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:
Dec. 21, 2004
Filed:
Oct. 28, 1999
Matsushita Electric Industrial Co., Ltd., Kadoma, JP;
Abstract
An optical head with high light utilization efficiency that includes a diffractive optical element and a light source emitting beams with a plurality of wavelengths that can read plural types of information recording media. A beam emitted from a light source selectively emitting a beam with a first wavelength and a beam with a second wavelength that is approximately twice as long as the first wavelength is collimated into a parallel beam by a diffraction collimator lens, is bent by a mirror for bending an optical path, and then is focused by a diffraction objective lens on an information recording medium. Outgoing light from these diffractive lenses is substantially a second-order diffraction light with respect to the beam with the first wavelength and is substantially a first-order diffraction light with respect to the beam with the second wavelength.