Optical head, optical information storage apparatus, and their fabrication method

Abstract

A method of manufacturing an optical head includes joining of a first substrate on which a plurality of lenses are formed in an array, a second substrate on which a plurality of prisms and mirrors are formed in an array, and a third substrate on which a plurality of detectors and light sources are formed in an array, after positioning of the individual substrates, and cutting the joined substrates along the rows and columns of the array.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a divisional application of U.S. application Ser. No. 11 / 211,438, filed Aug. 26, 2005, the contents of which are incorporated herein by reference.CLAIM OF PRIORITY [0002] The present application claims priority from Japanese application JP 2005-052252 filed on Feb. 28, 2005, the content of which is hereby incorporated by reference into this application. BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to an optical head for reproducing or recording information on optical information storage media, an apparatus for reproducing and / or recording optical information, and their manufacturing method. [0005] 2. Background Art [0006] Optical disc units for CDs and DVDs are widely available examples of optical information reproducing apparatuses. In CDs, light with the wavelength of 780 nm is focused beyond a 1.2-mm thick substrate by an optical head with the numerical aperture ...

AI Technical Summary

Benefits of technology

[0017] In Patent Document 2, the objective lens is not integrated, as in Patent Document 1, and therefore this prior art is not suitable for the minimization of the optical system as a whole. Further, with regard to the prism, complex laminated prisms must be individually adjusted and affixed to a semiconductor laser / photodetector module, resulting in an increased adjustment time and manufacturing cost.

[0023] For ease of assembly and better dissipation of heat from the laser, the cavities in the prism / mirror substrate are provided by throughholes, and the semiconductor lasers are mounted on the semiconductor substrate before the prism / mirror substrate and the lens substrate are joined together.

[0029] Because the optical head of the invention is manufactured with the lenses, mirrors, prisms, light sources, and photodetectors already disposed on the wafers, and adjustments are made with reference to alignment marks or the like, ultra-small optical heads can be manufactured accurately in large quantities at low cost without requiring the handling of small components for adjustment purposes.

[0030] By causing the light beam to be incident on the detector after being reflected by the bottom and top surfaces of the prism / mirror substrate once or more, the magnification of the optical system can be increased while the thickness of the prism / mirror substrate is reduced.

Problems solved by technology

However, as the lens becomes smaller in size, other optical components must also be reduced in size, which would make it very difficult to handle such components for assembly or adjustment purposes.

In Patent Document 1, although the semiconductor laser, photodetector, and prism are combined, the objective lens is not, which is not quite advantageous in terms of minimization of the optical system.

Further, the prism must be individually affixed, resulting in a difficulty in handling and an increased time for adjustment, thereby making it difficult to achieve reduction in manufacturing cost.

In Patent Document 2, the objective lens is not integrated, as in Patent Document 1, and therefore this prior art is not suitable for the minimization of the optical system as a whole.

Further, with regard to the prism, complex laminated prisms must be individually adjusted and affixed to a semiconductor laser / photodetector module, resulting in an increased adjustment time and manufacturing cost.

In Patent Document 3, although the objective lens is integrated, the number of components is large and adjustment is difficult, such that reduction of manufacturing cost is difficult to achieve.

Particularly, it is difficult to secure sufficient positioning accuracy for the diffraction grating because it is disposed in an upright manner in the optical system.

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