Parts Of A Microscope And How They Work ?

Microscopes connect our realm to that of the microbes, which we can’t see with our naked eyes. It is much like a complex magnifying glass, and to operate it, one needs to know its parts. In this blog, I will discuss about the parts of a microscope.

What are the parts of a microscope?

Structurally, a compound microscope has three parts:

Head: The head is a hollow cylindrical tube connecting the eyepiece lens to the objective lens. The light bends inside this tube before reaching the eyepiece lens. It is connected to the nosepiece. It is also known as the body tube.

Arm: Arm connects the head to the base of the microscope. One can hold the arm and carry the microscope to the workstation.

Base: The foundation on which the microscope stands. It provides stability to a microscope. Electronic devices like lights and switches are fitted into the base. One can hold the base and the arm for additional stability while carrying a microscope.

Individual parts of a microscope are further divided into mechanical and optical parts. Mechanical parts are mainly used to maneuver the mounted slide and focus the lenses on the specimen. Optical parts consist of the lenses and the mirror that align the light at an angle, providing a bright field of view.

parts of a microscope
Parts of a microscope. Credit Wikimedia/Mikael Häggström, M.D.

Mechanical Parts

1. Stage: Slides are mounted on the stage. It is a flat, rectangular part attached to the arm’s lower end with inclination joints. It has a hole called an aperture in the middle through which light can pass into the body tube and then to the eyepiece.

2. Inclination joint: Sometimes, we need to tilt the microscope to view the specimen, usually if the workstation is a bit high. The inclination joint helps us to adjust the tilt of the microscope.

3. Clips: We use clips to hold the slide in place on the stage. Clips come with two knobs used to move the slide sideways and up and down.

4. Rotating nosepiece: The nosepiece is connected to the lower end of the body tube. The objective lenses are embedded in this nosepiece. We can change the magnification by rotating the nosepiece.

5. Diaphragm: The diaphragm controls the intensity of light that passes through the microscope. It is attached just below the stage. There are two types of diaphragm: disc and iris diaphragm.

6. Condenser lens: Some microscopes have a light source under the diaphragm. Condenser lens focuses the light on the specimen to render a detailed image. However, it is mainly found in microscopes with 400x magnification.

7. Coarse adjustments: Coarse adjustments are knobs that move the body tube up and down to focus on the specimen. These adjustments are reasonable enough for 10x magnification.

8. Fine adjustments: These are smaller than coarse adjustments and are used to fine-focus on the specimen. They are usually used in magnification equal to or more than 40x.

9. Rack stop: Rack stop is an adjustment that prev

10. Lighting equipment called the illuminator and switches are fitted into the base of the microscope.

Optical parts of a microscope

1. Eyepiece or Ocular lens: Eyepiece lenses are attached to the top end of the body tube and have a small amount of magnification of their own. The magnified image is seen through this lens.

2. Objective lens: Objective lenses are the closest to the slide and are embedded in the nosepiece. They can be of varying magnification. Light enters into the body tube through the objective lens.

3. Mirror: Many microscopes do not come with a light source. Hence, the user has to rely on an outer source of light (e.g., sunlight). We adjust the mirror to align the source of light.

Bonus: Although compound microscopes are easy to transport, they can never fit in a pocket. Foldscopes are origami-based microscopes that are small enough to fit in a pocket. These are made out of paper, and the lenses are 3D printed. According to creator Manu Prakash, “The capabilities of Foldscope are equivalent to conventional microscopes that cost thousands of dollars.

These easily portable, biodegradable microscopes can be used in areas struck with poverty and also for on-site checking of water samples.

Without the microscope, we could have never detected that germs cause diseases and food spoilage. We would have been in the dark about the presence of cells in our bodies. A whole other world in biology would have been left undiscovered without microscopes.

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