Apparatus for detecting extraneous substances on a glass plate
December 27, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References Re33991 Foreign substance inspecting apparatus Automatic contaminants detection apparatus Foreign particle detecting method and apparatus Method and apparatus for measuring properties of thin materials using polarized light Surface analysis system and method Discriminating type flaw detector for light-transmitting plate materials Apparatus for detecting foreign particles on a surface of a reticle or pellicle Patent #: 4999510 InventorsAssigneeApplicationNo. 813837 filed on 12/27/1991US Classes:356/239.8, Detection of an object or particle on surface250/559.09, With polarization250/559.41, With foreign particle discrimination circuitry356/338, With photocell detection356/369Of surface reflectionExaminersPrimary: Rosenberger, Richard A.Assistant: Pham, Hoa Q. Attorney, Agent or FirmForeign Patent References
International ClassesG01N 021/00G01J 004/00 Foreign Application Priority Data1990-12-27 JPAbstractAn apparatus for detecting extraneous substances on a glass plate includes a first light projecting system arranged above a plane under examination on a glass plate, the surface of which is irradiated with an S-polarized laser beam at a first elevation angle, a second light projecting system arranged above the surface thereof which is irradiated with a P-polarized laser beam at a second elevation angle greater than the first elevation angle, and a light receiving system for receiving scattered light from the surface irradiated with the laser beams respectively emitted from the first and the second light projecting system at an elevation angle smaller than the first elevation angle. The light receiving system is arranged on a side opposite to the direction of irradiation with the normal line set up at the laser beam irradiation point therebetween and the output level of the P-polarized laser beam is set in specific relation to the S-polarized laser beam.Field of SearchBY POLARIZED LIGHT EXAMINATIONWith birefringent element With polariscopes Including polarimeters With electro-optical light rotation Of surface reflection FOR SIZE OF PARTICLES By particle light scattering BY PARTICLE LIGHT SCATTERING With photocell detection At right angles to the light beam (e.g., nephelometer) At variable angle to the light beam For light comparison means Of back-scattered light Using plural photocells OF LIGHT REFLECTION (E.G., GLASS) With diffusion Polarizing | |
