You tend to only see microscopes in scientific laboratories or school classrooms.
Microscopes are optical instruments that allow you to view a small specimen as an enlarged image.
Many scientists use these tools to view things at a cellular level.
Even though microscopes are most often used in those settings, who says you can’t have one in your own home?
If you are thinking about purchasing a microscope for scientific reasons or simply to use it for a hobby, this guide will be for you.
We will cover what a microscope is and how they work. This guide will also review five different models and give some advice on choosing the right one.
By the end of this article, you will know how microscopes work and whether this tool will be a good fit for you.
Let’s get started.
What Is a Microscope?
A microscope is an optical instrument that people use to enlarge small objects through a lens.
For example, many scientists use microscopes to observe things at a cellular level, such as the nucleus and mitochondria of a cell.
One of the main characteristics of microscopes is that they are tabletop instruments. Unlike binoculars or monoculars, microscopes are not portable.
You can typically find microscopes in labs or schools on counters.
Most modern microscopes have many parts, but the most important component of all microscopes is the lens.
We will explain how this works in the next few sections.
How Does a Microscope Work?
A microscope is a complex instrument that uses a lot of different parts to produce a magnified image.
The most common type of microscope is the compound microscope. These types of microscopes have two lenses which are either curved pieces of plastic or glass.
The main job of the lenses is to bend incoming rays of light to magnify the image for the viewer.
This process makes the objects look a lot bigger than they are.
Three basic stages occur when a microscope magnifies an image.
- Light is reflected onto the object being viewed from underneath the specimen/object. There is a mirror underneath the plate where the object goes on. The machine directs light onto that mirror, which then reflects the light upwards.
- The light that travels through the specimen then enters the objective lens. This lens converts the light into a magnified image.
- The magnified image that the objective lens produced enters the eyepiece lens. Simultaneously, the eyepiece lens works similarly to a magnifying glass and magnifies the image again.
Since there are many different types of microscopes, this process will not be the same across the board.
However, this is the general magnification process that you will find in many models.
Parts of a Microscope
To fully understand how a microscope works, you should know about all of the different parts of a microscope. So let’s take a look.
Structural Components of a Microscope
- The head and body: The head and body represent the top part of the microscope. This area is where many optical components are, such as the eyepiece and eyepiece tube.
- The base: The base represents the very bottom of the microscope. This component supports the microscope and is where the illuminator is (the mirror reflecting light onto the object/specimen).
- The arm: The arm of the microscope connects to both the base and the head. This component supports the head. Furthermore, people can carry the machine by the arm.
Optical Components of a Microscope
- Eyepiece: The eyepiece is at the top of the microscope and is what you look into. Eyepieces will normally have 5x to 30x magnification power.
- Eyepiece tube: This component is what supports the eyepiece. Some eyepiece tubes will also have an adjustment ring on them. You will only see these rings on binocular microscopes, not monocular microscopes.
- Nosepiece: The nosepiece is what houses the objective lenses. These lenses are mounted on a turret that rotates so that users can choose what lens they want to use.
- Focus knob: All microscopes will have a focus knob on them so people can adjust the lens focus.
- Objective lenses: Objective lenses are the most important pieces of a microscope. Each microscope will have up to five lenses, ranging from 4x to 100x. Objective lenses can either be rear or forward-facing.
- Stage: The stage is the platform on the microscope that you place your objects on. Some stages are mechanical, meaning the stage will be able to move.
- Stage clips: People will use stage clips when they don’t have a mechanical stage. Stage clips allow the user to move the specimen manually to view all sides of the object.
- Aperture: The aperture refers to the hole in the stage. The reflected light will travel through the hole and onto the specimen.
- Illuminator: The illuminator is near the base of the microscope. You will find low voltage halogen light bulbs in most microscopes.
- Iris diaphragm: This component controls the amount of light that reaches the specimen on the stage. This part is located just below the stage.
- Condenser: Condensers collect the light from the illuminator and focuses it onto the stage. You can find this part under the stage.
- Condenser focus knob: The condenser focus knob can move the condenser either up or down. Doing so will help control the lighting.
Types of Microscopes
If you are interested in getting your own microscope, it will be good to know all of the different kinds.
This section will review five different models and will explain how they work.
It is worth noting that there are lots of different microscope models; this list is just five popular ones. So let’s get into it.
Simple Microscopes
Simple microscopes have double convex lenses that have a short focal length. The biconvex lens works as a magnifying glass.
Unfortunately, most simple microscopes only have one level of magnification; you cannot adjust it.
Furthermore, the maximum magnification power on many simple microscopes is 300x.
Unlike other microscopes, simple microscopes do not have a powered light source; this tool only uses natural light.
Due to this reason, you may not see your specimen with as much detail.
