Page 1 of 13 Types of Microscope: Optical and Electron Microscope (With Figure) Microorganisms are usually not visible to naked human eye. They can be made visible, only when they are magnified under microscopes. Microscopes are instruments, which can produce enlarged images of very small objects, making it possible to view them, which, otherwise, cannot be seen distinctly by naked human eye. Different types of microscopes are used by the microbiologists for specific purposes. Microscopes are of the following types (Figure 4.1). A. Light or Optical Microscopes: In light or optical microscopes, ‘light waves’ are used to produce the enlarged images of very small objects and magnification is obtained by a system of ‘optical lenses’. Ordinarily, microbes do not absorb much light, but staining them with dyes greatly increases their light absorbing ability, resulting in greater contrast and color differentiation. B. Light microscopes are of four types as described below: (1) Bright-field Microscope: In a bright-field microscope, the microscopic field (the circular area visible under microscope) is brightly illuminated and the microbes (or biological specimen) appear darker, as they absorb some of the light passing through them. It is of two types as follows: (a) Simple Microscope: A simple microscope is used to obtain small magnifications. A single biconvex lens magnifies the size of the object to get an enlarged virtual image.
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Page 1 of 13
Types of Microscope: Optical and Electron
Microscope (With Figure)
Microorganisms are usually not visible to naked human eye. They can be made visible, only
when they are magnified under microscopes. Microscopes are instruments, which can produce
enlarged images of very small objects, making it possible to view them, which, otherwise, cannot
be seen distinctly by naked human eye. Different types of microscopes are used by the
microbiologists for specific purposes. Microscopes are of the following types (Figure 4.1).
A. Light or Optical Microscopes: In light or optical microscopes, ‘light waves’ are used to
produce the enlarged images of very small objects and magnification is obtained by a
system of ‘optical lenses’. Ordinarily, microbes do not absorb much light, but staining
them with dyes greatly increases their light absorbing ability, resulting in greater contrast
and color differentiation.
B. Light microscopes are of four types as described below:
(1) Bright-field Microscope:
In a bright-field microscope, the microscopic field (the circular area visible under microscope) is
brightly illuminated and the microbes (or biological specimen) appear darker, as they absorb
some of the light passing through them.
It is of two types as follows:
(a) Simple Microscope:
A simple microscope is used to obtain small magnifications. A single biconvex lens magnifies
the size of the object to get an enlarged virtual image.