67. Using a diffraction grating with a period of d = 20 mm, it is required to resolve a sodium doublet with sodium lengths with wavelengths λ1 = 589.0 nm and λ2 = 589.6 nm in the second-order spectrum. Determine at what minimum length in the lattice this is possible.

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)