1. INTRODUCTION TO MICROSCOPY
A microscope is an instrument used to see objects that are very small for the naked eye. The science of examining small objects using such a tool is called microscopy. Microscopic means invisible to the eye except aided by a microscope.
2. HISTORY
FIRST Zacharias Jansen (1580–1638) invented a compound light microscope and after that Antony van Leeuwenhoek in 1632–1723 invented a simple (one-lens) microscope that earned a lot of importance worldwide. Robert Hooke in 1635–1703 further refined the compound microscope by adding the part STAGE in it. Carl Zeiss (1816–1888) and Ernst Abbe (1840–1905) were the two business man and they added the sub stage, condenser and established superior lenses.
3. GENERAL PRINCIPLES OF MICROSCOPY
There are four basic principles on which microscopy is dependent which are as follows,
i. Wavelength of radiation ii. Magnification iii. Resolution iv. Contrast

i. Wavelength of radiation
The range of visible light is 400-700nm. Different rays have different wavelengths as shown in fig 1. So, before the experimentation one should know the specific wavelength of a particular radiation

ii. Light refraction and image magnification
Light is refracted when it enters from a medium of light into glass. When a light bends while passing through a lens, then light rays are focused at a point that particular point is known as Focal point and due to which a larger image of the object is observed.