• Current Optics and Photonics
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• 제6권2호
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• pp.171-182
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• 2022

A single-photon laser and mid-wave infrared (MWIR) common aperture optical system was designed and developed to detect and range a long-distance civil aviation aircraft. The secondary mirror of the Ritchey-Chretien (R-C) optical system was chosen as a dichroic lens to realize the design of a common aperture system for the laser and MWIR. Point spread function (PSF) ellipticity was introduced to evaluate the coupling efficiency of the laser receiving system. A small aperture stop and narrow filter were set in the secondary image plane and an afocal light path of the laser system, respectively, and the stray light suppression ability of the small aperture stop was verified by modeling and simulation. With high-precision manufacturing technology by single point diamond turning (SPDT) and a high-efficiency dichroic coating, the laser/MWIR common aperture optical system with a 𝜑300 mm aluminum alloy mirror obtained images of buildings at a distance of 5 km with great quality. A civil aviation aircraft detection experiment was conducted. The results show that the common aperture system could detect and track long-distance civil aviation aircraft effectively, and the coverage was more than 450 km (signal-to-noise ratio = 6.3). It satisfied the application requirements for earlier warning and ranging of long-range targets in the area of aviation, aerospace and ground detection systems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1031-1032
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• 2007

Gap servo NF (Near Field) system is one of technologies to reduce beam spot size by increasing NA (Numerical Aperture) of lens. To achieve higher NA, SIL (Solid Immersion Lens) is used. In the case of using a blue LD (405 nm) as the light source the gap distance should be controlled under 100 nm with much tighter margin. Because of very small gap distance between SIL bottom and the surface of media, relative tilt tolerance is limited. In this paper, we presented 2-axis tilt mechanism for skew adjustment within small tilt margin.

• 대한전자공학회논문지
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• 제27권12호
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• pp.1889-1893
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• 1990

In this paper, ultrasonic microscope system has been constructed with the small aperturre acoustic lens and the angle controller, and the new type of B-scanultransonic imaging has been analyzed. The system with small aperture lens was used to detect flaw existing within the thick specimen and its resolution was in the range of one wavelength at interior plane of sample. The anle controller was used to excited surface acoustic wave or shear wave. In order to obtain B-scan image of the flaw existig at interior of solids, shear wave has been excited and backscattering signals from the flaw have been processed. In experimental results, B-scan ultransonic images have been obtain from the flaws of varable shape and measured flaw size from the images has been in good agreement with practical size in the range of 10% error.

• 한국안광학회지
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• 제5권1호
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• pp.1-6
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• 2000

본 연구는 안경렌즈와 안광학계를 광학계로 이루고 있는 합성광학계에 wavelength는 3가지로 ${\omega}{\upsilon}_1=0.588{\mu}$, ${\omega}{\upsilon}_2=0.486{\mu}$ ${\omega}{\upsilon}_3=0.656{\mu}$로 하였고 Entrance Beam Radius(mm)는 1mm로 Field angle(deg)는 5.7296e-0.5, Image Aperture는 0.053055 mm, Exit Aperture는 0.903711 mm로 Reflective focal length는 25.181514 mm, Petzval radius는 -19.21839 mm, n=1.523의 조건에서 OSLO를 이용하여 spot size, focus shift, optical focus를 산출하였다. spot size는 후면곡률반경이 1 mm~30 mm까지는 0.002 mm~0.07 mm size가 다음과 같이 큰 수치로 나타났고 50 mm 이상에서는 거의 비슷한 0.0005 mm~0.002 mm가 나왔고 focus shift에서는 3가지 종류의 렌즈에서 50 mm가 focus shift가 적게 나타났고 전체적인 경향은 1 mm~15 mm 까지는 수치가 높다가 25 mm까지는 낮아지다가 다시 높아지는 양상을 보였으며 optical focus는 100 mm가 가장 좋았고 100 mm 렌즈를 후면곡률반경으로 하여 optical focus 산출하였으며 산출한 optical focus를 최적화한 결과 값이 $60{\pm}1mm$로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.874-875
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• 2008

Gap servo NFR (Near Field Recording) system is one of technologies to reduce beam spot size by increasing NA (Numerical Aperture) of lens. To achieve high NA, SIL (Solid Immersion Lens) is used. In case of using a blue LD (405 nm) as the light source the gap distance should be controlled under 100 nm with much tighter margin. To develop NFR disc drive with very small gap distance between SIL bottom and the surface of media, we need to research for the vibration characteristics and design considerations. This paper deals with a study on vibration characteristic of NFR disc drive.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.4-11
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• 2005

In this paper, we propose novel optics design for media inside near-field recording (NFR) using hemispherical solid immersion lens (HMS). To obtain strong advantage of data protection and high data capacity simultaneously, HMS based near field optics using aplanatic position of super hemisphere is designed. In this design, to improve small optical tolerance of this aplanatic position, additional aspheric lens surface is added on top of the HMS and it is combined with zoom optics which composed of two single lenses having low numerical aperture (NA). Also, to compensate chromatic aberration which happens seriously in optics using blue laser diode, diffractive optical element is used. Using zoom optics, additional aspheric lens surface, and diffractive optical element together, wavefront aberration and chromatic aberration are effectively reduced in broad range of cover layer thickness and wavelength variation. In addition, In this paper, effect of gap induced aberration is investigated by analyzing different behavior of each TM and TE wave for designed media inside dual-layer NFR optics.

