The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 30, 1996
Filed:
Jul. 28, 1995
Shohei Kobayashi, Hachioji, JP;
Olympus Optical Co., Ltd., Tokyo, JP;
Abstract
An optical head for reading and/or writing information from and/or from a magneto-optical record medium including a semiconductor laser, a composite prism having a glass prism, a birefringent prism and a dielectric multilayer film interposed between the glass prism and birefringent prism, an objective lens and fist and second photodetectors. A laser beam emitted by the semiconductor laser impinging upon the glass prims is reflected by the dielectric film and is projected onto the record medium by the objective lens. A return beam reflected by the record medium is incident upon the dielectric film via the objective lens, and a part of the return beam transmitted through the dielectric film is separated by the birefringent prism into a first ordinary beam and a second extraordinary beam which are received by the first and second photodectors, respectively. The glass prism and birefringent prism are made of materials which satisfy a condition that a difference between refractive indices of the birefringent prism for ordinary light and extraordinary light is not less than 0.03 and a difference between a refractive index of the glass prism and at least one of the refractive indices of the birefringent prism is not less than 0.15.