The production of an elliptically polarized wave when a linearly polarized light wave passes through a substance that has differences in the extinction coefficients for left- and right-handed polarized light. The size of this effect is given by φ = π/λ(ηl – ηr), where φ is the ellipticity of the beam that emerges (in radians), λ is the wavelength of the light, and ηl and ηr are the absorption indices of the left- and right-handed circularly polarized light, respectively. Circular dichroism is a property of optically active molecules and is used to obtain information about proteins. See also CD spectrum.
φ = π/λ(ηl – ηr)