Large-amplitude resonant varifocal mirror with an acoustic cavity

We report a large-amplitude resonant varifocal mirror with an acoustic cavity under atmospheric pressure. The amplitude of resonant varifocal mirror with acoustic cavity was measured by changing the cavity length. The amplitude of varifocal mirror was changed periodically depending on the cavity length. The period is in excellent agreement with the half of calculated wavelength of the acoustic wave. The maximum amplitude was about 4 times larger than the minimum amplitude. For designing of the acoustic cavity length, a theoretical approach on the basis of interaction between mechanical vibration and acoustic wave in the cavity is also described and compared to experimental results.