• Title/Summary/Keyword: Lens power

Search Result 335, Processing Time 0.027 seconds

Construction and operational characteristics of a Ultra-Short pulse Cr4+:YAG laser (극초단 펄스 Cr4+:YAG 레이저의 제작 및 동작 특성)

  • Lee Bong Yeon;Lee Dong Han;Lee Chi Weon;Yoon Seok Beom;Choo Han Tae
    • Korean Journal of Optics and Photonics
    • /
    • v.15 no.5
    • /
    • pp.455-460
    • /
    • 2004
  • We have developed a mode-locked ultra-short pulse C $r^{4+}$:YAG laser, as well as a continuous wave C $r^{4+}$:YAG laser. The laser was pumped by a Nd:YAG laser and its characteristics were investigated. In continuous wave mode, we obtained as much as 600 mW at 1.436 ${\mu}{\textrm}{m}$ with pumping power of 6 W, by using an output coupler with a reflectivity of 98%. The power slope efficiency was 10%, when the gain medium was cooled to 19$^{\circ}C$. The tuning range was varied from 1.39 ${\mu}{\textrm}{m}$ to 1.55 ${\mu}{\textrm}{m}$ and the maximum power was 400 mW at 1.492 ${\mu}{\textrm}{m}$ with a 3-plate birefringent filter. The C $r^{4+}$:YAG laser was mode-locked by a Kerr lens mode locking method. Mode locking at 1.436 ${\mu}{\textrm}{m}$was initiated by slightly rocking a mirror mount. But the pulses were very unstable because of the strong water absorption at this region. So we shifted the lasing wavelength to 1.492 ${\mu}{\textrm}{m}$ by using a 3-plate birefringent filter. Then we obtained stable state mode-locking with the maximum average power of 280 mW for a pumping power of 6 W. The pulse width of 43 fs was measured using an autocorrelator and the repetition rate was 104.5 MHz.

A Study on Concentrating Photovoltaic Module with Plate Structure (평판 구조의 집광형 태양광 모듈 구조에 관한 연구)

  • Park, Seung-Jae;Hong, Min-Sung
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.22 no.4
    • /
    • pp.629-634
    • /
    • 2013
  • This study aims to investigate a new structure for a concentrating photovoltaic (PV) module using a III-V compound semiconductor solar cellto solve the problems of existing concentrating PV modules and to explore a concentrating optical system with a flat structure, which shows remarkable advantages in terms of manufacturing cost, installation, and maintenance. This study should greatly contribute toward the development of concentrating PV modules. This study was performed to achieve an improvement in efficiency and economy and to implement an actual product. A new source of renewable energy is the only way in which countries that cannot produce oil can even emerge as an energy power. Therefore, this work can serve as a fundamental study that will help South Korea grow into a country that is a PV power generation force.

Investigation of the Thermal Characteristics of LED Bulb Utilizing Simulation of Finite Volume Method (FVM) (유한체적법(FVM)의 시뮬레이션을 활용한 LED 벌브의 열 특성 고찰)

  • Park, Kyoung-Min;Moon, Cheol-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.28 no.10
    • /
    • pp.1-8
    • /
    • 2014
  • Heat dissipation of the high power LED is a critical issue. To estimate the junction temperature of the LED chip is most important in characterizing the heat dissipation, but it is impossible to directly measure it. In this study, surface temperatures of the 12.8W LED bulb was measured for 5 points using a data logger and compared with the simulated results using a thermal simulator based on FVM (finite volume method) to secure a reliability of the simulation. Effects of some factors such as lens, emissivity and air inlet were investigated using simulation works and then the results were analysed.

Development of a remote controlled mobile robot system for monitoring nuclear power plant (원전 이동감시 및 방사선 측정용 원격조종 로봇 개발)

  • 구관모;이범희;우희곤
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1996.10b
    • /
    • pp.511-515
    • /
    • 1996
  • A remote controlled mobile robot system has been developed and tested to monitor the radiation area in the nuclear power plant. The mobile robot system operates according to car-driving-like commands and is capable of radiation measurement and visual inspection in unmanned situations under radiation. The robot system is equipped with a radiation sensor and two cameras with appropriate illumination set-ups. The camera with auto-focus function and 8-times zoom lens is mounted on the pan/tilt rotational base and the other is mounted on the front panel of the robot system. All commands regarding the motion of the mobile robot and various sensors are given through the monitoring system which is designed to provide an integrated man-machine interface.

  • PDF

A Study of the Retina Image Controllability using a Sledge (망막 영상 조절 장치에 관한 연구)

  • 이숙희;이영춘;양연식
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1997.10a
    • /
    • pp.273-276
    • /
    • 1997
  • Seeing is an intelligent act. Retina is the most important part among the components of eye which is comprised of iris, pupil, lens, optic disk, and so forth. Because retina acts like a photo receiver to detect light from every object, if damaged, animals have a severe problem to live along with themselves and sometimes they lose their sight. In the ophthalmology, doctors use special instrument to see exact retina image of object and operate the surgery by rotating focus control knob. In this study, a basic test is done to achieve the auto focus control instrument. Specially made sledge and attenuator are installed on the optic bed to change the distance and laser power between the first reflective mirror and the second one. Control panel which is compiled by Visual C t t to control stepping motors ,laser power and photodiode are implemented with ADA-board.

