1. The problem statement, all variables and given/known data Given a "new type" of optical fiber (index of refraction n = 1.23), a laser beam is incident on the flat end of a straight fiber in air. Assume nair = 1.00. What is the maximum angle of incidence Ø1 if the beam is not to escape from the fiber? (See attached file for diagram). 2. Relevant equations Snell's Law: n1*sin(Ø1) = n2*sin(Ø2) 3. The attempt at a solution I know the answer is 45.7°, I just can't seem to generate it. For the beam not to escape from the fiber, the angle of incidence must be the critical angle, such that Ø2=90° (or sin(Ø2)=1). But I don't know if I'm supposed to try to find the critical angle, then work backwards to find the initial angle of incidence from the air into the fiber or not. There's no cladding to consider in this problem, so I'm just very confused.