Since these microscopes are the most basic, people typically use them for reading small text or as a simple magnifying glass.
Compound Microscopes
Compound microscopes are more complex than simple microscopes. These machines have at least two convex lenses, including the eyepiece and the objective lens.
Furthermore, compound microscopes have illuminators that provide a powered light source to light up the specimen on the stage.
This feature allows the viewer to see the objects more clearly. Compound microscopes also provide multiple magnification power levels.
As a result, you can flip through different lenses and decide what one you want to look through.
Another distinguishing factor of compound microscopes is that they can magnify up to 2000x.
Due to its more complex features, many people use the compound microscope for scientific research (studying microorganisms, for instance).
Electron Microscopes
Electron microscopes are unlike any other model.
These microscopes do not use powered light sources to illuminate specimens. Instead, electron microscopes use accelerated electrons to do the job for them.
These electrons go through the specimen and produce a digital image. This image allows scientists to see the detailed structure of whatever organism they are studying.
Even though these kinds of microscopes provide high-resolution renderings, they have a major downside.
Unfortunately, the accelerated electrons destroy samples which means that scientists cannot study live organisms with an electron microscope.
Phase-Contrast Microscopes
Phase-contrast microscopes use a contrast-enhancing technique to produce high-contrast images of specimens that are transparent.
These microscopes translate small variations in a specimen’s phase and convert them into changes in amplitude.
The machine can then represent the changes in amplitude with image contrast.
Scientists use this tool to produce images of living cells, thin tissue samples, lithographic patterns, microorganisms, subcellar particles, and more.
This type of microscope is widely favored since the process does not harm living organisms.
Interference Microscopes
Interference microscopes use a complex process that measures the differences in a path between two split beams of light.
The machine then uses this data to produce an image that has enhanced contrast, making it easier to see the details of the specimen.
A few different kinds of interference microscopy include classical interference, differential interference, contrast interference, and fluorescent interference contrast microscopy.
Choosing a Correct Microscope For The Job
Since there are so many different microscopes out there, it can be hard to choose one.
In this section, we will provide some helpful tips on choosing the correct microscope for the job.
From lenses to power cords, there are many things to consider when narrowing your choice down.
What Is the Job?
The most important factor to narrow down is the job you will be doing. What exactly do you want to do with your microscope?
If you want to use your microscope for scientific purposes, such as studying specimens, you will probably want something more complex than a simple microscope.
On the other hand, if you simply need a tool for reading purposes, then a simple microscope will be good enough.
Other Factors To Keep in Mind
- Specimen type – Before you choose a microscope, you should know what kind of specimen you will be studying and its size. These factors will affect the kind of microscope you choose.
- Image output – Another thing to decide is how you want to view your specimen. Do you want to look at it through the eyepiece or study it on a digital screen?
- Microscope head – You will need to decide if you want a monocular head or a binocular head. Monocular heads are cheaper, but they also make it harder to analyze the specimens in detail.
- Eyepiece type – While most microscopes come with a normal eyepiece with a 10x magnification, some microscopes come with digital screens. You may want to choose a machine with a digital screen if more than one person looks at the specimen at one time.
- Magnification level – Something else to keep in mind is magnification level. If you want to see a specimen in great detail, try to choose a microscope with a high magnification level.
- Lighting – You will need to decide if you want a microscope with a light in it or one without. If your microscope does not have a light, you will need to make sure the room you use it in is well-lit. Simple microscopes will not have a lightbulb.
- Power source – Microscopes will either have a power cord or a battery slot. If you are using your scope quite regularly, we recommend using one with a power cord. That way, you won’t have to replace the batteries constantly.
When To Use Each Type of Microscope
- Simple microscope: A simple microscope is the most basic you can get. If you are a beginner at microscopy, this tool will be good to start with. Just keep in mind that it won’t go above 300x magnification. This tool will work well for simple tasks.
- Compound microscope: If you want to observe microorganisms, you may want to get a compound microscope. These scopes are great for those already comfortable with microscopes wanting to take their skill to the next level.
- Electron microscope: Electron microscopes will work well for those who want a digital image. These tools are much more advanced, expensive, and complex. Only invest in this kind of microscope if you need it.
- Phase-contrast microscope: This instrument is another complex machine. Phase-contrast microscopes will work if you want to study transparent organisms.
- Interference microscope: This machine is another microscope that produces an image. Go with an interference microscope if you want a high-contrast image of a live specimen.
Microscope Lenses
The lens setup of each microscope will be different. For example, some models will only have three lenses while others will have five.
Regardless, there are three main lenses that you will find in the majority of microscopes: the eyepiece, condenser, and objective lens.
Eyepiece Lens
The eyepiece lens is at the very top of the microscope. This lens is what your eye is closest to.
Users will look through the eyepiece lens to see the magnified image. Most eyepiece lenses will have a magnification power of 10 or 15x.
