Objective lens for optical pick-up

Details Objective lens for optical pick-up Objective lens for optical pick-up

2005-03-29

2005-03-29

Hindi, Nabil (Department: 2655)

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

Reexamination Certificate

active

06873590

ABSTRACT:
Disclosed is an objective lens of an optical pick-up that converges light beams of two different wavelengths onto recording layers of optical discs of two different recording densities, respectively. The objective lens includes a refractive lens whose one surface is divided into a common area through which a light beam of a low NA, which is necessary and sufficient for an optical disc having low recording density, passes and a high NA exclusive area through which a light beam of a high NA, which is necessary only for an optical disc having high recording density, passes. A diffractive lens structure is formed in both the areas. The diffractive lens structure in the common area maximizes the diffraction efficiency of the first order and that in the high NA exclusive area maximizes the diffraction efficiency of the second or third order at the wavelength corresponding to the optical disc having high recording density.

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patent: 6088322 (2000-07-01), Broome et al.
patent: 6118594 (2000-09-01), Maruyama
patent: 6191889 (2001-02-01), Maruyama
patent: 6344935 (2002-02-01), Maruyama
patent: 6667943 (2003-12-01), Maruyama et al.
patent: 20010008513 (2001-07-01), Arai et al.
patent: 1102251 (2001-05-01), None
patent: 1-338431 (2001-12-01), None

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