1. The problem statement, all variables and given/known data: Calculate the penetration depth of an evanescent wave undergoing TIR from glass (n = 1.5) to air interface, such that the amplitute is reduced to 1/e times its original value. Wavelength of the incident light is 5000 angstroms and 60 degrees. First make sure that incident angle of 60 degrees produces TIR - the critical angle is less than 60 degrees. 2. Relevant equations 3. The attempt at a solution I proved that the critical angle is less than 60 degrees. How does that relate to penetration depth and the amplitute of the evenescent wave?