Robust design of diffractive optical elements for forming flat-top beams with extended depth of focus

Robust designs of single-diffractive optical elements (DOEs) on forming flat-top beams with extended depth of focus for different wavelengths and beam sizes are presented. The design process includes spatial Fourier filtering that results in a smooth DOE phase profile, for converting a Gaussian incident beam with arbitrary phase distribution (random/spherical) into a flat-top beam with extended depth of focus. We show that the depth of focus increases with the decrease in wavelength as well as with the increase in beam waist. We also determined the errors caused by decentering and tilting of the DOEs.