Development for visual test equipment of the ultrasonic pulse waveform; Development and test result of polarized light schlieren method equipment (1)

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It is necessary for detecting and characterizing the defects with ultrasonic non-destructive testing to know the characteristics of the sound field and the pulse waveform transmitted by a ultrasonic probe. As a visual measuring technique relating the ultrasonic pulse waveform and sound pressure field generated by the probe, schlieren method for the wave in water and photo-elastic method for the wave in solid were used separately. Since there is a difficulty to observe simultaneously the sound field in the water and the solid by each method respectively, various types of the probe, such as a immersion type probe which is widly used in ultrasonic testing, cannot by evaluated and authorized the overall performance of the probe. To remove this difficulty, we have developed the polarized light schlieren method, which is combined the schlieren method with the photo-elastic method, for the visualization of ultrasonic pulses in both water and solid simultaneously. Following the principle of the polarized light schlieren method, we have made the visual test equipment having two concave mirrors, a polarizer and a knife edge made by polarizer film. Using this equipment, we have examined the performance and the possibility of the quantitative measurement of ultrasonic wave from the visual images. travelling directivity, frequency and wave mode of ultrasonic wave by using the polarized light schlieren method. In the future, we intend to improve the performance of our equipment and visualize the various ultrasonic wave behavior, especially liquid and solid interface. From the test results of this equipment, it is confirmed that ultrasonic wave in both water and transparent solid model, made by pyrex glass, is visualized simultaneously through the window of the water tank, and it is suggested that it can be evaluated quantitatively the sound pressure field.