Compound Microscope

A microscope is not just a tool; it is an opening into the world that can not be seen with the naked eye. The best innovation in the realm of microscopes and the microscopic world is the compound microscope discovered in early 1590 by Dutch spectacle-maker Zacharias Janssen. The use of more than one magnifying lens with high-resolution power offers clear and precise results with a focus on the finest details, making it the best. 

1.0Compound Microscope Principle

A compound microscope enlarges objects by passing light through them. At first, the objective lens makes an image larger, and then the eyepiece makes the image even larger. This coupling of optical elements enables us to look at the fine structure, as fine as the cells/bacteria structure itself. The crispness and detail of a microscope image, that is, the microscope's resolution, is affected by the quality of its optical elements and by the numerical aperture of the microscope.

2.0Parts of Compound Microscope

A compound microscope consists of several key components that are capable of magnifying small objects or specimens. Understanding these parts is essential for knowing how a compound microscope actually works. These components are:

1. Eyepiece (Ocular Lens): The eyepiece is located at the top of the microscope and is used to look through and observe the magnified specimen. It works along with the objective lens for more magnification of the image. 
2. Revolving Nosepiece: The revolving nosepiece holds the objective lens, allowing it to rotate and change the lens from low magnification, that is, 4X, to high magnification. 
3. Objective Lenses: These lenses have various degrees of magnification (4X, 10X, 40X, 100X) and are equipped with a rotating nosepiece. Each compound microscope consists of more than two objective lenses, which allows the viewer to adjust the power based on your need for magnification.
4. Stage: It is the flat platform where the specimen is placed for observation. It generally has clips or mechanical supports, known as stage clips, to fix the slide in place. 
5. Condenser Lens: The work of a condenser lens is to focus light on the specimen and is located below the stage for this work. The light enhances the contrast and resolution of the image.
6. Diaphragm (Iris or Disc): It is located below the condenser lens to control the light emitted by it, adjusting the increase or decrease in the brightness of the image. 
7. Coarse Focusing Knob: The Coarse knob is used to adjust the distance between the stage and objective lens, which helps in making adjustments in the focus of the microscope for better magnification. 
8. Fine Focusing Knob: This knob is used for adjustment of the stage, where small changes can make a big difference. It results in a sharper and clearer image of the specimen.  
9. Light Source (Illuminator): As the name suggests, an illuminator is the source of light which illuminates the specimen from under the stage. It can be anything that produces light, including a bulb, LED light, or mirror that shall help direct light onto the specimen. 
10. Arm and Base: The Arm and base work as the mechanical support and stability to the whole structure of the compound microscope. 

See the compound microscope diagram given below to thoroughly understand every part of a compound microscope. 

3.0Simple vs. Compound Microscope

Simple Microscope	Compound Microscope
It consists of a single lens, usually a complex lens.	More than one lens is used with different magnifications.
It is simple, compact and easy to travel with.	It is a more complex structure with multiple components.
Focused only by adjusting the distance between the lens and the object or specimen.	Different components work together to focus on the specimen, which results in a clearer image.
It depends upon the ambient light or external light source for brightness.	It has an in-built light source for better illumination of the specimen.

4.0Compound Microscope Use

The compound microscope is an effective instrument with many uses, some of which include: 

• It enables researchers to accurately examine cells, tissues, and microbes in the field of biology. 
• Physicians and pathologists use it in medical science to diagnose patients by analysing tissue samples and blood cells.
• It is employed in material science to examine microstructures, identify flaws, and assess the characteristics of materials in the study of Earth, which is called Geology.
• Compound microscopes are also used for educational purposes in labs, research institutes, and classrooms to analyse a wide range of specimens.

5.0Advantages and Disadvantages of Compound Microscopes

Advantages of Compound Microscope

• High Magnification: A compound microscope, with a magnification of up to 1000x, allows you to see fine details in small objects.
• Clearer Images: The objective lens attached to the eyepiece provides a very high level of visibility, which leads to sharp and clear images.
• Versatile: It is applied in many disciplines, such as biology, medicine and material science.
• Portable: Compound microscopes are smaller and more portable than advanced microscopes like electron microscopes.

Disadvantages of Compound Microscope

• Limited Magnification: A compound microscope does not have a higher magnification than 1000x, much less than an electron microscope.
• Shallow Depth of Field: The depth of field is shallow at higher magnifications, which makes it more challenging to maintain focus on thicker specimens.
• Requires Skill: To use the microscope effectively, you need practice in focusing, adjusting light, and positioning the specimen correctly.