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total internal reflection (TIR)


Total reflection of a light ray at the boundary between two media occurring when the angle of incidence in medium 2 exceeds the angle whose sine equals n1/n2, the ratio of indices of refraction when the ray is propagating in the direction from medium 2 toward medium 1.

NOTE: This term was changed in ANSI/IES RP-16-17 Addendum 4. Previous name: total internal reflectance, TIR.

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