• 한국광학회:학술대회논문집
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• 한국광학회 1998년도 제15회 광학 및 양자전자 학술발표회 논문집
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• pp.70-71
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• 1998

• 한국광학회지
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• 제9권5호
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• pp.342-347
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• 1998

비선형 Kerr 매질을 통과하는 Gaussian 빔에 대해 aberration-free approximation과 Huygens-Fresnel 회절 이론을 적용하여 Z-scan 투과율에 대한 해석해를 유도하였다. 비정질 $As_2S_3$ 박막에 대해 Z-scan 실험을 수행하였으며 이론과 비교하여 잘 일치함을 알았다. 633nm 파장에서 측정된 비선형 굴절률${\gamma}$의 크기와 기호 $+8.65{\times}10^{-6}\textrm{cm}^2/W$이며, 또한 먼 영역(far-field)에서 빔 세기분포를 측정하여 자기 집광(self-focusing)효과를 가시적으로 확인하였다.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
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• pp.40-41
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• 2004

• 자연과학논문집
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• 제7권
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• pp.11-17
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• 1995

미소 반도체 $Bil_3$ 콜로이드의 광학적 비선형 굴절율을 원형 대칭 빛살을 사용한 Z 스캔 방법으로 측정하였다. 파장 $0.532\mum$, 펄스폭 20ns에서 비선형 굴절율은 주로 열적 요인에 의한 것이었으며, 그 크기는 -1.53 x $10^12($cm^2/W) 이었고, 비선형 흡수율 크기는 7.1 x $10^8$ (cm/W) 이었다.

• 한국광학회:학술대회논문집
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• 한국광학회 1999년도 제16회 광학 및 양자전자 학술발표회Proceedings of 16th Optics and Quantum Electronics Conference, 1999
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• pp.190-191
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• 1999

• 한국광학회지
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• 제6권4호
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• pp.345-351
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• 1995

유한한 폭을 갖는 배경에서 기본 어두운 공간솔리톤의 진행특성을 실험적으로 연구하여 전산시늉한 결과와 비교하였다. 실험적으로 빔의 세기가 증가함에 따라 어두운 솔리톤의 폭이 감소하고 배경의 폭은 증가함을 확인하였고 무한한 폭의 배경을 가정한 솔리톤 상수로부터 구한 굴절율의 변화량은 Z-스캔 방법으로 구한 굴절율의 변화량보다 작았다. 유한한 폭을 갖는 배경에 놓인 기본 어두운 솔리톤의 진행을 전산시늉하여 진행거리에 따른 배경의 첨두세기, 어두운 솔리톤의 폭 그리고 솔리톤 상수의 변화를 연구하였다. 유한한 크기의 배경에서 솔리톤상수의 변화를 고려하여 구한 굴절율의 변화량은 Z-스캔 방법으로 구한 굴절율의 변화량과 일치하였다.

• 한국광학회지
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• 제5권4호
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• pp.481-486
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• 1994

높은 정전기장이 인가된 유기용액의 분자배향도를 측정하는 수단으로 z-scan방법을 사용하였다. 무게비로 0.5%의 4-dimethylamino-4'-nitrostilbene을 cyclopentanone에 녹인 혼합용액을 시료로 z-scan실험을 수행하였으며 측정된 등방비선형 굴절율 $n_{2}$값은 $1.064{\mu}m$파장에서 $-0.905\times10^{-8}\textrm{cm}^2/MW$였다. 3.45KV/nm 정전기장을 인가한 경우에 측정된 $n_{2}$의 비등방비 값은 1.34였으며 분자배향도계수 $

_2 및

_4$값은 0.092 및 -0.128이였다.

• Journal of Korean Dental Science
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• 제13권1호
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• pp.28-34
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• 2020

Purpose: The purpose of this study was to investigate the influence of different implant computer software on the accuracy of image registration between radiographic and optical scan data. Materials and Methods: Cone-beam computed tomography and optical scan data of a partially edentulous jaw were collected and transferred to three different computer softwares: Blue Sky Plan (Blue Sky Bio), Implant Studio (3M Shape), and Geomagic DesignX (3D systems). In each software, the two image sets were aligned using a point-based automatic image registration algorithm. Image matching error was evaluated by measuring the linear discrepancies between the two images at the anterior and posterior area in the direction of the x-, y-, and z-axes. Kruskal-Wallis test and a post hoc Mann-Whitney U-test with Bonferroni correction were used for statistical analyses. The significance level was set at 0.05. Result: Overall discrepancy values ranged from 0.08 to 0.30 ㎛. The image registration accuracy among the software was significantly different in the x- and z-axes (P=0.009 and <0.001, respectively), but not different in the y-axis (P=0.064). Conclusion: The image registration accuracy performed by a point-based automatic image matching could be different depending on the computer software used.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.60.2-60.2
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• 2011

A study of the non-linear optical properties of nanocrystal-Si embedded in SiO2 has been performed by using the z-scan method in the nanosecond and femtosecond ranges. Substoichiometric SiOx films were grown by plasma-enhanced chemical-vapor deposition(PECVD) on silica substrates for Si excesses up to 24 at/%. An annealing at $1250^{\circ}C$ for 1 hour was performed in order to precipitate nanocrystal-Si, as shown by EFTEM images. Z-scan results have shown that, by using 5-ns pulses, the non-linear process is ruled by thermal effects and only a negative contribution can be observed in the non-linear refractive index, with typical values around $-10-10cm^2/W$. On the other hand, femtosecond excitation has revealed a pure electronic contribution to the nonlinear refractive index, obtaining values in the order of 10-12 cm2/W. Simulations of heat propagation have shown that the onset of the temperature rise is delayed more than half pulse-width respect to the starting edge of the excitation. A maximum temperature increase of ${\Delta}T=123.1^{\circ}C$ has been found after 3.5ns of the laser pulse maximum. In order to minimize the thermal contribution to the z-scan transmittance and extract the electronic part, the sample response has been analyzed during the first few nanoseconds. By this method we found a reduction of 20% in the thermal effects. So that, shorter pulses have to be used obtain just pure electronic nonlinearities.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.58-58
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• 2010

Reactive or unstable adsorbates are often difficult to study spectroscopically. They may have, for instance, resonance states lying close to the Fermi level, inducing them to desorb or decompose by the probe itself, low-energy tunneling electrons. In order to overcome this limitation, we developed a novel method, which we call x-ramp scan. The method sweeps the bias voltage, with the simutaneous scan along the imaging direction, in a constant current mode. This mapping yields the tip-height variation as a function of bias, or Z(V), at nominally always fresh surface. We applied this method to the investigation of methanol-induced molecular features, attributed to methoxy, found on NiAl(110) surface. These were produced by methanol molecules deposited by a pulse injection method onto the metallic surface. Our study shows adsorbed methoxy are very reactive to the bias voltage, rendering the standard spectroscopy useless. Our new x-ramp scan shows that the decomposition of adsorbates occurs at the sample bias of 3.63 V, and proceeds with the lifetime of a few milliseconds. The details of the method will be provided at the discussion.