How to use a light microscope
Welcome again. Hope you are fine and want to start learning veterinary histology. The goal of veterinary histology is to understand the tissue structure (cell, tissue, organs) with a microscope.
There are two main types of microscopes named light microscope and electron microscope. Commonly, we use using light microscope in our laboratory. So, first, you should know the different parts of a microscope, and also, you should know how to use a light microscope.
What is microscope
Okay, the microscope is an optical instrument used to view an animal body’s tissue structure (tissues that cannot view normal eyes). It helps to magnify the tissue structure several times more than the normal structure.
A light source is transmitted through the tissue section (thinly sliced tissue section of the body; we will learn more on tissue preparation) and make magnified images of the focused area of the tissue, which we may view by eyepiece of a microscope.
“You should know the different steps of permanent slide preparation.”
Types of microscope
Generally, modern microscopes are classified into two main groups – light microscopes and electron microscopes. There are different types of the light microscope; like –
- Compound microscope
- Phase-contrast microscope
- Fluorescence microscope
- Dark field microscope
In elector microscope, you will find two types –
- Transmission electron microscope
- Scanning electron microscope
We commonly use light microscopes at our laboratory, so I will discuss different important parts of light microscopes with their uses (how to use a light microscope).
“This is basic needs to start learning veterinary histology. Here, I am not going to discuss details on different types of microscope. I am going to discuss the important parts and uses of light microscope only. You may have better idea on microscope; this article is not for the expert; it’s only for the beginners or who want to memorize different parts of light microscope and their uses.”
In a light microscope, one lens (commonly known as objective) or group of lense are used to magnify the image of the focused area of tissue structure embedded on the glass slide.
Different parts of a microscope
First, we should be familiar with the different parts of a microscope from a compound microscope. Okay, let’s start to identify the followings parts –
- On and off switch
- Voltage regulator
- Light source
- Base of microscope
- Stage (mechanical stage)
- Stage adjuster
- Stage clip
- Coarse adjustment knob or coarse adjuster
- Fine adjustment knob or fine adjuster
- Condenser
- Light filter
- Mirror
- Arm of microscope
- Locked screw
- Rotatable head of the microscope
- Body tube
- Draw tube
- Nose piece
- Objectives (4X, 10X, 20X, 40X and 100X)
- Eyepieces
Okay, let’s start to know the functions of different microscope parts.
The on and off switch is located at the base of the microscope. You may regulate the light intensity with the help of a voltage regulator. A light source or illuminator is located at the base of the microscope.
Light is regulated and reflected through the mirror or directly transmitted through the thin translucent tissue embedded on a glass slide. A stage is a place where the prepared glass slide is placed. You will find a round area on the stage where the light is transmitted to tissue.
The mechanical stage is regulated with the help of a mechanical stage regulator or stage adjuster. You will find a clip-like structure (commonly known as a staged clip) with the mechanical stage, which helps place the glass slide on the stage.
With the help of a stage regulator or adjuster, you may adjust or focus the specific area of the glass slide’s tissue (our main object). You may control the glass slide and move it left and right; again, forward and backward direction.
A coarse adjustment knob or coarse adjuster is located at the lower portion or above the base. Commonly it is a round structure. It is used for adjusting the body tube for proper focusing. You may control the stage (up and down) with the help of a coarse adjuster, and thus you may set or adjust the body tube properly for better focusing on the object (tissue on a glass slide).
A fine adjustment knob or fine adjuster is located with a coarse adjuster. If you want to clarify the focused area of the tissue, you need to use a fine adjuster. You need to rotate it to clarify the focused portion of the tissue slide.
The condenser is located below the stage of the microscope. It helps collect the light from the light source or the illuminator and focus the light on the object (tissue on a glass slide). You may use a light filter (located within the condenser) to control the transmission of light through the tissue or object. You will find a mirror under the stage of the microscope. It helps to reflect the light which is collected by a condenser.
The arm of a microscope is attached to the microscope’s stage and the body tube. The body tube is the outer tube attached with the nose pieces at its lower end and the draw tube at its upper end. The nose piece is a circular structure. There are four or five.
Objectives (4X, 10X, 20X, 40X and 100X) are fitted with nose pieces. Eyepieces (generally, 5X or 10X) are located at the upper portion of the body tube. It has a convex lens and magnifies the images.
“If you want to carry microscope, you should hold the arm with one hand and stage with other hand.”
How to use a light microscope
I hope you got an idea of the different parts of microscopes with their uses. Now, you should know how to use the light microscope. Okay, let’s start –
Let’s on the switch of a microscope.
Down the stage with the help of a coarse adjustment knob as much as possible.
Take a glass slide (tissue or object) and place this slide on the stage with the help of a staged clip.
Rotate the nose pieces, and first, you should set the lower objective (lens; 4X). You may control the glass slide with the help of a mechanical stage adjuster.
Look through the eyepieces, and let’s fix the draw tube by manipulating the mechanical stage (with the help of a coarse adjustment knob)
You should focus on the specific area of the object or tissue (with the help of a coarse adjustment knob)
It would be best if you used a fine adjuster to clarify the focused area of the tissue.
Now, you should change objectives (4X, 10X, 40X, and 100X, if necessary). When you need to use 100X, it is recommended to downing the mechanical stage and set the objective just the upper portion of the slide. You should use immersion oil for viewing the image of the focused area of the object (tissue)
Some important terms related to microscope
You should know the following term –
Magnification
Magnification is the ability to make an image (object) larger (several times higher than normal).
Magnification is calculated by (multiplying mechanical tube length multiplied by eyepiece magnification) divided by the focal length of the objective. So, we should know what the focal length of the objective is.
Focal length
Focal length is the minimum distance required between the objectives and the top of the intermediate image plane for better viewing the image from the object.
For the 4X objective, the focal length is 40 mm (micrometer)
For the 10X objective, the focal length is 16 mm
For the 40X objective, the focal length is 4mm and
For the 100X objective, the focal length is about 2 mm
Higher magnification makes shorter focal length.
“If you want to use 10X lens in eyepieces and 4X objective, then the magnification will be 40 times larger. If you use 10X, 40X and 100X objectives with 10X lens in eyepieces, then you will find 100, 400 and 1000 times magnified image.”
Resolution
Resolution is the ability to identify the two objectives from each other.
Conclusion
I hope you got an idea about the different parts of a microscope and how to use a light microscope in a laboratory. If you want to know more about different types of microscopes, you should go through the books.
If you think that information’s not enough, I recommend you learn from class lectures or books. If you want to learn the basic histology from different organ systems of the animal body, you may visit this link. You should know about the different steps of permanent slide preparation. If you want to get this article, I recommend you connect with me or follow my upcoming articles.
“If possible, I will update or enrich information, pictures, and videos on this topic in future.”
If there is any mistake in the above information or if you have any suggestions for me, please, let me know in the comment box. Thank you so much.