a feature that has moved with the lens from a feature that has not moved with the lens by comparing the first and second image lens angular shift to the first and second image feature angular shift of the corresponding feature;
classifying the corresponding feature that has the first and second image feature angular shift within about ±
5 degrees of the lens angular shift, and is not a normal lens feature, as a lens defect; and
rejecting the lens if the lens includes a pre-determined number of lens defects.
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Abstract
A method for inspecting lenses, especially wet contact lenses provided in a volume of liquid inside a container is described. A first image of the lens at a first position in the container is obtained, the lens then being moved to a second position within the container where a second image is obtained. A computer algorithm processes the first and second images to compare features that have moved with the lens to those features that have not moved with the lens whereby lenses are rejected if a feature has moved with the lens but is not a normal feature of the lens.
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Citations
25 Claims
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1. A method of inspecting an ophthalmic lens for defects, comprising;
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providing an ophthalmic lens in a volume of liquid in a cavity of a container; obtaining a first image of the ophthalmic lens at a first position in the container, the first image comprising a first image of a center of the ophthalmic lens and a first image of a lens edge of the entire ophthalmic lens, the lens edge including an outer peripheral edge of the ophthalmic lens, or an inner edge of the ophthalmic lens, or a distance between the outer peripheral edge and the inner edge of the ophthalmic lens, or combinations thereof; causing the ophthalmic lens to move from the first position in the container to a second position in the container; obtaining a second image of the ophthalmic lens at the second position, the second image comprising a second image of the center of the ophthalmic lens and a second image of the lens edge of the entire ophthalmic lens, the lens edge including the outer peripheral edge of the ophthalmic lens, or the inner edge of the ophthalmic lens, or the distance between the outer peripheral edge and the inner edge of the ophthalmic lens, or combinations thereof; processing the first image and second image with a computer algorithm to locate features in the images; generating a first lens edge profile from the first image by measuring first image linear radial distances around a perimeter of the first image of the lens, each first image linear radial distance being measured from the first image of the center of the ophthalmic lens to the first image of the lens edge, wherein the lens edge used for the measuring is one of the outer peripheral edge of the ophthalmic lens, or the inner edge of the ophthalmic lens, or both, all of the first image linear radial distances are measured using the same lens edge, and the first image linear radial distances so measured vary around the perimeter of the lens; generating a second lens edge profile from the second image by measuring second image lens linear radial distances around a perimeter of the second image of the lens, each second image linear radial distance being measured from the second image of the center of the ophthalmic lens to the second image of the lens edge, wherein the lens edge used for the measuring is one of the outer peripheral edge of the ophthalmic lens, or the inner edge of the ophthalmic lens, or both, all of the second image linear radial distances are measured using the same lens edge, the second image linear radial distances are measured using the same lens edge as the first image linear radial distances, and the second image linear radial distances so measured vary around the perimeter of the lens; determining an amount of rotational, movement of the lens from the first position to the second position by calculating a first and second image lens angular shift between the first lens edge profile and the second lens edge profile; calculating a first and second image feature angular shift between a corresponding feature located in the first and second images; distinguishing a feature that has moved with the lens from a feature that has not moved with the lens by comparing the first and second image lens angular shift to the first and second image feature angular shift of the corresponding feature; classifying the corresponding feature that has the first and second image feature angular shift within about ±
5 degrees of the lens angular shift, and is not a normal lens feature, as a lens defect; andrejecting the lens if the lens includes a pre-determined number of lens defects. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25)
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21. An automated ophthalmic lens inspection system comprising:
- a camera;
a light source;
a carrier capable of moving an ophthalmic lens in a lens container from a first position in the container to a second position, the camera being arranged to receive light from the light source via the lens carrier; and
a processing unit for receiving first and second lens images taken by the camera, the processing unit having a first processing module for detecting features in the images taken by the camera;
a second processing module for ascertaining movement of the lens by comparing a first lens edge profile generated from the first lens image and a second lens edge profile generated from the second lens image, the first lens edge profile is generated by the processing unit from the first lens image by measuring first image linear radial distances around a perimeter of the lens in the first image, each first image linear radial distance being a measurement from a center of the lens in the first image to a lens edge in the first image, wherein the lens edge used for the measurement is one of an outer peripheral edge of the lens, or an inner edge of the lens, or both, all of the first image linear radial distances are measured using the same lens edge, and the first image linear radial distances so measured vary around the perimeter of the lens, and the second lens edge profile is generated by processing unit from the second lens image by measuring second image linear radial distances around the perimeter of the lens in the second image, each second image linear radial distance being a measurement from the center of the lens in the second image to the lens edge in the second image, wherein the lens edge used for the measurement is one of the outer peripheral edge of the lens, or the inner edge of the lens, or both, all of the second image linear radial distances are measured using the same lens edge, the second image linear radial distances are measured using the same lens edge as the first image linear radial distances, and the second linear radial distances so measured vary around the perimeter of the lens; and
a third processing module for comparing the movement of the features detected by the first processing module to the movement of the lens as ascertained by the second processing module by calculating, at least in part, a first and second image lens angular shift between, the first lens edge profile and the second lens edge profile.
- a camera;
Specification