Refraction: Total Internal Reflection (TIR)

*Shine a laser light source into a semi-circle glass prism.
*At a 40 degree ANGLE.  Notice in the first picture how the light goes straight through.
*In the second picture, light is refracted and reflected.
*In the last picture, the light is ONLY refracted.
*Total Internal Refraction (TIR)
*Angle of Incidence is larger than the Critical Angle of the medium.