The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 16, 1998
Filed:
Jun. 04, 1996
Frank C Demarest, Middletown, CT (US);
Zygo Corporation, Middlefield, CT (US);
Abstract
An improved method and apparatus for compensating for differences in the data age of the measurements among measurement axes in an interferometer (18), such as a heterodyne interferometer, in which known values of time delay occur in the measurement (34, 38, 38a, 41 and 42) and reference signal (44) paths. A time value is measured (52) for the signal transmission over these paths for a given clock (48) period interval and the measured time value (52) is adjusted (56) for the given interval against the known time delay for compensating for the data age. The known time delay is subtracted from the measured time value for providing the adjusted time value (60) for the given interval. The adjusted time value (60) is converted into a phase measurement, and this phase measurement is converted into the dynamic interferometric position measurement (64, 68) for providing a position measurement (72, 74) independent of any velocity of movement of the object whose position is being measured and having reduced data age differences between the signal paths providing the measurement.