The incident ray is refracted towards the normal as it enters the glass prism from air. It is then refracted away from the normal at the boundary between glass and air as it leaves the prism.

It is then refracted away from the normal at the boundary between glass and air as it leaves the prism.

His glass prisms not only let light pass through but also redirected ... ray II is converged by the prism refraction, and ray III is recycled by other prisms. Credit: Zong Qin You might already ...