When it comes to highest power laser applications CO<sub>2</sub>-lasers are one of the most prominent choices. In most applications the raw laser beam which exhibits a Gaussian or Gaussian-like shape is employed. In contrast, homogeneous top hat profiles or customized beam shapes offer several application-specific advantages. Up to now the possibilities of beam shaping for CO<sub>2</sub>-lasers were very limited based on traditional approaches only. To make the advantages of homogeneous beam profiles also accessible for CO<sub>2</sub> sources LIMO has expanded its range of production capabilities for the manufacturing of ZnSe micro-optics. LIMO's proprietary production technology is based on computer-aided design and no etching technique is involved at all. A Gaussian-to-top-hat converter made of ZnSe is demonstrated. The properties of the micro-lens surface, the generated beam profile with a CO<sub>2</sub>-laser as well as first application results are shown.
Direct laser patterning of various materials is today widely used in several micro-system production lines like inkjet
printing, solar cell technology, flat-panel display production and medicine. Typically single-mode solid state lasers and
their higher harmonics are used especially for machining of holes and grooves. The most prominent lasers are pulsed
Nd:YAG lasers and their harmonics @ 266, 355 and 532 nm. Recently, the striking advantages of flat top intensity
distributions for the efficiency and quality of these processes were demonstrated. The use of LIMO's compact Gaussian-to-
top-hat converter enables the creation of steeper and sharper edges. Additionally, the higher energy efficiency of
rectangular top hat profiles compared to smooth, circular Gaussian shapes allows for faster patterning. A standard
method to reduce process times is the use of optical scanning systems. Yet, the application of Gaussian-to-top-hat
converters in combination with a scanner was hindered by distortions of the top hat introduced by the F-Theta focussing
lens of the scanners even at very small deflection angles (<2°). We solved this challenge by implementing an alternative
scanning approach (patent pending). Scanning results obtained with a 50x50μm<sup>2</sup> top hat field (homogeneity down to
<10%) in a scan area of 156x156mm<sup>2</sup> will be presented. The minimal distortions of the top hat observed within the scan
area make LIMO's compact Gaussian-to-top-hat converter excellently suited for industrial scanning applications, e.g. for
the processing of solar panels.