  • PDF

Measurement of Flow Field in a Domestic Boiler Circulation Pump by PIV (PIV에 의한 가정용보일러용 순환펌프의 내부 유동장 계측)

  • Im, Y.C.;Kim, J.H.;Choi, M.S.;Lee, Y.H.
    • Journal of Power System Engineering
    • /
    • v.3 no.2
    • /
    • pp.13-19
    • /
    • 1999
  • The purpose of the present experimental study is to apply multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to high-speed flow region within a domestic boiler circulation pump. Two different kinds of flow rate($27{\ell}/min,\;19{\ell}/min$)are selected as experimental condition. A volute casing and Impeller made of transparent Polycarbonate were made for the easy access of the illumination laser via fiber optical line and cylinder lens assembly to the measuring region. A CCD camera is syncronized with AOM to acquire clear original particle images. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. The instantaneous and time-mean velocity distribution, velocity profile and kinetic energy are represented quantitatively at the full-scale region for the deeper understanding of the unsteady flow characteristics in a commercial circulation pump.

  • PDF

Lifetime Estimation of High Power White LED for Lighting Use (고출력 조명용 White LED의 수명예측)

  • Lee, Myeong-Hoon;Shin, Seung-Jung;Kwack, Kae-Dal
    • Proceedings of the KSME Conference
    • /
    • 2008.11a
    • /
    • pp.1343-1348
    • /
    • 2008
  • LEDs which have many merits are widely used in the field of light devices, and have rapidly replaced old light devices such as incandescent or fluorescent lamps. Long life, on the order of 50,000 to 100,000 hours, is one of the key features of light emitting diodes(LEDs) that has attracted the lighting community to this technology. High Power white LEDs have yet to demonstrate this capability. This paper planed accelerated life test that has two factor(temperature, current) and two levels. Finally, using ALTA programs, we estimated the common shape parameter of Weibull distribution, life-stress relationship, B10 life and accelerating factors.

  • PDF

The Design and Fabrication of New Structure Reflector for LED Source (LED 광원에 적합한 새로운 구조의 반사경의 설계 및 제작)

  • Jeong, Hak-Geun;Jung, Bong-Man;Han, Su-Bin;Park, Suk-In;Kim, Kyu-Deok
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
    • /
    • 2006.05a
    • /
    • pp.154-156
    • /
    • 2006
  • A few ten mW white LED can substitute for the indicator light source and it is required to study several watt multi-chip semiconductor light sources in order to replace the light sources for general illumination such as incandescent lights and fluorescent lanes. Since the optical technology used for several mW white LED light source uses only 30% to 52% of the light it is required to develop the design technology of optical system and lens to improve the efficiency more than 80% for insuring the high power of white LED. In this paper, we designed and fabricated new structure reflector to increase the efficiency and is easy to make high power multi-chip LED lamp.

  • PDF

Photopolymer Solidification Phenomena Considering Laser Exposure Conditions in Micro-stereolithography Technology (마이크로 광 조형에서 레이저 주사조건에 따른 광 경화성수지의 경화현상)

  • 이인환;조동우;이응숙
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.21 no.3
    • /
    • pp.171-179
    • /
    • 2004
  • Micro-stereolithography technology has made it possible to fabricate a freeform 3D microslructure. This technology is based on conventional stereolithography, in which a UV laser beam irradiates the open surface of a UV-curable liquid photopolymer, causing it to solidify. In micro-stereolithography, a laser beam of a few $\mu m$ diameter is used to solidify a very small area of the photopolymer. This is one of the key technological elements, and can be achieved by using a focusing lens. Thus, the solidification phenomena of the liquid photopolymer must be carefully investigated. In this study, the photopolymer solidification phenomena in response to variations in the scanning pitch of a focused laser beam was investigated experimentally. The effect of layer thickness on the solidification width and depth was also examined. These studies were conducted under the conditions of relatively lower laser power and relatively higher scanning speed. Moreover, the photopolymer solidification phenomena for the relatively higher laser power and lower scanning speed was investigated, too. In this case, comparing to the case of lower laser power and higher scanning speed, the photopolymer absorbed large amount of irradiation energy of the laser beam. These results were compared with those obtained from a photopolymer solidification model. From these results, a new laser-scanning scheme was proposed according to the shape of the 3D model. Samples by each method were fabricated successfully.

A Calculation of the Propagation for Focused Beams Using BPM (BPM을 이용한 안테나 배열의 집속 빔 전파 해석)

  • Kim Jaeheung;Cho Choon Sik;Lee Jae W.
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.16 no.5 s.96
    • /
    • pp.465-471
    • /
    • 2005
  • A method of calculation fur propagating and focusing of focused beams generated in antenna arrays, using BPM(Beam Propagation Method), is presented in this paper. Based on the diffraction theory, the beam focusing and Propagation is studied specially for the case of the antenna way fed by the Rotman lens that is able to focus microwave power on its focal arc or generate multiple beams. There are difficulties in performing a full-wave simulation using a commercial EM simulation tool for propagating and focusing of beams because of the structural complexity and the feeding assignment of the antenna array. Therefore, as an alternative solution, the BPM is presented to calculate the beam propagation from the aperture-type antennas. From the point of view of optics, the propagations of the lens have been simplified from the Fresnel diffraction integral to the Fourier transform. Using Fourier Transform, a beam propagation method is developed to show improvement of the resolution by controlling the wavefront of wave Propagating from an aperture-type antenna array. The beam width(or spot size) and the intensity are calculated for a focused beam propagating from an array having $10\lambda$ of its size. For the beams with $20\lambda,\;30\lambda$, and $50\lambda$ of geometrical focal length, the half-power beam widths(or spot size) are about 1.1\lambda,\;1.3\lambda,\;and\;1.9\lambda$ respectively.