Miniature opto-mechanical anemometer

A method for measuring the flow of a fluid in two directions, the method comprising the steps of:

• a) positioning a flexible arm section in a flow of a fluid, the flexible arm section having a long axis with a base end and a distal end;
• b) orientating the flexible arm section transverse to the flow of the fluid with the base end of the flexible arm section being fixed motionless against the flow of the fluid;
• c) causing the distal end of the flexible arm section to bend freely in response to the flow of the fluid, so that the flexible arm section perturbates about a nominal position in response to fluctuations in the flow of the fluid, so that the flexible arm section perturbates about a nominal position in response to fluctuations in the flow of the fluid;
• d) projecting a beam of light from the distal end of the flexible arm section toward an optical detector, wherein the optical detector is located in a pathway of the beam of light;
• and
• e) monitoring a location of the beam of light impacting on the optical detector, the optical detector being responsive to the position of peak intensity of the beam of light on a face of the optical detector, and where the optical detector is capable of monitoring perturbations in the position of peak intensity having frequencies up to 1000 Hz.

An apparatus for detecting fluctuations in the flow of a fluid comprising:

• a directional light emitter positioned transverse to the flow of the fluid, further comprising:
• a flexible arm section having a long axis with a base end and a tip end, wherein the base end is fixed by connection to a wall of a passageway orientated substantially parallel to the direction of the flow of the fluid and the tip end is unsupported, to allow the flexible arm section to bend with the flow of the fluid, and where the flexible arm section has been mechanically stiffened to resist nominal motion of the flow such that the orientation of the flexible arm section is substantially perpendicular to the wall when the flow of the fluid is nominal and non-fluctuating;
• and
• a light source connected to the flexible arm section and configured to project a beam of light from the tip end of the flexible arm section;
• and
• at least one optical detector positioned to be responsive to the beam of light, wherein the optical detector is configured to sense a lateral movement of the beam of light as the directional light emitter deflects in response to the flow of the fluid.

A method for measuring the flow of a fluid in two directions, the method comprising the steps of:

• a) positioning a flexible arm section in a flow of a fluid, the flexible arm section having a long axis with a base end and a distal end;
• b) orientating the flexible arm section transverse to the flow of the fluid with the base end of the flexible arm section being fixed motionless against the flow of the fluid;
• c) causing the distal end of the flexible arm section to bend in response to fluctuations in the flow of the fluid, where the flexible arm section has been mechanically stiffened to resist nominal motion of the flow such that the orientation of the flexible arm section is substantially perpendicular to the wall when the flow of the fluid is nominal and non-fluctuating;
• d) projecting a beam of light from the distal end of the flexible arm section toward an optical detector, wherein the optical detector is located in a pathway of the beam of light;
• and
• e) monitoring a location of the beam of light impacting on the optical detector, the optical detector being responsive to the position of peak intensity of the beam of light on a face of the optical detector.