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:
Nov. 16, 1993
Filed:
Apr. 21, 1992
David Fink, Los Angeles, CA (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
A method and apparatus for frequency shifting an optical beam where the frequency shifted beam remains both spatially and temporally coherent with no spread in frequency and can be continually tuned in frequency shift over a wide range without any change in beam pointing or beam quality with time. This is achieved by changing the effective optical path length of the resonant cavity of a laser by translating an optical wedge, such as a prism, across the optical path in the direction of the wedge gradient. In a first embodiment, a rotating helical phase plate is used to linearly increase the optical path of a transmitted or reflected beam with time, thereby frequency shifting the exiting beam. In another embodiment, the rim of a wheel with a spirally increasing or decreasing radius is used in which the outer periphery of the wheel is a mirror. Spinning the wheel at a constant rotational speed increases or decreases the optical path of a reflected beam linearly with time, thereby frequency shifting the reflected beam. The helical phase plate can be used in either a transmissive mode or a reflective mode, whereas the spiral wheel is used primarily in a reflective mode.