Position detecting system
Patent 4589773 Issued on May 20, 1986. Estimated Expiration Date: 
May 20, 2003. 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.
May 20, 2003. 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 3909131 Noncontact optical gauging system Electro-optical triangulation rangefinder for contour measurement Apparatus and method for optical clearance determination Flatness measuring apparatus Patent #: 4332477 InventorsAssigneeApplicationNo. 06/333295 filed on 12/22/1981US Classes:356/623, Triangulation250/205, Controlling light source intensity250/559.31, With triangulation250/559.38, Determining range from detector356/3.04With a single staring photodetector having one elementExaminersPrimary: Rosenberger, R. A.Attorney, Agent or FirmInternational ClassG01B 11/02 (20060101)Foreign Application Priority Data1981-02-23 JPAbstractA position detecting system suitable for the position control of the surface of a workpiece mounted in an electron beam exposure system is disclosed which includes an electrically-driven light source, a first optical system for focusing a light beam from the light source on a workpiece, a position-controlling table for mounting thereon the workpiece, a second optical system for focusing light reflected from the workpiece on a predetermined image surface, a photodetector having a light receiving surface arranged on the image surface, and a negative feedback amplifier for controlling the light source by the output of the photodetector.Other References
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