MACHINE OF MICROSCOPE

              MICROSCOPE-ITS MECHANISM AND THEORIES
A microscope comprises 'systems' of lenses, designed to magnify small objects invisible to normal eyes and make them clearly visible. (Normal eyes cannot see objects smaller than 0.1 mm or 100 um). In a compound microscope ,the objectives produce a real. inverted and enlarged image of the object within the focal plane of the eye piece which in turn produces a virtual erect and further magnified image about the plane of the objective. With a good microscope, the magnified image must not be blurred i.e, the object must be seen in its exact details.
  A microscope should therefore have the following properties:
1.Magnification
2.Definition
3.Resolution
              MICROSCOPE-ITS CARE OR MAINTENANCE
Both skill and care are required for successful microscopy. It is a precision  and carelessness
in its operation may ruin it.
UNPACKING:
After removing the packing material and screws, the microscope can be pulled out. The accompanying instruction manual should be carefully studied and component parts assembled strictly according to the instruction.
CARE OF MICROSCOPE:
1.The instrument should not be exposed to sunlight, dust or any source of heart and moisture.
2.When not in use, it should be kept covered or inside its box.
3.if dust settles on any of its mechanical parts, remove it first by a camel hair brush and then by soft linen.
4.Move the microscope only by its upright limb and not by its draw-tube
5.While using draw-tube careful spiral motion is to be applied.
6.Only finest machine oil is to be used on the bearing. Grease or immersion oil should never be used.
7.For smaller screws, use proper screw drivers. Scalpels or knives must not be used.
8.Coarse adjustment. The tube should be occasionally withdrawn from the body and the sides carefully wiped with cloth moistened with xylol and lubricated with small quantity of machine oil the excess of which is to be wiped off. The teeth may also be cleaned with a tooth brush but should never be lubricated.
9.Fine adjustments. If these do not work satisfactorily the instrument has to be sent to an appropriate workshop.
10.objective and eye pieces-Dusts must not be allowed to settle on the lenses.Fingers should not come in contact with them. The lenses may be cleaned by soft camel hair brush and by a lens paper. Oil immersion objective must be cleaned immediately after its use with lens paper or with well washed soft linen. If the oil has dried up, the same should be removed by linen/lens paper moistened with xylol . Alcohol must not be used. In tropical regions moulds grow on dirty lens surfaces when relative humidity and temerature rise. Lens must be kept clean to avoid mould growth. This can be minimized by keeping the optics in a desiccator or with silica gel. Some authorities favor use of radium or fungicide. 

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.