• 한국정밀공학회지
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• 제29권3호
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• pp.261-265
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• 2012

In this study, glassy carbon was ground for lens core of glass mold press. Ultraprecision grinding process was applied for machining of core surfaces. During the process, brittle crack occurred because of hard-brittleness of glassy carbon. Author investigated optimized grinding conditions from the viewpoint of ductile mode grinding. Geometrical undeformed chip thickness was adopted for critical chip thickness that enables crack free surface. Machined cores are utilized for biaspheric glass lens fabrication and surfaces of lens were compared for verification of ground surface.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.624-628
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• 2013

With the recent development of less-costly uncooled detector technology, expensive optics are among the remaining significant cost drivers in the thermography camera. As a potential solution to this problem, the fabrication of IR lenses using chalcogenide glass has been studied in recent years. We report on the molding and evaluation of a ultra-precision chalcogenide-glass lens for the thermography camera for body-temperature monitoring. In addition, we fabricated prototype thermography camera using the chalcogenide-glass lens and obtained the thermal image from the camera. In this work, it was found out that thermography camera discerned body-temperature between 20 and $50^{\circ}C$ through the analysis of thermal image. It is confirmed that thermography camera using the chalcogenide-glass lens is applicable to the body-temperature monitoring system.

• 한국정밀공학회지
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• 제27권6호
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• pp.7-16
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• 2010

Physical fundamentals of ultrashort femtosecond lasers are addressed along with emerging applications for precision manufacturing and metrology. Femtosecond lasers emit short pulses whose temporal width is in the range of less than a picosecond to a few femtoseconds, thereby enabling extremely high peak-power machining with less thermal damages. Besides, the broad spectral bandwidth of femtosecond lasers constructed in the form of frequency comb permits absolute distance measurements leading to ultraprecision positioning control and dimensional metrology.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 추계 기술심포지움 논문집
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• pp.101-104
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• 2000

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.135-139
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• 2012

In this study, we synthesized the chalcogenide glass($Ge_{19}Sb_{23}Se_{58}$) for infrared optics by meltquenching method and verified the effect of cooling condition on the glass properties. The structural and optical properties of the glass were analyzed by XRD, FT-IR and SEM image. The glass synthesized under the cooling temperature of $980^{\circ}C$ shows transmittance of 58% at $8\sim12{\mu}m$, which was decreased as the cooling temperature was decreased. In addition, thermal and hardness also were measured. From the analysis results, we ascertained the feasibility as a molding materials for infrared optics.

• 연구논문집
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• 통권30호
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• pp.129-135
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• 2000

Double boss type composite pressure bottles have been developed widely but single boss type had not because there are some difficulty in technical point. In this paper a research was performed to develop composite pressure vessel in conjunction with design, fabrication, and test. Fiber pattern and angles were decided by CADFIL software and they are [liner/$15^{\circ}$/$15^{\circ}$/$90^{\circ}$/$18^{\circ}$/$90^{\circ}$/$21^{\circ}$/$21^{\circ}$/$90^{\circ}$]. Fabrication of bottles was done by AEA's 5-axis filament winding machine. During fabrication fiber optic sensor were embedded to measure were behavior of structure at the applied internal pressure. Even though satisfied test results were not obtained, the experimental set-up of fiber optics showed the possibility for the application of filament wound vessels. However, the conventional strain and fabrication of single boss composite bottles.

• 한국광학회지
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• 제19권4호
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• pp.287-293
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• 2008

망원경의 조립 및 평가를 위해서는 평행광선을 만들어주는 시준장치가 반드시 필요하다. 최근에 고해상도 카메라의 초점거리가 길어짐에 따라 상대적으로 적은 부피를 차지하는 Cassegrain 형태의 시준장치가 많이 사용되고 있다. 하지만 이러한 형태는 적외선 광학계를 평가할 때 부경이 가지는 온도로 인하여 불필요한 열복사선을 방출하여 적외선 광학계의 평가 정밀도를 떨어뜨리게 된다. 본 논문에서는 직경이 800 mm이고 초점거리가 2 m인 적외선 광학계를 평가하기 위하여 초점거리는 6m이고 물리적인 직경 1 m, 유효 직경이 930 mm인 비축포물면을 Zerodur를 이용하여 가공하고 측정한 과정을 설명한다. 약 4개월간의 작업 끝에 면의 최종 파면수차는 30.4 nm rms($\lambda$/138, ${\lambda}=4.2\;{\mu}m$)를 얻어서 적외선 광학계뿐만 아니라 가시광 영역 광학계도 측정 가능한 성능을 보유하였다.

• 한국광학회지
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• 제24권1호
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• pp.17-22
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• 2013

High performance plastic optical fiber (POF) $N{\times}N$ star couplers are implemented based on fusing and combining technology. A set of cladding-removed POFs are fused into a solid body by heating and pressing them together to form the transition region between the input and output sides. The operation principle of the proposed star coupler is explained based on ray optics. To demonstrate the performance of the device, $2{\times}2$, $4{\times}4$ and $6{\times}6$ type POF couplers were fabricated and characterized. Performances of the POF star couplers were evaluated in terms of the flatness of the coupling ratios and excess losses.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.60-61
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• 2005

Polycapillary optics are fabricated for hard X-ray waveguide. The Calculation of propagation conditions in polycapillary are conducted to obtain the focal length and spot size as well as the demension of the polycapillary optic devices. X-ray energy of 8 KeV is propagated in the polycapillary optics which the exit diameter of 2.3 mm. and 17 mm in length.

• Current Optics and Photonics
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• 제4권6호
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• pp.509-515
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• 2020

A practical single photon source for fiber-based quantum information processing is still lacking. As a possible 1.55-㎛ quantum-dot single photon source, an InGaAsP/InP-air-aperture micropillar cavity is investigated in terms of fabrication tolerance. By properly modeling the processing uncertainty in layer thickness, layer diameter, surface roughness and the cavity shape distortion, the fabrication imperfection effects on the cavity quality are simulated using a finite-difference time-domain method. It turns out that, the cavity quality is not significantly changing with the processing precision, indicating the robustness against the imperfection of the fabrication processing. Under thickness error of ±2 nm, diameter uncertainty of ±2%, surface roughness of ±2.5 nm, and sidewall inclination of 0.5°, which are all readily available in current material and device fabrication techniques, the cavity quality remains good enough to form highly efficient and coherent 1.55-㎛ single photon sources. It is thus implied that a quantum dot contained InGaAsP/InP-air-aperture micropillar cavity is prospectively a practical candidate for single photon sources applied in a fiber-based quantum information network.