Equivalent source algorithm for secondary phase factor sampling problem

The relation of sampling principle to secondary phase sampling problem is analyzed. Based on Fresnel diffraction principle, the computation method for non-focal position is deduced, a new method, the equivalent source field method, is proposed to rebuild the source field to reflect the phase board encountered by the propagating field. As a results, phase boards as many as possible could be inserted into the transmitting path of the field with second phase factor, and still the accurate output field could be got. Comparing the out field intensity obtained by the equivalent source field method with using the light field analysis formula based on the Fresnel diffraction principle, the result shows that within 100 mm defocus distance, the relative error between the two is less than 10-13, so t