大数值孔径光学系统表面光线的入射角较大，会导致薄膜的偏振分离，诱发偏振像差，影响光学系统的聚焦特性.本文利用矢量光衍射理论，建立了光学薄膜各参量与光学系统聚焦光场的模型.利用该模型分析了线偏振光入射时，光学薄膜对光学系统聚焦光斑的扰动.在此基础上，探讨了应用了不同约束条件下得到的光学薄膜对最终聚焦光场的影响，确定了减小薄膜扰动光学系统光斑的设计方法，即额外添加透射率差和位相差的约束条件，并且适当增加位相差约束的权重.利用该方法优化设计的薄膜，相比于普通减反膜而言，对系统聚焦光场中心强度的提升可达约12.5%.%The incident angles of the optical systems with high numerical apertures, such as lithography or microscope, are larger than those of normal ones. For these systems, polarized illumination is widely adopted. The coatings on their surfaces will make s and p polarization components of oblique incident light experience diverse amplitudes and phase modulations, and induce extra polarization aberrations. We apply the vectorial diffraction theory to assess the effects of coating-induced polarization aberrations on the focusing properties of these systems. By applying the generalized Debye integral, the relationship between the parameters of coating and electric field vector near the focal spot is established. Considering x linearly polarized light as the incident light field, we evaluate the potential influence of the coatings on the intensity and the full width at half maxium of focal spots. In the further discussion, we compare the results of different coatings when the various optimization goals are set, and certify that the phase difference caused by coating has more effect on focusing property. Based on this, the additional constraint conditions of coating design are proposed to suppress such disturbance, i.e. to properly increase relative weight of phase constraint conditions. With this proposed constraint conditions, we design and optimize an anti-reflection coating with low polarization aberrations. By applying this designing, the central intensity of focal spot can be enhanced by 12.5%, and the light energy utilization will be improved effectively.
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