公开(公告)号：JP2001050903A

公开(公告)日：2001-02-23

申请号：JP2000185724

申请日：2000-06-21

Applicant: PHASE METRICS INC

Inventor： CHEN LI ,  CHHIBBER RAJ

IPC: G01N21/95 ,  G01N21/958 ,  G11B5/84

Abstract: PROBLEM TO BE SOLVED: To achieve effective inspection by reflecting light from a laser light source on first and second surfaces and filtering light being reflected from the second surface with a spatial filter for detecting by a first photodetector. SOLUTION: An optical inspection system 10 consist of a laser 18 for reflecting a light beam 20 from a substrate 12, a spatial filter 28, a lens assembly 38, and the like. The substrate 12 reflects one portion 24 of light on a first surface 14 and one portion 26 of light on a second surface 16. The spatial filter 28 for filtering light on the second surface is set to a constriction with an opaque part 30, and the constriction includes an opening 32 for transmitting the light 24 up to first and second photodetectors 34 and 36. Reflection light from the second surface 16 enters a lens assembly 38 at an angle that differs from that of the reflection light 24 from the first surface 14 according to factors such as an incidence angle ϕ of a light beam 20, the thickness of a substrate 12, a refractive index, or the like. A control device 52 processes the output signals of the first and second photo detectors 34 and 36 to determine the characteristics of the certain surface of the substrate 12.