Contact lens defect analysis and tracking system and method

Abstract

A manual inspection system and method for inspecting contact lenses for defects, comprising: an image acquisition system having at least two high-resolution cameras; a top-illuminated light head for acquiring bright-field images; a back-lit illumination module for acquiring dark-field images; at least one other back-lit illumination module for acquiring different types of bright-field images; an interchangeable mechanism for changing the measuring tool suitable for a specific product; a rotating wheel embedded with multiple optical filters to meet different imaging requirements; a first camera; a second camera; a glass template or measuring tool; a flexible template measuring tool, as an optional overlay; an XYZ stage for positioning the contact lens; creating a database on a computer that tabulates geometric information and detailed defect information and their respective location information; and subsequently analyzing the database images to derive corrective actions for the manufacturing process to improve the quality and yield of contact lenses.

Description

Technical Field

[0001] The present invention relates to systems and methods for identifying defects in contact lenses from magnified images and subsequently storing specific defect areas in images of contact lenses sorted by manufacturing lot number for traceability and analytical purposes. More particularly, the present invention relates to a system for classifying and tabulating defect types in contact lens images, such as scratches, bubbles, and other manufacturing defects and variations related to the geometric properties of the contact lenses, thereby enabling process monitoring to improve manufacturing quality. Background Art

[0002] The present invention relates to inspection systems and methods for quality assurance during manual inspection processes. More specifically, the present invention relates to systems and methods for inspecting contact lenses that require detailed inspection of suspect contact lenses by placing them in a contact lens holder and enabling a human operator to further select defective areas of interest for further analysis. In automated inspection systems, defective lenses are typically physically separated and placed in trays or other forms of transport. Rejected contact lenses may have minor or major defects requiring analysis. The analysis results are shared with manufacturing process operators, who can use the data to fine-tune or adjust the automated inspection system's inspection parameters to improve inspection quality. Manufacturers often employ manual inspection using magnified projection systems, commonly known as optical inspection projectors, to enable operators to identify defects that automated systems may not be able to identify. Current manual inspection systems use brightfield illumination, without the option for darkfield illumination. While this method is cumbersome and time-consuming, the magnified images inspected by humans can detect and classify certain types of defects much better than automated systems, particularly when lenses need to be flipped to inspect very small defects. Furthermore, automated systems identify defects and typically store an entire image of the lens, not just the area of ​​interest. If a facility exists to store images of defects, the resolution of the area of ​​interest is typically the same as the entire contact lens image. Performing a detailed sample inspection of a number of contact lenses is an important aspect of any inspection system, as certain defects may require further analysis through the use of different calibration reference templates. Certain types of defects may require different types of reference templates to aid in specific measurements, such as angle and distance from the center of the lens. Different templates introduced at locations in the image with very small aberrations facilitate accurate and reliable inspection. Apparatus and methods that address this need in the industry are the basis of the present invention.

[0003] It is generally accepted that manual inspection is required, especially when certain defects are not correctly classified or cannot be detected even with the improved algorithms in the automated inspection system. The manual inspection system will help programmers classify or reclassify defects into their respective areas to continuously improve and achieve the best level of inspection quality in their automated systems.

[0004] The system and method can magnify a contact lens and project the image onto a large screen appropriately integrated with two high-resolution cameras, one for displaying the image on a computer and the other mounted on a rotating arm to enable manual positioning of the camera at an area of ​​interest in the magnified image, so that full or partial images can be captured using darkfield and brightfield illumination, and stored in different categories for further analysis. The analyzed data can then be used to identify process or any other problems in manufacturing and take corrective measures to address these problems, which is the purpose of the present invention. Summary of the Invention

[0005] Contact lenses, hereinafter also referred to as CLs, are devices used to fit on the eye to help correct vision-related problems associated with myopia, hyperopia, and other focus-related problems within the eye.

[0006] During the manufacturing process, contact lenses can develop a number of defects, which may be related to the type of polymer used, thermal effects to which the polymer may be subjected, separation of the contact lens from the injection mold, printing on the cosmetic lens, and so on. Automated inspection systems integrated into the manufacturing process are typically programmed to remove any identified defective lenses, which are then placed in separate trays. Selected inspected lenses deemed good are then analyzed offline by a technician or experienced operator, who then manually tabulates their inspection results and reports them to the process engineer. Any defects identified will help the process engineer subsequently adjust the process parameters in the automated inspection system, thereby further optimizing and improving the quality of the inspected lenses.

