Method and apparatus for detecting defects using focus compensation
OwnerLewis Damer, James Kopchinskiinventors
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Abstract
A method and apparatus for detecting a defect in an article that causes deflection of a beam when the beam strikes the defect. A beam used for detecting defects may be directed across at least a portion of the article. The distance traveled by the beam changes as the beam is directed across the article. The beam is focused correspondingly with the changing distance traveled by the beam.
Claims20
A method useful for detecting a defect in an article that causes deflection of a. beam when the beam strikes the defect, comprising:
- directing a beam used for detecting defects across at least a portion of an article, wherein the distance traveled by the beam changes as the beam is directed across the article;
- and
- focusing the beam to correspond to the changing distance traveled by the beam.
An apparatus useful for detecting a defect in an article that causes deflection of a beam when the beam strikes the defect, comprising:
- means for directing a beam used for detecting defects across at least a portion of an article, wherein the distance traveled by the beam changes as the beam is directed across the article;
- and
- means for focusing the beam to correspond to the changing distance traveled by the beam.
An apparatus useful for detecting a defect in an article that causes deflection of a beam when the beam strikes the defect, comprising:
- at least a first optical element that directs a beam used for detecting defects across at least a portion of an article, wherein the at least one optical element causes the distance that the beam travels between the optical element and the article to change as the beam is directed across the article, wherein the at least a first optical element comprises at least one of a scanning mirror and a parabolic mirror;
- and
- at least a second optical element that focuses the beam to correspond to the changing distance traveled by the beam, wherein the at least a second optical element comprises a parabolic mirror, and wherein the at least a second optical element is configured to focus the beam such that a substantially constant spot size of the beam on the article is maintained as the beam is directed across the article.
Dependencies are inferred from the claim text.