KR20010068324A - Light head structure of near field recording and reproducing system - Google Patents

Light head structure of near field recording and reproducing system Download PDF

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Publication number
KR20010068324A
KR20010068324A KR1020000000180A KR20000000180A KR20010068324A KR 20010068324 A KR20010068324 A KR 20010068324A KR 1020000000180 A KR1020000000180 A KR 1020000000180A KR 20000000180 A KR20000000180 A KR 20000000180A KR 20010068324 A KR20010068324 A KR 20010068324A
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South Korea
Prior art keywords
light
objective lens
near field
lens
sil
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KR1020000000180A
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Korean (ko)
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KR100632507B1 (en
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박건순
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구자홍
엘지전자 주식회사
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1387—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector using the near-field effect
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1374—Objective lenses
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1381—Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B2007/13727—Compound lenses, i.e. two or more lenses co-operating to perform a function, e.g. compound objective lens including a solid immersion lens, positive and negative lenses either bonded together or with adjustable spacing

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Head (AREA)

Abstract

PURPOSE: An optical head of near field optical recording/regeneration apparatus is provided to improve data recording density and to increase efficiency by realizing grating area at the lower side of an objective lens and reducing intensity and beam spot size of evanescent light to be generated from SIL. CONSTITUTION: An objective lens(21) focuses light. A SIL(solid immersion lens)(22) generates receives the focus light and generates an evanescent light(23). A grating is formed at the lower side of the objective lens(21). The grating is formed in a direction to enlarge reflection angle of beam that is made an incidence through the objective lens(21). The objective lens(21) and the solid immersion lens(22) are able to be formed at one of mechanism. A beam shield film is adhered on the solid immersion lens(22) as a film to obstruct permeation of light.

Description

근접장 광 기록/재생 장치의 광 헤드 {Light head structure of near field recording and reproducing system}Light head structure of near field recording and reproducing system

본 발명은 근접장 광 기록 재생 장치에 관한 것으로, 특히 광 빔의 스폿 사이즈를 줄여주는 개선된 대물렌즈를 포함한 광헤드 구조에 관한 것이다.The present invention relates to a near field optical recording and reproducing apparatus, and more particularly to an optical head structure including an improved objective lens that reduces the spot size of a light beam.

현재까지 광을 이용한 데이타의 기록은 대물렌즈를 이용하여 레이저 빔을 기록막을 갖고 있는 디스크에 집광시켜 신호를 기록 및 재생하는 형태로 발전되었다. 그간 더 많은 기록 용량이 요구됨에 따라 한장의 디스크에 더 많은 정보를 담기 위해 가능하면 레이저 빔을 모아 빔의 스폿을 작게 만드는 일이 진행되어 왔다.Until now, recording of data using light has been developed in the form of recording and reproducing signals by condensing a laser beam onto a disk having a recording film using an objective lens. In the meantime, as more recording capacity is required, work has been made to collect laser beams to make spots of the beams as small as possible in order to contain more information on a single disc.

빔의 스폿을 줄이기 위해서는 대물렌즈의 개구수(Numerical Aperture)를 키우는 방법과 단파장의 레이저를 사용하는 방법이 있고, 빔의 크기와 무관하게 크로스토크(Cross-talk)를 보상해 트랙간 거리를 감소시키는 방법 및 에러보상법의 개선등으로 기록밀도를 높이려는 시도가 계속 진행되고 있다.In order to reduce the spot of the beam, there is a method of increasing the numerical aperture of the objective lens and using a short wavelength laser, and reducing the distance between tracks by compensating crosstalk regardless of the beam size. Attempts have been made to increase the recording density due to improvements in the method and the error compensation method.

그러나, 대물렌즈를 이용하여 스폿을 만드는데는 빛의 회절한계 때문에 그 크기를 줄이는데 한계가 있고, 개구수를 키우면 빛의 초점 심도가 작아지게 되어 포커싱하는데 어려움이 따르는 등 여러 문제점을 갖고 있다.However, there are limitations in making spots by using an objective lens because of the diffraction limit of light, and the size of the spot is limited. Increasing the numerical aperture reduces the depth of focus, which makes it difficult to focus.

