Patent ID: 8953156
Filing Date: 2015-02-10
Classification: G01N

Abstract:
1. A defect detection device, comprising: a illumination optical system configured to emit a laser onto a surface of an inspection target object, in an inclined direction; and a detection optical system configured to focus, by use of an objective lens, scattered light from the inspection target object resulting from the laser emission, to thereby form an image on a solid-state imaging element; wherein the detection optical system includes a distribution filter including a combination of a wave plate having a fast axis direction and a slow axis direction, and a distribution polarization element; wherein the detection optical system is configured to control a polarization direction of scattered light from roughness of the inspection target surface, to control a polarization direction of scattered light from foreign matter or a defect on the inspection target object surface, and to select a polarization direction of light to be transmitted, thereby selectively polarizing and transmitting a type of polarized light; and wherein the distribution polarization element is configured to align the polarization directions to increase a ratio of: (a) the scattered light from foreign matter or a defect on the inspection target object surface to (b) the scattered light from the roughness of the inspection target surface.