Applying of refractive beam shapers of circular symmetry to generate non-circular shapes of homogenized laser beams

摘要

Creating of non-circular laser spots, for example of linear, elliptical or rectangle shape, with uniform intensity profile is important in various laser techniques in industry, scientific and medical applications. This task can be successfully solved with applying of refractive beam shaping optics of field mapping type in combination with some additional optical components. Due to their unique features, such as: low output divergence, high transmittance and flatness of output beam profile as well as extended depth of field, the refractive field mappers provide a freedom in further manipulation with intensity profile and shape of a laser beam. Typically design of refractive field mapping beam shapers has circular symmetry, therefore creating of non-circular spot shapes requires applying anamorphic optical components (cylinder lenses, prism pairs, etc.) ahead of or after a beam shaper. As result it becomes possible to provide various combinations of spot shape and intensity profiles, for example: roof-like spot with uniform intensity in one direction and Gaussian or triangle profile in another direction, linear spots with aspect ratio up to 1:1000, elliptical spots of uniform intensity, etc. Applications include flow cytometry instrumentation, particle image velocimetry, particle size analyzing, hardening, cladding, annealing, and others.This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts for creating laser spots of non-circular symmetry. Examples of real implementations will be presented as well.