Simultaneous measurement of nanometric longitudinal displacement and micrometric lateral displacement by using one line CCD camera

摘要

This paper proposes a simultaneous measurement technique of 2 displacement components by using a laser beam and one high-speed line CCD camera. The laser beam is divided to two beams. One beam is reflected by a corner reflector attached on an object and the reflected beam is superimposed with the other beam. The superimposed beam is expanded by a microscope objective lens and then passed through both a wedge-shape birefringent plate and a polarizer making a fringe pattern. This pattern has a light intensity distribution like a sinusoidal shape whose envelope curve has one peak. The pattern is captured by the line CCD camera and is used to extract nanometric longitudinal displacement and micrometric lateral displacement measurement.