Coupler All-fiber Velocity Interferometer System Impact Study

All fiber velocity interferometer takes on some merit such as straightforward structure, easy adjustment and not strict demand of laser light coherence. The merit makes it necessary that all fiber velocity interferometer will replace traditional laser velocity interferometer in the kingdom of instantaneous velocity measure.The paper introduces a new kind of all fiber velocity interferometer, which possesses the characteristics such as straightforward structure, a wide velocity measure range, good precision and so on. The structure sketch map of the all fiber velocity interferometer is given in this paper, and then we analyze its work principle and list several system's pivotal technique indexes.Fiber coupler is an indispensable part of all fiber velocity interferometer, which makes it important to analyze the influence of coupler to system. The paper describes the coupling model theory of 2×2 coupler, which is then used to reason out the phase identity of 2×2 coupler. Because of the restricted produce technics, applied 2×2 coupler can't be ideal. For example, the coupling ratio is not 1 : 1, the two light-waves constituting the coupler are not uniform, the coupler has loss, etc. It is studied that how the nonideal factors influence the velocity system's degree of modulation and the detectors' phase difference relation. In addition, that how the delay fiber between the two 2×2 couplers can influence the system is discussed in the paper. Finally, it is analyzed that it can improve the system sensitivity if the 2×2 coupler is replaced by a 3×3 coupler.The experimentations of all fiber velocity interferometer include Hopkinson Bar experimentation, 37mm artillery experimentation, and the new gun experimentation. The paper writes up the three experimentation courses, and analyzes the experimentation results.