Patent ID: 7333913

Claim:
A clearance measurement system, comprising: a reference geometry disposed on a first object having an otherwise continuous surface geometry, wherein the otherwise continuous surface geometry comprises a circular structure extending along a plurality of blades that are independent from the reference geometry, wherein the reference geometry comprises a multi-level structure having a plurality of different levels relative to the otherwise continuous surface geometry, a plurality of reference geometries each having a different level relative to the otherwise continuous surface geometry, or a combination thereof; a sensor disposed on a second object, wherein the sensor is configured to generate a first signal representative of a first sensed parameter from the first object and a second signal representative of a second sensed parameter from the reference geometry; and a processing unit configured to process the first and second signals to estimate a clearance between the first and second objects based upon a measurement difference between the first and second sensed parameters, wherein the second signal representative of the second sensed parameter corresponding to reference geometry changes as a function of the clearance between the first and second objects, wherein the sensor system is configured to measure the clearance as the first object moves relative to the second object.