In principle, the real n and imaginary k parts of the complex refractive index of a crystal can be determined by measuring, when possible, its transmission and reflection spectra. We show that it is possible to derive the frequency dependence of n and k in a simple way by using exact expressions for the interference-free transmittance and reflectance to describe low-resolution data. We also derive n and k data starting from one high-resolution spectrum. As an example, we have measured the room-temperature transmittance and reflectance of MgO in the far-infrared region. Reliable n and k data are then obtained in the frequency region 50–250 cm−1.
© 1992 Optical Society of America
Original Manuscript: July 24, 1991
Published: August 1, 1992
S. Cunsolo, P. Dore, and C. P. Varsamis, "Refractive index of crystals from transmission and reflection measurements: MgO in the far-infrared region," Appl. Opt. 31, 4554-4558 (1992)