There are different ways to design and build beam shapers; generally, it is based on diffractive or refractive optical elements. Both solutions have different kinds of advantages and disadvantages. Diffractive designs are very sensitive to parameters like wavelength, nevertheless, they are in general easier to manufacture. The refractive design offers more flexibility in terms of wavelength. In general, there are two possibilities for manufacturing such refractive beam shapers, either on basis of spheres or on basis of aspheres. Concerning the production of aspheres there have always been strong limitations either in terms of the surface form - only a small deviation from best fit sphere/plano surface is possible - and/or in terms of surface accuracy. As fully discussed in literature it is necessary to increase form accuracy in case of using aspherical forms with small aspherical departures. In other words, the quality of the beam shaper does not necessarily improve by using aspherical forms with small aspherical departures. On the contrary, one has to increase the form accuracy of the beam shaper element in order to keep beam quality standards.
Based on ten years of experience a technology has been developed that allows us manufacturing of optical surfaces in almost all kinds of forms, shapes and sizes. By now it is possible to produce aspherical forms both concave and convex, with strong departures from the best fit sphere as well as with inflection points from 4 to 200 mm in diameter.
By now it is possible to manufacture aspherical surfaces with big departures while securing high accuracies. It is the purpose of this paper to give an understanding of how the refractive approach can be applied for the fabrication of aspherical beam shapers.