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:
May. 22, 1990
Filed:
Nov. 19, 1986
Joseph H Haritonidis, Cambridge, MA (US);
Stephen D Senturia, Boston, MA (US);
David J Warkentin, Cambridge, MA (US);
Mehran Mehregany, Merriam, KS (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
A thin diaphragm receives pressure across one side and faces a beam splitter on the other side. The beam splitter is integrally attached to the diaphragm and serves as a local optical reference plane for the entire assembly. Coherent light from a light source is partially reflected at the beam splitter. The remainder of the light is reflected from the diaphragm. The reflected beams recombine at a detection point and have a phase difference which is a function of the amount of deflection of the diaphragm. The detected recombined beams are indicative of the deflection of the diaphragm. Optical calibration of the aseembly is a function of the distance between the diaphragm and beam splitter which remains as predefined because the beam splitter is integral with the diaphragm. A vent in the small cavity formed between the diaphragm and beam splitter enables the diaphragm to sense small pressures with increased sensitivity. Through micro-fabrication techniques, the diaphragm is made sensitive to dynamic and static pressure. Detection of the thermal expansion of the assembly as well as deflection of the diaphragm enables a sensed pressure measurement as a differential between the detected thermal expansion and deflection.