Microscope Parts | A Guide on their Location and Function

The microscope parts discussed here are of a compound microscope. A simple microscope has just a lens, stage, and a light source. But a compound microscope has many parts like

  1. Eyepiece
  2. Body Tube
  3. Revolving nosepiece
  4. Objective lens (Three 10x, 45x,  100x)
  5. Coarse adjustment
  6. Fine adjustment
  7. Arm/handle
  8. Rack stop
  9. Fixed stage
  10. Mechanical Stage
  11. Clips
  12. Side-ward movement knob
  13. Front and back movement knob
  14. Condenser and Diaphragm
  15. Mirror (convex and concave mirror)
  16. Base
  17. Pillars

A compound microscope consists of parts that assist in viewing with a naked eye, a sample holder, a magnifying lens, and a light source.

Microscope Parts in detail

There are almost 15 parts in a microscope. But we can divide them based on their purpose in the instrument like

A) Parts which assist in viewing the object

B) Part which helps in adjustment for a clear view

C) Part which provides sufficient light to the object to be seen

D) Support tine parts that help to hold the sample and others.

However, for ease of study, we will see them based on their location from top to bottom of a compound microscope.

microscope parts and functions

Image of a compound microscope with parts labeled.

Eyepiece

It is the part that you encounter when viewing an object in the microscope from the top.

This is the first lens that helps to magnify the image. Based on the magnification power, the lens can be of 5X, 10X, 15X, or more.

It is a transparent glass lens that enables us to see the object clearly. This eyepiece can be removed and put back into the tube column.

It has two glass lens one at the top, which is just flat while the other towards the object is slightly convex to the bottom. One can remove the eyepiece and wipe it with a cloth to free it of any dust particles.

Body Tube

It is a long columnar shaped tube which holds the eyepiece and also the nosepiece, including the objective lens. It holds the nose piece immediately to the end to which objective lenses are fixed. It has rulings that help move it up and down to get a clear view of the object.

Revolving nosepiece

It is a circular metallic piece holding the magnifying lenses to the tube. It revolves freely to select the required lenses needed to focus.

Objective lens

These are the lenses that help to magnify the objects on the slide placed on the stage. The resolutions most common are 10x, 45x, and 100x with 10x having the lowest magnification power and 100x having the highest magnification power. These three eyepieces can be removed and replaced if required.

Coarse adjustment

This is an adjustment knob present at the junction of the arm and the tube. It has a larger knob than the lower one.

It is routinely used for rough adjustment. One needs to use it to adjust the eyepiece till it reaches the slide but not touch it.

From there, fine adjustment can be used to get a clear resolution.

Fine adjustment

This is a smaller and circular knob seen below the coarse adjustment knob. It is fixed to the arm of the microscope.

It helps to adjust the magnification lens to the correct height for better resolution. Its movement is slow and excellent.

This knob is essential besides the coarse adjustment knob for easy and precise focus. Also, the chances of damage to the sample slide on the stage are eliminated due to this knob.

Arm or Handle

It holds the eyepiece, objective lens, stage, light source in a straight line. It is also useful to carry the microscope from one place to another.

Rack stop

This is a small threaded pin that helps to fix the column tube at a particular height after being adjusted to the desired height by the adjustment knobs. Once the adjustment of height is made, the rack stop is tightened to hold the tube at the set height. To further decrease or increase the height, the rock stop has to be loosened.

Fixed Stage

It is the place where the slide containing the test sample is placed for evaluation.

It is a square-shaped metallic plank consisting of 2 clips on the top and 2 adjustment knobs.

The clips help to hold the slide in place. In contrast, the knobs help in side-wise movement or forward and backward movement.

The stage is always kept clean during and before the start of experimentation. The stage has an orifice through which light from the mirror falls in the slide. This light helps in the visualization of the microscopic sample.

Mechanical stage

As the name indicates, this is movable and has clips to hold the slide. This mechanical stage has fine calibrations, as shown in the image above.

Clips

As mentioned before, these are two in number. They help in fixing the slide in a specific spot on the stage.

Due to this, once the sample is focused clearly, there is no chance of accidental movements.

Side-ward movement knob

This know is located over or below the stage based on the design. It helps to move the slide toward the left or right directions when you need to have a clear view of the sample through the lens.

Front and back movement knob

This is another knob situated on the stage and control forward and backward movements of the slide.

Without these knobs, it would be hard to visualize the viewable fraction of the sample.

Condenser & Diaphragm

The condenser

It is located below the stage. This is set under the fixed stage and can be lowered. The
the function of the condenser is to convert the parallel rays of the light reflected from the iris diaphragm into a cone.

The condensed beam of light passes through the aperture of the fixed stage and falls on the slide.

Iris-diaphragm

This is present below the condenser and consists of a dark-colored shutter (a movable cover). This shutter can be opened and closed with a side knob.

This helps gather light from the mirror and focus it on the stage.

It is a closure that helps to close the aperture below the stage through which light from the source falls on to it. For low light intensity, the diaphragm is closed, while for more intensity is kept wide open.

Mirror (convex and concave mirror)

This is fixed to the base below the diaphragm. It is meant to reflect parallel rays of the light into the condenser (towards the stage).

On one side, it has a convex lens and, on another side, a concave lens. This is present in older microscopes without artificial illumination.

The mirror can be rotated and fixed at any angle to help light fall onto the stage.

Base

This is the foot of the microscope over which the entire weight of the instrument rests. It is heavy and flat linked to the arm.

Pillars

These are the erect pillar which emerges from the base and provide a hinge to hold the arm of microscope.

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