US 6,603,542 B1 · High sensitivity optical inspection system and method for detecting flaws on a diffractive surface

Abstract

An improved high sensitivity optical inspection system for detecting flaws on a diffractive surface containing surface patterns includes: a first and a second illumination means for illuminating predetermined regions on the diffractive surface to generate a scattered intensity distribution in response to either a flaw or a surface pattern; means for detecting the intensity level of the scattered intensity distribution at a plurality of locations about the diffractive surface; means for establishing a minimum detected intensity level; means, responsive to the minimum detected intensity level, for indicating the absence of a flaw on the illuminated region of the diffractive surface when the minimum detected intensity level is below a threshold intensity level and for indicating the presence of a flaw on the illuminated region of the diffractive surface when the minimum detected intensity level exceeds the threshold intensity level; and means for moving the diffractive surface to generate a scan pattern on the diffractive surface to inspect the entire surface.

Claims54

Dependent claims

An optical inspection system that detects flaws on a diffractive surface containing surface patterns, comprising:

at least one optical source that provides a first beam, the first beam illuminating a first region of the diffractive surface and generating a first scattered intensity distribution, the optical source providing a second beam, the second beam illuminating a second region of the diffractive surface distinct from the first region and generating a second scattered intensity distribution;
a plurality of detectors positioned about the diffractive surface, the detectors detecting the first and second scattered intensity distributions;
a detection circuit coupled to the detectors that determines if a flaw is present on the diffractive surface;
and
a movable mounting table that securely retains the diffractive surface, the mounting table moving the diffractive surface with respect to the first and second beams to generate a scan pattern on the diffractive surface.

2 more elements

A method of using an optical inspection system to inspect a diffractive surface containing surface patterns to detect flaws on the diffractive surface, the method comprising the steps of:

(i) illuminating a first region of the diffractive surface with a first beam to generate a first scattered intensity distribution;
(ii) illuminating a second region of the diffractive surface distinct from the first region with a second beam to generate a second scattered intensity distribution;
(iii) detecting an intensity level of the first and second scattered intensity distributions generated by the first and second beams, the intensity level being detected at a plurality of locations about the diffractive surface;
(iv) processing the detected intensity level of the first and second scattered intensity distributions to determine if a flaw is present;
and
(v) moving the diffractive surface to generate a scan pattern on the diffractive surface, the scan pattern covering the entire diffractive surface.

3 more elements

Dependencies are inferred from the claim text.

High sensitivity optical inspection system and method for detecting flaws on a diffractive surface

Life of this patent

High sensitivity optical inspection system and method for detecting flaws on a diffractive surface

Life of this patent

Abstract

Claims54