Device for calculating diffraction efficiencies of a diffraction lens, lens with grating element, and optical system for reading

摘要

A device for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, comprises a first memory for storing information about diffraction efficiencies of the regions; a second memory for storing information about weights corresponding to the regions; and a first processor for retrieving information from the first and the second memory, and calculating diffraction efficiencies of the entire diffraction lens using the formula $\mathop{\mathrm{image}}\begin{array}{cc}{E}_j=\underset{m=1}{\overset{M}{\∑}}\⁢W_m\⁢{\mathrm{\η}}_{\mathrm{mj}}& \left(1\right)\end{array}$;wherein: ;j: integer indicating the order of diffraction light ;E_j: diffraction efficiency for j-th order diffraction light of the diffraction lens ;M: positive integer (M1) indicating the number of regions for which the diffraction efficiency is calculated ;m: index of the region for which the diffraction efficiency is calculated ; _mj: diffraction efficiency for the j-th order diffraction light of the m-th region (stored in the first memory) ;W_m: weight for the math region (stored in the second memory means). ;Thus, the diffraction efficiency of the diffraction lens can be calculated easily.