Optics: measuring and testing – By light interference
Reexamination Certificate
2006-08-15
2006-08-15
Toatley, Jr., Gregory J. (Department: 2877)
Optics: measuring and testing
By light interference
C356S495000
Reexamination Certificate
active
07092100
ABSTRACT:
An arrangement and method for reliably finding the wave form extrema of interference signals produced by a quadrature phase shift interferometer (QPSI) takes advantage of the quadrature property of I and Q signals. The zero-crossing points in the I and Q signals are determined. Peak detection is performed for peaks and valleys in the Q signal in close proximity to the zero-crossing points in the I signal, and for peaks and valleys in the I signal in close proximity to the zero-crossing points in the Q signal. These represent the maximum and minimum points of the I and Q signals. From these points, intensity envelopes are created and QPSI phase wrapping is performed to determine the phase angle and ultimately, out-of-plane displacement may be determined.
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patent: 2004/0196468 (2004-10-01), Wang et al.
Pressesky Jason L.
Wang Jianmin
Connolly Patrick J
McDermott Will & Emery LLP
Seagate Technology LLC
Toatley , Jr. Gregory J.
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