이에 따라, 최근에는 SIL을 이용하여 빔의 스폿 크기를 SIL의 굴절률 이상만큼 감소시킬 수 있는 기술이 개발되어 기록밀도를 획기적으로 높이는데 도움을 주고 있으며, SIL과 기록층이 광의 근접장 내에 있어야 하므로, 이를 근접장 기록(Near Field Recording)이라 부르고 있다. 근접장 광 기록 재생 광학계의 원리는 다음과 같다. 렌즈 내부로 임계각 이상의 각도를 갖고 입사하는 빛은 굴절률이 밀한 곳에서 소한 곳으로 진행할 때, 내부에서 빛이 그 다음 경로로 진행하지 않고 전반사된다. 이 때, 빛의 전반사에 의해서 렌즈의 표면에는 아주 미세한 세기의 광이 존재하는데, 이를 에버네슨트 웨이브(Evanescent Wave)혹은 소산파라고 한다. 이러한 에버네슨트 웨이브를 이용하면, 기존의 원격장(Far Field)에서는 빛의 회절 현상때문에 나타나는 분해능의 절대적인 한계, 즉 회절 한계 때문에 불가능했던 고분해능이 가능하게 된다. 기본적으로 근접장 광은 빛의 파장보다 훨씬 작은 영역에 국한되어 존재하므로 불확정성의 원리에 의해 그 물리적 성질이 원격장과는 전혀 다르게 된다. 근접장 광 기록 재생 및 재생 광학계는 렌즈내에서 빛을 전반사시켜 렌즈 표면에 에버네슨트 웨이브를 발생시키고,에버네슨트 웨이브와 디스크의 커플링에 의하여 기록 및 재생을 하게 된다.Accordingly, recently, a technology that can reduce the spot size of the beam by using the SIL by more than the refractive index of the SIL has been developed to help significantly increase the recording density. Since the SIL and the recording layer must be in the near field of light, This is called near field recording. The principle of the near field optical recording and reproducing optical system is as follows. Light entering the lens at an angle greater than or equal to the critical angle is totally reflected inside the light instead of traveling to the next path as the refractive index progresses from the dense place to the small place. At this time, due to the total reflection of light, a very small intensity of light exists on the surface of the lens, which is called an Evanescent wave or dissipation wave. The use of such evernet wave enables high resolution, which is impossible due to the absolute limit of resolution due to the diffraction phenomenon of light in the far field. Basically, near-field light exists in a region much smaller than the wavelength of light, so the physical properties of the field are very different from the remote field due to the principle of uncertainty. Near-field optical recording reproduction and reproduction optical systems totally reflect light in the lens to generate an Evernet wave on the surface of the lens, and record and play back by coupling the Evernet wave to a disk.

도 1은 대물렌즈 및 SIL을 포함한 근접장 광 기록 재생 장치의 대물렌즈와 SIL의 개략도를 도시한 도면이다. 도면에 도시된1은 임계각을 나타낸 것으로, 임계각1이상의 각도를 갖고 입사되는 A 영역의 광은 SIL 렌즈의 하면에서 전반사되고, 이때 SIL 렌즈의 하면에서는 상기 언급한 바와 같은 미세한 에버네슨트 광 E 가 발생하게 된다.1 이하의 각으로 입사되는 B영역의 광은 SIL의 하면에서 전반사되지 않고 여러각도로 난반사됨으로써, 데이타의 기록 재생에 영향을 주는 노이즈로 작용하게 된다.2는 대물렌즈에서 입사되는 전체 내부 반사각(Total Internal Reflection Angle)을 나타낸다.1 is a diagram showing a schematic diagram of an objective lens and a SIL of a near field optical recording and reproducing apparatus including an objective lens and a SIL. Shown in the drawings 1 represents the critical angle, which is the critical angle The light of region A incident at an angle of 1 or more is totally reflected at the lower surface of the SIL lens, and at this time, the fine Evernet light E as described above is generated at the lower surface of the SIL lens. Light of the B area incident at an angle of 1 or less is not reflected at the lower surface of the SIL but is diffusely reflected at various angles, thereby acting as a noise that affects the recording and reproduction of data. 2 represents the total internal reflection angle incident from the objective lens.

그러나,이러한 방식의 근접장 광 기록 재생 장치에서도 아직도 해결해야 할 많은 과제를 안고 있다. 그 중, 중요한 문제의 하나는 대물렌즈를 통해 SIL로 입사되는 모든 광을 이용하지 않고 SIL 내에서 전반사되어 발생한 아주 미약한 강도를 갖는 에버네슨트 광만을 이용하므로, 근접장 광학계에서는 기록 재생을 위한 광의 강도를 증가시키는 일이 무엇보다 중요하다 할 수 있다. 즉, 도 1에 도시된 바와 같이, A 영역의 광을 증대시킨다면 SIL 렌즈에 맺히는 빔 스폿의 크기가 한결 줄어들 뿐 아니라 이때 발생하는 에버네슨트 광으 강도도 증대되고, 에버네슨트 빔 스폿의 크기도 줄어들어 종래기술보다 고밀도의 데이타를 효율적으로 기록할 수 있게 된다.However, such a near field optical recording and reproducing apparatus still has many problems to be solved. One of the important problems is that it does not use all the light incident to the SIL through the objective lens, but uses only Evernet light having a very small intensity generated by total reflection in the SIL. Increasing strength is of paramount importance. That is, as shown in FIG. 1, increasing the light in the A region not only reduces the size of the beam spot formed on the SIL lens but also increases the intensity of the aberrant light generated at this time, and also the size of the abernant beam spot. It is possible to record more dense data more efficiently than the prior art.

