Our Objective

To study the different parts of a compound microscope. 

The Theory

What is a Compound Microscope?

 A compound microscope is high magnification microscope that uses two lenses to achieve the real and magnified images of objects and a high magnification microscope that uses two lenses to achieve the real and magnified images of objects and helps multiply the magnification level. The first lens is referred to as the objective lens and typically has a 4x, 10x, 40x or 100x magnification ability. The second lens is known as the eyepiece lens. 

Parts of Compound Microscope

The parts of the compound microscope can be categorized into: 

• Mechanical parts 
• Optical parts 

Mechanical Parts of a Compound Microscope 

• Arm 
  • The whole microscope is handled or carried by the curve-shaped structure called the arm. 
• Body tube 
  • The body tube separates the objective and the eyepiece of microscope. The body tube can be shifted down and up using the adjustment knobs. 
• Foot or base 
  • It is a U-shaped structure and supports the entire weight of the compound microscope. 
• Stage 
  • The flat and rectangular plate that is connected to the arm’s lower end is called the stage. It is the platform upon which the specimen or slide are placed for studying and examining the various features. The height of the mechanical stage is adjustable on most compound microscopes. It has Stage clips on the stage that hold the slide in place on the mechanical stage.  The centre of the stage has a hole through which light can pass. 
• Clips 
  • The upper part of the stage is connected to two clips. These clips on the stage used to hold the slide in its position. 
• Diaphragm 
  • The diaphragm is  found under the stage of the microscope and its primary role is to control the amount of light that reaches the specimen. It’s an adjustable apparatus, hence controlling the light intensity and the size of the beam of light that gets to the specimen. 
  •  The diaphragm can be of two types: 
    • Disc diaphragm 
    • Iris diaphragm 
• Nose piece 
  • The nose piece is circular and a rotating metal part that is connected to the body tube’s lower end. The nose piece has three holes wherein the objective lenses are embedded. 
• Fine adjustment knob 
  • It is the smaller knob, which is used for sharp and fine focusing of the object. For accurate and sharp focusing, this knob can be used. 
• Coarse adjustment knob 
  • It is a large knob that is used for moving the body tube down and up for bringing the object to be examined under exact focus. 
• Light Source  
  •  The light source in the microscope is a lamp that you turn on and off using a switch. You can adjust the intensity of light by turning the light adjustment knob. 

Optical Parts of Compound Microscope 

•  Eyepiece lens or Ocular 
  • At the top of the body tube, a lens is planted which is known as the eyepiece. On the rim of the eyepiece, there are certain markings such as 4X, 10X, 40X and 100 X. These indicate the magnification power. The object’s magnified image can be observed with the help of an eyepiece. 
• Condenser   
  •  A condenser sits between the stage and the diaphragm. The condenser controls how much light from the illuminator is permitted to pass up through the aperture, it controls the intensity of the light. 
• Objective lenses 
  • The objective lens gathers light from the specimen, magnifies the image of the specimen, and projects the magnified image which can be observed through eyepiece. There are three objective lenses are as follows: 
    • Oil immersion objective – 100X 
    • High power objective – 45X 
    • Low power objective – 10X 

Precautions 

• The objective lenses and eyepiece should be cleaned with the help of silk cloth and cleaning liquid before use. 
• The microscope should not be tilted when working, using it. 
• When an object needs to be studied, focus on the low power objective first and then move to high power. 
• When focusing, care needs to be taken to ensure that the objective lens never strikes the stage or the slide. 
• Only the fine adjustment knob should be used when the high-power objective is employed. 
• Coverslip should always be used to cover well-mount preparations before observation under the microscope is made. 
• Do not dismantle the microscope. 
• An oil immersion lens should never be used without the use of oil.

Learning Outcomes 

• Students can learn the parts of compound microscope. 
• Students can learn the precautions that need to be taken while using the microscope. 
• Students will be able to do the experiment more accurately in the real lab once they understand the steps through the animation and simulation.