Method to make accurate measurements of refractive index

One of the important parameters used in optics is the refractive index. There are different methods to measure the refractive index in the visible region. One of the techniques used to carry out these measurements uses the method of minimum deviation that suffers a ray of light when crossing a prism. Other common methods are based on the determination of the critical angle and in the Brewster angle. A method of determination of the refractive index using prisms was described recently by Hsiu. In the method of Hsiu, the incident beam is normal to the first surface of the prism the refraction is manifested only in the second surface. The relationship obtained under this configuration is ( ) α δ α sen sen n + = , where α the angle of the prism and δ the deviation angle that suffers the beam in the second surface. The method of Hsiu can be used to determine refractive index of lens doing some modifications. Most of these methods are based on the application of the refraction law. The method that we propose in this paper considers the diffraction of the light.