Patents by Inventor Yoshiaki Ohtsu

Yoshiaki Ohtsu 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).

  • System and method for detecting the relative positional deviation between diffraction gratings and for measuring the width of a line constituting a diffraction grating
    Patent number: 5625453
    Abstract: A deviation detecting system for detecting a relative positional deviation between first and second diffraction gratings, includes a light source, an illuminating device for projecting first and second light beams from the light source, having different directions of polarization, onto the first and second diffraction gratings along different directions, a first signal detecting device for detecting a first interference light signal from the first diffraction grating, being based on a combination of diffraction light of the first light beam and diffraction light of the second light beam, a second signal detecting device for detecting a second interference light signal from the second diffraction grating, being based on a combination of diffraction light of the first light beam and diffraction light of the second light, a first phase difference detecting device for detecting a phase difference between the first and second interference light signals and, a second phase difference detecting device for producing
    Type: Grant
    Filed: October 26, 1994
    Date of Patent: April 29, 1997
    Assignee: Canon Kabushiki Kaisha
    Inventors: Takahiro Matsumoto, Yoshiaki Ohtsu, Kenji Saitoh, Koichi Sentoku