Dynamic pressure, air bearing type polygonal scanner and method of producing the same

摘要

A polygonal scanner of the present invention includes a rotary body including a ceramic rotary sleeve and a metallic cylindrical member shrinkage-fitted on the rotary sleeve. The cylindrical member is formed with mirror surfaces constituting a polygonal mirror. A dynamic pressure, air bearing supports the rotary body. The mirror surfaces overlap the rotary sleeve in the axial direction of the rotary sleeve. A hole greater in diameter than the dynamic pressure, air bearing is formed in the top wall of the cylindrical member. The cylindrical member includes a stress removing portion positioned between the mirror surfaces and the rotary sleeve for removing a stress ascribable to shrinkage-fitting.