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. 07, 2003
Filed:
Nov. 20, 2000
Klaus Bohnert, Oberrohrdorf, CH;
Hubert Brandle, Oberengstringen, CH;
ABB Research Ltd, Zurich, CH;
Abstract
The invention relates to a frequency-coded fiber laser pressure sensor ( ) which is especially suitable for measuring isotropic pressures in oil wells. The sensor principle provided for in the invention is based on the fact that in a fiber laser ( ) doped with Er a monomode or bimodal sensor fiber ( ) is positioned whose pressure-related birefraction results in a frequency shift and beat frequencies between the orthogonal linear polarisation modes x, y or the spatial modes LP and LP line. The beat frequencies are easily measured using a frequency counter ( ). Temperature-related variations in birefraction are compensated in a differential arrangement of two sensor fiber segments ( ). Fiber-integrated Bragg gratings ( ) with low bandwidths (0.2 nm) are especially suitable as laser end reflectors. The pressure sensor ( ) is characterized by a large measurement range (100 Mpa) and a high triggering capacity , (kPa), is readily multiplexed and can be housed in a very compact, light-weight and robust pressure-resistant housing ( ).