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A novel method of a six-degree-of-freedom (DOF) posture measurement in a linear stage by employing a single unit of an optical encoder is introduced.
This method consists of a diffractive optical element, a corner cube, four separate two-dimensional position-sensitive detectors, four photodiodes and auxiliary optics components
The circularly polarizing interferometric technique was integrated to measure the displacement of the stage along the traveling axis in a robust manner.
With a single travel of the stage, it provided a six-DOF motion error with a high resolution, less than 0.03 arcsec, 20 nm and 0.4 nm for angular errors, dY and dZ, and dX, respectively, at the same time.
Aug, 2011
Measurement Science and Technology, Vol.22, 105901
