Study of wide-spectrum and high-resolution diffraction optical elements by stacks of binary phase gratings.

This work theoretically investigates wide-spectrum and high-resolution diffraction optical elements (DOE) that are made of stacks of low-resolution binary phase gratings, whereby the two-dimensional grids in different grating layers are arranged with specified displacements. We remodel the common Kinoform algorithm for this multi-scale architecture. Numerical computations show that, by increasing the number of stacking layers, the resolution of diffraction fields can be improved and that the stability of optical elements within broad spectrums is significantly enhanced. Practical concern on largely increasing the number of grating layers are efficiency of the optical designs in theory and the manufacture of stacks of ultra-thin grating films.