Patent ID: 6392749
Filing Date: 2002-05-21
Classification: G01B,G01N

Abstract:
A system for measuring a height of an object comprising:a first electromagnetic signal source for transmitting a first signal toward a first position on the object at a first angle; a second electromagnetic signal source for transmitting a second signal toward the first position on the object at a second angle; a spinning device for rotating the object to change the first position; a first position sensitive detector to receive a portion of said first signal that reflects off of said object, and to determine a radial portion of said first signal (S1r) and a circumferential portion of said first signal (S1c); a second position sensitive detector positioned at a right angle from said first position sensitive detector, to receive a reflected portion of said second signal that reflects off of said object, and to determine a radial portion of said second signal (S2r) and a circumferential portion of said second signal (S2c); a processor for determining the height of the first position based upon a difference between S2r and S1r that does not include slope information.