Dependence of absorbance of a sample on the type of polarization of the measuring beam. This polarization may be linear, corresponding to linear dichroism (LD) in which the difference in absorption for two perpendicularly linearly polarized beams is measured, ΔAl = AZ - AY, or circular dichroism (CD) in which the difference in absorption for left minus right circularly polarized beams is measured, ΔAC = AL - AR.