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다중 패턴의 회절광학소자 제작을 위한 레이저 직접 노광시스템의 공정 연구
김영광,이혁교,김영식,이윤우 한국반도체디스플레이기술학회 2019 반도체디스플레이기술학회지 Vol.18 No.2
Diffractive Optical Elements(DOEs) diffracts incident light using the diffraction phenomenon of light to generate a desired diffraction image. In recent years, the use of diffraction optics, which can replace existing refractive optical elements with flat plates, has been increased by implementing various optical functions that could not be implemented in refractive optical devices and by becoming miniaturized and compacted optical elements. Direct laser lithography is typically used to effectively fabrication such a diffractive optical element in a large area with a low process cost. In this study, the process conditions for fabricating patterns of diffractive optical elements in various shapes were found using direct laser lithographic system, and optical performance evaluation was performed through fabrication.
자동차 배기계용 머플러 MIG 용접에 의한 미세조직 변화 및 열 변형 해석에 관한 연구
이승호(Seung Ho Lee),김억수(Eok Soo Kim),박진영(Jin-Young Park),최준(Jun Choi) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.5
Metal inert gas (MIG) welding is commonly used for automotive muffler assembly. However, the thermal deformation caused by high temperature leads to dimensional problems of the muffler fabrication. Therefore, the welding deformation has to be predicted prior to the actual welding process to improve the quality of welded structures. In this study, the prediction for the thermal deformation of the automotive muffler was modeled by using SYSWELD software. A heat source fitting method was applied for MIG welding modeling to obtain accurate simulation results, which iteratively adjusts the heat source conditions until the morphology of fusion zone agrees with that of the test specimen. The simulation results were verified with experimental results. Microstructural changes, the phase of the MIG welded part were observed by analysis instruments such as optical microscope and electron back-scatter diffraction. The observations show a good agreement with the simulation results. Besides, we have observed the weld zone to measure its hardness using hardness tester. Using the relation of hardness, we have performed the welding analysis to investigate the residual stress and the deformation shape of the weld zone. As a results, an optimized MIG welding process of the muffler for automotive exhaust system was proposed by the theoretical and experimental results.
Diffractive Optical Element for Noise-reduced Beam Shaping of Multi-array Point Light Source
이종현,한준구,김휘 한국광학회 2021 Current Optics and Photonics Vol.5 No.5
An arrayed diffractive optical element design for the beam-shaping of a multi-array light source is proposed. This is an essential device for recent optical security and face recognition applications. In practice, we devise a DC noise reduction technique featuring high fabrication error tolerance regarding the multi-array light source diffractive optical elements, as a necessary part of the proposed design method. The spherical diverging illumination leads to DC-conjugate noise spreading. The main idea is tested experimentally, and the multi-array light source diffraction pattern is investigated numerically.
류승환,채수용,정학근,장철용,박형호 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.9
We report the direct patterning of diffractive optical elements (DOEs) on a flat conventionallateral-type light-emitting diode (LED) surface. Silicon dioxide, used as a diffractive optical element,was deposited on the flat surface of an LED by using plasma-enhanced chemical vapor depositionand was patterned by using nano-imprint lithography and ion-coupled plasma etching to producenanometer-scale DOEs. This method suggests a new approach for the mass production of DOEsby minimizing the size of the optical device through direct patterning on the LED surface. Theresulting DOEs also act as focal Fresnel lenses, leading to an enhancement of the external lightextractionefficiency of lateral-type LEDs based on the scattering effect and the concentration ofthe emitted light.
