Patents by Inventor Willem Kalf

Willem Kalf has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Optical focus sensor, an inspection apparatus and a lithographic apparatus
    Patent number: 8125615
    Abstract: To detect whether a substrate is in a focal plane of an inspection apparatus, an optical focus sensor is arranged to receive a radiation beam via an objective lens. The optical focus sensor includes a splitter configured to split the radiation beam into a first sub-beam and a second sub-beam. With an aperture and a detector in the light path of each of the sub-beams it is possible to detect whether the substrate is in focus by comparing the amount of radiation received by each of the detectors.
    Type: Grant
    Filed: October 9, 2008
    Date of Patent: February 28, 2012
    Assignee: ASML Netherlands B.V.
    Inventors: Willem Kalf, Ronald Franciscus Herman Hugers
  • Optical Focus Sensor, an Inspection Apparatus and a Lithographic Apparatus
    Publication number: 20090091726
    Abstract: To detect whether a substrate is in a focal plane of an inspection apparatus, an optical focus sensor is arranged to receive a radiation beam via an objective lens. The optical focus sensor includes a splitter configured to split the radiation beam into a first sub-beam and a second sub-beam. With an aperture and a detector in the light path of each of the sub-beams it is possible to detect whether the substrate is in focus by comparing the amount of radiation received by each of the detectors.
    Type: Application
    Filed: October 9, 2008
    Publication date: April 9, 2009
    Inventors: Willem KALF, Ronald Franciscus Herman Hugers