US 6,034,766 AGranted

Optical member inspection apparatus

AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha

InventorsMasayuki Sugiura, Kiyoshi Yamamoto, Taichi Nakanishi

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Abstract

An optical member inspection apparatus is disclosed. A light shielding plate functions to cast a shadow region so that a line sensor receives an image producing a particular defined image data output, generally speaking a dark image representing an absence of light from an illuminator. When an inspection target optical member is inserted in the light path to intersect that shadow region, the line sensor produces the same image data in the event that there is no defect in the optical member. However, a defect in the optical member will enable light from outside that shadow region to be diffused to impinge on the line sensor thereby producing a change in the image data output. Evaluation of the change in the image data output can provide an indication of the degree of defectiveness.

Claims26

Dependent claims

An optical member inspection apparatus for detecting an optical defect of an inspection target optical member, the apparatus comprising:

an imaging lens;
a line sensor arranged at a position conjugate to said inspection target optical member with respect to said imaging lens;
an illuminator for illuminating said inspection target optical member;
a light shielding member interposed between said inspection target optical member and said illuminator, for preventing direct illumination of said line sensor by said illuminator by shielding an optical path of light which would be incident upon said line sensor after direct transmission from said illuminator through said inspection target optical member, so that an optical image obtained by said line sensor is formed from light from said illuminator diffused by said optical defect;
a numerical system which determines a numerical value for said optical image obtained by said line sensor, said numerical value being indicative of said optical defect of said inspection target optical member;
and
a discrimination system which makes a decision whether said numerical value exceeds a predetermined discrimination reference value.

4 more elements

An optical member inspection apparatus for detecting an optical defect of an inspection target optical member, comprising:

an imaging lens;
an image rotator which is arranged on an object side of said imaging lens so as to be freely rotatable around an optical axis of said imaging lens;
a fixing member for fixing said inspection target optical member on said optical axis on a side opposite to said imaging lens via said image rotator;
a line sensor which is arranged on a position conjugate to said inspection target optical member fixed on said fixing member with respect to said imaging lens;
a diffusion plate which is arranged on a side opposite to said image rotator via said inspection target optical member fixed on said fixing member, and diffuses an illumination light toward said inspection target optical member;
a light shielding member which is interposed between said diffusion plate and said inspection target optical member, and shields an optical path of an illumination light which is incident upon said line sensor after transmitting through said inspection target optical member and being incident upon said imaging lens;
a first rotating mechanism for rotating said light shielding member around said optical axis;
a second rotating mechanism for rotating said image rotator so that a shadow of said light shielding member formed by said imaging lens always covers said line sensor, in synchronism with rotation of said light shielding member by said first rotating mechanism;
numerical system which determines a numerical value for an optical image obtained by said line sensor;
and
discrimination system which makes a decision whether said numeral value exceeds a predetermined discrimination reference value.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/035,055Filed 5 Mar 1998
Priority: JP 9-0507605 Mar 1997
Granted: 7 Mar 2000
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01N 21/958
Characterised by the material or shape of the object to be examined: inspecting transparent materials or objects, e.g. windscreens
G01M 11/0242
Testing optical properties: by measuring geometrical properties or aberrations
G01M 11/0278
By measuring geometrical properties or aberrations: detecting defects of the object to be tested, e.g. scratches or dust
G01N 2021/9511
Characterised by the material or shape of the object to be examined: optical elements other than lenses, e.g. mirrors