Optical equipment of fiber laser Doppler velocimeter

摘要

A beam expander (32,33) is used with a perforated concave lens (32) and a plano convex lens (33) to expand a beam diameter to make a small measurement volume (0) to increase an intensity of light scattered, which contributes a reduction of a number of an optical components and a complicated optical adjustment, and makes a small probe diameter. The perforated part of the expand lens (32b) plays a role of a space filter to cut off troublesome light scattered when a beam passes through a lens. A three points supporting mechanism adjustment of the focused beam positioning into the fiber core and the incident beam aperture adjustment in the fiber's numerical aperture are used. A high resolution of the adjustment is achieved so that a high transmitting efficiency of a laser power into the fiber is achieved.