Microscopy is a vital technique in many fields of science, including biology, medicine, and materials science. It allows scientists to observe and study objects and phenomena at a very small scale, often much smaller than can be seen with the naked eye. There are many different types of microscopy, each with its own set of basic techniques and protocols. In this essay, we will discuss some of the most common basic techniques in microscopy, including light microscopy, electron microscopy, and atomic force microscopy.
Light microscopy is the most common type of microscopy and is used to observe objects at a scale of up to about 1000 times their original size. It is based on the principles of refraction and reflection, and uses light to illuminate the sample and a lens system to magnify the image. There are several different types of light microscopy, including brightfield microscopy, where the sample is illuminated from below and appears darker against a bright background; darkfield microscopy, where the sample is illuminated from the side and appears bright against a dark background; and fluorescence microscopy, where the sample is illuminated with light of a specific wavelength and emits light of a different wavelength, allowing for the visualization of specific structures or molecules.
Electron microscopy uses a beam of electrons instead of light to observe samples at a much higher magnification, up to about one million times their original size. There are two main types of electron microscopy: transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In TEM, the sample is thinly sliced and the electrons pass through the sample, creating an image of the internal structure. In SEM, the electrons are focused onto the surface of the sample and the resulting interactions are used to create an image of the surface structure. Electron microscopy is particularly useful for studying the fine details of cells and tissues, as well as inorganic materials such as metals and ceramics.
Atomic force microscopy (AFM) is a relatively newer type of microscopy that uses a sharp probe to scan the surface of a sample and measure the forces between the probe and the sample. It allows for the visualization of surface features at a scale of about 0.1 nanometers, making it useful for studying the surface properties of materials and biological samples. AFM can be used in a variety of modes, including contact mode, where the probe is in contact with the sample; non-contact mode, where the probe is held above the sample by a repulsive force; and tapping mode, where the probe oscillates at a high frequency, allowing for imaging of soft or delicate samples.
In conclusion, microscopy is a crucial technique in many fields of science, with a wide range of applications. The basic techniques discussed in this essay, including light microscopy, electron microscopy, and atomic force microscopy, are just a few examples of the many types of microscopy available to scientists. These techniques allow us to observe and study objects and phenomena at a very small scale, providing valuable insights and advances in our understanding of the world around us.