文章中写的是For light incident at high angles of incidence, like for a 45° dichroic beamsplitter, the bent substrate creates a slight divergence of the transmitted beam axis similar to the effect of a small wedge in the substrate. Unless the radius of curvature is very small (much less than one meter) the quality of the transmitted beam remains largely unaffected.
Reflected light, however, is significantly impacted by a bent filter substrate. This situation typically arises when an excitation beam is reflected off of a dichroic beamsplitter before reaching a sample, or when an imaging beam is split into two colors using a dichroic beamsplitter. Two main effects may occur: (1) the position of the focal plane shifts and (2) the size (or shape) of the focused spot changes or the quality of the image is compromised.
我觉得对透射的解释已经比较到位了，为什么对反射比透射大确实没有解释，但是这个很好理解。滤光片弯曲之后就变成了前后曲率一样的弯月透镜，弯月透镜在焦距上的前后面很大程度上互相抵消，所以这种透镜的焦距很大，而反射面只有一次反射，不像透射光有后表面的抵消，所以就焦距比较小，所以焦面偏移就大。
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发表于 2021-7-13 09:02