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:
Aug. 23, 2005
Filed:
Dec. 18, 2001
Changhuei Yang, Singapore, SG;
Adam Wax, Boston, MA (US);
Ramachandra R. Dasari, Lexington, MA (US);
Michael S. Feld, Newton, MA (US);
Changhuei Yang, Singapore, SG;
Adam Wax, Boston, MA (US);
Ramachandra R. Dasari, Lexington, MA (US);
Michael S. Feld, Newton, MA (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
The methods of the present invention are directed at an accurate phase-based technique for measuring arbitrarily long optical distances with sub-nanometer precision. A preferred embodiment of the present invention method employs a interferometer, for example, a Michelson interferometer, with a pair of harmonically related light sources, one continuous wave (CW) and a second source having low coherence. By slightly adjusting the center wavelength of the low coherence source between scans of the target sample, the phase relationship between the heterodyne signals of the CW and low coherence light is used to measure the separation between reflecting interfaces with sub-nanometer precision. As the preferred embodiment of this method is completely free of 2π ambiguity, an issue that plagues most phase-based techniques, it can be used to measure arbitrarily long optical distances without loss of precision.