Results 1 - 10 of 64
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[en] The key technologies for co-axial Lidar with LD were developed for commercialization of ceilometer lidar. The summary of the developed technologies is bellow - Optical system of the LD collimation and LD transmitting system is designed by ray-tracing program Zemax Pro. The performance of the optical system is analyzed and optimized - Optical system design of the Lidar receiving system is conducted by ray-tracing program Zemax Pro. The receiving lens and hole mirror were manufactured and applied to prototype lidar system - Design and development of data analysis algorithm for measurement of cloud height and boundary layer of the atmosphere. The operation and analysis program for the lidar prototype is designed and developed. The results of this study is development of key technologies for Commercialization of lidar system, which can be used for improving the performance of small lidar ceilometer and aerosol lidar. To extend the applicability of this study, more efforts are need for conducting additional development aerosol lidar technology to have higher quality competitiveness.
[en] The laser weld technique of vanadium developed to experiment for neutron diffraction of HANARO. The demands for this laser welding technique were applied to process control in vanadium film welding and to fabricate various sizing vanadium cans. The vanadium can had a advantage to have less coherent in neutron. KAERI developed the fabrication jig of 6-12 mm diameter cans using 0.125 mm vanadium thin film, and investigated the laser welding procedure for making the various diameter and length of vanadium cans using the fabricated jigs and Nd:YAG laser. (author)
[en] Laser contouring system capable of measuring relief profiles using a line-shaped laser beam with anisotropic magnification optics composed with two cylindrical lenses was developed. The anisotropic magnification optical system allows it to obtain higher resolution in the relief profile measurements. The image processing and 3-D display software are developed to reconstruct 3-D shape. The power supply of laser diode with adaptive current control circuit is designed. (author). 4 refs., 5 tabs., 33 figs
[en] The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool
[en] The effect of wavefront distortion of laser beam of a laser Doppler vibrometer in the turbulence media was investigated for application of adaptive optics to laser vibrometer, using a real-time holographic interferometer with a digital high-speed camera. The interference fringe patterns of the wavefront were compared with the oscilloscope signal of the laser vibrometer. The wavefront distortion due to the turbulence media induced low visibility and degraded the performance of the vibrometer. From the experiments, when the area in which the wavefront distortion is above one wavelength is larger than about one-half of the whole laser beam area, the vibration signal from laser vibrometer was destroyed. The frequency dependence of the performance of the vibrometer on wavefront distortion seems to be negligible. In the future, an adaptive optics system for wavefront correction of the laser vibrometer in the turbulence media will be studied
[en] We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs
[en] Resonant ultrasound spectroscopy (RUS) is a useful technique for measuring the elastic properties of materials. In this study, two experimental approaches for performing RUS are experimentally analyzed and compared: (1) contact transduction using piezoelectric transducers (PZT) and (2) laser transduction using pulse laser excitation and laser interferometric detection. A single Zircaloy sample cut from a nuclear pressure tube was used for this study. By virtue of the non-contact nature, the quality factor, Q, for laser RUS is shown to be higher than the contact RUS. In addition, the probe beam for laser-RUS can be scanned to form a 2D image of each vibrational mode, which in turn enables unique mode identification. These defining characteristics of laser-RUS enable straightforward discrimination of closely spaced resonant modes and provide key advantages for improving the resolution of resonant ultrasound spectroscopy.
[en] We developed 3D laser camera sensors for weld seam tracking and inspection of radioactive NPP pipes. The developed sensor's optical system adopts the optical triangulation method with the line beam generation and imaging optics. A laser line extraction algorithm accompanying preprocessing of noise reduction has been developed on images captured from the sensor. Experimental results validate the physical accuracy of the sensor hardware and the robustness of the image processing algorithms. A 3D shape reconstruction algorithm from multiple laser lines was proposed and the resulting 3D shape was visualized on the developed 3D graphic program environment utilizing OpenGL graphic libraries. And also, two D.O.F precise servo controlled mechanism was developed. The experimental results on weld seam tracking and inspection tasks show the practical feasibility of the developed sensors and the image processing algorithms. (author)
[en] The effect of wavefront distortion of laser beam of a LDV(Laser Doppler Vibrometer) in the turbulence media was investigated for application of adaptive optics to LDV. The high-speed tip/tilt adaptive optics system and closed-loop steering algorithm were developed for real-time correction of the direction fluctuation of the laser beam of LDV. The measuring performance of the LDV was improved when the steering system was applied to LDV at the vibration frequency range of 10 Hz - 30 Hz. The high-speed Shack-Hartmann wavefront sensor(400 Hz) was developed to measure the performance of the LDV due to wavefront distortion. The wavefront distortion due to the turbulence media induced low visibility and degraded the performance of the vibrometer. From the experiments, when the wavefront distortion is above 2 wavelengths in the cross section of the laser beam(dia. 20 mm), the vibration signal from laser vibrometer was severely degraded. When the wavefront distortion is smaller than one wave, the vibration signal was good. From the this research, high-speed closed-loop tip/tilt control technique of the laser beam was developed and applied to the laser metrology area. In the future, the adaptive optics system for wavefront correction will be applied to other research area
[en] Laser Ultrasonic inspection technique has several advantages in Non-Destructive Testing over other methods, such as the ability to achieve broad-banded excitation and remote source of ultrasound by optical means on hot or rough samples and in hostile environments. Laser Ultrasonic technique can inspect underwater micro cracks of a depth of 1 mm or less which are barely detectable with conventional methods. Laser Ultrasonic is very powerful inspection method for nuclear power plant components such as the inner surface of BMI nozzle of PWR plants. In this project, Laser Ultrasonic inspection system and techniques for nuclear power plant components was developed. The developed technologies are Laser Ultrasonic NDT system, experimental verification of detection of degraded components using laser ultrasonic, and application techniques : Laser Beam delivery technique using optical fiber, Remote 3-D shape measurement algorithm