Beam shaping to generate uniform 'Laser Light Sheet' and Linear Laser Spots

摘要

Generation of "Laser Light Sheet" beams and linear laser spots characterized by uniform irradiance distribution is important in various laser techniques like Particle Image Velocimetry (PIV), Laser-Induced Fluorescence (LIF), hardening, annealing, cladding, uniform laser illumination of linear spatial light modulators. This task can be successfully solved with using refractive beam shaping optics of field mapping type in combination with additional optical components. Due to their unique features: low output divergence, high transmittance, flatness of output phase front and irradiance profile, as well as extended depth of field, the refractive field mappers provide freedom in further manipulation of intensity profile and shape of output beam. Typically design of refractive field mapping beam shapers has circular symmetry; therefore to create linear spot shapes it is suggested to apply anamorphic optical components like cylinder lenses, prism pairs, etc. The combined beam shaping systems allow achieving very high aspect ratio, up to 1:1000, of linear spots with simultaneous providing extended depth of field, i.e. it is possible to realize a "Laser Light Sheet" characterized by keeping uniform intensity of linear spot over extended distance along optical axis. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts for creating linear laser spots and "Laser Light Sheet". Examples of real implementations will be presented as well.