Microscope

These are used for most of the biological works, and employ system of lenses called the eyepiece and  the objective.
1.MECHANICAL PARTS:
a)Foot or base (often horseshoe shaped)

b)Stage: It may be fitted with a vernier scale. there is an aperture in the center through which the object  is illuminated from below.

c)The Arm: It is connected to the foot generally by means of hinged joint, near which the stage is attached.

d)Body tube: The tube has two parts, the external tube and the inner draw tube. the external tube carries in its lower end a revolving nosepiece. The draw tube is fixed in its upper part with which the tube length can be adjusted, Many modern microscope has a fixed tube length with no draw tube .

e)Fine and coarse adjustment knobs

f)Case of different types with additional envelope for microscope to protect it from dust and light.

2.OPTICAL PARTS:
a)The mirror: The mirror has plane and concave surface and is carried by a tailpiece. The plane surface is to be used with the condenser and concave surface without it. Many modern microscopes do away with mirror by having built-in illuminating system.

b)Substage condenser: 'Abbe condensers' are used. They are neither chromatically, nor spherically corrected but serve the purpose for ordinary low power microscopy. For microbiology, aplanatic or achromatic condensers are better definition.

c)Objectives: Types. Usually these are of three types:2/3" or 16 mm (*10), 1/6" or 4 mm (*40) and 1/12" or 2 mm (*95), 16 mm and 4 mm objectives are the 'dry' ones and 2 mm one is the immersion type. Typical engravings are shown in Fig.1.1.