User Guide

490 Series Microscope
AmScope Proprietary Page 26 of 64
A phase contrast system incorporates two
components to segregate light, so out-of-
phase waves can be realigned. The two
components are the annulus in the
condenser and the phase ring in the objective
lens.
The condenser’s annulus separates light into
surround light and diffracted light. Light
passing directly through the annulus creates
a hollow cone called surround light. This light
passes directly through the optical system
and is intercepted by the phase ring in the
objective lens.
Light diffracted by the edges of the annulus
passes more centrally through the specimen
in the objective lens.
As the light collectively passes through the objective lens, it is further segregated by the
phase ring. The phase ring shifts the phase of the surround light either positively or
negatively so the waves are in-phase.
Since human sight is incapable of perceiving light phase, the aim of phase contrast is to
translate the disparities in phase into perceivable variations in brightness.
There are several techniques
available for increasing the contrast
between the specimen and the
background, each tailored for a
particular purpose. Phase-contrast
does so by manipulating the phase
of light, and is useful for observing
the inner mechanics of cellular
structures, especially live cells,
without the need for staining.