본 발명의 목적은 근접장 광 기록 재생 장치에서 기록/재생에 사용되는 빔의 강도를 증가시키고,또한 SIL 내부에 형성되는 빔 스폿 크기를 줄여 기록 데이타 밀도를 향상시키는 수단을 제공하는 데 있다.It is an object of the present invention to provide a means for increasing the intensity of a beam used for recording / reproducing in a near field optical recording / reproducing apparatus, and for improving the recording data density by reducing the beam spot size formed inside the SIL.

도 1은 근접장 광 기록 재생 장치의 대물렌즈와 SIL의 개략도를 도시한 도면.1 is a schematic diagram of an objective lens and a SIL of a near field optical recording and reproducing apparatus.

도 2는 근접장 광 기록 재생 장치에서 본 발명에 따른 대물렌즈와 SIL의 개략도를 도시한 도면2 is a schematic diagram of an objective lens and a SIL according to the present invention in a near field optical recording and reproducing apparatus;

** 도면의 주요 부분에 대한 부호의 설명**** Explanation of symbols for the main parts of the drawings **

11 : 통상적인 대물렌즈 12,22 : 솔리드 이멀젼 렌즈(SIL)11: conventional objective lens 12,22: solid emulsion lens (SIL)

21 : 그레이팅이 형성된 대물렌즈21: objective lens with grating

13,23 : 에버네슨트 광13,23: Everness light

상기와 같은 목적을 달성하기 위해, 본 발명은 대물렌즈를 통해 SIL에 입사되는 광의 강도를 증가시키고, 기록되는 데이타의 밀도를 증대시키기 위한 개선된 대물렌즈를 채용한 근접장 광 기록 재생 장치를 제공하는 것을 특징으로 한다.In order to achieve the above object, the present invention provides a near field optical recording and reproducing apparatus employing an improved objective lens for increasing the intensity of light incident on the SIL through the objective lens and increasing the density of the data to be recorded. It is characterized by.

상기와 같은 특징을 갖는 본 발명의 바람직한 실시예를 첨부된 도면을 참조하여 설명하면 다음과 같다.Referring to the accompanying drawings, preferred embodiments of the present invention having the features as described above are as follows.

도 2 는 본 발명에 따른 SIL렌즈를 도시한 도면이다.3은 도 1에 도시한 바와 같은 임계각이고4는 역시 도 1에 도시된 바와 같은 전체 내부 반사각을 나타낸다. 본 발명에 따르는 대물렌즈의 하면에는 도면에 도시한 바와 같이 그레이티(Grating)이 형성된다. 근접장 기록 재생 장치의 광원에서 입사되어 광학계를 거쳐 대물렌즈를 통과한 빛은 상기 대물렌즈의 하면에 형성된 그레이팅 영역에서 빛의 반사각도가 한층 더 커지게 된다. 따라서, 도면에 도시한 바와 같이4의 영역이 도 1에 도시한2의 영역보다 한층 더 커지게 되고, SIL의 하면에서 전반사되는 입사광 영역인 A 영역이 도 1에 도시한 종래 장치에 따른 영역보다 확대되어, 실제 에버네슨트 광을 발생시키는 광의 강도가 증가하게 되므로, 본 발명에 따른 SIL에서 발생하는 에버네슨트 광의 강도가 증가하게 되어, 데이타의 기록 재생 효율을 향상시키게 된다. 또한,상기 그레이팅을 형성함으로써, 대물렌즈와 SIL사이의 거리를 종래기술에 따른 거리에 비해 더욱 짧게 유지하는 것이 가능해짐으로써, SIL하면에 맺히는 광의 빔 스폿 크기가 작아지게 되고, 이에 따라 SIL하면에서 디스크 방향으로 발생하는 에버네슨트 광의 빔 스폿 크기도 작아지게 되어 고밀도 데이타 기록 재생이 가능하게 되며, 또한 상기 대물렌즈와 SIL을 일체형으로 헤드 슬라이더에 형성할 수 있음으로서, 그만큼 헤드 슬라이더의 크기를 줄일 수 있게 된다.2 is a view showing a SIL lens according to the present invention. 3 is the critical angle as shown in FIG. 4 also represents the total internal reflection angle as shown in FIG. 1. Grating is formed on the lower surface of the objective lens according to the present invention as shown in the drawing. The light incident from the light source of the near field recording / reproducing apparatus and passing through the objective lens has a larger reflection angle of light in the grating area formed on the lower surface of the objective lens. Therefore, as shown in the figure The area of 4 is shown in FIG. The area A becomes larger than the area 2, and the area A, which is the incident light area totally reflected from the lower surface of the SIL, is enlarged than the area according to the conventional apparatus shown in FIG. 1, so that the intensity of the light that generates the actual evernet light is increased. In addition, the intensity of the Evernet light generated in the SIL according to the present invention is increased, thereby improving data recording and reproducing efficiency. In addition, by forming the grating, it is possible to keep the distance between the objective lens and the SIL shorter than the distance according to the prior art, so that the beam spot size of the light formed on the lower surface of the SIL becomes smaller, and thus, at the lower surface of the SIL. The beam spot size of the Evernet light generated in the disc direction is also reduced, enabling high-density data recording and reproducing. Also, the objective lens and the SIL can be integrally formed on the head slider, thereby reducing the size of the head slider. It becomes possible.

