Patent ID: 7435941

Claim:
A system for measuring a characteristic of an optical article, comprising: a light source for producing light; an optical element for focusing the light along a probe path to converge at a reference location associated with an expected position of an optical article, wherein the reference location is moved during a scan to thereby focusing at least two different positions along an optical axis of the probe path; a sensor for detecting the light from the at least two different reference locations during the scan, wherein the sensor comprises a position sensitive diode device operable to generate two signals, a first signal associated with a location of an intensity centroid along one direction and a second signal associated with a location of an intensity centroid along a second direction, the second direction orthogonal to the first direction; and a processor, wherein the processor is configured to receive signals from the sensor associated with each spot of received light and determine a deflection angle and a direction of the deflection angle of the light from the probe path.