The microscope was invented in the 17th century. In its most basic design, it is formed by an objective and an ocular lenses.
The object to be observed is placed near the focus of the objective lens, extending the image, which will also be magnified by the ocular lens.
In the microscopes, there are usually several tobjectives mounted on a revolving revolver. The most common powers range from 5x to 100x. Also, it is usual to swap the eyepieces. The most normal powers are 5x and 10x, but they can reach 15x and 20x.
The total power of a microscope is obtained by multiplying the power of the objective and the ocular. The maximum increase of an optical microscope is 1500x or 200 nm resolution. These limits are due to the diffraction of light.
There are two main categories of microscopes:
a- Classic microscope: it is for studying microscopic samples. The object is almost touching on the object. The light goes through the sample. Big increases.
b- Stereoscopic microscope: it is for studying larger samples. The object is quite separate from the objective. The light is reflected in the sample. Few increases There are two eyepieces to have a vision in three dimensions.