New optical assembly for quasi-tophat beam shaping

InnoVision has developed a new optical assembly for generating a quasi-tophat laser beam profile from gaussian beams.

laser beam befor shaping

laser beam after shaping

In most applications for selective ablation using of gaussian beam profiles are impossible.Especially with fs laser where nonlinear absorption becomes predominant. Therefore beam shaping is crucial. Nowadays tophat converters are used that generate from gaussian profiles tophat beam profiles. Exactly in working distance the beam profile is very good. But slightly off working distance the beam profile becomes dramatically worse.

To overcome this issue InnoVision developed a solution for tophat profile where the tophat changes only slightly with different working distances. Therefore the tophat is not ideal. The Quasi tophat is at the beam waste. Before and behind the ideal working distance the peak intensity is lower. That prevents damages. (Beam shaper using diffractive optical elements (DOE) usually have strong hotspots behind the ideal working distance. see

Our solution converts beams with M2 < 1,5 to beams with  M2 between 1,5 and 2,5.  This solution allows better integration in industrial production systems and the use of galvo scanner. Also focus controls are no longer important. The processing of 3D parts is much more easy.

The beam shaping unit has been testes at the laser labs at TH Köln campus Gummersbach.

The main application of the beam shaping unit is:

  • ps and fs laser where multimode fibers can not be used,
  • single-mode fiber laser.

The system can be easier integrated in laser material processing systems than „gauss-to-tophat-converter“.

We sell the optical assembly or we develop a customized solution for your systems with laser, scanner and bean path.

Now, we are working on combining quasi-tophat with Bessel focus to achieve very long working distances. This unit can be easily used in in the next generation of ps and fs laser that will have much  higher pulse energy. For this laser we also developed a multi-spot solution for galvo scanners. In contrast to usual multi-spot solution using DOEs our solution allows to adjust beam distances and the energy of each beam.