• 정보저장시스템학회논문집
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• 제2권1호
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• pp.13-20
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• 2006

In this paper, we propose novel optics design for media inside near-field recording(NFR) using hemispherical solid immersion lens(HMS). To obtain strong advantage of data protection and high data capacity simultaneously, HMS based near field optics using aplanatic position of super hemisphere is designed. In this design, to improve small optical tolerance of this aplanatic position, additional aspheric lens surface is added on top of the HMS and it is combined with zoom optics which composed of two single lenses having low numerical aperture(NA). Also, to compensate chromatic aberration which happens seriously in optics using blue laser diode, diffractive optical element is used. Using zoom optics, additional aspheric lens surface, and diffractive optical element together, wavefront aberration and chromatic aberration are effectively reduced in broad range of cover layer thickness and wavelength variation. In addition, in this paper, effect of gap induced aberration is investigated by analyzing different behavior of each TM and TE wave for designed media inside dual-layer NFR optics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.629-632
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• 1989

The scattered light intensity from a spherical particle passing through the cross-over region of two coherent laser beams, varies periodically. Photodetection of this light beams produces a periodic signal of varying amplitude. The phase of the signal varies with the particle size and refractive index, the beam crossing angle and wavelength, and the position and size of the scattered ligth collecting aperture. In this paper the phase variation with respect to the particle absorptive index of retraction, collecting lens size and beam crossing angle is calculated using both Mie scattering theory and reflection theory. The two theories show good agreement in phase predictions, especially for large absorptive indices and for small collection lenses. Both theories predict phase to be inversely proportional to the beam crossing angle.

• 한국광학회지
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• 제19권2호
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• pp.87-94
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• 2008

공초점 내시 현미경의 경우 살아있는(in vivo) 동물체들의 뇌 속에서의 암세포나 특정 세포를 분석할 수 있으며, 비 침습적으로 얻을 수 있는 기술과 동시에 실시간으로 암을 검출할 수 있는 장점이 있다. 공초점 내시 현미경의 경우 최소 직경과 고 분해능을 요하게 된다. 본 논문은 최소 직경을 가지는 GRIN 렌즈와 유동적으로 움직일 수 있는 광섬유 다발을 연결시킴으로써 보다 측정에 용이하도록 하였다. 직경이 1 mm이고 수치구경이 0.5이며 pitch가 0.25인 GRIN렌즈를 사용하였으며, 광섬유 다발은 30,000개의 코어로 구성된 유동적인 광섬유 다발을 사용하였다. 본 논문은 GRIN 렌즈에 의해서 발생되었던 구면수차는 광학보상자를 이용하여 보정하였다. 그 결과 설계되어진 공초점 내시 현미경 대물렌즈의 경우 종 분해능은 $1.63\;{\mu}m$이고 축상물점과 비축물점에서의 에너지 분포가 100%일 때 각각의 spot size는 축상물점에서 $0.3\;{\mu}m$ 비축물점에서 $0.83\;{\mu}m$의 결과를 얻었으며 보다 값싸고 제작에 용이한 양산 비구면 렌즈로 대체 구현된 결과에서는 종 분해능이 $1.74\;{\mu}m$이고, 축상 물점에 대한 spot size는 $1.1\;{\mu}m$이고 비축물점에서는 spot size가 $2.94\;{\mu}m$로 설계되었다.

• 한국컴퓨터그래픽스학회논문지
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• 제30권2호
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• pp.11-19
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• 2024

최근 방위 산업에서는 전시상황에서 병사의 전투력 및 생존성 증대를 위하여 지하 공간, 좁은 통로등에서 적에게 노출되지 않으며 정찰임무를 수행할 수 있는 소형 생체 모방 로봇의 수요가 늘어나고 있다. 특히 소형생체 모방 로봇에 사용 가능한 생체모방 영상 센서에 대한 연구가 많이 진행되고 있다. 그중 복안영상센서는 작은 크기, 적은 수차, 넓은 화각 등의 장점을 갖으며, 복안영상센서를 통해 출력된 복안 영상을 이용해 깊이 추정, HDR 등을 구현 하여 다양한 임무에서 활용 가능하다. 다만 복안영상은 작은 렌즈 크기와 렌즈의 구조로 인하여 영상의 품질이 저하되는 현상이 발생한다. 특히 복안영상으로 출력된 각 Sub-Aperture 이미지를 융합 시 이미지 품질이 많이 저하된다. 본 논문은 이미지 융합 시 이미지의 품질이 저하되는 문제를 극복하기 위하여 여러 이미지 개선 기능과 생성 신경망의 한 종류인 ESRGAN를 사용하여 복안영상 품질 향상 알고리즘을 제안한다. 본 논문에서 제안한 알고리즘은 이미지 전처리부, 이미지 융합부, 이미지 개선 부로 구성된다. 제안한 알고리즘을 복안 영상에 적용하면 영상 품질을 높힐 수 있어, 복안 영상을 이용한 다양한 연구에 활용될 수 있다.