이상에서 설명한 바와 같이, 본 발명에 따른 근접장 광 기록 재생 장치는 대물렌즈의 하면에 그레이팅 영역을 구현하여 SIL에 입사되는 빔 스폿을 줄이고, 또한 SIL에 입사되는 빔의 강도를 증대시켜, 실질적으로 SIL에서 발생하는 에버네슨트 광의 강도 및 빔 스폿 사이즈를 줄임으로써 데이타 기록밀도의 향상 및 효율을 증대시킬 수 있는 효과가 있다.As described above, the near field optical recording and reproducing apparatus according to the present invention implements a grating area on the lower surface of the objective lens to reduce the beam spot incident on the SIL, and also increases the intensity of the beam incident on the SIL, thereby substantially reducing the SIL. By reducing the intensity and the beam spot size of the abernegent light generated in the PDP, the data recording density can be improved and the efficiency can be increased.

Claims (5)

광을 집속시키는 대물렌즈와 상기 집속광을 수신하여 에버네슨트 광을 발생시키는 솔리드 이멀젼 렌즈를 포함하여 구성된 근접장 광 기록 재생 장치의 광 헤드 구조에 있어서,In the optical head structure of a near field optical recording and reproducing apparatus, comprising: an objective lens for focusing light; and a solid emulsion lens for receiving the focused light to generate everbergent light. 상기 대물렌즈의 하면에 그레이팅(Grating)이 형성된 것을 특징으로 하는 근접장 광 기록 재생 장치의 광 헤드Grating is formed on the lower surface of the objective lens, the optical head of the near field optical recording and reproducing apparatus 제 1항에 있어서,The method of claim 1, 상기 그레이팅은 대물렌즈를 통해 입사된 빔의 반사각도를 증대시키는 방향으로 형성된 것을 특징으로 하는 근접장 광 기록 재생 장치의 광 헤드The grating is an optical head of a near field optical recording and reproducing apparatus, wherein the grating is formed in a direction of increasing the reflection angle of the beam incident through the objective lens. 제 1 항에 있어서,The method of claim 1, 상기 대물렌즈와 상기 솔리드 이멀젼 렌즈는 하나의 기구물에 형성될 수 있는 것을 특징으로 하는 근접장 광 기록 재생 장치의 광 헤드The optical head of the near field optical recording and reproducing apparatus, wherein the objective lens and the solid emulsion lens may be formed in one apparatus. 제 1 항에 있어서,The method of claim 1, 상기 빔 차단막은 빛의 투과를 저지하는 필름제로 상기 솔리드 이멀젼 렌즈상에 부착된 것을 특징으로 하는 근접장 광 기록 재생 장치The beam blocking film is a near field optical recording and reproducing apparatus, wherein the beam blocking film is attached to the solid emulsion lens by a film that blocks light transmission. 제 2 항에 있어서,The method of claim 2, 상기 환형 빔 차단막의 중심부에 해당하는 상기 솔리드 이멀젼 렌즈 부분에는 빔 스폿이 형성되고, 상기 중심부 이외의 빔 차단막 부분에서는 입사되는 빔을 차단하는 것을 특징으로 하는 근접장 광 기록 재생 장치.And a beam spot is formed at a portion of the solid emulsion lens corresponding to the center of the annular beam blocking film, and blocks an incident beam at a portion of the beam blocking film other than the center.
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