The minimum deviation of a ray of light refracted by adjacent faces of a triangular prism is widely used in experimental situations, and is commonly present in the academic literature and in the textbooks. Although, the mathematical proof of the conditions of occurrence of minimum deviation is not easily founded in textbooks, and this deviation is therefore attributed to experimental data. In this work, a mathematical proof of the necessary condition for the minimal deviation is presented. We believe this proof is accessible to undergraduate students of introductory physics and calculus courses, therefore helping to fill this literature gap.
optics; prism; refraction; minimal deviation
