Types of Light Microscopes

Bright-field

Commonly used in laboratory applications as the standard microscope; produces images on a bright background

Example of Bright-field

Bacillus (rod-shaped) showing endospores

Dark-field

Increases contrast without staining by producing an image with a DARKER background; viewing LIVE specimen

Example of dark-field

Borrella burgdorferi

Phase Contrast

uses refraction (bending of light) and interference to create high contrast images WITHOUT staining; useful for seeing LIVE specimen

Example of Phase Contrast

Pseudomonas sp.

Differential Interference Contrast (DIC)

uses interference to produce high-contrast images with a three-dimensional appearance; useless to view STRUCTURES within living and unstained specimen

Example of Differential Interference contrast (DIC)

Escherichia Coli

Fluroescence

uses fluorescent stains to produce an image; used to identify pathogens and to distinguish between living and dead cells; used for immunofluorescence

Example of Fluorescence

P. Putida

Confocal

uses laser to produce 2-dimensional that can construct into 3-dimensional images; used to examine thick specimens like biofilm

Example of Confocal

Escherichia coli

Two-photon

uses scanning technique (fluorochrome) and long wavelength to penetrate deep specimen, like biofilm

Example of two-photon

mouse intestine cells