• Optical Science and Technology
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• v.8 no.2
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• pp.22-26
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• 2004

회절 광학 소자(Diffractive optical element)는 광학 시스템에 있어서 광을 조절하기 위하여 굴절(refraction) 또는 반사(reflection)보다는 주기 구조(periodic structures)에 의한 회절(diffraction)을 이용한 소자라 할 수 있다. DOE의 장점으로는 수차(aberration)가 없는 point-to-point 이미지가 가능하며 광 power를 사용한 평판(flat subface)이 가능하고 비구면과 같은 수차 조절이 가능하다. 단점으로는 HOE(Hologram Optical Element: DOE의 일종)의 수차가 이 구조의 특정 파장에서 나타나고 가시영역의 일정 영역에서 매우 분산적 (dispersive)이다. 또한 상대적으로 시장의 성장에 비하여 찾는 고객의 수가 적다는 점이다.(중략)

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.98-99
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• 2002

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.3-8
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• 2006

The demand fer small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased by using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable fur mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-replication process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the surface profiles of master, mold and molded pattern were measured by optical scanning profiler. The geometrical deviation between the master and the molded DOE was less than $0.1{\mu}m$. The diffraction efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was $84.5\%$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.45-46
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• 2013

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.35-40
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• 2005

The demand for small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable for mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-molding process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the shapes of master, mold and molded pattern were measured by optical scanning profiler. The deviation between the master and the molded DOE was less than 0.1um. The efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was $84.5\%$.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.105-111
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• 2006

A novel image quality evaluation method, which is based on combination of the rigorous grating diffraction theory and the ray-optic method, is proposed. It is applied for design optimization and, tolerance analysis of optical imaging systems implementing diffractive optical elements (DOE). The evaluation method can predict the quality and resolution of the image on the image sensor plane through the optical imaging system. Especially, we can simulate the effect of diffraction efficiencies of DOE in the camera lenses module, which is very effective for predicting different color sense and MTF performance. Using this method, we can effectively determine the fabrication tolerances of diffractive and refractive optical elements such as the variations' in profile thickness, and the shoulder of the DOE, as well as conventional parameters such as decenter and tilt in optical-surface alignments. A DOE-based 2M-resolution camera lens module designed by the optimization process based on the proposed image quality evaluation method shows ${\sim}15%$ MTF improvement compared with a design without such an optimization.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.117-124
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• 2007

In order to operate CD and DVD compatibly in a pickup system, the objective lens comprise diffractive optical element(DOE) zone and aspheric curvature on its lens surface. The DOE objective lens is effective to simplify this dual-purpose pickup system of the 655nm and 785nm wavelength by using only one lens, but requires more precision manufacturing process and system due to the complicated shape. This paper presents the overall manufacturing process of this objective lens and describes main parameters in each process, for the correction of the aspheric surface in its core, the shrinkage compensation after injection molding, and the uniformity compensation by adjusting molding conditions.

• Current Optics and Photonics
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• v.8 no.1
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• pp.72-79
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• 2024

Recent flat-panel displays have become increasingly complicated to facilitate multiple display functions. In particular, the form of multilayered architectures for next-generation displays makes precise three-dimensional alignment of multiple panels a challenge. In this paper, a diffractive optical alignment marker is proposed to address the problem of three-dimensional alignment of distant dual panels beyond the depth-of-focus of a vision camera. The diffractive marker is effective to analyze the positional correlation of distant dual panels. The possibility of diffractive alignment in multilayer display fabrication is testified with numerical simulation and a proof-of-concept experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1810-1817
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• 2004

A diffractive optical element(DOE) for an optical pickup system is proposed in this thesis. Optimization algorithms are used to synthesise the DOE to meet a detailed specification of the two kind of cost function. The one isso called as apodization which refers to the process of suppressing the secondary maxima and the other is so called as sharpness which refers to the process of reducing the size of primary maxima. The result obtained by simplex optimization method is that the apodization and sharpness are well achieved separately. In apodization, the secondary maxima is reduced up to 39%. And in sharpness, the size of first maxima is reduced to 95.2％.

• Journal of the Optical Society of Korea
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• v.1 no.2
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• pp.74-80
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• 1997

300mm F/4.0 telephotolens with diffractive hybrid lens was designed, and its optical performance was tested and compared with a traditional lens system. DOE(Diffractive Optical Element) reconstructs wavefronts using wave phenomena of light to focus the incident light onto the focal point and has negative Abbe number while a traditional lens uses geometrical phenomena of light and has positive Abbe number. Therefore, a diffractive hybrid lens containing both refractive and diffractive elements can remarkably correct chromatic aberration and spherical aberration of an optical system. We investigated and analyzed the optical properties of a diffractive hybrid lens for the visible spectrum, and we used a difractive hybrid lens to design and evaluate a 300mm F/4.0 telephotolens without the special LD(Low Dispersive) glass lens which is costly and difficult to manufacture. Most traditional telephotolenses use the special LD glass for chromatic aberration correcton. Optical performance tests such as resolution and characteristics of aberration of both lens systems using a diffractive hybrid lens and traditional lens were performed.