1. The problem statement, all variables and given/known data I am currently studying the optical Michelson Interferometer and I am in need of help with a derivation. The equation I need to derive is that for the intensity of the light arriving at the viewing point. The equation is given below. 2. Relevant equations I(Δ)=I/2 + (1+cos(2∏vΔ/c)) Where Δ=2(d2-d1) (i.e the path difference of the rays) 3. The attempt at a solution I understand the need for the I/2 term to be the beam splitter splitting the intensity of each ray to half. I can see how the bracketed terms lead to the result for destructive and constructive interference by substituting in some values, but cannot derive the equation 'from scratch'. Many thanks to anyone that can explain the derivation to this equation.