A clearance measurement system is provided. The clearance measurement
system includes a reference geometry disposed on a first object having an
otherwise continuous surface geometry and 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. The clearance measurement system also includes 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.