| Popis: |
Using a Nd:YAG laser in single and double pulse mode, the dynamic behavior of bubbles generated by a small airgun, placed in a water tank, has been investigated. Single pulse holograms of the bubble have been obtained with the purpose of investigating the shape and smoothness of the surface. Interferometric holography, or double pulse holography, of the bubble has been performed in order to detect the pressure wave from the gun at the early stages of the bubble expansion. The optical phase delay of the laser beams traversing the test section is caused by a local change in the refractive index of the water in the tank due to the acoustic disturbance. A theory for relating the change of the refractive index to bubble parameters is presented. Modeling of interferometric holograms has been performed with the aim of qualitatively comparing them with the recorded holograms. From the holograms it is observed that the surface of the bubble is relatively smooth during the first expansion. During the contraction, a... |
