APPARATUS AND METHOD FOR FOCUSSING AN OPTICAL BEAM

摘要

Apparatus (62) is described for focussing an optical beam. The apparatus includes an optical transmission component, such as a waveguide (56) having a first end (54), a first lens (58) for focussing light from the optical transmission component (56) to a remote probe volume (60) and focus adjustment means (66) for setting the range (R) of said remote probe volume (60) from the apparatus (62). The first lens (58) is spaced apart from the first end (54) of the optical waveguide (56) and the focus adjustment means (66) comprises one or more optical elements (70) and means for removably inserting any of said one or more optical elements (70) into the free-space optical path between the first end (54) of the optical waveguide (56) and the first lens (58). In this manner, the focus or range (R) of the device may be set as required. A laser radar (lidar) device for wind speed measurements that incorporates the focussing apparatus (62) is also described.