Wavelength-independent laser beam shaping
This paper presents a beam shaping device namely, a Diffractive Optical Element (DOE), which is used to change a beam having a Gaussian intensity profile into a beam with a uniform intensity profile. The DOE used in this work was fabricated from ZnSe and its performance was evaluated using a cw CO 2 laser. In most cases such elements are effective only at a specific design wavelength. However, in this paper we report on the design conditions which allow for wavelength independent elements. It was found that the DOE was able to successfully transform a Gaussian beam into a flattop beam for four different wavelengths in the range 9.2 μm to 10.6 μm. We also present experimental results on misalignment effects and it was found that small radial offsets of the incident beam on the DOE had a significant disruptive effect on the flattop beam profile. © 2010 SPIE.