Optical member inspecting apparatus and method of inspection thereof

A method for inspecting an optical member, in which light emitted from a light source is diffused by a diffusing means before being made incident on said optical member, light emitted from said optical member being picked-up by an image pick-up means, said diffusing means comprising a central portion and a peripheral portion, a diffusion transmittance of said peripheral portion being higher than that of said central portion, wherein said method comprises:

• (a) a process to input an image including an image of said optical member from said image pick-up means;
• (b) a process to separate said image of said optical member from said input image;
• (c) a process to binarize said image of said optical member using a primary threshold value lower than an average luminance of said image of said optical member;
• (d) a process to binarize said optical member image by using a secondary threshold value higher than said average luminance of said optical member image;
• and
• (e) a process to judge whether or not said optical member is defective by taking first and second binarized signals obtained respectively through said two binarizing processes as defects of different types.

An optical member inspection apparatus, comprising:

• a light source;
• means for diffusing light emitted from said light source, said diffusing means comprising a central portion and a peripheral portion, a diffusion transmittance of said peripheral portion being higher than that of said central portion;
• means for picking-up an image of an optical member to be inspected, said image pick-up means being positioned to receive light emitted from said light source and transmitted through said diffusing means and said optical member, said image pick-up means being adjustable in magnification;
• a reference value storing means in which a value of a reference outline of said optical member and a recommended magnification of said image pick-up means are registered for each type of said optical member;
• means for calculating a reference frame using said reference outline value and said recommended magnification read from said reference value storing means in accordance with a type of said optical member;
• and
• means for displaying said reference frame superimposed on an image of said optical member picked-up by said image pick-up means.

A method for inspecting an optical member, in which light emitted from a light source is diffused by a diffusing means before being made incident on said optical member, light emitted from said optical member being picked-up by an image pick-up means, said diffusing means comprising a central portion and a peripheral portion, a diffusion transmittance of said peripheral portion being higher than that of said central portion, wherein said method comprises:

• (a) a process to input an image including an image of said optical member from said image pick-up means;
• (b) a process to separate said optical member image from said input image;
• (c) a process to calculate a reference frame using a value of a reference outline of said optical member and a recommended magnification of said image pick-up means, said calculated reference frame and said calculated recommended magnification are prestored according to a type of said optical member;
• (d) a process to adjust a magnification of said image pick-up means so that an outline of an image of said optical member, picked-up by said image pick-up means, may coincide with said reference frame;
• and
• (e) a process to judge whether or not said optical member is defective in accordance with an image of said optical member picked-up by said image pick-up means at said adjusted magnification.

A method for inspecting an optical member to be inspected, in which light emitted from a light source is diffused by a diffusing means, before being made incident on said optical member, light emitted from said optical member being picked-up by an image pick-up means, said diffusing means comprising a central portion and a peripheral portion, a diffusion transmittance of said peripheral portion being higher than that of said central portion, wherein said method comprises:

• a first process to input an image including an image of said optical member from said image pick-up means;
• a second process to binarize said input image and execute a preliminary separating operation in which said image of said optical member is roughly separated from said input image according to a luminance distribution of said binarized input image;
• a third process to judge whether or not said preliminary separating operation has been successfully executed in said second process;
• a fourth process to execute a main separating operation in which an image to be inspected is separated from said roughly separated image of said optical member;
• and
• a fifth process to binarize said separated image to be inspected that is separated in said main separating operation, and judge whether or not said optical member is defective,
• wherein said fourth and fifth processes are performed only when it is judged in said third process that said preliminary separating operation has been successfully executed in said second process.

An optical member inspection apparatus, comprising:

• means for picking-up an image of an optical member to be inspected to output said image of said optical member;
• means for binarizing said output image of said optical member to detect a suspected mold defect;
• a first counter counting a number of appearances of said suspected mold defect at a common position on a plurality of optical members molded by a common mold;
• and
• means for deciding that said suspected mold defect appearing at said common position is a real mold defect, when said number of appearances reaches a first predetermined number.

A method for separating an image of a mark, formed on an optical member to be inspected, from an image of said optical member input from an image pick-up means picking-up an image of said optical member, said method comprising:

• a first process to binarize said input image of said optical member to draw a figure corresponding to said mark or a defect of said optical member from said binarized input image;
• a second process to expand a binarized image of a reference mark having no defect;
• a third process to generate a primary image, including a figure corresponding to said mark and a figure corresponding to said defect, said defect being located in a vicinity of said figure corresponding to said mark, by executing an AND operation of said binarized input image and said expanded binarized reference mark per pixel;
• a fourth process to generate said image of said mark by removing all figures of defects not connected to said figure corresponding to said mark from said primary image, in accordance with information regarding said reference mark;
• and
• a fifth process to generate an image excluding said image of said mark, by extracting said image of said mark generated at said fourth process from said binarized input image.

