What is the Difference Between Dichroism and Birefringence?

Dichroism and birefringence are two distinct optical phenomena that occur in anisotropic media, which are materials with different physical properties in different directions. The key difference between the two lies in their effects on light polarization:

• Dichroism: This phenomenon is the ability of a substance to absorb light that is vibrating in a certain plane differently than light vibrating in other planes. In other words, dichroism induces polarization, meaning it filters or absorbs light based on its polarization direction.
• Birefringence: This phenomenon involves the double refraction of light in a material that is transparent, resulting in a retardation of one of the orthogonal polarization light field components with respect to the other. In simpler terms, birefringence retards or slows down light with orthogonal (i.e., perpendicular) polarization compared to light with parallel polarization.

Both dichroism and birefringence are elementary types of polarization properties in anisotropic media, with dichroism affecting the absorption of light based on its polarization and birefringence affecting the refraction of light based on its polarization.

Comparative Table: Dichroism vs Birefringence

Here is a table comparing the differences between dichroism and birefringence:

Both dichroism and birefringence are optical properties of anisotropic materials, but they have different effects on light. DichroismSelective attenuation of the medium, whereas birefringence retards one of the light field components having orthogonal polarization. Dichroism affects the absorption of light vibrating in a certain direction, while birefringence is manifested by the double refraction of light in a material that is transparent.