A new all-fiber velocity interferometer system for any reflector

A new type of all-fiber velocity interferometer(AFVISAR),working at the 532 nm, has been developed which has the advantages of both the traditional velocity interferometer(VISAR) and the AFVISAR.The interferometer consists of only fibers or fiber coupled components and has no optical elements such as optic lens or reflectors. It is very compact and easy to operate. Unlike AFVISAR, the laser beam in this new VISAR system arrives at and reflects from the target surface through a multimode fiber component, goes back into and interferences with each other in a [3*3] single-mode fiber coupler. Its working principle was elaborated in this paper. Preliminary experiments using shock Hopkinson bar device show that the new interferometer can successfully probe the velocity profiles of a metal specimen along the axial or radial direction.In addition,the theoretical strike velocity is 50.16 m/s and the velocity measured by the new AFVISAR is 49.36 m/s.