Problem 2. Suppose that a Michelson interferometer is illuminated by a source emitting a doublet of vacuum wavelengths, 21 and 22. As one mirror is moved, the fringes periodically disappear and then reappear. If a displacement Ad of the mirror causes a one-cycle variation in fringe visibility, derive an expression for Ad in terms of Aλ = 2-1. Then calculate Ad for the sodium doublet, where λ₁ = 588.995 nm and 2 = 589.592 nm.

Problem 2. Suppose that a Michelson interferometer is illuminated by a source emitting a doublet of vacuum wavelengths, 21 and 22. As one mirror is moved, the fringes periodically disappear and then reappear. If a displacement Ad of the mirror causes a one-cycle variation in fringe visibility, derive an expression for Ad in terms of Aλ = 2-1. Then calculate Ad for the sodium doublet, where λ₁ = 588.995 nm and 2 = 589.592 nm.