[0007] During the analysis process, it's common for operators manually inspecting lenses to make mistakes, especially when using optical comparators to identify the area, location, and type of defects, leading to incorrect conclusions. Due to the nature of optical comparators, identifying defects using current methods is cumbersome and inconvenient. Whether it's size, color, location, or type, accurate representation of the defect is extremely important, especially if the data is to be used to calibrate the manufacturing process. Any errors in the data can lead to numerous iterations in the calibration process, which can be time-consuming and error-prone.

[0008] A manual inspection system and method for inspecting contact lenses for defects, comprising: an image acquisition system having at least two high-resolution cameras; a top-illuminated optical head for acquiring bright-field images; a back-lit illumination module for acquiring dark-field images; at least one other back-lit illumination module for acquiring different types of bright-field images; an interchangeable mechanism for changing the measuring tool suitable for a particular product; a rotating wheel embedded with multiple optical filters to meet different imaging requirements; a first camera for capturing a full view of the contact lens at a beam splitter; and a second camera suitably mounted on a rotating arm to capture a portion of the contact lens viewed on a projection screen. a glass template or measuring fixture mounted in a suitable position to enable superimposed images of the lens and fixture on a projection screen for measurement; a flexible template measuring fixture, as an optional superimposition, in place of the glass template, suitably mounted on the projection screen for easy measurement of defects and geometry of contact lenses; an XYZ stage for positioning contact lenses; creation of a database on a computer that tabulates geometric information and detailed defect information along with their respective location information; and subsequent analysis of the database images to derive corrective actions to the manufacturing process to improve the quality and yield of contact lenses.

[0009] According to the present invention, a contact lens defect analysis system and method are provided, comprising: a lens image acquisition block including a high-resolution camera; a front lens group arranged to capture an image of a curved lens through a beam splitter; and at least two sets of illumination modules designed to use LEDs in the visible light spectrum to illuminate the lens under inspection, a first set of illumination modules being a top light head module, referred to herein as a top light head, and at least a second set of illumination modules being referred to herein as a back light head, comprising at least three illumination modules, referred to herein as appropriately arranged darkfield light heads. The darkfield light head illuminates the bottom of the lens to produce a darkfield image of the lens, and the second illumination module, a brightfield light head, illuminates the lens to produce a brightfield image of the lens. The contact lens defect analysis inspection system uses the back lens group to project a magnified image of the contact lens, superimposed with an image of a calibrated measuring instrument, onto a large screen, allowing a human operator to clearly view the defect. The large screen is an important element of the device that helps minimize strain on the operator's eyes. After viewing the image on the large screen and then deciding to capture an image, the operator presses a key on the computer to capture the selected image using the first camera. A beam splitter divides the optical path into two to produce two aberration-free images, one of which is captured by the first camera. The other aberration-free image (the main path) continues to propagate through the rear lens group to ultimately create a magnified image on the large screen and is then captured by the second camera. If the operator then decides that the defect viewed on the large screen needs to be further classified, the provided second camera is used to capture an image of a specific area around the defect. As a result, at the end of the process, the classification of the defect is more accurate, detailed, and rich in information, with batch traceability, batch code, and manufacturing date, as well as many other parameters such as machine number, operator code, etc.

[0010] An object of the present invention is to provide an apparatus and method that uses rear projection instead of current front projection images to easily view images, thereby visually detecting defects on a magnified image of a contact lens projected on a viewing screen with an image of a measuring instrument superimposed thereon, and accurately measuring the size, location, and type of the defects. Unlike rear projection, images viewed in front projection systems hinder close viewing by an operator due to lighting obstacles.

[0011] Another object of the present invention is to provide a device and method for creating a database of images of defects (using an image acquisition system appropriately integrated with a first camera and a second camera), wherein the image of the entire contact lens is captured by the first camera and the specific area of ​​the defect is captured by the second camera. Aberration-free images of the contact lens are captured at an intermediate stage using a beam splitter. Another object of the present invention is to provide a device and method for manually inspecting a contact lens that is appropriately positioned on a cuvette using at least one darkfield illumination module and at least one brightfield illumination module.

[0012] One object of the present invention is to provide a device and a method for manually inspecting contact lenses using a second camera to capture specific areas of an image projected on a screen, which allows for a more detailed classification of defects. A further object of the present invention is to provide a device incorporating a transparent overlay serving as a measuring device that can be interchanged for different product types to enable measurement of geometrical properties of contact lenses.

