How Do Microscopes Work?
Last Updated on June 7, 2021 by Gabriel Goddy
Have you tried to magnify an object using a microscope before? It’s almost certain you wondered how microscopes work. If you did, then being in this guide, is a great choice. Make sure to read through this guide for a better understanding of microscopes.
What Is A Microscope?
A microscope is an instrument that is used to magnify small objects. Some microscopes can even be used to observe an object at the cellular level, allowing scientists to see the shape of a cell, its nucleus, mitochondria, and other organelles. While the modern microscope has many parts, the most important pieces are its lenses. It is through the microscope’s lenses that the image of an object can be magnified and observed in detail.
A simple light microscope manipulates how light enters the eye using a convex lens, where both sides of the lens are curved outwards. When light reflects off of an object being viewed under the microscope and passes through the lens, it bends towards the eye. This makes the object look bigger than it actually is.
Different Types of Microscopes
- Stereo Microscopes
Stereo microscopes are used to look at a variety of samples that you would be able to hold in your hand. A stereo microscope provides a 3D image or “stereo” image and typically will provide magnification between 10x – 40x. The stereo microscope is used in manufacturing, quality control, coin collecting, science, high school dissection projects, and botany. A stereo microscope typically provides both transmitted and reflected illumination and can be used to view a sample that will not allow light to pass through it.
The following are samples often viewed under a stereomicroscope: coins, flowers, insects, plastic or metal parts, printed circuit boards, fabric weaves frog anatomy and wires.
- The Compound Light Microscope
Commonly binocular (two eyepieces), the compound light microscope, combines the power of lenses and light to enlarge the subject being viewed.
Typically, the eyepiece itself allows for 10X or 15X magnification and when combined with the three or four objective lenses, which can be rotated into the field of view, produce higher magnification to a maximum of around 1000X generally.
The compound light microscope is popular among botanists for studying plant cells, in biology to view bacteria and parasites as well as a variety of human/animal cells.
It is a useful microscope in forensic labs for identifying drug structures.
Compound light microscopes are one of the most familiar of the different types of microscopes as they are most often found in science and biology classrooms.
- Inverted Microscopes
Inverted microscopes are available as biological inverted microscopes or metallurgical inverted microscopes. Biological inverted microscopes provide magnification of 40x, 100x, and sometimes 200x and 400x. These biological inverted microscopes are used to view living samples that are in a petri dish.
An inverted microscope allows the user to place the petri dish on a flat stage, with the objective lenses housed beneath the stage. Inverted microscopes are used for in-vitro fertilization, live-cell imaging, developmental biology, cell biology, neuroscience, and microbiology. Inverted microscopes are often used in research to analyze and study tissues and cells and in particular living cells.
Metallurgical inverted microscopes are used to examine large parts at high magnification for fractures or faults. They are similar to the biological inverted microscope in the magnification provided, but one primary difference is that the samples are not placed in a petri dish, but rather a smooth side of the sample must be prepared so it can lay flat on the stage. This smooth sample is polished and is sometimes referred to as a puck.
- USB Computer Microscope
Although not well suited to the same scientific applications as other light microscopes, the USB Computer microscope, among the different types of microscopes, can be used on almost any object and requires no preparation of the specimen.
It is essentially a macro lens used to examine images on a computer screen plugged into its USB port.
However, the magnification is restricted and is not comparable to your standard compound light microscope at only up to 200X with a relatively small depth of field.
- Electron Microscope
Among the different types of microscopes, the Electron Microscope(EM) is a powerful microscope available and used today, allowing researchers to view a specimen at nanometer size.
The transmission electron microscope(TEM), the first type of EM, is capable of producing images 1 nanometer in size. The TEM is a popular choice for nanotechnology as well as semiconductor analysis and production.
The second type of electron microscope is the scanning electron microscope(SEM) is approximately 10 times less powerful than TEMs, they produce high-resolution, sharp, black and white 3D images.
