1. The problem statement: A wavelength (λ)550 nm light ray traveling thru a viscous medium n1= 1.46 strikes a a crystal n3=1.5 protected by a film n2=1.25. 2. Relevant equation: How can I determine the min thickness of the antireflective coating used to minimize the reflection of the incident light? 3. The attempt at a solution I think I can determine it by using 2t+0.5λ1+0.5λ3= (m+0.5)λ2 where m=1 and then solving for t. Any guidance would be greatly appreciated.