Interference Microscopy (A Type of microscope )

Interference Microscopy

The basic difference between interference microscopy and phase contrast microscopy is that the former does not rely on the diffraction of light by the object, but generates mutually interfering beams which produce contrast. It is this feature that enables the microscope to accurately measure the phase change in an object as small as 1/300th of a wavelength. In addition, this technique gives the viewer a three dimensional image of the object under study.

For interference microscopy, the brightfield microscope is modified by the addition of a special beam-splitting (Wollaston) prism to the condenser. When a beam of light is split by the prism, one passes through the specimen, which alters the amplitude of the wave; while the other does not pass through the specimen and serves as a reference beam. These two dissimilar beams then pass through the objective and are recombined by a second beam-combining (Wollaston) prism. This recombination of light waves gives a three-dimensional image (Fig 3.27).

Some applications of interference microscopy

1. To study individual parts of living cellswith maximum resolution of detail.

2. To estimate dry mass when it is applied as ahighly accurate optical balance.