Calculation of a diffractive lens having a fixed focal position at several prescribed wavelengths

A method for calculating a “spectral” diffractive lens, which ensures the preservation of the focal position at several prescribed wavelengths is proposed. The method is based on minimizing the function characterizing the difference between the complex transmission functions of the spectral lens for given wavelengths and the complex transmission functions of diffraction lenses calculated separately for each of the given wavelengths. As examples, spectral diffractive lenses are calculated for three and seven wavelengths. The simulation results of the calculated lenses confirm good performance of the proposed method.