An optical member inspection apparatus for judging whether or not an optical member to be inspected is defective, a mark being formed on said optical member, wherein said optical member inspection apparatus comprises:

• means for picking-up an image of said optical member to output said image of said optical member;
• means for binarizing said image of said optical member and for drawing a figure corresponding to said mark or a defect of said optical member from said binarized input image;
• means for expanding a binarized image of a reference mark having no defect;
• first generating means for generating a primary image including said figure corresponding to said mark and a figure corresponding to said defect, said defect being located in a vicinity of said figure corresponding to said mark, by executing an AND operation of said binarized input image and said expanded binarized reference mark per pixel;
• second generating means for generating said image of said mark by removing all figures of defects not connected to said figure corresponding to said mark from said primary image, in accordance with information regarding said reference mark;
• third generating means for generating an image excluding said image of said mark, by extracting said image of said mark generated by said second generating means from said binarized input image;
• and
• means for judging whether or not said optical member is defective in accordance with at least one of said image of said mark generated by said second generating means and said image excluding said image of said mark that is generated by said third generating means.

An optical member inspection apparatus, comprising:

• a plurality of image inputting means respectively provided for a plurality of types of inspection;
• means for consecutively supplying an optical member to be inspected to respective image input positions of said plurality of image inputting means;
• means for judging that said optical member is defective, when a defect of more than a predetermined value is detected on said optical member in at least one type of inspection amongst said plurality of types of inspection;
• and
• a supply order controlling means for controlling said supplying means in accordance with a frequency of existence of said defect for each of said plurality of types of inspection, said frequency of existence being statistically obtained through an inspecting operation, so as to firstly supply said optical member to one of said image input positions corresponding to a type of inspection in which a frequency of detection of said defect is higher than any other type of inspection amongst said plurality of types of inspection.

An optical member inspection apparatus, comprising:

• means for picking-up an image of an optical member to be inspected to output said image of said optical member;
• means for setting a plurality of areas to be inspected in said image of said optical member, wherein one of said plurality of areas is an outermost area including a boundary line defining a designed effective aperture of said optical member;
• means for setting a criterion for judgement for each of said plurality of areas, said criteria being different from one another, wherein a criterion set for said outermost area is alleviative as compared other said criteria;
• and
• means for judging whether or not each of said plurality of areas is defective in accordance with a corresponding criterion from said criteria set by said criterion setting means.

An optical member inspection apparatus, comprising:

• means for consecutively placing each of a plurality of optical members to be inspected, firstly, at a first position and subsequently at a second position, wherein said each optical member is picked-up at said first position and a predetermined mark is stamped on said optical member at said second position;
• means for picking-up an image of said each optical member at said first position to output said image;
• means for judging whether or not said each optical member is defective according to said image of said optical member output from said image pick-up means;
• and
• means for stamping said predetermined mark on said each optical member at said second position, depending on a judgement of said judging means regarding said optical member,
• wherein said placing means conveys one optical member to be inspected, which has not yet been inspected, to said first position while conveying another optical member to be inspected, which has been already inspected at said first position, to said second position.

A method of inspection and marking, comprising:

• an inspection process to inspect whether or not an optical member to be inspected is at an inspection position;
• and
• a marking process to stamp a mark on said optical member at a marking position different, from said inspection position, according to a result of inspection of said inspection process,
• wherein an optical member to be inspected, which has not yet been inspected, is conveyed to said inspection position while another optical member to be inspected, which has been already inspected at said first position, is being conveyed to said second position.

A method of controlling a luminance of light emitted from a light source used in an inspection apparatus for inspecting an optical member, wherein said light emitted from said light source is transmitted to means for picking-up an image of said optical member through said optical member, an image output from said image pick-up means being image-processed to obtain an image of said optical member, wherein said method comprises the following steps:

• forming a histogram which shows a luminance distribution of said image of said optical member by a number of pixels;
• obtaining a threshold value according to a discriminant analysis method, based on said histogram;
• and
• controlling said luminance of light emitted from said light source in accordance with said threshold value.

An optical member inspection apparatus, comprising:

• means for lighting an optical member to be inspected;
• means for picking-up an image of said optical member lighted by said lighting means to output said image of said optical member;
• means for image-processing said image of said optical member so as to inspect said optical member;
• means for forming a histogram which shows a luminance distribution of said image of said optical member by a number of pixels;
• and
• means for obtaining a threshold value according to a discriminant analysis method, based on said histogram, and for controlling a luminance of light emitted from said lighting means in accordance with said threshold value.