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:
Oct. 10, 1989
Filed:
Oct. 16, 1986
Barry R Hill, St. Helens, GB;
Pilkington Brothers plc, , GB;
Abstract
An interferometer is provided for producing an interference pattern from light such as laser light which travels along first and second optical paths and at the end of each such path there is a respective fixed mirror for directing light to a common optical path. Means are provided to vary the optical path length of light in the or each first or second optical path to produce an interference pattern in the common optical path, which means comprises a pair of parallel-plane optical flats in accordance with one embodiment of the invention, which are each rotated in an oscillating manner to produce a linearly varying optical path length during rotation. According to another aspect of the invention first detector means are provided for detecting a reference part of the interference pattern produced to derive therefrom a reference signal, and second detector means are provided for receiving the interference pattern to thereby derive signals indicative of successive parts of the interference pattern. Means are provided for comparing the reference and successive interference pattern signals to derive therefrom signals which indicate the optical path difference corresponding to the interference pattern.