Evaluation of the imaging performance of hybrid refractive–diffractive systems using the modified phase function model

The imaging performance of a hybrid refractive–diffractive system is limited by the diffractive efficiency of the diffractive optical element (DOE). This phenomenon is explained in this paper by the wavefront deformation from the ideal wavefront at the exit pupil. The modified phase function model is developed to correct the wavefront deformation, and the application of the model is extended to the harmonic diffractive optical element (HOE) and the multi-layer diffractive optical element (MOE) as well. The general phase delay factor is derived for DOE, HOE and MOE. The validity of our model is verified by comparison with the weighted summation model of orders using a simple hybrid optical system example. Finally, the performance of the hybrid system with a HOE for dual waveband is evaluated