Results 1 - 10 of 52
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[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] A high purity He-3 cell manufacturing technology was developed for uses in a He-3 neutron polarizer. To fabricate a high purity cell, a high purity gas inlet system, a high precision gas pressure measurement system, a residual gas analyzer, and a high temperature baking oven were constructed. By utilizing these systems and instruments, a high purity polarized gas cell with a long lifetime, various shapes and sizes, and high gas pressure up to 1.5 bar were made with GE-180 glass and fused quartz. To make easy use of a He-3 neutron spin filter possible, an in-situ He-3 neutron polarizer was developed based on a magnetostatic box. In addition, to measure the polarization ratio of the He-3 cell in real time basis a NMR system was designed and installed inside the magneto static box. The developed high purity helium-3 cell and the in-situ He-3 neutron polarizer could be employed to provide polarized neutrons for the neutron instruments in neutron imaging, SANS, TAS, or reflector.
[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] 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] A laser ultrasonic testing system using a confocal Fabry-Perot interferometer and a pulsed Nd:YAG laser is developed for the fatigue test of materials. To stabilize the fringe pattern of the confocal interferometer, an adaptive stabilization fringe control system is developed using two photodiode signals. The closed-loop fringe control system is operated automatically. The optical system is composed of many polarization components, such as a half-wave plate, quarter-wave plates and polarization beam splitters to improve the signal to noise ratio. The laser ultrasonic system carried out performance test. The optical configuration of the interferometer system and the stabilization module are investigated in this paper. The experimental results of the basic experiments are also described
[en] The application of the laser profilometry technique to inspection of tube is investigated for the in-service inspection of the SMART SGC tube. The state of the art of the laser tube inspection apparatus is analyzed for detection of ovality and inner-surface defect of the tube. A laser profilometer sensor system for measuring inner-diameter of the tube is instrumented for the experimental study of the laser measuring sensor. Using the new developed laser profilometer and a commercial laser tube inspection sensor system, the application of the laser profilometer system to inspection of the tube inner surface is investigated experimentally. As conclusion, the laser profilometer sensor can be applied to inspection of the tube successfully
[en] The ultrasonic testing method has been used in the fields of Non-Destructive Testing (NDT) for many decades. The conventional transducers are mainly used to generate and detect an ultrasonic signal. But in the case of a specimen with a complex geometry and a narrow space, it is difficult to detect cracks by using the ultrasonic inspection method using conventional transducers. And the contacting transducer method can not be applied to the inspection of some irradiated structures, such as nuclear reactor pressured vessels and internals. The laser ultrasonic method that uses laser beams for the generation and detection of an ultrasonic signal is applicable to the inspection of these parts since it is inherently a non-contact inspection method and broadband. Nowadays laser ultrasonic testing is a widely used non-destructive inspection technique for many industrial fields. The laser ultrasonic techniques consist of a pulsed laser for an ultrasonic wave generation and a laser interferometer for the detection of an ultrasonic signal. There are many kinds of interferometers to detect an ultrasonic signal, such as the Michelson or Mach- Zehnder interferometer, Fiber-optic interferometer, Wave-mixing interferometer, Confocal Fabry- Perot interferometer, etc.. In many industrial applications, a sample surface may not be optically flat and some environmental vibrations can exist. In these industrial applications, a confocal Fabry-Perot interferometer is more useful than other plane interferometers because the confocal interferometer can receive many speckles scattered over a wide angle
[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. The vanadium can had a advantage to have less coherent in neutron. KAERI developed the fabrication Jig of 8 mm diameter can using 0.125 mm vanadium thin film, and investigated the laser welding procedure for making vanadium can using the fabricated jig and Nd:Yag laser. (author). 3 refs., 4 tabs., 4 figs