The transparent adhesive must be homogeneous and low in absorption of light, and its refrangibility must be same as that of the material to be bonded.
作为光透性胶粘剂，必须均匀，对光具有低的吸收，和被粘接材料的折射率相当。
2
This article begins with introducing the conception of refrangibility, and then the relation between refractive index and density of the gas is established.