[0013] Another object of the present invention is to provide an apparatus that incorporates a large viewing screen to enable a human operator to obtain a focused image of a contact lens using the XY and Z stages. A focused image is essential for accurate measurement. Another object of the present invention is to provide a large viewing screen that is appropriately positioned behind the second lens group for easy viewing.

[0014] Other features and objects of the present invention will become apparent from the detailed description of preferred embodiments included hereinafter and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] It will be convenient to further describe the invention with reference to the accompanying drawings which illustrate arrangements of the invention. Those skilled in the art will appreciate that other arrangements of the invention are possible and therefore the particularity of the accompanying drawings should not be understood as superseding the generality of the foregoing description of the invention.

[0016] Figure 1 is a diagrammatic representation of an optical illumination and imaging system according to the present invention.

[0017] Figure 2 A typical sampling of measuring instruments is shown.

[0018] Figure 3 Shown is an image of a contact lens illuminated with a bright field illumination module.

[0019] Figure 4 An image of a contact lens with an image of a measuring instrument superimposed is shown.

[0020] Figure 5 A sampling of different models of measuring instruments is shown. DETAILED DESCRIPTION

[0021] Although the present invention is applicable to various types of optical transmissive components, it will be described taking a contact lens as an example.

[0022] Reference Figure 1 According to an embodiment of the construction of the present invention, a system is shown that helps analyze and identify defects, aberrations, contamination, deformation and geometric characteristics, the system including at least one image acquisition module, a simulated observation screen, an optical module, multiple lighting modules including top lighting, bottom lighting (bright field) and another bottom lighting (dark field), a pair of measuring instruments made of glass or transparent film, and at least another image acquisition module mounted on a flexible rotating frame.

[0023] The image acquisition module includes two high-resolution cameras 15 and 20 connected to a computer 10 for image capture and storage. Camera 20 is positioned in a fixed position, while camera 15 is mounted on a rotating gantry (not shown) that moves in different directions 25 to enable an operator to capture a specific area of ​​interest of the image of lens 35 shown on screen 60. Camera 20 is positioned to capture an intermediate image of lens 35 through beam splitter 50. A rotating wheel 33 with a plurality of filters arranged around the rotating wheel is mounted on a rotating mechanism 34 to enable an operator to use different filters to observe different types of defects without changing any optical settings or configurations.

[0024] A pair of optical modules 40 and 55 are used to focus the image of lens 35 positioned on cuvette 30 .

[0025] A pair of illumination modules 38, 39 can capture back-contrast images useful for defect analysis and classification purposes ( Figure 3 ), and the top bright field lighting module 42 enables precise printing and color inspection of cosmetic lenses.

[0026] A rotating wheel 33 is mounted on 34. The rotation mechanism can be a manual or motorized system for rotating the plurality of filters 31 and 32 in unison with the optical axis 58. It is important to note that, depending on the application, more filters can be implemented in the rotating wheel 33, or replaced with another wheel having a different set of filters. For illustrative purposes, only two filters 31 and 32 are shown.

[0027] Interchangeable measuring fixtures are also commonly referred to as measurement templates or fixtures 45. Fixtures 45 are placed at the intermediate image plane to produce a superimposed image on the image of lens 35, projected onto screen 60, and to capture the intermediate image using camera 20, which does not have an optical lens. Fixtures 45 can be interchanged to suit measurement requirements. Figure 1 Position 57 in the diagram indicates the viewing direction of the quality control operator, while Figure 4 An example of an overlay image that an operator can view on screen 60 is shown. 62 is another flexible template that can be mounted to measure other defects in the image. Template 62 can be a commercially available flexible film or a calibrated glass plate.

[0028] The diffuser 48 is positioned so that it can be rotated in and out to diffuse the brightfield and darkfield illumination of the contact lens 35 .

[0029] Figure 2 express Figure 1 Typical measuring instruments in 45.

[0030] Reference Figure 3 , image 70 is a simulated image of contact lens 35 with bright field illumination module 37 turned on. Defects 73 and 74 represent tears in contact lens 35. Box 75 is a magnified view of defect 73. Image 70 may also be captured by camera 20 through beam splitter 50 for storage in central server or computer 10.

[0031] Figure 4 Is displayed in Figure 1 60 is an illustration of an overlaid image of the contact lens 35 and an image of the pattern of the measuring device 45. It is important to note that Figure 4 The image shown does not include the measuring device 62. Figure 1 The screen 60 shows Figure 4 The defects 73 and 74 in the image may be further captured using the camera 15 at different zoom levels to be stored on the central server or computer 10 for further analysis or classification.

