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Objective lens and optical pickup device

A technology of optical pickup device and objective lens, which can be used in beam guiding device, optics, beam source, etc., and can solve problems such as large refractive index change and spherical aberration.

Inactive Publication Date: 2011-09-14
KONICA MINOLTA OPTO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, compared with glass objective lenses, plastic objective lenses have a large change in refractive index due to temperature changes, so there is a problem that spherical aberration is likely to occur due to temperature changes

Method used

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  • Objective lens and optical pickup device
  • Objective lens and optical pickup device
  • Objective lens and optical pickup device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0178] Table 1 shows the lens data of the objective lens Example 1. image 3 (a) is a longitudinal spherical aberration diagram (λ=405nm) of Example 1, image 3 (b) is a schematic diagram of the sine condition violation amount (λ=405nm) in Example 1. A pupil coordinate of 1.0 is equivalent to NA0.85. Figure 4 It is a schematic curve of lens tilt sensitivity in Example 1. Figure 4 The solid line, dotted line, two-dot dash line such as figure 1 described in . In this embodiment, |LTR3| / |DTR3|=1.8, |LTR3(+)| / |DTR3(+)|=0.9. The sine condition violation amount OSC is -0.013 minimum and 0.005 maximum. Among them, the refractive index change caused by the temperature of the objective lens material: dn / dT=-9×10 -5 , Wavelength change caused by temperature change of semiconductor laser: dλ / dT=0.05nm / °C, using the conditions shown in Table 2 to calculate the spherical aberration caused by temperature change and protective substrate thickness difference as the minimum magnificati...

Embodiment 2

[0188] Table 3 shows the lens data of the objective lens Example 2. Figure 5 (a) is a longitudinal spherical aberration diagram (λ=405nm) of Example 2, Figure 5 (b) is a schematic diagram of the sine condition violation amount (λ=405nm) in Example 2. A pupil coordinate of 1.0 is equivalent to NA0.85. Figure 6 It is a schematic curve of lens tilt sensitivity in Example 1. Figure 6 The solid line, dotted line, two-dot dash line such as figure 1 described in . In this embodiment, |LTR3| / |DTR3|=1.3, |LTR3(+)| / |DTR3(+)|=0.5. The minimum value of sine condition violation OSC is 0 and the maximum value is 0.007. Among them, the refractive index change caused by the temperature of the objective lens material: dn / dT=-9×10 -5 , Wavelength change caused by temperature change of semiconductor laser: dλ / dT=0.05nm / °C, using the conditions shown in Table 4, the magnification to minimize the spherical aberration caused by temperature change and thickness difference of the protective...

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Abstract

Provided is an optical pickup device which can record / reproduce information appropriately at the time of temperature change or when a multilayer disc is used. Also provided is an objective lens for use therein. Since spherical aberration resulting from a change in refractive index of an objective lens (OBJ) increases when a temperature change occurs, a finite luminous flux is made to impinge on the objective lens (OBJ) by moving a collimate lens (CL) in the direction of the optical axis by means of a uniaxial actuator (AC1), thus minimizing spherical aberration. Since spherical aberration also increases when a (BD) is a multilayer optical disc and when an interlayer jump from a layer to a second layer of a plurality of information recording surfaces takes place, the collimate lens (CL) is moved accordingly in the direction of the optical axis. In contrast, since the tilt sensitivity of the objective lens (OBJ) is increased, occurrence of third-order comatic aberration is limited effectively even when a finite luminous flux is made to impinge on the objective lens (OBJ).

Description

technical field [0001] The present invention relates to an optical pickup device for recording and / or reproducing information using a short-wavelength light source and an objective lens used therein. Background technique [0002] In recent years, along with the increase in capacity and density of optical discs, development and practical use of high-density optical discs such as Blu-ray Discs (hereinafter referred to as BDs) have progressed. In order to perform optimum recording or reproduction on a high-density optical disc with increased recording capacity, it is necessary to reduce the amount of light collected by the optical system of the optical pickup device used in the optical pickup device (hereinafter sometimes referred to as an optical information recording and reproduction device). Spot diameter. Since the spot system is proportional to λ / NA (where λ is the wavelength of the light source and NA is the numerical aperture of the objective lens), the spot diameter ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/135G02B13/00G02B13/18G11B7/125
CPCG11B7/1374G02B27/0025G11B2007/0013G11B7/13922
Inventor 户塚英和
Owner KONICA MINOLTA OPTO