| 摘要 |
A foreign particle detecting apparatus comprises a light source for radiating coherent light onto an object to be detected on a surface of which a circuit pattern is formed, a focusing device for focusing the light emitted from the light source onto the object to be detected at a predetermined angular aperture, a device for moving the incident light focused at the predetermined angular aperture relative to the object to be detected, and a detector for receiving scattered light produced upon incidence of the focused light onto the object to be detected, and which detects foreign matter on the object to be detected on the basis of an output signal from the detector. Foreign matter is discriminated from the circuit pattern on the basis of the output signal from the detector means. The detector comprises at least two light-receiving elements, separated by a spatial angle substantially equal to or slightly larger than the angular aperture of the incident light, for individually outputting signals.
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