The infrared reflectance of water at incidence angles of 70° and 75° has been measured in the spectral region between 2 and 25 µm. We have used the measured reflectances of polarized radiant flux to determine the real part of the refractive index from the Fresnel equations. The imaginary part of the refractive index can be accurately determined from reflection measurements alone only in regions of strong absorption; in other regions we have used values based on measurements of transmittance. We give values of the optical constants in tabular form and compare them with recent determinations by other investigators.
MARVIN R. QUERRY, BASIL CURNUTTE, and DUDLEY WILLIAMS, "Refractive Index of Water in the Infrared," J. Opt. Soc. Am. 59, 1299-1304 (1969)