A microscope is an instrument that can be used to observe small objects, even cells. The image of an object is magnified through at least one lens in the microscope. This lens bends light toward the eye and makes an object appear larger.
Types of Microscopes
The basic objective of a microscope is to magnify small objects. More than magnification, the most important function of a microscope is to provide resolution. It should render high-quality details of the desired specimen in order to proceed with the experiment and analysis. Simple and compound are some of the earliest known microscopes that have been recently replaced by electron and fluorescent microscopes. The different types of microscopes are as follows
These are basic microscopes that use light to magnify objects. The lenses in these microscopes refract the light for the objects beneath them to appear closer. The different types of light or optical microscopes are:
- Compound microscope
- Simple microscope
- Dissection or stereo microscope
Instead of light, these microscopes use beams of electrons to generate images. The two well-known electron microscopes are:
- CHM (Transmission Electron Microscope) – the electrons transmit or pass through a very thin specimen.
- MES (Scanning Electron Microscope) – It scans through the surface of the specimen by focusing the electron beam.
As a result of technical advancements, one can also find more efficient microscopes like scanning probe microscopes and scanning acoustic microscopes.
- A simple microscope is a basic light microscope that has only one lens. The condenser part is absent in simple microscopes. They work on natural light and there is less usage of hooks and knobs for adjustments. On the other hand, compound microscopes have 2 adjustment knobs – fine and coarse. Their magnification is also higher than the simple microscope.
A compound microscope is a high-power microscope that has higher magnification levels than a low-power or dissection microscope. It is used to examine tiny specimens like cell structures that cannot be viewed at lower magnification levels. A compound microscope is made up of both structural and optical components. The 3 basic structural components are – the head, arm and base.
- The body or head comprises the optical parts present in the upper part of the microscope
- The arm connects and supports the base and head of the microscope. Also, it is used to carry the microscope.
- Base of the microscope supports the microscope and comprises the illumination
The optical part of the microscope includes:
- Eye tube
- Objective lenses
- Nose piece
- Adjustment knobs
- Condenser and condenser focus knob
The ocular or eyepiece is what an observer looks through and is present in the upper portion of the microscope. The centerpiece clasps the eyepieces which are positioned above the objective lens. The objective lenses are the main optical lenses. They range in various magnifications from 4x to 100x and generally include 3 to 5 lenses on a single microscope. Nose piece houses the objective lenses.
The fine and coarse focus knobs are the adjustment knobs that are often used to focus the microscope. They are coaxial knobs. This means the focusing system of both fine and coarse focus are mounted on the same axis. There is also a condenser focus knob which moves the condenser up or down to control the lighting
The stage is where the specimen to be viewed is placed. A mechanical stage is often used when working on a specimen at a higher magnification. This is when delicate movement of the specimen is required. Stage clips are operated to hold the slide in place. To see different areas of the specimen, the observer must physically move the slide. A separate knob is present to move the slide in the mechanical stage. The aperture is a tiny hole in the stage via which the transmitted light enters the stage.
An illumination acts as the light source and is typically located at the microscope’s base. Most light microscopes operate on halogen bulbs with low voltage and also have variable and continuous lighting control within the base. A condenser is typically used to gather and focus the illumination light onto the specimen. It is found beneath the stage and is often observed in conjunction with a diaphragm or iris. Iris or Diaphragm regulates the amount of light that reaches the specimen. It is situated above the condenser but beneath the stage.
Functions of Microscope
The primary function of a microscope is to study biological specimens. A microscope solely functions on two concepts – magnification and resolution. Magnification is simply the ability of the microscope to enlarge the image. Whereas the ability to analyses minute details depends on the resolution.
Compound and dissection microscopes are the two types of microscopes that are mostly used in schools for educational purposes.
Functions of compound microscope
- It simplifies the study of viruses and bacteria.
- They are used in pathology labs to make an easy diagnosis of diseases.
- They are also used in forensic laboratories to identify human fingerprints.
Both simple and compound microscopes can be used for microbiological studies. Specimens like fungi and algae can be viewed under these microscopes. Microscopes can also be used to study soil particles
Functions of dissection microscope
- Help to study the topography of solid samples.
- It is used for dissections and micro surgical procedures
- It is also used in forensic engineering
Functions of electron microscope
Electron microscopes are expensive devices that are mostly used in industrial and medical research.
- They are used for micro characterization of a sample
- Helps in tissue imaging
- Device testing
- Mineral liberation analysis
Frequently Asked Questions
What are the different uses of simple and compound microscopes?Compound microscope is a high-power microscope and has better resolution than a simple microscope. A simple microscope is used in fields where there is no need for rigorous research. It is used in the study of soil particles, fungi and algae. A compound microscope is used in places of extensive research like pathological and forensic labs.
What is the function of a diaphragm in a microscope?Iris or diaphragm is the rotating disc found under the stage. Its main role is to control the amount of light passing through the specimen. It is located below the microscope stage and above the condenser lens. An Abbe condenser with an iris diaphragm is often found in most high-quality microscopes. They govern the focus and quantity of light applied to the specimen when used together.
What is the function of stage and stage clips in a microscope?The stage is a flat platform of a microscope where specimen slides can be placed. A mechanical stage is often used when working on a specimen at a higher magnification. This is when delicate movement of the specimen is required. It has knobs to move the slide to the right and left, down and up. Stage clips are operated when there is no mechanical stage to hold the specimen.
What is the function of a nose piece in a microscope?A turret or revolving nose piece of a microscope is a part that holds objective lenses (can be two or many). The vital role of the nose piece is to rotate those objective lenses and help to change the magnification power.
What is the function of the arm and base in a microscope?Arm is the structural component that supports the eye tube and ocular lenses and connects the microscope head portion to the base of the microscope. Base is the bottom part that supports the whole microscope and houses the illumination.