Types of microscopes

Microscopes may be divided into biomedical, industrial, and stereoscopic microscopes. Biomedical and industrial microscopes may be further divided into those where the object lens is positioned above the specimen - upright microscopes - and those where the object lens is positioned below the specimen, or inverted microscopes.

Biomedical microscopes

These microscopes are used for viewing stained or unstained transparent biological specimens. Upright biomedical microscopes are used for viewing slide glass preparations for biological or medical purposes. Inverted biomedical microscopes are used for viewing petri dishes or cells and tissues in culture containers.

slide glass preparations
[fig.]
Upright microscope
[fig.]
Inverted microscope

Industrial microscopes

Industrial microscopes are used for industrial uses such as semiconductor wafer or liquid crystal board inspection, or for viewing metal specimens. Inverted microscopes are easier to use in this context because operators do not need to adjust the stage each time the specimen is changed, there is no limit on specimen height, and large specimens may be used.

[fig.]
Upright microscope
[fig.]
Inverted microscope

Stereo Microscopes

These microscopes show the specimen three dimensionally, and are used for inspection or assembly of fine instrumentation such as watches or electronics.

What is a Microscope?

Microscopes allow magnified images of illuminated specimens to be viewed using 2 lenses (an objective and an eyepiece lens). Microscopes that use two lenses are called compound microscopes.
Single lens microscopes, of which this antique created by Leeuwenhoek (1632-1723) is an example, use only a single lens to magnify the specimen. Compound microscopes were first invented in the late 16th century in Holland, when Zacharias Janssen and his father discovered that using two lenses greatly aided in magnification. However, compound microscopes of the time suffered from chromatic and spherical aberrations in the lens, which gave single lens microscopes an advantage both in clarity and magnifying power.
In the 19th century, however, these problems with the compound microscope were successfully resolved. Also, up until that time, microscopes had been designed based on experience and the design had no scientific grounds. A German named Ernst Abbe (1840-1905), however, established a method to design microscopes utilizing logical calculations.
Since then, microscope design has progressed rapidly to the present day, with a wide array of advanced microscopes now available depending on specimen and research purpose.

Slide glass preparations

Slide glass preparations are prepared by slicing the specimen into extremely thin slices between several to 30-40 microns thick. These slices are then sandwiched and sealed between glass slides to preserve them.