Unlock instant, AI-driven research and patent intelligence for your innovation.

Diffraction element and optical disk device

A technology of diffraction elements and optical disc devices, which is applied in the direction of diffraction gratings, beam guiding devices, optical elements, etc., and can solve the problems of high diffraction efficiency and differences

Inactive Publication Date: 2006-09-27
SANKYO SEIKI MFG CO LTD
View PDF2 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, in the case of the diffraction element described in Patent Document 1, a large difference occurs in the phase of the main beam between the region having the groove portion and the flat portion where the groove portion is not formed.
Therefore, there is a problem that it is impossible to prevent the occurrence of the difference
[0006] In the case of the diffraction element described in Patent Document 2, since the duty ratio of the grating is changed, in the region where the duty ratio deviates from 50:50, the diffraction efficiency of higher orders such as 3rd, 5th, and 7th diffracted light becomes higher. There is a problem that the effect is reversed when trying to improve the laser light utilization efficiency slightly like the optical disc device for recording.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Diffraction element and optical disk device
  • Diffraction element and optical disk device
  • Diffraction element and optical disk device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0032] (overall composition)

[0033] figure 1 It is an explanatory diagram schematically showing the composition of essential parts of the optical disc device according to Embodiment 1 of the present invention.

[0034] figure 1 Among them, the optical disc device 1 of this embodiment includes a semiconductor laser 2 and a photodetector 3 that emit a laser beam having a wavelength of, for example, 650 nm. The optical disc device 1 has an optical system 40 in which a beam splitter 41 , a collimator lens 42 , an adjustment mirror 43 , and an objective lens 44 are provided from the semiconductor laser 1 to the optical recording disc 10 . These optical elements constitute a forward optical path for guiding laser light emitted from the semiconductor laser 2 to the optical recording disc 10 . The optical system 40 is also provided with a sensor lens 45 between the beam splitter 41 and the photodetector 3, and is composed of an objective lens 44, a debugging mirror 43, a collimat...

Embodiment approach 2

[0049] Figure 5 (a), (b), and (c) are a plan view, a cross-sectional view when the diffraction element is cut along the groove longitudinal direction, and a perspective view of the diffraction element used in Embodiment 2 of the present invention, respectively. Embodiments 2, 3, and 4 described below have the same basic configuration as Embodiment 1, and therefore the same parts will be described with the same reference numerals.

[0050] Such as Figure 5 As shown in (a), (b), and (c), in the optical disk device 1 of this embodiment, as in Embodiment 1, any groove portion 81 of the diffraction element 8 has a groove portion 82 sandwiched between both sides. The depth dimension d from the upper surface 820 of the protruding part 82 to the bottom 810 of the groove part 81 varies with the position.

[0051] However, in this embodiment, as in Embodiment 1, the depth dimension of any groove portion 81 changes continuously in the longitudinal direction of the groove portion 81 (...

Embodiment approach 3

[0057] Figure 6 (a), (b), and (c) are a plan view, a cross-sectional view when the diffraction element is cut along the groove longitudinal direction, and a perspective view of the diffraction element used in Embodiment 3 of the present invention, respectively.

[0058] Such as Figure 6 As shown in (a), (b), and (c), in the optical disk device 1 of this embodiment, as in Embodiment 1, any groove portion 81 of the diffraction element 8 has a groove portion 82 sandwiched between both sides. The depth dimension d from the upper surface 820 of the protruding part 82 to the bottom 810 of the groove part 81 varies with the position. That is, in any of the groove portions 81 , the bottom 810 is formed in a curved shape that is depressed at the center in the longitudinal direction, and in any of the ridge portions 82 , the upper surface 820 is flat. Therefore, in any groove portion 81, the bottom 810 of the groove portion 81 is lower than the central region 86 in the longitudinal di...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
wavelengthaaaaaaaaaa
Login to View More

Abstract

The present invention provides a diffraction element and an optical disk drive capable of improving the flexibility for setting the aperture and the optical magnification by making it possible to set the spot shape of the main beam and the diffraction efficiency as desired. In the optical disk drive 1, the diffraction element 8 for forming three beams has a high +-primary diffraction efficiency at the center area 86 in the length direction of the groove 81 and a low +-primary diffraction efficiency at both ends 87, 88. Accordingly, since the 0th light from the center area 86 loses its light intensity largely but the 0th light from both ends 87, 88 loses its light intensity less, the shape of the peak of the 0th light has raised skirts and an equivalent effect is obtained as increasing the NA. Thus, the main beam spot can be made small in diameter when focusing it on the optical recording disk 10. Further, since wasteful high order diffraction light is not generated, the sub-spot can be made large.

Description

technical field [0001] The present invention relates to a diffraction element in which grooves and ridges are alternately arranged, and an optical disk device having the diffraction element. Background technique [0002] As a composition for recording or reproducing information on an optical recording disk, various compositions have been proposed, but when any composition is adopted, the optical disk device basically has a laser source, a photodetector, and a structure that guides the laser light emitted from the laser source to the light source. The optical system for the forward path of the recording disc, and the return path for directing the return light reflected from the optical recording disc to the photodetector. Furthermore, in an optical disc device, various diffractive elements are used. [0003] For example, when the disclosed technology utilizes DPP (differential push-pull) etc. to obtain the tracking error signal, the main beam composed of 0-order light and th...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/09G11B7/135G02B5/18
CPCG02B5/1861G11B7/1353
Inventor 酒井博
Owner SANKYO SEIKI MFG CO LTD