What are the components of a microscope

A microscope is a piece of laboratory optical equipment used to magnify small things that are too small for the details to be seen by the naked eye. The microscope is the microbiologist’s most basic tool, and every microbiology student needs some background knowledge on parts of a microscope and how microscopes work.

The microscope was developed in the 16th century. Antony van Leeuwenhoek made the first modern microscope. He is also known as the father of microscopy. Microscopy is the technical term in which the microscope is used for investigation.

Do you know?
Antoni van Leeuwenhoek is the first person to see bacteria.

There are different types of microscopes based on their working mechanism and functions, but the microscopes can be broadly classified into;

• Light (optical) microscope and
• Electron microscope

Table of Contents

• The Light Microscope  
• Parts of Compound Microscope    
  • Illuminator (Light Source)
  • Diaphragm (Iris)
  • Condenser
  • Aperture
  • Stage
  • Objective lens
  • Body Tube
  • Ocular Lens (eye-piece)
  • Coarse and Fine Adjustment Knob
  • Arm
  • Base
• Microscope Worksheet

The Light Microscope  

Light microscopes are used to examine cells at relatively low magnifications. Magnifications of about 2000X are the upper limit for light microscopes. The highest resolution of a light microscope is about 0.2 μm. The use of blue light to illuminate a specimen gives the highest resolution. It is because blue light is of a shorter wavelength than white or red light. For this reason, many light microscopes come fitted with a blue filter over the condenser lens to improve resolution.

The common light microscope used in the laboratory is called a compound microscope. It is because it contains two types of lenses; ocular and objective. The ocular lens is the lens close to the eye, and the objective lens is the lens close to the object. These lenses work together to magnify the image of an object. 

Parts of Compound Microscope    

There are twelve parts in a compound microscope. They are as follows:  

It is located at the top of the microscope, and the ocular lens or eyepiece lens is used to look through the specimen. It also magnifies the image formed by the objective lens, usually ten times (10x) or 15 times (15x). Usually, a microscope has an eyepiece of 10x magnification power. Advanced microscopes have eyepieces for both eyes and are called binocular microscopes.

A binocular microscope lets the user see the image with both eyes at once. It improves the quality of microscopical work as it is more restful, particularly when examining specimens for prolonged periods.

The eyepiece tube, also known as the eyepiece holder, holds the eyepiece lens together. They are flexible in the binocular microscope that rotates for maximum visualization. They are not flexible in the monocular microscopes.

Revolving Nose Piece

The revolving nosepiece holds several objective lenses of varying magnification. It is movable, and the user can rotate it to achieve desired magnification levels. Ideally, a microscope should be parfocal, i.e. the image should remain focused when objectives are changed.

Coarse and Fine Adjustment Knob

Coarse Adjustment Knob

The coarse adjustment knob located in the arm of a microscope moves the stage up and down to bring the specimen into focus. The coarse adjustment helps to get the first focus. The gearing mechanism of the adjustment produces a large vertical movement of the stage with only a partial revolution of the knob. Because of this, the coarse adjustment should only be used with low power (4x and 10x objectives) and never with high power lenses (40x and 100x).

Coarse and fine adjustment knob of a microscope

Fine Adjustment Knob

A fine adjustment knob is generally present inside the coarse adjustment knob. It helps in bringing the specimen into sharp focus under lower power. It also helps for overall focusing when using a high-power lens.

Arm

The arm of the microscope supports the tube and connects it with the base. The arm as well as the base help to carry the microscope. In the case of high-quality microscopes,  an articulated arm with more than one joint is present.

Base

The base is the bottom of a microscope. It helps to support the microscope. A microscopic illuminator is also present in it.

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