Most microorganisms are too small to be seen with the naked eye. They are typically measured in micrometers (µm), and the size of most microorganisms ranges from 0.2 to 2 µm. In comparison, the human eye can typically see objects that are larger than about 40 µm.
To see microorganisms, scientists use a microscope. A microscope is an instrument that uses lenses to magnify the image of an object. There are different types of microscopes, but the most common type used to view microorganisms is the light microscope. This microscope uses light to illuminate the specimen and then uses lenses to magnify the image.
There are different types of microscope but the most common one used to observe microorganisms is the bright-field microscope, where the specimen is illuminated with a light source coming from the bottom and the observer sees the specimen on a bright background.
Alternatively, scientists can also use other techniques to visualize microorganisms such as electron microscopy, where electrons are used instead of light to illuminate the specimen and provide a higher magnification. Additionally, other techniques such as fluorescence microscopy, can be used to observe microorganisms that have been labeled with fluorescent dyes.
In summary, microorganisms are too small to be seen with the naked eye and require the use of a microscope to be observed. There are different types of microscopes and techniques that can be used to visualize microorganisms, depending on the specific needs and characteristics of the microorganism.