Among the scientific, industrial and laser applications where the beam shaping optics is applied there are several techniques which cannot be fully realized without providing collimated beams of uniform intensity profile and flat wave front. This relates, for example, to techniques based on spatial light modulators (SLM): holographic techniques like Computer Generated Holography (CGH), optical trapping and laser illumination in confocal microscopes.
The optical task of converting an initial laser beam with Gaussian or similar intensity distribution to a flattop beam of low divergence is successfully solved by the refractive beam shapers of field mapping type. Refractive field mapping beam shapers transform the laser beam profile in a controlled manner, by accurate introduction and further compensation of wave aberrations. The resulting collimated output beam has a uniform intensity and flat wave front. It also has low divergence - comparable to that of the input beam. In other words, the field mappers transform the beam profile without deterioration of the beam consistency and without increasing its divergence.
This feature is very important for further manipulation of the resulting beam and makes it possible to realize various optical layouts like ones based on applying beam-expanders/reducers to vary the final spot size or anamorphotic attachments to generate a linear spot shape of required length. A noteworthy fact is that some of above mentioned techniques, for example CGH, present, in essence, beam shaping on the basis of diffractive optics. This means the refractive beam shapers of the field mapping type can improve the performance of beam shaping systems of other types! No doubt, the combination of features of various beam shaping techniques can be very fruitful and allows additional advantages in the realization of laser technologies.
We will consider some optical layouts incorporating refractive field mapping beam shapers πShaper produced by the company AdlOptica GmbH and describe features of their application to diffractive beam shaping technique with CGHs.