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:
Jul. 07, 1992
Filed:
May. 15, 1991
Beat Halg, Cham, CH;
Landis & Gyr Betriebs AG, Zug, CH;
Abstract
A device for optically measuring a pressure difference in a medium by means of a Fabry-Perot interferometer, comprises a transparent plate and a diaphragm block connected to the transparent plate, the diaphragm block comprising a substrate, a measuring diaphragm formed along the inner surface of the substrate, and a spacer separating the inner surface of the transparent plate and the inner surface of the substrate. A first planar mirror is disposed on the inner surface of the plate and a second planar mirror is disposed on the inner surface of the measuring diaphragm so that they constitute the Fabry-Perot interferometer. The measuring diaphragm is shiftable by a distance (H) in response to a pressure difference (.delta.p) exerted on inner and outer surfaces of the measuring diaphragm whereby the optical length (L) of the Fabry-Perot interferometer changes as a function of the pressure difference (.delta.p). The substrate includes a depression on one side only so that the material remaining under the depression is of a predetermined thickness and comprises the measuring diaphragm. Since the measuring diaphragm constitutes a portion of the substrate and is a continuation of the crystalline structure of the substrate, there are no mechanical stresses at the joining points of the substrate and the measuring diaphragm. Preferably, the measuring diaphragm constitutes a doped layer of the substrate and serves as an etching barrier for the substrate.