Parts of a Compound Microscope and Their Functions

Who Invented Compound Microscope?

Who Invented Compound Microscope? It is really a tricky question, however In the late 16th century, a Dutch father-son team named Hans and Zacharias Janssen invented the first compound microscope. 

They discovered that putting a lens at the top and bottom of a tube and looking through it magnified objects on the other end. The device laid the groundwork for future breakthroughs, but it was only magnified by 3X to 9X.

Compound Microscope Definition

All modern light microscopes are made up of a combination of more than one glass lens. The main parts of compound microscope are the condenser lens, the objective lens, and the eyepiece lens, and these instruments are referred to as compound microscopes. 

Each of these components is made up of microscope lens combinations that are required to produce magnified images with minimal artefacts and aberrations.

Structure of Microscope

Compound microscope (Microscope Diagram: 1) parts can be categorized into two major categories: Mechanical parts and Optical parts.

Parts of Compound Microscope

Microscope Diagram 1: Parts of Compound Microscope

Mechanical Parts of Compound Microscope

Compound microscope mechanical parts (Microscope Diagram: 2) include base or foot, pillar, arm, inclination joint, stage, clips, diaphragm, body tube, nose piece, coarse adjustment knob and fine adjustment knob.

  • Base: It’s the horseshoe-shaped base structure of microscope. All of the other components of the compound microscope are supported by it.
  • Pillar: A compound microscopes pillar is a modest, strong vertical projection that emerges from the foot or base.
  • Arm: This is the portion of the microscope that connects the base to the head and the eyepiece tube to the base.  It serves to support the microscope’s head and is also used to transport the microscope.
  • Stage: The stage is a flat and rectangular plate attached to the lower end of the arm. The specimen is placed on the stage so that the various aspects can be studied and examined. A hole in the centre of the stage allows light to pass through.
  • Inclination: It’s a joint that connects the arm to the pillar of a compound microscope. The inclination joint allows you to tilt the microscope.
  • Clips: The upper part of the stage is connected to two clips. Clips hold the slides on which the samples will be placed on the stage, which is located on the side of the specimen holder.
  • Diaphragm: Diaphragm attached to the stage from below. It controls the amount and intensity of light that enters the microscope. It can be either an iris diaphragm or a disc diaphragm.
  • Condenser: It’s a lense that’s hidden beneath the stage. The size of the light beam is controlled by it. It collects and directs light from the mirror to the objective lens. A knob on one side beneath the stage can be used to lower or raise the condenser.
Parts of a Compound Microscope and Their Functions

Microscope Diagram: 2 Parts of a Compound Microscope and Their Functions

  • Body Tube: It is the tubular structure of microscope, hollow component of the microscope arm that is attached to the top half of the arm. With the use of adjustment knobs, it can be adjusted up and down.
  • Nose Piece: It’s a spinning metal element affixed to the lower end of the body tube in a circular pattern. It has three holes for objective lenses to be inserted into.
  • Fine adjustment knob: It is the smaller knob that is used to microscope focus the object sharply and finely. This knob can be utilised for precise and sharp focusing.
  • Coarse adjustment knob: It is a huge knob that is used to move the body tube down and up in order to bring the thing into precise focus.

Optical Parts of Compound Microscope

  • Eyepiece lens: It’s a lens that’s attached to the body tube’s top structure of microscope. On the rim, a number (5X, 10X, 15X) is always written. This number represents the compound microscope magnification power of the device. With the eyepiece, you may see a magnified image of the thing.
  • Mirror: It is either fastened to the pillar or the lower end of the arm. On one side, it has a flat mirror, while on the other, it has a concave mirror. Light rays are reflected into the microscope by a mirror.
  • Objective lenses: The revolving nose piece at the bottom of the body tube is equipped with three objective lenses. Low power (10X), high power (45X), and oil immersion objectives are the three options (100X).

Compound Microscope Magnification

Compound microscope magnification is determined by multiplying the eyepiece and objective powers. When viewed through a 5X eyepiece with a 10X objective, an item is magnified 5 x 10=50 times. The magnification is 10 x 45 = 450 times when using a 10X eyepiece and a 45X objective.

How to Use the Compound Microscope

  1. The individual who is going to use the lens must first set up the eyepiece. They must position the mirror so that the maximum amount of light reaches the stage’s far end. This ensures that the specimen receives enough light to be seen.
  2. So that a clear image of the specimen can be seen, the dust on the lenses, mirror, and stage is cleaned.
  3. The slide to be studied should be placed on the stage, and clips should be used to keep the slide from moving.
  4. The light from the mirror below the stage reflects the item of focus when the person looks through the eyepiece.
  5. Turn the nose piece so that the low power objective is aligned with the object in the slide.
  6. This light passes through the objective lens and into the person’s eye through the eyepiece.
  7. When the coarse adjustment knob on the microscope is utilised, a more unobstructed view of the specimen is achieved. The fine adjustment knob provides a precise representation of the sample.
  8. Increase or decrease the fine adjustment knob to make the image as sharp and clear as possible.
  9. Turn the nose piece to face the target and align the high power objective with it. To make the image of the object as sharp and clear as possible, use the fine adjustment knob once more.

Compound Microscope Uses

  1. Compound microscope uses in pathology labs makes disease diagnosis simple.
  2. Compound microscope uses in forensic labs it easy to detect human fingerprints.
  3. A compound microscope can be used to detect the presence of metals.
  4. The use of a compound microscope makes studying germs and viruses much easier.
  5. Compound microscope uses in schools makes learning biology easy for all children.

Precautions When Using Compound Microscope

  1. The microscope should be elevated using both arms and the base at the same time.
  2. To ensure that dust accumulated on the lens does not obstruct the viewing of the slide or the focus, the eyepiece and objective lens must be cleaned using silk cloth and transparent liquid.
  3. Tilting or shaking the microscope while using it should be avoided. The light received by the lens is altered as a result of this bouncing, and the seeing of the object of focus changes.
  4. The specimen must always be focused first with a low-resolution lens, then with a high-resolution lens to target it further.
  5. After you’ve finished using the compound microscope, focus the lower-power objective lens on the stage.
  6. When using the coarse adjustment lens, make sure the objective lens does not come into contact with the focus slide. When the coarse adjustment lens is used quickly, it might compress the specimen to be studied, resulting in inaccurate results, as well as damage to the example and slide.
  7. The fine adjustment knob should only be used when employing a high-resolution lens for a specimen. The coarse adjustment knob should not be used to observe tiny details since it cannot provide accurate results.
  8. On the specimen slide, always use a coverslip. This prevents additional particles from accumulating on the sample and influencing the outcome.
  9. For correct results while using an oil immersion lens, the oil should always be used. Because the refractive index can be modified without the use of oil, the reading of the specimen can be manipulated.
  10. After using the microscope, always store it in a box. In weak light, the concave part of the mirror is used to get a better vision. It is not permissible to dismantle the microscope.

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