Final answer:
The orientation of fast and slow rays can be determined using birefringent crystals, which split an unpolarized light beam into two polarized rays.
Step-by-step explanation:
We can determine the orientation of the fast and slow rays using birefringent crystals. Birefringent crystals have the property of splitting an unpolarized beam of light into two beams with different indices of refraction, leading to the creation of the ordinary and extraordinary rays. Each of these rays will have a distinct orientation based on its specific polarization and the properties of the birefringent material through which it has passed.