A microscope is the mostimportant instrument use to view the things that cannot be seen with the nakedeyes. Ø HISTORY:The microscope was availableduring the mid 1600s. In 1665 an English scientist named ROBERT HOOK develop optical microscope and made key observation .Heobserved the cells using the optical microscope.
ANTON VAN LEEUWEN-HOEK ( 1632-1723) discover simple glass lens ofconvex surface and made successful observation of microscopic organisms whichhe named animalcules. He is consider as one of the first who give the correctdescription of protozoa , fungi and bacteria.In 1870 ERNT ABBE develop a compound microscopelens that help to create magnified and fine images.
He also develop oilimmersion lens for improve resolution as well as clarity of image.Ø TYPES OFMICROSCOPE:There are two types ofmicroscope.1. Light microscope2. Electron microscopeü LIGHTMICROSCOPEThe light microscope whichis used in laboratory is called compound microscope in which visible light oruv lights are used to illuminate the objects.Light microscope consistof four system.a. The support systemb.
The magnification systemc. The illumination systemd. The adjustment systema. THE SUPPORTIN SYSTEM :It include main bodycomponents.Foot: The bottom ofthe microscope used for support.Resolving nosepiece: It holds two or more objective lenses and canallow rotation to easily change the power.
Stage: The flat platform used to place the slide.Stage clip: It holds the slide in proper place.Arm: It is the tube connected to base of the microscope.b. THEMAGNIFICATION SYSTEM :It is fixed at the bottomof the body tube just above the preparation under examination. This systemconsist of two lenses:1. Objective lens : It has different powerLow power 10x (5 – 6 mm)High power 40x (0.5 – 1.
5 mm)Oil immersion 100x (0.15 – 0.20 mm) 2. Eye piece :It is present on the top of the body tube where you place your eye it is alsocalled ocular.Numerical aperture: It is the measurement of the angle maximumcone of light that can enter the objective. Resolving power: the ability of the lens to distinguish withtwo objects at a particular distance apart.Working distance: working distance of an objective is thedistance between the front lens of the objective and the object slide when theslide is flows.
Total magnification: Total magnification = magnificationof objective lens x magnification of Eyepiecec. THE ILLUMINATION SYSTEM :Source of light: A steady light source used in place of amirror.Mirror: two type of mirror concave sight and plane sight , ifmicroscope has a mirror , it is used to reflect light.Condenser: The purpose of the condenser lens is to focusthe light onto the specimen between the mirror and stage.
Diaphragm: It regulates the amount of light on thespecimen.d. THEADJUSTMENT SYSTEM : 1. course adjustment system: It is used first to achieved an appropriatefocus.2. Fine adjustment screw: It is used to bring objects into perfectfocus.3.
Condenser adjustment screw: It is used to raise or lower the condenser inorder to adjust the illumination.4. Iris diaphragm lever: It can be moved to closed or open thediaphragm this reducing or increasing the intensity of life.5. The mechanical stage: These are usually two screw which are use tomove the glass slide on mechanical stage. One of them is used to move a slidebackward and forward while the other moves the slide right and left