Phase Contrast Microscopy

Basic Setup  - The setup is similar to a bright field except for two modifications:
 * Annular Diaphragm – dark circle surrounded by another dark circle surrounding it.
 * A ring of light is generated which initiates the effect of phase contrast. It has two rings, but light only goes through the inner ring, which initiates more bending of light
 * Located below condenser (lets through a ring of light that helps the light to bend)
 * Phase shifting element – this takes the foreground and background light and focuses it by phase shifting the two sources of light.
 * Located in objective
 * Focuses the direct ray (direct ray straight up, incident rays are refracted)
 * Controls speed/brightness depending on index of refraction
 * Advance – to make brighter by speeding up the light
 * Retard – to make darker by slowing down the light

Appearance of Field and Object
Looks similar to bright field but objects are more sharply defined because it focuses the direct rays of light off the specimen and helps to eliminate the scattering of the light. Unstained organisms, motility, morphology, inclusions (areas of higher density within specimen)

Uses
Hospitals, cancer research to see details of cells

Look at unstained, living specimens (morphology and motility)

Can clearly see inclusions (endospores in bacteria)

Can be used even with mycoplasma