What type of interaction does a laser have when it bounces off a surface without penetration?

When a laser beam encounters a surface and bounces off without penetrating it, that interaction is classified as reflection. Reflection occurs when light travels to a surface and is redirected back into the medium from which it originated, without any alteration to the internal structure of the surface or the light's energy.

In the context of lasers, this means that the laser light maintains its characteristics, such as coherence and phase, while changing direction based on the angle at which it strikes the surface. This property of lasers makes reflection an important aspect in various applications, such as laser scanning and optical alignment.

In contrast, absorption would involve the energy of the laser being taken in by the material, resulting in a change in energy state or transformation into heat. Transmission describes the passage of light through a medium, which does not apply when the laser beam does not penetrate the surface. Scattering would imply a diffuse redirection of light in various directions, rather than a clean bounce, which is not characteristic of the behavior seen in reflection.