With DIC microscopy, two slightly separate, plane polarized beams of light are used to create a 3D-like image of the unstained specimen. A polarizer, placed just after the light source, creates plane polarized light that is passed through a Wollaston prism which splits the beam into two beams that have their axis of vibration at 90° relative to each other. The beams cross and go through the condenser and emerge separated by a small distance. The two beams go through slightly different parts of the specimen where small differences in refractive indexes of the cellular components alter their wave path lengths differently. Next, the two beams enter the objective, and pass another Wollaston prism that recombines them. This second prism is offset slightly from the first, creating a difference between deviated and undeviated beams. Since the two beams went through slightly different parts of the specimen, they will have different path lengths; therefore the waves can interfere if they are vibrating in the same plane. Therefore, the combined beam passes a second polarizing filter that is 90 degrees to the first one, which polarizes the bipolar beam and so the combined polarized light can have negative interference – gives light and dark areas of specimen.