Condenser Lens
The main job of a condenser lens is to focus light onto the object on the stage. However, not all microscopes have condenser lenses.
Typically microscopes with a power of 400x or above will have this type of lens.
Condenser lenses will increase the sharpness and resolution of the image in a high-power microscope.
Objective Lenses
All microscopes have objective lenses. There are two primary types of objective lenses: refractive and reflective.
Many monoculars will have three or four objective lenses. Each lens will have a different magnification power, ranging from 4x to 100x.
Refractive Objectives
Refractive lenses refract and bend the light that comes through the system.
Microscopes that require a very fine amount of detail will have refractive objective lenses in them.
Some refractive systems will only have two lenses, while others can have up to fifteen lenses.
Reflective Objectives
Reflective objective lenses have a mirror-based design that includes a primary and secondary system.
Reflective lenses will magnify the specimen on the microscope stage and will relay the image to the eyepiece lens.
Generally, reflective objective systems will produce better light efficiency and higher power, leading to more detailed images.
Illumination
Illumination is one of the most important aspects of microscopy.
There are a few different illumination set-ups that different models have, which can greatly affect the quality of the final image.
Almost all microscopes use backlight illumination compared to direct light illumination.
This is because direct light will often wash out the object under study and lower the detail of the image.
There are three different types of illumination: Koehler, darkfield, and epi-illumination.
- Koehler illumination: This kind of illumination occurs when incident light, such as the light from a light bulb, lights up the object from behind.
- Darkfield illumination: With darkfield illumination, direct rays of light shine on the object from an oblique angle. This type of illumination works best for transparent objects.
- Epi-illumination: This kind of illumination produces light from above the object instead of below. Some people prefer this kind of illumination since it is compact.
Focus
All microscopes have a focusing mechanism. Focusing the scope simply refers to adjusting the settings to make the object clearer.
When you adjust the microscope’s focus, you are moving the object either further or closer away from the objective lens; doing so will increase the sharpness of the image.
There are two basic kinds of focus mechanisms you will find on any microscope. Some microscopes will have a stage that moves.
On others, the head or the tube of the microscope will move.
In general, the rack and pinion focusing mechanism is the most popular system you will find on microscopes.
Microscope Maintenance
If you have a microscope or are looking to get one, you will know how expensive it can be.
To avoid costly repairs, you should always practice proper maintenance habits. In this section, we will review a few tips on how to take care of your microscope.
Storing the Microscope
When storing the microscope, the most important thing to do is to cover it with a dust cover, even when you store it in a cabinet.
Furthermore, make sure always to keep the eyepieces on the machine. If dust collects in the eyepiece tube, it can be difficult to clean.
Handling the Microscope
When you carry the microscope, make sure to carry it by the base and the arm.
Holding the machine like this will decrease the chance of dropping it.
Furthermore, holding the microscope by the stage, for example, could cause misalignment.
If you are carrying the microscope quite often, you can also buy a carrying case.
Cleaning the Lenses
Eyepiece Lens
You will need lens paper and a lens cleaning solution to clean the lens properly. To clean the eyepiece lens, wet the lens cleaning paper with the solution.
You can then clean the lens in a circular motion. Make sure to be gentle with the lens. After, dry the wet lens with dry lens paper.
Objective Lens
Cleaning the objective lenses will be a bit trickier. You will need to buy immersion oil for this.
It is essential to clean the immersion oil from the microscope immediately after using it. You can do this with lens cleaning paper.
If there is some dust stuck in the objective lenses due to dried oil, you may need to use an oil-soluble solvent such as turpentine.
Mechanical Maintenance
There will be times when you may have to adjust some things, such as screws or other metal parts.
Before you do any kind of mechanical maintenance, make sure to always refer to the user manual.
Furthermore, avoid using force while fixing your scope or over-tightening screws; this could lead to damage.
Conclusion
We hope that this ultimate guide to microscopes has helped you learn more about this optical instrument.
A microscope is an optical instrument that allows you to view small objects, such as microorganisms, as an enlarged image.
While there are many different kinds of microscopes, this guide covered five popular models: simple, compound, electron, phase-contrast, and interference microscope.
There are a few things to keep in mind when choosing a microscope. For instance, think about what kind of specimen you will be studying and the size of it.
Furthermore, you should think about the lighting, magnification level, the power source, and what kind of microscope head you want.
The next thing you should do after choosing what kind of microscope you want is to learn how to maintain the expensive machine properly.
There are a few general tips to follow. First, make sure always to use a dust cover and store the scope with the eyepieces on.
Furthermore, carry the machine by the base and arm. Finally, never grab the scope by the stage.
You can clean the eyepiece lens with lens paper and lens cleaning solution and the objective lens with immersion oil.
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