Final answer:
Contrast in differential interference contrast (DIC) microscopy depends on the rate of change of refractive index across the specimen.
Step-by-step explanation:
Contrast in differential interference contrast (DIC) microscopy depends on the rate of change of refractive index across the specimen.
DIC microscopy separates a polarized light source into two beams polarized at right angles. After passing through the specimen, the beams are recombined and realigned to create an interference pattern caused by the differences in their optical path and the refractive indices of the parts of the sample they passed through. This interference pattern results in an image with contrast and shadowing that cannot be observed with traditional optics.