Patents by Inventor Peter I. Tillett

Peter I. Tillett 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).

  • Patent number: 4169240
    Abstract: An automatic focusing system is described for use with scanning systems having a poor signal to noise ratio video signal obtained by repetitive scanning. Typically the system is applicable to a scanning electron microscope.A preliminary filtering of the video signal is performed using a filter which eliminates video signal content corresponding to the fundamental and low harmonics of the repetitive scanning.Basic noise reduction is achieved using an N-path filter (typically N=8) commutated at a frequency equal to N.times.line repetition frequency of the electron beam scanning. The output signal is rectified and averaged to give a d.c. level proportional to the high frequency content of the video signal clustered around harmonics of the line scan repetition rate. This d.c. level is maximized by making stepwise adjustments in the current flowing in the focusing coil of the electron beam scanner and comparing d.c. levels before and after adjustment.
    Type: Grant
    Filed: August 1, 1977
    Date of Patent: September 25, 1979
    Assignee: Cambridge Scientific Instruments Limited
    Inventors: John D. Anderson, John F. Watney, Peter I. Tillett