Optics: measuring and testing – Lens or reflective image former testing
Reexamination Certificate
1997-12-19
2001-03-13
Font, Frank G. (Department: 2877)
Optics: measuring and testing
Lens or reflective image former testing
C356S239100, C356S237200
Reexamination Certificate
active
06201600
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention in general relates to inspection systems and more particularly to a system which automatically inspects objects such as lenses to determine various defects.
2. Description of Related Art
In the field of optics manufacture a need exists for determining the presence, as well as severity, of defects in optical components such as lenses for eyeglasses, contact lenses and intraocular lenses (IOL), by way of example.
Widely used current inspection techniques include the individual examination of each component by a human operator using a microscope or other magnifying device for defect and quality control. Although defects may be determined using this process, it is tedious and subject to human error. In addition, various defects may not be discernible to the human eye.
To improve the examination process, some manufacturers utilize machine vision technology whereby the examination procedure is done automatically using digital video cameras for image capture and image processing for defect determination. This process is a significant improvement over the human operator method but is still not capable of properly or sufficiently enhancing the entire range of defect types and products.
The present invention not only can identify a greater range of defects in an optical component than previous techniques but is able to accommodate a greater variety of different product types.
SUMMARY OF THE INVENTION
Apparatus is provided for determining defects in an optically transmissive object having a lens portion, an intraocular lens being an example. At least one camera is provided, along with a light source for directing light at the camera. An object inspection location is disposed between the light source and camera for receiving an object to be tested. At least two, and preferably three masks are used during the inspection of the object. One of the masks is a bright field mask which allows light to be transmitted through the object, another of the masks is a dark field mask which blocks light which would normally pass through the object and the third is a transition mask which is constituted by a fine pattern of alternating light transmitting and light blocking regions. Images of the object under test are obtained with the masks alternatively in place and a signal processor process the images to obtain indications of predetermined defects.
REFERENCES:
patent: 5500732 (1996-03-01), Ebel et al.
patent: 5515159 (1996-05-01), Sites et al.
patent: 5640464 (1997-06-01), Ebel et al.
patent: 5828446 (1998-10-01), Davis
patent: 5847822 (1998-12-01), Sugiura et al.
Nelms Anthony Scott
Roche Bernard A.
Sites Peter Winston
Font Frank G.
Northrop Grumman Corporation
Punnoose Roy M.
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