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김성훈(S. H. Kim),백경윤(K. Y. Beak),김영남(Y. N. Kim),양인영(I. Y. Yang) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
In this paper, resonant ultrasound spectroscopy(RUS) was used to determine the natural frequency of a spherical and a aspherical lens. The objective of the paper is to evaluate defect and shape error by using nondestructive evaluation method with Resonant Ultrasound Spectroscopy(RUS). The principle of RUS is that the mechanical resonant frequency of the materials depends on density, and the coefficient of elasticity. We evaluated existence of flaws through comparison with resonant frequency of a spherical and a aspherical lens. The spherical glass lenses were made of BK-7 glass, one"s diameter in 2㎜ and 5㎜. The polished spherical glass lenses had no deflection or a deflection below 2.0㎛. Also, The aspherical lens were made of same material and ones diameter in 7㎜ and thickness in 3.4㎜. In the experiment, we were performed to investigate relationship between frequency measuring parameter( β) and mass of each specimens. The difference between resonant frequency and mode of aspherical glass lens which has no defect was distinguished from aspherical glass lens which has some defects.