retrodirective

[ re-troh-di-rek-tiv, -dahy- ]
/ ˌrɛ troʊ dɪˈrɛk tɪv, -daɪ- /

adjective Optics.

(of a mirror, reflector, etc.) having three reflecting surfaces so oriented that a ray of light is reflected in a direction parallel but opposite to its original direction.

Origin of retrodirective