VMC 211: General Veterinary Microbiology (1+1)

COMPONENTS OF MICROSCOPE

Body tube

• The basic structure of the microscope is the base and body tube. All the other structures are attached to body tube.
• The base consists houses an illuminating source. The illuminating source is usually an ordinary bulb. There is also provision to increase or decrease the brightness of the light source.

Stage

• It is plateform over which the specimen to be viewed is kept.
• The stage has provision to the specimen forward –backward and laterally.

Lens systems

• Normally two lens systems are present, namely objective and ocular. The ocular lens system is called as eye piece. Usually a microscope will have four different objective lenses with different magnifying power.
• The magnification is displayed over the lenses as 4,10,40 and 100. The first two are referred to as low power objectives, the lens 40 as high dry and the 100 as oil immersion objective.
• The objective lenses provide primary magnified image which is further amplified by the ocular lenses.
• The magnifying power of ocular lenses are specified over the tube as 5,7 or 10. Based on the number of ocular lenses available the microscope is called as monocular or binocular. The magnification in a microscope is the product of objective and ocular lenses.

Condenser

• It is usually positioned above the light source and below the stage.
• It is set of two lenses which collect and concentrate the light passing through upward from the light source.
• The amount of light entering the condenser is also controlled by an iris diaphragm, a shutter controlled by a lever.

Controls

• Microscope has controls to
  • Adjust the intensity of light
  • Regulate the amount of light entering the condenser.
  • Regulate the amount of light that comes out of the condenser.
  • Move the specimen over the stage.
  • Position the right objective
  • Adjust the focus (coarse and fine adjuster)

 

 

Light source Condenser Adjustment knob Fine adjustment knob On off switch Stage adjustment Stage Revolving nose piece with objectives Eye piece Tube for camera attachment Light path in microscope

Units

• 1 meter = 1000 milli meter (mm)
• 1 mm = 1000 micrometer (um)
• 1um = 1000 nanometer (nm)