Measuring spin direction by means of coherent light? Let us assume that we have the ferromagnetic surface where all atoms have the same direction of spins. And we can  interact with the single atom in such lattice.
Is it possible to measure the direction of the atom's spin, by means of coherent light?
 A: In the optics regime, every time a wave impinges on a surface it is modifying the angular momentum of an electron. Since the electron PE is usually comparable to the visible regime.
As for measurements with coherent waves. I don't think this is an easy task, though I think it is possible. I mention waves, because depending on the energy level of your electron it could require UV or higher energy waves. The light must be coherent to measure the angular momentum  of an electron because the polarization of the wave determines how it will interact with the electrons. You would need to tune your wavelength to the material's electron shell that your interested in. If that electron shell has electrons that are only spinning in one direction, then I suppose yes, based on the polarization of the transmitted/reflected wave you could theoretically identify the spin state of the electron. 
If you want to see a paper that determines spin states using linearly polarized light then please see attached. I personally think I would prefer to use only completely polarized right or left light. However, I am not an expert on the topic and the attached paper uses linear polarized light. Maybe they explore this topic in more detail...
