Patent ID: 9588056
Date: 2017-03-07
CPC Classifications: G01N

Claim:
1. A method of detecting one or more particles on a substrate comprising: conveying the substrate over an arcuate surface and producing a first bend in at least a portion of the substrate directing a laser beam emitted by a broad area laser through a slow-axis cylindrical lens and a fast-axis cylindrical lens separate from the slow-axis cylindrical lens onto an exterior surface of the substrate at an apex line of the first bend, wherein a central axis of the laser beam is within 10 degrees of a plane tangent to the apex line, the slow-axis cylindrical lens imaging the laser beam onto an image plane transverse to a direction of the laser beam, the fast-axis cylindrical lens collimating the laser beam along a fast axis of the laser beam, the slow-axis cylindrical lens and the fast-axis cylindrical lens forming a rectangular area of illumination of the laser beam at the image plane transverse to the direction of the laser beam, and the laser beam producing scattered light from the one or more particles on the exterior surface at the apex line; restricting a numerical aperture of the laser beam along a fast-slow axis of the slow-axis cylindrical lens using a numerical aperture restricting aperture plate positioned between the slow-axis cylindrical lens and the fast-axis cylindrical lens; and detecting the scattered light with a detection device.