retroreflectorn.
/ˈrɛtrəʊrᵻˌflɛktə/, U.S. /ˈrɛtroʊrəˌflɛktər/, /ˈrɛtroʊriˌflɛktər/ A device or instrument which reflects light in such a way that it travels back along the path it took prior to reflection, irrespective of the angle of incidence of the light.
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the world > matter > physics > electromagnetic radiation > light > reflection > [noun] > reflecting device
reflector1777
retroreflector1949
1949 U.S. Patent 2,471,750 3 Each light ray reversed in direction by the retroreflector..returns to strike that portion of the test surface from which it was initially reflected.
1976 Sci. Amer. Feb. 51/1 Pulses of laser light are beamed through a telescope on the earth at one of the retroreflectors placed on the moon.
2003 N.Y. Times (National ed.) 27 Mar. a4/2 A projector projects it on the garment's front, which is covered with tiny reflective beads called retroreflectors. The process creates an illusion of invisibility.
This entry has been updated (OED Third Edition, March 2010; most recently modified version published online March 2022).
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n.1949