LIGHT-REFLECTION FROM A NATURALLY OPTICALLY-ACTIVE BIREFRINGENT MEDIUM

The measurement of natural optical activity by means of specular light reflection can provide an alternative method for spectroscopy of chiral materials that is in some cases (e.g., for thin films and opaque materials) more advantageous than current methods based on light transmission. The Fresnel amplitudes for specular reflection of light from a naturally chiral, birefringent medium are derived on the basis of a theory that takes account of spatial dispersion in both the electric and the magnetic material relations. Previous derivations neglecting the lightinduced magnetization result in Fresnel amplitudes that violate the law of energy conservation (Poynting's theorem). The differential reflection of left- and right-circularly polarized light by chiral uniaxial media is examined as a function of angle incidence and shown to peak near Brewster's angle. The measurement of the differential circular reflection may possibly be best accomplished by photoelastic modulation of the probe-beam polarization followed by synchronous detection; the experimental prospect for achieving this is discussed. © 1990 Optical Society of America.