• Journal of Advanced Marine Engineering and Technology
• /
• 제33권1호
• /
• pp.153-158
• /
• 2009

Stable and tunable dual-wavelength erbium-doped fiber ring laser(EDFL) using a single fiber Bragg grating(FBG) and two coil heaters is proposed and demonstrated. Installing two identical coils into a single FBG, the FBG is symmetrically divided into two different portions. While a current supply to the coil, the refractive index of the FBG under the coil is changed. The FBG can operate as a joint of two different FBGs. Due to the thermo-optic effect of a fiber, the resonance wavelength split into two peaks. The spacing between two adjacent channels was changed as much as the difference of heating power. It was tuned up to 3 nm of wavelength under the electrical power with a 1000 mW. Moreover, the lasing wavelength can be individually tuned without influencing to the adjacent channel.

• 한국광학회지
• /
• 제21권3호
• /
• pp.91-96
• /
• 2010

디지털 홀로그램을 이용하여 상을 재생 할 때 재생상의 크기는 재생거리와 파장의 함수이다. 이러한 재생거리와 파장 의존성을 제거하기 위하여 이중푸리에변환법이 제안되었고, 이중푸리에변환을 이용하면 일정 크기의 재생상을 얻을 수 있다. 일반적으로 사용된 광원의 파장보다 큰 단차의 높낮이 측정은 단일파장 디지털 홀로그래픽 방식으로 측정이 가능하지 않기 때문에 2 파장홀로그래피가 제안되었는데, 두 파장에서 얻어진 각각의 재생상의 크기가 같아야 하는 제약이 있다. 본 연구에서는 투과 및 반사형 2 파장 디지털 홀로그래픽 현미경을 이용하여 각각의 파장별로 홀로그램을 촬영하고 이중푸리에변환을 이용하여 재생함으로써 두개의 파장에서 얻어진 재생상의 크기를 같게 만들어 주는 과정 없이 단차를 가진 샘플의 3차원 높낮이 측정을 할 수 있었다.

• 한국가시화정보학회지
• /
• 제12권3호
• /
• pp.9-14
• /
• 2014

Two-photon microscopy (TPM) has been used in plant research as a high-resolution high-depth 3D imaging modality. However, TPM is known to induce photo-damage to the plant in case of long time exposure, and optimal excitation wavelength for plant imaging has not been investigated. Longer excitation wavelength may be appropriate for in vivo two-photon imaging of Arabidopsis thaliana leaves, and effects of longer excitation wavelength were investigated in terms of imaging depth, emission spectrum. Changes of emission spectrum as a function of exposure time at longer excitation wavelength were measured for in vivo longitudinal imaging. Imaging depth was not changed much probably because photon scattering at the cell wall was a limiting factor. Chloroplast emission spectrum showed its intensity peak shift by 20 nm with transition of excitation wavelength from 849 nm or below to 850 nm or higher. Emission spectrum showed different change patterns with excitation wavelengths in longitudinal imaging. Longer excitation wavelengths appeared to interact with chloroplasts differently in comparison with 780 nm excitation wavelength, and may be good for in vivo imaging.

• 한국통신학회논문지
• /
• 제14권2호
• /
• pp.177-187
• /
• 1989

연마된 단일 모드 광섬유를 이용하여 파장 분할 광결합기를 만들때 결합계수는 파장과 두 코아 사이의 거리에 따라서 다르다. 파장 분할은 중심 파장에 따른 결합 계수의 변화율의 함수이며 두개의 코아 사이의 거리에 따라서 변화율이 다르다. 본 논문은 두개의 파장을 분리할 때 최소의 파장 분할 구간을 얻을 수 있는 조건을 두개의 코아 사이의 거리의 함수로 제시하여 파장범위에 따르는 최적화가 다르다는 것을 알 수 있었다.

• 산업기술연구
• /
• 제28권B호
• /
• pp.235-238
• /
• 2008

In this paper, we have developed wavelength swept laser system for the swept source optical coherence tomography(SS-OCT). A laser is constructed by using the two SOAs parallel configuration, fiber Fabry-Perot tunable filter(FFP-TF). The wavelength sweeps are repetitively generated with the repetition period of 50Hz. The wavelength tuning range of the laser is more than FWHM of 80nm centered at the wavelength of 1310nm and the line-width of the source is 0.12 nm.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
• /
• pp.25-28
• /
• 2002

We have been fabricated white organic light emitting diode with two-wavelength ard mixing blue emit in DPVBi (4, 4-bis(2, 2-diphenylvinyl)-1, 1 -biphenyl)layer and yellow emit in rubrene (5, 6, 11, 12-tetraphenylnaphthacene)as emitting layer which are controlled with thickness. This device emits white light emitting in CIE (0.29, 0.33), 1000cd/$m^2$ at DC 18V.