The Transmission Electron Microscopes and Scanning Electron Microscopes have practical applications in such fields as biology, chemistry, gemology, metallurgy, and industry as well as provide information on the topography, morphology, composition, and crystallographic data of samples.
Importance of Microscopes
Microscopes have opened up a whole new dimension in science, By using Microscopes scientists were able to discover the existence of microorganisms, study the structure of cells, and see the smallest parts of plants, animals, and fungi.
Electron microscopes help create the very tiny electrical circuits found on Silicon microchips, Scanning microscopes are much more sophisticated, and they have higher magnifications than light-refracting microscopes.
Microscopes are used to diagnosis the illness in hospitals and clinics all over the world, Microscopes magnify the blood samples, so, The doctors can see the malaria parasites attacking the red blood cells.
Microscopic examination confirms the laboratory tests that may be positive for the disease, Technicians count the number of red blood cells infected with malaria to give the doctors an idea of how advanced the disease is in a patient.
Microscopes use the simple visible light refracting lenses, Electrons, x-rays, and infrared rays, They are to detect smaller and smaller structures, Scanning electron microscopes can resolve the viruses which are far smaller than any cell, They enlarge the view of tiny viruses, which allows scientists to develop the vaccines and cures for infectious diseases in the humans and the animals.
Scanning electron microscopes have magnifications up to several million times to view the molecules, the viruses, and the nano-particles, They use the corrective software to increase the magnification and the resolution of images, The computers help the nano-technologists use high-powered electron microscopes to view the objects only a few molecules thick.
Electron microscopes help prepare the small surfaces for sectioning into small slices, Microscopes enlarge the images of silicon chips to help the engineers create more efficient electronic devices, When more circuits are fitted onto a small chip, the computational power of silicon microchips increases.
Microscopes are used in viewing the specimens that are relatively very small in size, they are used to view the cellular structures of organs, germs, and bacteria, They play a very important role in the laboratory for the tissues and organisms which are too small to be seen clearly with the naked eye.
How Does a Microscope Work?
To be useful, a microscope must accomplish three things: it must magnify the object you are trying to view, resolve the details of the object, and make these details visible.
Understanding these ideas is the first step to learning how a microscope works. The optical or light microscope uses visible light transmitted through, refracted around, or reflected from a specimen.
Light waves are chaotic; an incandescent light source emits light waves traveling in different paths and of varying wavelengths. Some of the lenses in a microscope bend these light waves into parallel paths, magnify and focus the light at the ocular.
The power to enlarge the image of the specimen when viewed through a microscope is known as magnification and is dependent upon how much the lenses bend the light waves.
Magnification is expressed in numeric multiples of how much enlargement occurs with a lens. If the magnification of a lens is 2X then it roughly doubles the size of the image of the object.
With a compound microscope, the total magnification can be determined by multiplying the magnifications of the objective and ocular lenses. Consequently, an ocular lens of 10X coupled with a 40X objective yields a total magnification of 400X.
However, the higher the magnification the closer the lens must be to the specimen. Since a higher magnification lens bends light more severely, the specimen is brought into focus a shorter distance from the lens and this is known as the focal length.
Generally, a lens providing higher magnification will also provide better resolution. These two factors working together are very important in determining how a microscope works?
The resolution of a specimen is highly dependent upon the light waves. The shortest distance between two points that the microscope can define as clearly being separate points is the resolution of the microscope.
Resolution is perhaps more important than magnification in understanding how a microscope works? If the points cannot be clearly focused then they are closer together than the resolution of the microscope and, regardless of the magnification, the image quality will be poor.
The resolution is determined by the frequency of the light waves illuminating the specimen and the quality of the lens. A rule of optical physics is that the shorter the wavelength the greater the resolution.
Usually expressed in microns, the best resolution a light microscope can produce is 0.2 microns or 200 nanometers. Discounting the light source, a lens having a resolution of 0.5 microns won’t resolve points as close together as a 0.3 micron
Microscopes are great tools, as you must have read above. They are useful in so many ways and various fields. If your job requires magnifying objects, then you’d need any of the microscopes listed above.