Beam Expander is critical for Beam Shaping

Some laser material processing applications, whether using an X-Y stage or galvanometer scan head or polygon scan head, can benefit from beam shaping.  The typical laser has a Gaussian beam.  The energy of the Gaussian beam is highest at the center.  Beam shaping optics can convert the Gaussian profile to a Top Hat, or donut or other profile that may work better in a given application.

 It is common practice to expand the beam as it comes out of the source to meet the requirements of the material processing optics.  And, the expansion ratio might need to change to adapt to the beam diameter of different sources.  In straight forward Gaussian systems, typical beam distortion induced by the beam expander has minimal effect on the working spot.  So, little thought is given to beam expander distortion because it is usually not an issue.

Beam shaping optics depend on a true Gaussian beam at the input to give the desired profile at the output.  The old adage “Garbage in = Garbage out” definitely applies to beam shaping.  However, a problem at the beam expander can be easily overlooked since “it has worked fine in our Gaussian systems”.  A suitable beam profiling camera is essential for alignment and setup of a system with beam shaping. 

There are any number of suppliers of beam expanders but many are not good enough for beam shaping applications. One sure brand of beam expanders to trust for beam shaping applications is Geomatec.  The Geomatec beam expanders are designed and tested for ultra-low beam distortion.  Geomatec is a Japanese laser optics manufacturer that produces Beam Expenders and F-Theta lenses which are among the best in the world:

GEOMATEC BEAM EXPANDERS

In summary, whether using an X-Y stage or galvanometer scanner or polygon scanner with beam shaping, pay close attention to beam distortion.  Use a suitable beam profiling camera to evaluate the beam before and after beam shaping.  Geomatec beam expanders will provide the results required.