Two-point Photonic Doppler Velocimetry System Based On Bare Fiber Probe

Photonic Doppler Velocimetry (PDV) is novel of laser velocimetry system. It is widely used in the velocity measurement of the shock wave, detonation wave and other short-time high-velocity moving objects. The velocities of different points of the target can be obtained using the multi-point measurement so as to find out the deformation of the target surface. However, for multi-point measurement, the larger GRIN lens probe spacing limits the spatial resolution of measurement. In this paper, a two-point Photonic Doppler Velocimetry System based on bare fiber probe is proposed experimentally analyzed.This paper designs10bare fibers bundle as probes. And using it constructs two-point Photonic Doppler Velocimetry System.In this paper, many velocity measurement experiments are made with different distances between probes spacing, and also the experiments results on different distances between the probes to the target are also given. Two-point velocity measurement with spatial resolution of375μm is experimentally realized, which improve the spatial resolution of PDV measurement system.Because of smaller probe spacing, the measuring results obtained from a probe could be influenced by the reflected light from another probe. Finally, the influence of stray light emitted from another probe on the measurement results has been studied theoretically and experimentally. the results show that the measuring results are not affected by the stray light when the target surface has the same velocity, and the measuring errors are related not only with the velocity difference of two points but also with the intensities and phases of sensing and stray light when the target surface has different velocity.