Method of making optical elements for an optical disc system

Abstract

A large diameter glass wafer is pattern-etched to provide a plurality of elongated lens elements arranged side-by-side, the etching leaving small rods in place to keep the lens elements connected to the wafer during mirror processing. The etching provides curved surfaces for lenses and flat surfaces for mirrors. The mirrors are formed by selectively depositing reflective material on the flat surfaces. The reflective material may comprise an oxide, nitride, sulfide, or fluoride of a transition metal. The flat surfaces that define the mirrors are disposed at angles to the longitudinal dimension of each lens element. In use in an optical disc system, light from a laser diode is reflected by the mirrors and directed at an optical disc through a first lens. Light returns from the disc on a parallel path through a second lens, passes through the lens element, and is directed at a photodetector. The system may include an elongated base element attached to each lens element. Pattern-etching of a second glass wafer provides multiple base elements per wafer. Each base element may include an angled surface on which a reflective material is deposited to form a mirror for reflecting laser light during use in the system.