Abstract: A coherent laser radar that uses two coherent femtosecond fiber lasers to perform absolute ranging at long distance. One coherent femtosecond fiber lasers acts as a source and the other as a local oscillator for heterodyne detection of the return signal from a cooperative target. The system simultaneously returns a time-of-flight range measurement for coarse ranging and an interferometric range measurement for fine ranging which is insensitive to spurious reflections that can cause systematic errors. The range is measured with at least 3 ?m precision in 200 ?s and 5 nm precision in 60 ms over a 1.5 m ambiguity range. This ambiguity range can be extended to 30 km through reversal of signal and LO source roles.
Type:
Grant
Filed:
September 16, 2010
Date of Patent:
October 15, 2013
Assignees:
The National Institute of Standards and Technology, as Presented by the Secretary of Commerce, The United States of America as Represented by the Secretary of Commerce
Inventors:
Nathan R. Newbury, Ian Coddington, William C. Swann