Noun
retroreflection (countable and uncountable, plural retroreflections)
(physics) reflection in which the reflected rays are parallel to the incident rays
Because the function of the eye is to form an image on the retina, an eye focused on a distant object has a focal surface that approximately follows the reflective tapetum lucidum structure, which is the condition required to form a good retroreflection. Source: Internet
For one, it is sometimes preferable to have an imperfect, slightly divergent retroreflection, as in the case of road signs, where the illumination and observation angles are different. Source: Internet
However, phase-conjugate mirrors have an inherently much greater accuracy in the direction of the retroreflection, which in passive elements is limited by the mechanical accuracy of the construction. Source: Internet
In that case, the sphere surface behaves as a concave spherical mirror with the required curvature for retroreflection. Source: Internet