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Lens system for scanning device

A lens system and lens technology, applied in the field of lens systems

Inactive Publication Date: 2009-09-23
KONINK PHILIPS ELECTRONICS NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This displacement cannot be compensated by the focus servo system of the scanning device, because the response time of this servo system is much greater than the short time interval between read and write states

Method used

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  • Lens system for scanning device
  • Lens system for scanning device
  • Lens system for scanning device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0032] figure 1 A first embodiment of a device 1 for scanning an optical record carrier 2 is shown. The record carrier comprises a transparent layer 3 on one side of which an information layer 4 is arranged. The side of the information layer facing away from the transparent layer is protected from environmental influences by a protective layer 5 . The side of the transparent layer facing the device is called the entrance face 6 . The transparent layer 3 acts as a substrate for the record carrier by providing mechanical support for the information layer.

[0033] Alternatively, the transparent layer may only have the function of protecting the information layer, while mechanical support is provided by a layer on the other side of the information layer, for example by a protective layer 5 or by another information layer and the information layer. Layer 4 is connected to the transparent layer to provide mechanical support. The record carrier may comprise two or more informati...

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Abstract

A lens system includes a lens (18) and a non-periodic phase structure (16). A temperature-dependence of the spherical aberration of the lens is compensated by a temperature dependence of the spherical aberration of the non-periodic phase structure. A wavelength-dependence of the defocus of the lens is compensated by a wavelength- dependence of the defocus of the non-periodic phase structure. A wavelength-dependence of the spherical aberration of the non-periodic phase structure is compensated by a wavelength- dependence of the spherical aberration of the lens.

Description

field of invention [0001] The invention relates to a lens system for focusing a radiation beam on an information layer of an optical record carrier. The invention also relates to an optical head comprising such a lens system and a scanning device comprising such an optical head. Background technique [0002] In the field of optical recording, an increase in the information density of a record carrier is accompanied by a corresponding decrease in the size of the radiation spot used to scan the record carrier. The reduction in spot size is achieved by a shorter wavelength and larger numerical aperture (NA) of the radiation beam incident on the record carrier. The compact disk (CD) system uses a wavelength of 780 nm and a numerical aperture of 0.45. Digital Versatile Disk (DVD) systems have higher information density and use a wavelength of 640 nm and a numerical aperture of 0.65. The recent move towards even higher information densities has led to Blu-ray Disc (BD) systems ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/135G11B7/125
CPCG11B7/1353G11B7/1372G11B2007/0006G11B7/1275G11B7/13922
Inventor H·M·J·布茨S·斯塔林加
Owner KONINK PHILIPS ELECTRONICS NV