兩向色性
Dichroism \Di"chro*ism\, n. [Gr. ? two-colored; di- = di`s- twice + ? color.] (Opt.) The property of presenting different colors by transmitted light, when viewed in two different directions, the colors being unlike in the direction of unlike or unequal axes.
dichroism n : pleochroism of a crystal so that it exhibits two different colors when viewed from two different directions