Characterization of an open-loop controlled scanning stage using a knife edge optical technique

Abstract

Our experimental confocal microscope project required the construction of a high performance scanning stage. In order to understand the scanning stage behavior we modeled each axis of motion as a damped harmonic oscillator, and measured its mechanical response using an optical knife edge technique. In order to maximize the scan stage accuracy and performance we used the characterization results of the stage to implement first order correction for such influences as the mass, the damping, and the stiffness of the springs of the scanning stage. We show that the stage can be driven over a range of frequencies and motion wave forms, without inducing primary resonant response, and this results in an improved quality of the confocal images. We have constructed a novel scanning motion incorporating the corrected results. The linearity of motion was found to be better than with a ramp or sine wave driving voltage, enabling an order of magnitude increase in speed of acquisition.