VIBRATION MEASURING METHOD BY PULSE LASER HOLOGRAPHY

摘要

PURPOSE:To obtain the modes and relative phases of vibration modes togeter with the information on amplitude distribution and perform accurate analysis of modes by reflecting two shots of illuminating rays of double pulse laser with a rotary reflecting means and projecting the same to the measuring object from different angles. CONSTITUTION:In making a hologram by projecting the pulse laser light emitted from a double pulse laser device 1 to the measuring object 11, a rotary reflecting mirror 23 is provided between a beam splitter 2 and the measuring object 11 and two shots of illuminating rays are reflected while this rotary reflecting mirror 23 rotates to project the rays to the measuring object from respectively differnt angles. Here, the measuring object 11 is vibrated by an exciter 16 and the first shot of the radiated there to in a vibration zero state while it is being monitored with an oscillo- scope 13. the angle of the illumination light is changed in various ways in the exposure of a photographic plate 8 so that interference fringes appear in the hologram reconstruction image. At the time of emitting the second shot of laser light, the rotary plane mirror 23 is made at a different angle and the laser light is raidated to the measuring object 11 in the maximum negative amplitude state and is exposed simultaneously to the photographic plate 8, whereby the hologram is obtained.