Fiber optic seismic sensor based on MEMS cantilever
AssigneeHalliburton Energy Services, Inc.
InventorsJohn W. Berthold, David B. Needham
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Abstract
A dual cantilevered beam structure is attached to a silicon frame. An optical fiber extends from a borosilicate wafer bonded to the bottom of the frame. A second borosilicate wafer is bonded to the top of the frame. The bottom borosilicate wafer is bonded to the optical fiber with a bonding agent having an index of refraction between the refractive index of the fused silica optical fiber and the refractive index of the borosilicate wafer. In an embodiment, the bonding agent has a refractive index substantially similar to optical cement. Light is reflected into the optical fiber from the beam structure for measuring seismic changes.
Claims21
An apparatus for measuring seismic movement comprising:
- a sensor having:
- a wafer;
- a frame attached to said wafer;
- a cantilevered mass pivotally connected to the frame, the cantilevered mass having two beams for pivoting the cantilevered mass relative to the frame;
- and
- a cavity located between the cantilevered mass and the wafer wherein the cantilevered mass is capable of moving to change the size of the cavity.
An apparatus for measuring seismic movement comprising:
- a MEMS sensor having:
- a frame;
- a borosilicate wafer connected to said frame;
- a cantilevered mass connected to said frame, said cantilevered mass movable with respect to said borosilicate wafer;
- and
- an optical fiber attached to the borosilicate wafer for directing light through said borosilicate wafer to said cantilevered mass and receiving light reflected from said cantilevered mass.
Dependencies are inferred from the claim text.