For 10 points, name this phenomenon in which a wavefront changes direction at an interface between two media so that it returns to the first medium, which takes place with mirrors.
This process is used on beams of neutrons to determine the surface structure of thin films. Its diffuse form is modeled well by a Lambertian model, in which intensity is directly proportional to the emission angle and so perceived radiance is constant. For a given polarization, this phenomenon is minimized at Brewster's angle. Above the critical angle, a "total internal" variety of this phenomenon occurs. For 10 points, name this phenomenon in which a wavefront changes direction at an interface between two media so that it returns to the first medium, which takes place with mirrors.
This process is used on beams of neutrons to determine the surface structure of thin films.
{reflection}