Fabry-perot based speed sensor
AssigneeRosemount Aerospace Inc.
InventorsAswin Kumar Vallamkondu, Ramesh Annamareddy, Mark Sherwood Miller
Life of this patent
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Abstract
Apparatus and associated methods relate to optically determining rotation frequency of a rotatable member using a Fabry-Perot cavity formed between a mirror and a movable reflective mirror. A cavity dimension between the mirror and a movable reflective mirror changes in response to movement of the movable reflective mirror. The movable reflective mirror is bonded to a magneto-strictive material having a thickness dimension that changes in response to changes in a magnetic field. A magnet generates the magnetic field, which changes in response to rotation of the rotatable member.
Claims18
A system for determining rotation frequency of a rotatable member, the system comprising:
- a single magnet for generating a magnetic field proximate the rotatable member, rotation of the rotatable member causing changes in the magnetic field generated by the single magnet;
- a Fabry-Perot cavity formed between a first mirror and a second mirror, which are parallel to one another, the Fabry-Perot cavity is located directly between the single magnet and the toothed phonic wheel, the second mirror bonded to a magneto-strictive material having a thickness dimension that changes in response to changes in the magnetic field caused by rotation of the rotatable member, thereby moving the second mirror relative to the first mirror;
- a light source configured to project light into the Fabry-Perot cavity;
- a detector configured to detect light reflected from the Fabry-Perot cavity;
- and
- a speed calculator configured to determine rotation frequency of the rotatable member based on a principal wavelength of light detected by the detector.
A method for determining rotation frequency of a rotatable member, the method comprising:
- generating, via a single magnet, a magnetic field proximate the rotatable member, rotation of the rotatable member causing changes in the magnetic field generated by the single magnet;
- moving, via a magneto-strictive material, a second mirror of a Fabry-Perot cavity in response to the changes in the magnetic field caused by rotation of the rotatable member;
- projecting, via a light source, light into Fabry-Perot cavity formed between a first mirror and the second mirror, which are parallel to one another and located between the single magnet and the toothed phonic wheel;
- reflecting, via the Fabry-Perot cavity, a reflected portion of the light projected into the Fabry-Perot cavity;
- detecting, via a detector, the light reflected from the Fabry-Perot cavity;
- and
- determining, via a speed calculator, rotation frequency of the rotatable member based on a principal wavelength of light detected by the detector.
Dependencies are inferred from the claim text.