Fiber optic read/write head for an optical disk memory system

Abstract

An optical read/write system is provided in which a laser diode for supplying read and write beams is mounted at a fixed location on a temperature stabilized platform. A single mode, polarizing-preserving optical fiber is connected between the read head and the diode to reduce the mass of the system. The light beam, which upon leaving the laser diodes is generally elliptical in shape, is passed through a magnifying lens before it impinges upon the receiving end of the optical fiber. This changes the generally elliptical shape of the laser beam to a generally circular shape. After passing through the optical fiber the light beam proceeds through an optical assembly which directs a portion of it onto the storage media. Some of the energy of the incoming laser light is reflected to monitoring diode which is coupled to a power control means that controls the power output of the laser. Reflected light from the storage media is also coupled to a second monitoring photo diode to detect data from the read beam that is reflected from the storage media. The write light beam after passing through a polarizing prism is transmitted through a quarter wavelength plate and a demagnifying lens, which directs the light onto the storage media. The demagnifying lens corrects the cross-sectional area of the beam so that it has a circular shape and is approximately the same size as it was upon leaving the laser diode.