We cannot see everything through our naked eyes. That’s when we need instruments like a microscope to look into the depth. The microscope is all about magnifying and resolving power. This is equivalent to its ability to magnify the objects and measure a distance between two separate objects, respectively. The concept of microscope has been with us since the late 16th century. And today, it has applications across various fields. In the scientific and research fields, it is used to study cells and living organisms. It is because of the invention of the microscope, we came to know about the existence of microorganisms. In forensic science, it is used to identify and compare samples, which helps in solving crimes. And the list goes on. Based on the features, we have different types of microscopes. In this discussion, we will look at some of them in detail.
1. Simple microscope
As the name suggests, this microscope is quite a simple one, plainly magnifying the objects for you. This way, you see an enlarged image of the object at hand. It uses a double convex lens, forming a magnifying image when the object is placed within its focal length. This means, if you place the object closer to the lens, then you can see a more magnified image. But it uses only a single lens, so the magnification capacity is just 10X. At the time of its invention, it was used to study the microbes occurring in freshwater. Today, it is mainly used to study biological specimens in the lab. Other than this, it is used in repair workshops to see the tiny parts of the object.
2. Compound microscope
Does the name compound microscope ring a bell? The chances are you might have used this microscope in your schools or colleges. The compound microscope is chosen when the samples to examine needs to be highly magnified. It uses two or more convex lenses to magnify the images further, and have a magnification capacity ranging from 40X to 1000X. Because it can magnify the objects 1000X, it is used to study cells. Additionally, it has its own light source, and the multiple lenses show a significant amount of details. Also, it is inexpensive and easily available. Thus, it is widely used for academic purposes.
3. Polarized microscope
Starting with the basic, polarized light is the light wave that vibrates only in one direction. Based on this concept, polarizing microscope functions. So what happens here is the behavior of the cell components is observed under polarized light. It is beneficial as it gives clear vision and increases contrast. The polarized microscope is used to study the minerals and rocks. Additionally, it is portable, meaning it can be taken to sites for examination. Basically, this microscope has a polarizer and analyzer that highlights the density and color difference on the surface of the sample. This makes it suitable to study birefringence materials. It is commonly used in pharmaceuticals, pathology, and geology.
4. Electron microscope
In the other types of microscopes that we studied till now, light was used to view the image. The electron microscope is an exception in this case, as the electron beams are used as an energy source. It can magnify the objects in nanometers. These electrons pass through the specimen and display a digital image on the monitor. Also, it has the highest resolution. But on the flip side, the samples are destroyed by the electron beams. So studying a live specimen is not always an option here. It is further classified into two types: Transmission and Scanning electron microscope.
Transmission electron microscope (TEM)
TEM generates a highly magnified image using a beam of electrons, which passes through the specimens. This is why the ultra-thin slices of specimens are used so that the electrons can pass through them and receive information. A projection image is then generated. It is used to study the interior of the cells. Unfortunately, the requirement of thin samples limits the use of TEM to experience and well-trained users.
Scanning electron microscope (SEM)
SEM is used to generate detailed images of the surface of the specimen. It is used as obtaining these images is not possible by TEM. Here, the electron beam is scanned onto the surface of the specimen to determine size and composition. This is done in a raster pattern. It is also used to detect contamination on the surface of the sample. What makes SEM different from TEM is that, here, you can get 3D images, whereas TEM only generates 2D images. There is no denying that the 3D images are more useful to interpret the results.
5. Stereo microscope
If you want to get the feel of holding a sample in your hand, then you might want to consider the option of observing it under a stereo microscope. The reason is the stereo microscope is used to get a 3D view of the object. And the image formed here is upright. Another name of this microscope is dissecting microscope. Since we are talking about the 3D view, the separate optical paths for each eye come as no surprise. Here, the magnification ranges from 10X to 50X. Mostly, it is used to study opaque objects such as flowers, insects, fossils, and many more. It is also used in educational institutes for dissection projects. Furthermore, pathologists use this microscope to perform dermatological examinations.
6. Fluorescence microscope
First things first, by exposing fluorescent dyes to ultraviolet rays, we can convert the invisible light that is the shorter wavelength rays to visible light that is the longer wavelength rays. So, in a fluorescence microscope, the specimen is stained with fluorescent dye. You may now wonder why is that the case? As mentioned, when the fluorescent substance is illuminated, it emits fluorescent light with a longer wavelength, making the sample more visible. This makes studying specific cells in the microbial population feasible. Likewise, it is used to observe live cells. It also provides high-quality 3D images of the cells. So, the researchers can also easily label the structures within the cells.