Differential Doppler velocimeter with a fiber channel and a miniature light-emitting probe

A new miniature head of a fiber probe for a laser Doppler velocimeter is proposed. A special feature of the probe is the presence of a wavefront divider in the form of a bilens. Analytical relationships are obtained between the parameters of the velocimeter under optimal alignment conditions. A report is given of an experimental study of the operation of a fiber velocimeter. A study is made of the influence of the mode composition of the radiation in the fiber waveguide on the characteristics of the probe field. Experimental evidence shows that it is possible to adjust the period of the interference field in the course of velocity measurements.