• 한국광학회지
• /
• 제23권6호
• /
• pp.251-254
• /
• 2012

이 파장 디지털 홀로그래피는 단파장 디지털 홀로그래피에 비해 보다 큰 단차를 얻는데 사용할 수 있다. 이파장 홀로그래피 방법을 이용하기 위해서는 각각의 파장에서 얻은 홀로그램으로부터 재생된 위상 이미지 크기가 동일하여야하는데, 위상 이미지 크기는 재생거리와 파장에 의존한다. 이러한 문제점을 해결하기 위하여 프레즈렐-불루스타인 변환법이 제안되었다. 이변환법은 재생상의 크기를 재생거리와 파장에 의존하지 않고 자유롭게 만들 수 있다. 본 연구에서는 프레즈렐-불루스타인 변환법을 이파장 홀로그래피에 적용하여 파장에 의존하지 않는 동일한 위상 재생상을 얻을 수 있음을 실험적으로 확인하였다.

• 한국경영과학회지
• /
• 제27권4호
• /
• pp.1-10
• /
• 2002

The ring routing and wavelength assignment problem arose in the planning of optical communication networks which use WDM rings. Traffic demands are given for each pair of nodes in an ring : each demand must be routed one of the two possible connections round the ring and the wavelength assignments must be made so that there are no conflicts : that is. no two connections whose routes share a link can be assigned the same wavelength along that link. The objective is to minimize the number of used wavelengths. We propose the local optimal routing for the problem and show that there always exists an optimal solution satisfying it. Furthermore we suggest a new lower bound for the problem and show that it is very efficient for the worst case example.

• 대한의용생체공학회:의공학회지
• /
• 제17권4호
• /
• pp.491-498
• /
• 1996

The development of a compact two-wavelength Nd:YAG laser for dental and ENT applications is presented. The Nd:YAG resonator generates either 1.06$\mu$m or 1.32$\mu$m. The wavelength selection is made at the control panel. The Nd:YAG laser parameters at 1.06$\mu$m are ; the maximum pulse duration of 150$\mu$s, repetition rates of I-100Hz, and the maximum average power of 25W. At 1.32$\mu$m, the pulse duration is the same where the repetition rates and the maximum average power are I-30Hz and lOW respectively. High voltage power supply consists of a simmer module and two identical high voltage DC converters. In order to make a complete medical laser system, an optical fiber delivery unit, foot pedal and water spray handpiece are also developed. The wavelength selection is reliable since no movement of optical or mechanical components is required. The high voltage power supply is compact, easy to be maintained and applicable for other laser systems due to its modular design.

• Restorative Dentistry and Endodontics
• /
• 제14권1호
• /
• pp.149-159
• /
• 1989

The purpose of this study was to assess the effects of wavelength and intensity of light curing units on the curing of composite resin. The wavelength and intensity of nine units were evaluated with Optical Multichannel Analyzer and Radiometer. Two-part split stainless steel mold with a cylindrical hole-3.0mm in diameter, 6.0mm in hgieht-was prepared. After placing a Mylar strip between two parts, 100 specimens were made by inserting each of four composite resins into the mold and irradiating for 20 seconds with five light units alternatively. The curing depths were measured by scraping method and evaluated by two-way ANOVA. And Vicker's hardness measurements were made on the longitudinally sectioned surface at 0.5mm interval. The results were as follows: 1. Visilux 2 showed a narrow spectral band within the effective wavelength in initiating polymerization and the highest intensity. Translux showed the diffuse spectrum of wavelength and the lower light intensity. 2. Visilux 2 showed the highest curing effect in any composite resin and then followed by Optilux, Efos 35, Heliomat and Translux. (p < 0.01) 3. Durafill showed the deepest curing depth in any light unit and then followed by Bisfil M, Silux and Heliosit. (p < 0.01). 4. Maximum hardness values showed 0.1mm and 0.5mm under top surface and then gradually decreased with depth.