Cells are present in all organisms, but they are hard to observe because they range in size from 4-100 micrometers (10^-6 meter). It’s impossible to observe cells with our eyes, but we have microscopes that can help us to see cells and tiny creatures, such as: bacteria, plankton and more. Many people believe that microscopes are complex, but this brief guide on using a microscope will explain the microscope parts, define the terms and explain how to use it.
The Three Main Structural Components of a Microscope:
1. The Head
This is sometimes referred to as the body of the microscope, but the terms are interchangeable, and they mean the same thing. This is where the optical components are located in the upper section of the microscope. These components are how we view, magnify and produce images from specimens on a slide.
2. The Base
This is the stable support for the entire microscope and it’s typically the heaviest section. This area is also where the microscopic illuminators are located.
3. The Arms
This is the area where the base is connected to the head and where the eyepiece tube is usually located. The arms support the head and this is where you hold the microscope when it’s carried. Certain high-quality models may have an articulated arm with multiple joins to maneuver the head for an improved viewing experience.
8 Simple Steps to Using a Microscope
Step 1: Setup the Microscope
The microscope should be set up on a flat tabletop or other surface that’s stable and where you have room to work. There should be a nearby outlet for the power cord if you’re using a model that has electric lighting. Certain compound microscopes use a mirror to focus natural light and these models don’t need power.
Step 2: Switch on the Light Source
If your microscope does have an artificial light source, it must be turned on. Then the diaphragm should be adjusted to the largest diameter hole to ensure that the most light passes through. If your microscope has an iris diaphragm, slide the lever until the most light passes through.
Step 3: Rotate the Nose Piece
The nose-piece should be set to the lowest power objective which is typically 4x at 40x magnification. It’s easier to scan slides at low settings because the field of view is wider at lower power settings.
Step 4: Placing the Slide
A microscope slide can be placed on the stage. This could be clipped to the mechanical stage if you have one or it may be placed under stage clips. Use a prepared slide when you use a microscope for the first time to make the process easier. If you don’t have a prepared slide, you can place strands of colored yarn on a blank slide and secure it with a cover slip. When you’re ready, move the slide until it’s in position under the objective lens.
Step 5: Adjust the Coarse Focus Knob
Adjust the larger coarse focus knob until the specimen comes into focus and then move the slide slowly to center the specimen. This can be achieved by gentle nudging with fingers or by adjusting the slide knob controls on a mechanical stage.
Step 6: Adjust the Fine Focus Knob
Adjust the smaller fine focus knob to precisely dial in the focus and then adjust the diaphragm to achieve optimal lighting conditions. The best way to achieve this is to start with the most light and then gradually reduce it until the image is clear and sharp.
Step 7: Scan the Slide
Scan the slide from right to left and top to bottom at low power for a specimen overview. Then center the specimen that you want to observe at higher power settings.
Step 8: Viewing at Higher Magnification
The nose-piece can be rotated to the 10x objective to achieve 100x magnification. This will require refocusing and the light will need to be increased until the image is clear again. This can be repeated at 40x using the same principles and this will reveal all the details that would be required for a high school biology lab class.
How do you Prepare a Specimen before Using a Microscope
1/ Wet Mount Slides
These are for living, aquatic and transparent liquid samples, they work like a sandwich, the bottom slide layer is where the sample is located and top cover-slip keeps them in place. The slide can be glass or plastic and the cover slips prevent evaporation and it protects the lens of the microscope.
To prepare a wet mound slide, place a drop of fluid (immersion oil, glycerin, water, or the liquid sample) on the slide. Living samples should be placed in the liquid with tweezers. The cover-slip is placed at the edge of the slide on an angle and then it slides into place and lowered until contact is achieved. The action should be slow to avoid air bubbles which will make it harder to focus on the specimen.
In liquid, certain living organisms move too rapidly to view and their progress can be slowed by adding a drop of “Proto Slow”. Certain organisms require more space, the extra separation can be made with strands of swab, tissue or cotton to increase the distance between the slide and cover-slip. When the liquid evaporates, the living sample may die and this process can be slowed with an application of petroleum jelly around the slide and cover slip rim.
2/ Dry Mount Slides
The sample is placed on the slide and covered with the cover slip. For a compound microscope, the sample needs to be as thin as possible which can be achieved by shaving the sample. For a dissection microscope, the size is less critical because the entire surface is examined.
To prepare a dry slide, use tweezers to place the sample, place the cover-slip on top and if the sample is softer, it can be squashed with a gentle press. If the sample won’t stay in place, it can be secured with clear nail polish. In some cases, you can observe a sample with no cover-slip but be careful to avoid bumping it into the lens.
Things to Do While Using a Microscope
- Wash your hands to minimize finger grease.
- Clean the eyepiece.
- Remove oil from the objective.
Things that You Should Not Do While Using a Microscope
- Never rub the microscope lens.
- Don’t place oil on a dry objective.
- Only touch a lens with lens paper.
- Don’t touch a lens with dry lens paper.
- Avoid wearing mascara.
Frequently Asked Questions about Using a Microscope
What power do you start with when using a microscope?
Starting at 4x at the lowest power gives you the highest field of view and this makes it easier to locate and position the slide.
What are some of the risks of using a microscope?
Microscope users can suffer from a number of health issues including headaches, stress, anxiety, eye fatigue, neck and back pain and more. This is caused by long working hours and frequent breaks should be taken throughout the day.
Which part should be used first in focusing on the microscope?
Initial focusing should always be made with the coarse adjustment knob.
What does the diaphragm do on a microscope?
The diaphragm controls the light width that reaches the condenser.
Should you wear gloves when using a microscope?
Yes, gloves protect your hands from stains and immersion oil, which is an irritant.
What to do after using the microscope?
Turn off the illuminator, allow the microscope to cool for a few minutes and then put it away. When the bulb is allowed to cool properly, it will extend the lifespan of your microscope.
Conclusion
How to use a microscope for beginners may seem complicated but the learning curve is shallow and it gets much easier with practice.