There are two basic types of microscopes. The one most people are familiar with looks down at the specimen with the light source coming from below and is called an upright microscope. An inverted microscope looks up at the specimen with the light source coming from above instead.
Inverted microscopes were first invented in 1850 by Tulane University's J. Lawrence Smith and debuted at the World's Fair in London in 1852. In the early 20th century, they began to be used for observation of living cells, particularly for aquatic life. It was also used for analysis of heavy metals like iron and steel before World War II.
An inverted microscope is most helpful when looking at heavy objects or those which are greatly effected by gravity. Material specimens like metal can be large and heavy. They require the large staging areas that inverted microscopes allow for.
The materials greatly affected by gravity include living cells and aquatic life that tend to pool and collect on the bottom of specimen containers. An inverted microscope looks at the sample from the bottom, making it easier to see the organisms with ease. It also allows users to see the samples in a more natural environment than a standard glass slide. Petri dishes allow more movement for the samples and are commonly used with inverted microscopes.
This type of microscope has been redesigned and improved on to accommodate particular uses. There are stages made particularly for processes like incubation and in vitro fertilization. The nosepieces have been made larger and revolvable, making to make it easier for scientists to identify and rotate objects. They have also been made heavier and sturdier, allowing for less vibration and greater ease of observation.
There are two grades of inverted microscopes. A routine inverted microscope is small and comes in low and medium power settings. These can be used in homes and small labs in schools. They are limited in what the can observe as they usually do not allow for fine focus and have relatively low power magnification.
A research inverted microscope comes in heavy power settings and can allow for a very fine focus. The major disadvantage to them is that they are extremely expensive and are usually only used by universities and medical institutions. They are usually able to accommodate video cameras and televisions to assist in research documentation. The improvements on the inverted microscope over the course of the 20th and 21st centuries have allowed it to be an integral part of advanced scientific research.