Non-paraxial Diffractive and Refractive Laser Beam Shaping

San Francisco, 1st of February, 2018, SPIE Photonics West

There are several reasons that a paraxial assumption in laser beam shaping is not justified, including 1) the use of laser diodes, which deliver a non-paraxial beam in the fast axis, 2) the use of lasers or other sources for wide-angle illumination, and 3) the generation of small focal spots with controlled profile by high NA lens systems. In order to keep the systems compact, it is not always possible to apply the beam shaping component in a paraxial region of the setup. We discuss the implications of the modeling and the design of diffractive and refractive freeform surfaces in non-paraxial regions of the fields to shape the profile of a laser beam in its far field, its focus or any other region. The fast physical optics approach employed enables the inclusion of freeform surfaces and diffractive beam shaping elements in the modeling. The design of beam shaping elements follows an inverse physical optics approach. We will discuss the pros and cons of refractive and diffractive solutions together with examples.