Tunable laser for dynamic measurement

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(11)

EP 1 674 823 A8

(12)	CORRECTED EUROPEAN PATENT APPLICATION
	Note: Bibliography reflects the latest situation

(15)	Correction information:
	Corrected version no 1 (W1 A1)

(48)	Corrigendum issued on:
	27.09.2006 Bulletin 2006/39

(43)	Date of publication:
	28.06.2006 Bulletin 2006/26

(21)	Application number: 05257949.7

(22)	Date of filing: 21.12.2005

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International Patent Classification (IPC):

G01B 9/02^(2006.01)

(84)	Designated Contracting States:
	AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR
	Designated Extension States:
	AL BA HR MK YU

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Priority:

21.12.2004 US 637967 P

(71)	Applicant: Davidson Instruments, Inc.
	The Woodlands TX 77381 (US)

(72)	Inventors:
	Lopushansky, Richard L. The Woodlands Texas (US) Jeffers, Larry A. Minerva, Ohio (US) Berthold, John W. Salem, Ohio (US)

(74)	Representative: Wilson, Alan Stuart
	Barker Brettell 138 Hagley Road Edgbaston Birmingham B16 9PW Birmingham B16 9PW (GB)

(54)	Tunable laser for dynamic measurement

(57) A method for monitoring changes in a gap which corresponds to changes in a particular environmental parameter using a tunable laser and interferometer at high frequency is disclosed. The laser light provided to the interferometer is swept through a small range of wavelengths. Light modulated by the interferometer is detected and a non-sinusoidal light intensity output curve is created, a reference point on the curve identified and subsequent sweep of the laser performed. The difference in time, wavelength, or frequency at the occurrence of the reference point between the two sweeps allows for measuring the relative changes in the gap and, as a result, the change in the environmental parameter.