Abstract
We report the design of diffractive beam splitters for dual-wavelength laser processing. They produce
beam arrays for two different wavelengths in the way the arrays coincide at target points on a workpiece
to process. The digitized surface profiles of the dual-wavelength splitters were designed using an
iterative algorithm by considering the splitting performances, the material dispersion, and the
wavelengths. For the chosen wavelengths of 1064 and 266 nm, as an example, we needed 32 phase
levels and 42 pixels to obtain splitting effi ciencies of > 80% and splitting uniformities of > 0.90. The
minimum pixel width was ~1% of the splitter period. The tolerances of the profi le errors were found to
be ~1% of the designed depths. The shorter the wavelength is, the more sensitive the splitter
performances are to the errors. Using achromatic splitters we can exploit the advantages of dualwavelength
laser processing and attain a high throughput.
