<title>Optimization of hydrodynamic bearings for subarcsecond laser scanner applications</title>

Abstract

Hydrodynamic fluid film bearings are preferred by today's electronic imaging industry because of their high accuracy, high speed capability, long service life, and low maintenance. In this paper, various performance aspects of hydrodynamic fluid film bearings are discussed in relation to the special requirements of the laser scanner application. Emphasis is placed on the non-repeatable wobble (NRW) of the laser beam deflected by the scanner spindle, since NRW has the most significant effect on image quality. Major factors affecting the laser beam's NRW are analyzed both experimentally and theoretically. Testing methods for bearing performance evaluation are also discussed. It is found that unlike the non-repeatable wobble of the spindle rotor, the non-repeatable wobble of the deflected laser beam is not a purely mechanical property of the bearings and the rotor, but rather a system property affected by many factors, one of the most important being the thermal/turbulence distortion. Based on these results, methods of optimizing bearing and system design to achieve sub-arc second laser bean NRW performance in various speed ranges are suggested.