( Chung Hyeok Lee ),( Eun Mi Jin ),( Hee Seok Seo ),( Tae-ui Ryu ),( Seung Phil Hong ) 대한피부과학회 2021 Annals of Dermatology Vol.33 No.3
Background: Fractional picosecond lasers is effective for the treatment of wrinkles or acne scars. Objective: To investigate the safety and efficacy of treatment with a fractional 1,064-nm picosecond laser with a diffractive optic element for facial wrinkles and acne scars. Methods: This prospective open-labeled trial comprised 22 subjects with facial wrinkles or acne scars. Subjects received three laser treatments with a fractional 1,064-nm picosecond laser at 3-week intervals. The efficacy and safety were evaluated at every visit and 2 months after the final treatment (14 weeks from the first treatment session). Global photographic assessments were performed by three blinded dermatologists and the subjects. Skin profilometry was performed using three-dimensional digital photographs; viscoelasticity was measured. Results: The overall mean global improvement scores assessed by the dermatologists at weeks 3, 6, and 14, were 1.8±1.46, 2.5±1.88, and 3.5±1.84, respectively, and those assessed by the subjects were 2.7±2.08, 4.1±2.24, and 5.0±2.52, respectively. Skin profilometry showed significant improvements in the skin wrinkles, texture, depressions, and pores. The gross elasticity and skin firmness significantly improved by 10.96% and 9.04%, respectively. The major adverse reactions were erythema, pruritus, and petechiae, which disappeared within 2∼3 days. Conclusion: The fractional 1,064-nm picosecond laser is an effective and safe therapeutic modality for skin rejuvenation. (Ann Dermatol 33(3) 254∼262, 2021)
Four-beam Interference Optical System for Laser Micro- structuring Using Picosecond Laser
Jiwhan Noh,Jaehoon Lee,Dongsig Shin,손현기,서정,Jeongseok Oh 한국광학회 2009 Current Optics and Photonics Vol.13 No.1
A four beam interference optical system for laser micro structuring using a pulse laser was demonstrated. The four beam interference optical system using a pulse laser(picosecond laser) can fabricate micro structure on mold material(NAK80) directly. Micro structure on the polymer can be reproduced economically by injection molding of the micro structure on the mold material. The four beam interference optical system was composed by the DOE(Diffractive Optical Element) and two lenses. The laser intensity distribution of four beam interference was explained by an interference optics point of view and by the image optics point of view. We revealed that both views showed the same result. The laser power distribution of a 1 μm peak pattern was made by the four beam interference optical system and measured by the objective lens and CCD. A 1 μm pitch dot pattern on the mold material was fabricated and measured by SEM(Scanning Electron Microscopy).
Design of optimized DOE to convert gaussian beam to uniform·beam for holographic application
Hwnag, Eun-Seop,Jeong, Hyen-Seop,Kim, Nam 충북대학교 컴퓨터정보통신 연구소 2006 컴퓨터정보통신연구 Vol.14 No.3
In this paper, the design of two diffractive optical elements for converting the Gaussian beam to the uniform beam using the simulation Tool(Code-V) is presented. DOEs, which are thin optical elements, are useful for mobile camera, thin lens system and optical system. We proposed an uniform design for holographic application using two DOEs. First, the general concept and theory in DOEs are presented. Second, the beam tracking process for uniform shaping is illustrated by applying DOE theory. In mathematical processing by the simulation, the DOE factor for making the beam distribution is obtained using the Code-V Tool. As a result, the uniform beam using optimized system is obtained.
Liang, Chuanyang,Zhang, Wei,Wu, Zhihui,Rui, Dawei,Sui, Yongxin,Yang, Huaijiang Optical Society of Korea 2017 Current Optics and Photonics Vol.1 No.1
The laser has been regarded as the potential illumination source for the next generation of projectors. However, currently the major issues in applying the laser as an illumination source for projectors are beam shaping and laser speckle. We present a compact solution for both issues by using a vibrating diffractive optical element (DOE). The DOE is designed and fabricated, and it successfully transforms the circular Gaussian laser beam to a low speckle contrast uniform rectangular pattern. Under a vibration frequency of 150 Hz and amplitude of $200{\mu}m$, the speckle contrast value is reduced from 67.67% to 13.78%, and the ANSI uniformity is improved from 24.36% to 85.54%. The experimental results demonstrate the feasibility and potential of the proposed scheme, and the proposed method is a feasible approach to the miniaturization of laser projection display illumination systems.
Diffractive Alignment of Dual Display Panels
박신웅,박정환,김휘 한국광학회 2024 Current Optics and Photonics Vol.8 No.1
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.