Here is your short paragraph on interference microscope!
Interference microscope is based on principles similar to those of the phase microscope. But it has some advantage, i.e., it gives quantitative data. It detects small continuous changes in refractive index, while the phase microscope shows only sharp discontinuities.
The variations of phase can be changed into such vivid color changes that a living cell may preparation.
With the interference microscope, which is also able to detect phase changes in the object, it is relatively easy to vary contrast and to select the most suitable contrast for a given object. It is also possible to obtain color effects in the object because of differences in optical paths.
The optical path is the product of the refractive index and the thickness of the object and is a measure of the distance light travels in passing through the object. Measurements of this type enable the investigator to make quantitative determinations, such as the determinations of dry weight.
Another advantage of the interference microscope over the phase contrast microscope is the absence of a halo around the object in view. In the phase-contrast microscope, direct light falls on the annulus and diffracted light falls on the entire phase plate.
Thus, there is incomplete separation of the two, resulting in a halo around the object. The absence of halo in interference microscopy is the result of complete separation of direct and diffracted light. Phase-contrast, therefore, has been called an imperfect type of interference contrast.