An optical instrument used for viewing very small objects, such as mineral samples or animal or plant cells, typically magnified several hundred times.
Microscopy:- Microscopy is the use of microscope to observe minute living organisms.
Invention of microscope:- The first compound microscope was developed by Zacharias Jansen and his son Hans in 1595 in Holland. It was simply a tube with lenses at each end and its magnification ranged from 3x to 9x.
Types of Microscope;- there are two main types of microscope.
- Light Microscope:– A Microscope that works on the principle of light is called light microscope. A light microscope works by passing visible light through a specimen.
Types of light microscope;- there are 2 types of light microscope.
a lens that produces an enlarged image, typically set in a frame with a handle and used to examine small or finely detailed things.
b) Compound microscope:- an optical instrument for forming magnified images of small objects, consisting of an objective lens with a very short focal length and an eyepiece with a longer focal length
2)Electron Microscope:-Type of microscopes that use electrons rather than visible light to produce magnified images is called electron microscope. an electron microscope works on the principle of light. There are two types of electron microscope.
A) Scanning electron microscope:- an electron microscope in which the surface of a specimen is scanned by a beam of electrons that are reflected to form an image.
B) Transmission electron microscope;-
a form of electron microscope in which an image is derived from electrons which have passed through the specimen, in particular one in which the whole image is formed at once rather than by scanning.
Terms used in Microscopy: Two important terms are used in microscopy.
- Magnification:- Magnification is the increase in apparent size of an object. It is an important factor in microscopy. It is denoted by X. A light microscope can magnify objects objects only about 1500 times. Electron microscope magnification power is 100000 to 2,50,000x.
- Resolution;- Resolution or resolving power is the measure of the clarity of an image.
Resolution of human eye is 0.1mm. Human eye can differentiate between 2 points which are at least 0.1mm apart.
Resolution power of a compound microscope is 0.2µm. Resolution power of an electron microscope is 0.2nm.