Hi, I'm Cathy with Level Up RN. In this video, I will be doing a brief review of the different types of microscopes used in microbiology. Aside from the bright field microscope, which I covered in a separate video in this video playlist. At the end of the video, I'm going to give you guys a quiz to test your understanding of some of the key facts I'll be discussing. And if you have our Level Up RN microbiology flashcards, go ahead and pull out your flashcards on microscopes so you can follow along with me and pay close attention to the bold red text on the back of the cards because those are the things that you are likely to get tested on in your micro class.
Let's first talk about a dark field microscope, which is basically a bright field microscope with an opaque disk between the illuminator and condenser lens. This produces a bright image on a dark background as opposed to a dark image on a bright background. This type of microscope produces high contrast, high resolution images without having to stain the organism. So it's useful for observing living unstained organisms.
Next, we have a phase contrast microscope, which uses a special condenser to split the light beam into direct and refracted light, which is then combined to create a high contrast image. This type of microscope is useful for observing the internal structures of living unstained organisms. A differential interference contrast microscope or DIC microscope uses polarized light that is split into two beams by a prism. This in turn produces an image that appears 3D. This type of microscope would also be useful for observing living unstained organisms.
Next, we have a fluorescence microscope. When using a fluorescence microscope, a fluorochrome or fluorescent dye is added to the specimen. These fluorochromes then absorb short wavelength light from the microscope and emit visible light with a longer wavelength. This produces a bright image on a dark background. This type of microscope is often used in a clinical setting to identify a particular pathogen in a patient sample. A confocal microscope uses a laser to scan one plane of the specimen at a time. And then these two-dimensional high-contrast images are used to construct a computer-generated 3D image. This type of microscope is good for observing thick, complex structures such as [biofilms?]. An electron microscope uses short wavelength electron beams as opposed to light and uses electromagnets instead of lenses. As a reminder, the shorter the wavelength, the higher the resolution. So this type of microscope is going to provide very high magnification and resolution, and it can be used to observe very small structures such as viruses, including the rotoviruses in this image. It's important to note that use of this microscope requires vacuum conditions because electrons would be scattered by air molecules. So because we require vacuum conditions, this type of microscope could not be used to observe living cells.
There are two main types of electron microscopes, including a transmission electron microscope and a scanning electron microscope. A transmission electron microscope creates 2D images of the internal structures of a specimen, whereas a scanning electron microscope creates 3D images of the surface of the specimen.
And lastly, we have a scanning probe microscope. This type of microscope uses very precise probes over the specimen's surface, which allows the computer to generate an extremely detailed 3D image. This type of microscope is primarily used in research, and it can be used to observe individual atoms. Two key types of scanning probe microscopes include a scanning tunneling microscope and an atomic force microscope.
All right, it's quiz time. And in this particular quiz, I want you to name that microscope. Are you guys ready? Number one, what type of microscope uses a laser to scan one plane of the specimen at a time, which is used to construct a computer-generated 3D image? The answer is a confocal microscope. Number two, what type of microscope uses an opaque disk between the illuminator and condenser lens producing a bright image on a dark background? The answer is a dark field microscope. Number three, this microscope splits light into two beams using a prism, which makes the image appear 3D? The answer is a differential interference contrast or DIC microscope.
All right. That's it for this video. I hope it was helpful. Take care and good luck with studying.
