Phase-contrast microscope

Definition

A phase-contrast microscope enhances the contrast of transparent and colorless specimens by converting phase shifts in light passing through the specimen into changes in amplitude, which can be visualized as variations in image brightness. This type of microscopy is particularly useful for observing live cells and their internal structures without staining.

5 Must Know Facts For Your Next Test

1. Phase-contrast microscopy exploits the wave characteristics of light to enhance image contrast.
2. It is especially useful for studying living cells, which are often transparent and hard to visualize with traditional light microscopy.
3. The technique involves a phase plate that shifts the phase of background light, making it interfere with diffracted light from the specimen.
4. Developed by Frits Zernike, who won the Nobel Prize in Physics in 1953 for this invention.
5. Phase-contrast microscopes can reveal cellular structures such as nuclei and organelles without requiring dyes or stains.

Review Questions

• How does a phase-contrast microscope enhance the visibility of transparent specimens?
• What are some specific applications where phase-contrast microscopy is particularly advantageous?
• Who developed the phase-contrast microscope and what recognition did they receive?

Related terms

Interference: A phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude.

Diffraction: The bending of waves around obstacles and openings, which can affect how light interacts with small structures under a microscope.

Optical Path Length: $$\text{The product of the refractive index of a medium and the physical distance traveled by light through that medium.}$$