[0032] Figure 4 The image 70 of the contact lens 35 located on the cuvette 30 with the bright field illumination modules 37 to 39 switched on is Figure 1 The superimposed image is composed of the images of the measuring instrument 45 in the image.

[0033] Figure 4 The superimposed image 70 in FIG. 5 is a superimposed image of the lens 35 and the measuring glass or film 45 , which enables the operator to measure positional information such as the size, color, X and Y position of the defects 73 and 74 , as well as geometric information such as the diameter of the contact lens 35 .

[0034] The measuring instrument 45 is one of the typical forms of commercially available instruments. Depending on the type of measurement required, several other types of commercially available instruments may be used, such as Figure 5 The appliance shown.

[0035] Figure 5 Another model of a measuring instrument 90 is shown, which can be used Figure 1The apparatus 45 in the embodiment can be replaced to measure many other detailed defects for analysis and subsequent correction of the manufacturing process.

[0036] refer to Figure 1 Measuring instrument 45 is a high-precision instrument capable of highly accurate defect measurement compared to measuring instrument 62. Measuring instrument 62, placed near transparent projection screen 60, is capable of roughly measuring defects in contact lens 35. Depending on the inspection requirements, the operator can choose to use either instrument 45 or instrument 62. This arrangement enables the device to be scalable for use with a variety of products beyond contact lenses. Any transparent object requiring inspection, such as glass lenses, plastic lenses, and calibration instruments, can be inspected efficiently and accurately.

[0037] The database of defect images and their associated full-resolution images enables operators to study, analyze, and classify defects according to their type. These results can also be used to set or fine-tune inspection parameters on automated machines to minimize misses and overkill, and subsequently achieve optimal quality control levels.

[0038] Although the present invention has been described with reference to various embodiments thereof, those skilled in the art will be able to modify the described embodiments without departing from the true spirit and scope of the invention. For example, the lighting module may be replaced with UV-type lighting, infrared LED lighting, or laser lighting, which may enhance certain types of defects better than common visible LED lighting.

Claims

1. A system for defect analysis and tracking of clean cosmetic contact lenses using rear projection, the system comprising: a glass cuvette curved to hold a contact lens; a pair of lighting modules oriented toward the glass cuvette for back and front lighting; a diffuser mounted on a horizontal rotating arm to assist in diffuse backlighting when needed; a rotating wheel mounted with at least two different optical filters arranged to observe different types of defects; a first optical module focused at the contact lens; a beam splitter that splits the light beam to produce two aberration-free images of the contact lens; a first camera connected to the computer and configured to capture one of the two aberration-free images at a first stage, and a second camera configured to capture an image from a viewing screen at a second stage; A second optical module is installed behind a calibration fixture for measuring various dimensions and defects of an inspected object and is used to project an overlay image onto the viewing screen, the overlay image being a superimposed image of the contact lens and the calibration fixture.

2. The system of claim 1 further comprising a tool holder featuring an interchangeable mechanism to accommodate various calibration tools for inspecting and measuring different types of contact lenses.

3. The system according to claim 1, wherein: The second camera is mounted on a rotating arm to manually position the second camera in front of the viewing screen to capture a magnified image of a specific feature on the contact lens.

4. A method for defect analysis and tracking of clean cosmetic contact lenses using rear projection, the method comprising the steps of: capturing images of the contact lens being inspected using backlighting and frontlighting; Dynamically pulsing the illumination module at different time domains to enhance defects and patterns including batch information; processing images captured from the first camera device to identify key features and tagging the key features to the batch information for tracking purposes; determining the key features and creating a database by mapping the defects to the batch information; triggering a second camera to capture a magnified image of a critical defect identified when processing the image from the first camera by manually positioning the second camera close to the identified defect on the viewing screen; Merging and labeling the magnified images to a designated batch, and enhancing the effectiveness of the database with a list of critical defects and magnified areas of the critical defects; The tabulated results and the database are transmitted to an external interface or printed for use by a quality assurance team to adjust the manufacturing process.

5. The method according to claim 4, wherein The measurement of the key feature or the defect includes changing a measuring tool used to measure various sizes and defects of the inspected object to adapt to the defect type.

6. The method according to claim 4, wherein: The measuring of the critical feature or the defect includes capturing images of the defect at a plurality of magnification settings for a particular defect type.

7. The method according to claim 4, wherein: The measuring of the critical features or the defects comprises enhancing features on the contact lens using different optical filters mounted on a rotating wheel.

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