冰岛的方解石展示出明显的双折射现象，透过它可以看到双重图像。

Iceland spar shows noticeable ___birefringence, creating double images when you look through it.

显微镜下的方解石晶体显示出明显的双折射现象。

The calcite crystal under the microscope shows strong ___birefringence.