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:
Apr. 17, 2007
Filed:
Apr. 26, 2005
Kun Yul Kim, Seoul, KR;
Kun Yul Kim, Seoul, KR;
Daewoo Electronics Corporation, Seoul, KR;
Abstract
A holographic ROM reader having a servo control is disclosed. The holographic ROM reader includes an objective lens for focusing light reflected from a storage medium, a pinhole plate provided with a pinhole, a diffraction grating, embedded into the pinhole of the pinhole plate, for diffracting the light focused by the objective lens to produce 0order diffracted light, +1order diffracted light and −1order diffracted light therethrough, a photo detector for detecting the amounts of the 0order, the +1order and the −1order diffracted light, and a servo controller for comparing an amount of light of an overlapped area of the 0order diffracted light and the +1order diffracted light with an amount of light of an overlapped area of the 0order diffracted light and the −1order diffracted light to control the position of the objective lens to pass the light through a center of the diffraction grating if the amounts of light are not identical to each other.