Compound Light Microscope

The compound microscope is a very common type of microscope. The
term "compound" means more than one lens is used.

Have two lenses  Primary lens is the one closest to the object and
then there is the secondary lens, which is furthest from the object. A
modern compound lens can magnify the original diameter of
specimens 1000x to 2000x.
Parts:

Eyepiece

Objectives

Fine Adjustment Knob

Power Switch

Stage

Diaphragm

Base

Body Tube

Nosepiece

Stage Clips

Stage Stop

Coarse Adjustment Knob

Aperture

Arm

Light Source
How does it work?

The secondary lens is used to magnify the image of the primary lens.
The primary lens is aimed at the condenser, or stage, and this is where
the object to be magnified in the form of a slide is placed. The stage is
illuminated with a light that shines through a diaphragm. The
diaphragm is used to control the amount of light. This microscope is
very common today and is still used as a teaching microscope.
Uses

Used in several fields of sciences like the Microbiology, Botany,
Geology, Genetics
The Fluorescence Microscope

Designed to view specimens that fluoresce naturally or glow when
treated with fluorescing chemicals. This means the specimens
themselves are the light source. There are many materials that glow
naturally, such as some chlorophyll and some minerals. They just need
to be illuminated by a specific wavelength to make them glow.
How does it work?

For specimens that do not glow naturally, they are treated with a
fluorophore. The treated and non-treated specimens are then
irradiated with a specific wavelength of light. This is absorbed by the
specimens and causes them to emit a light of longer wavelengths. This
is a different colour then the absorbed light. The microscope then
amplifies the light radiated by the specimen. The light is then run
through filters geared toward a specific wavelength, and an image is
produced on a dark background.
Uses

Medical Sciences

Environmental Sciences

Industrial
Transmission Electron Microscope (TEM)

Use high energy electrons to examine objects that are beyond the
scope of the naked eye.

Can obtain the topography of an object, which is its surface features,
determine its morphology or shape and size of an object

Determine the composition of the object and finally tell a scientist how
the atoms are arranged in an object.
How does it work?

Works like a light microscope but instead of light, a beam of electrons
is used. The beam of accelerated electrons is focused on the specimen
using an electron gun that is powered by several million volts. The
specimen to be viewed is in a vacuum chamber. The electrons
bombard and pass through the image, where they are captured by an
electron magnet that bends the light to produce a photo or image on a
screen. The bouncing of the electrons off of the sample produces
reactions. The various reactions are captured and transformed into an
image by the microscope. This type is the most powerful of all electron
microscopes. It can magnify something one million times.
Parts:

An electron source

Thermionic Gun

Electron beam

Electromagnetic lenses

Vacuum chamber

2 Condensers

Sample stage

Phosphor or fluorescent screen

Computer
Advantages
A Transmission Electron Microscope is an impressive instrument with a
number of advantages such as:

TEMs offer the most powerful magnification, potentially over one
million times or more

TEMs have a wide-range of applications and can be utilized in a variety
of different scientific, educational and industrial fields

TEMs provide information on element and compound structure

Images are high-quality and detailed

TEMs are able to yield information of surface features, shape, size and
structure

They are easy to operate with proper training
Disadvantages
Some cons of electron microscopes include:

TEMs are large and very expensive

Laborious sample preparation

Potential artifacts from sample preparation

Operation and analysis requires special training

Samples are limited to those that are electron transparent, able to
tolerate the vacuum chamber and small enough to fit in the chamber

TEMs require special housing and maintenance

Images are black and white
Scanning Electron Microscope (SEM)

The microscope uses electrons instead of light to create an image.

Produce three-dimensional images with high resolution and
magnification.

Have a larger depth of focus.
How it works?

As the electron beam traces over the object, it interacts with the
surface of the object, dislodging secondary electrons from the surface
of the specimen in unique patterns. A secondary electron detector
attracts those scattered electrons and, depending on the number of
electrons that reach the detector, registers different levels of
brightness on a monitor. Additional sensors detect backscattered
electrons and X-rays. Dot by dot, row by row, an image of the original
object is scanned onto a monitor for viewing.
Uses

Science Research

Medicine

Forensics
Bibliography
http://www.cas.muohio.edu/mbi-ws/microscopes/types.html
http://en.wikipedia.org/wiki/Fluorescence_microscope
http://en.wikipedia.org/wiki/Scanning_electron_microscope
http://en.wikipedia.org/wiki/Transmission_electron_microscopy
http://www.microscopemaster.com/transmission-electron-microscope.html
http://en.wikipedia.org/wiki/Microscope