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Objective lens for light pickup device-use and light pickup device

A technology of optical pickup device and objective lens, applied in the directions of beam guiding device, optics, optical components, etc., can solve the problem of increasing spherical aberration, etc., and achieve the effect of small amount of movement

Inactive Publication Date: 2012-08-15
KONICA MINOLTA OPTO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the NA of the light beam when recording / reproducing information is as large as 0.85, in a BD having a plurality of information recording surfaces, there is a problem that if the minimum spherical aberration is to be given to one information recording surface, the Spherical aberration increases on other information recording surfaces with different thicknesses of transparent substrates, making it impossible to properly record / reproduce information

Method used

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  • Objective lens for light pickup device-use and light pickup device
  • Objective lens for light pickup device-use and light pickup device
  • Objective lens for light pickup device-use and light pickup device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1）

[0348] Table 2 shows the lens data of Example 1. This embodiment is a multi-layer BD with more than 3 layers (T MAX =0.1mm, T MIN =0.05mm) for the plastic objective lens, set T=0.075mm (corresponding to d4 in the reference state). Figure 7 Showing the spherical aberration and the sinusoidal conditional curve of embodiment 1, Figure 8 A first-order differential curve of the aspherical shape in the optical disc-side optical surface of Example 1 is shown. Such as Figure 7 As shown, in the objective lens of Example 1, the sinusoidal condition violation amount OSC has a positive maximum value at a position of 84% of the effective radius. On the other hand, the sinusoidal condition violation amount OSC does not have a negative maximum value.

[0349] [Table 2]

Embodiment 1

[0351] paraxial volume

[0352]

[0353] variable

[0354]

baseline status

Transparent substrate thickness max.

Maximum transparent substrate thickness + high temperature

Minimum transparent substrate thickness

magnification

0.0000

-0.0079

-0.0107

0.0086

temperature

25

25

55

25

d0

∞

180.00000

133.50000

-163.00000

d4

0.075

0.100

0.100

0.050

N2

1.561516

1.561516

1.558517

1.561516

[0355] Aspheric coefficient

[0356]

Embodiment 2）

[0358] Table 3 shows the lens data of Example 2. This embodiment is compatible with multi-layer BD (T MAX =0.1mm, T MIN =0.05mm) for a plastic objective lens, set T=0.080mm (corresponding to d4 in the reference state). Figure 9 Showing the spherical aberration and the sinusoidal conditional curve of embodiment 2, Figure 10 A first-order differential curve of the aspherical shape in the optical surface on the disc side of Example 2 is shown. Such as Figure 9 As shown, in the objective lens of Example 2, the sinusoidal condition violation amount OSC has a positive maximum value at a position of 85% of the effective radius. On the other hand, the sinusoidal condition violation amount OSC does not have a negative maximum value.

[0359] [table 3]

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Abstract

Disclosed are an objective lens for light pickup device-use and a light pickup device that are compact and of low cost, while being capable of performing recording and / or reproduction of information for an optical disk having a multi-layer information recording surface. For the objective lens and the light pickup device, assuming a maximum transparent substrate thickness among transparent substrate thicknesses of an optical disk to be TMAX (mm), in a transparent substrate thickness T (mm) satisfying equation (1) below, the magnification M when the spherical aberration ([lambda]rms) is minimized satisfies equation (2) below, wherein at the magnification M, for between 70 percent and 90 percent of the effective radius, an offense against sine condition has a positive local maximum: (1) TMAX*0.85 = <T< = TMAX*1.1, (2) -0.003 =< M <= 0.003

Description

technical field [0001] The present invention relates to an objective lens for an optical pickup device capable of recording and / or reproducing information on an optical disc having three or more information recording surfaces in the thickness direction, and an optical pickup device. Background technique [0002] A known high-density optical disc system uses a blue-violet semiconductor laser with a wavelength of about 400 nm to record and / or reproduce information (hereinafter, "recording and / or reproduction" is described as "recording / reproduction"). For an example of an optical disc with NA 0.85 and a light source wavelength of 405nm for information recording / reproduction, the so-called Blu-ray Disc (Blu-ray Disc, hereinafter referred to as BD), for DVD (NA0.6, light source wavelength 650nm, storage capacity 4.7GB) is the same size as an optical disc with a diameter of 12cm, which can record 25GB of information per layer. [0003] However, most of the conventional BDs have ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/1374G02B13/12G02B13/18G11B7/135
CPCG02B13/18G11B7/1374G11B2007/0013
Inventor 木村彻小野雄树
Owner KONICA MINOLTA OPTO