Refractive index of a transparent liquid measured with a concave mirror
  This paper describes the spherical concave mirror method for measuring the index of refraction of transparent liquids. We derived the refractive index equation using Snell's law and the small-angle approximation. We also verified the validity of this method using the traditional spherical mirror and thin-lens Gaussian equations. 
Amitabh Joshi and Juan D. Serna
physics.class-ph physics.optics