Optimization And Implementation Of Wavefront Coding Imaging Systems Based On Zemax

Extended depth of field provides more information in object space.The wavefront coding,one of the depth of field extension ways,is a two-step technology including the optical encoding and the digital decoding.By inserting a phase mask in the pupil plane,the point spread function(PSF)and the modulation transfer function(MTF)are insensitive to misfocus.The images captured in the image plane are blurred,but can be decoded to be sharp ones using the same filter.Compared with the traditional imaging technology,wavefront coding can not only extend the depth of field,but also correct the aberrations caused by misfocus.A cubic phase mask is optimized in an ideal imaging system as an example of the wavefront coding technology.The bacterial foraging algorithm is proposed as the optimization algorithm in this paper.Fisher information is applied as the merit function.Wiener filter is applied as the decoding algorithm.The simulation results show that the optimized system is insensitive to the misfocus without resolution lost.Compared to the traditional simulated annealing algorithm,the optimization with the bacterial foraging algorithm is fast and easy to jump out of local optimal solution.Besides the optimization in an ideal optical system,this paper also proposes an integrative optimization method in the practical optical system considering all optical aberrations.A practical doublets system is designed using the integrative optimization method,while an ideal system with an optimized phase mask is also used for comparison.The simulation results show that the system designed by the integrative optimization method works well on both the on-axis and the off-axis fields,while the phase mask designed in the ideal system had a poor performance on the off-axis fields.As practical imaging systems have both the on-axis and off-axis fields,the integrative optimization will be one of the significant methods for the design of the practical wavefront coding systems.Experiments are used to verify the optimization theory proposed in this paper.A doublet system is used as an example.The liquid crystal spatial light modulator is used as the phase mask.The PSFs are captured as the deconvolution kernels for the digital decoding using Wiener filter.The experimental results show that the depth of field in the wavefront coding system is extended to 2.7 times of the traditional one.