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Acoustic Nonlinearity of Narrow-Band Surface Wave Generated by Laser Beam with Line-Arrayed Slit Mask

선배열 슬릿마스크를 이용한 협대역 레이저 여기 표면파의 음향 비선형성

  • 최성호 (한양대학교 자동차공학과) ;
  • 남태형 (한양대학교 자동차공학과) ;
  • 이태훈 (한양대학교 자동차공학과) ;
  • 김정석 (한양대학교 자동차공학과) ;
  • 장경영 (한양대학교 기계공학부)
  • Received : 2010.07.12
  • Accepted : 2010.10.25
  • Published : 2010.12.01

Abstract

We examined the mechanism of generation of higher harmonics by theoretically analyzing the frequency characteristics of a narrow-band surface wave generated by a laser beam with line-arrayed slit masks. We experimentally analyzed the effects of slit opening width and laser intensity on the acoustic nonlinearity of aluminum 6061-T6 alloy by using single-slit and line-arrayed slit masks. The magnitude of the harmonic wave depended on the slit opening width. In our experiment, we generated a 1.75-MHz surface wave by using an arrayed slit with intervals of 1.67 mm. The magnitude of the second harmonic component decreased about by 80% when the slit opening width was increased from 0.5 mm to 1.0 mm. In addition, the relationship between the magnitudes of the fundamental and the second harmonic wave showed good linearity, which agreed well with the typical behavior of acoustic nonlinearity.

Keywords

Laser;Surface Wave;Acoustic Nonlinearity;Harmonic Generation

Acknowledgement

Supported by : 한국연구재단(NRF)

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