Why is the resolution of an electron microscope higher than that of an optical microscope
The magnification of an optical microscope is smaller than that of an electron microscope. An optical microscope can only observe microscopic structures such as cells and chloroplasts, while an electron microscope can observe submicroscopic structures, that is, the structure of organelles, viruses, bacteria, etc
An electron microscope projects an accelerated and aggregated electron beam onto a very thin sample, where electrons collide with atoms in the sample to change direction, resulting in three-dimensional angular scattering. The size of the scattering angle is related to the density and thickness of the sample, so it can form images with different shades. The images will be displayed on imaging devices (such as fluorescent screens, films, and photosensitive coupling components) after amplification and focusing.
Due to the very short de Broglie wavelength of electrons, the resolution of a transmission electron microscope is much higher than that of an optical microscope, reaching 0.1-0.2nm and magnification of tens of thousands to millions of times. Therefore, the use of transmission electron microscopy can be used to observe the fine structure of samples, and even to observe the structure of only one row of atoms, which is tens of thousands of times smaller than the smallest structure observed by optical microscopy. TEM is an important analytical method in many scientific fields related to physics and biology, such as cancer research, virology, materials science, as well as nanotechnology, semiconductor research, and so on.
The highest resolution of an optical microscope
200 nanometers. The resolution of an optical microscope (with visible light wavelengths ranging from 770 to 390 nanometers) is closely related to the focusing range of the illuminating beam. In the 1870s, German physicist Ernst Abbe discovered.
Visible light, due to its wave characteristics, undergoes diffraction, making the beam unable to focus infinitely. According to this Abbe's law, the minimum diameter for focusing visible light is one-third of the wavelength of the light wave.
That's 200 nanometers. For over a century, the "Abbe limit" of 200 nanometers has been considered the theoretical resolution limit of optical microscopes, and objects smaller than this size must be observed using an electron microscope or tunnel scanning microscope.
Numerical aperture, also known as aperture ratio, abbreviated as NA or A, is the main parameter of the objective lens and condenser, and is directly proportional to the resolution of the microscope. The numerical aperture of the dry objective is 0.05-0.95, and the numerical aperture of the oil immersed objective (cedar oil) is 1.25.
Working distance refers to the distance from the front lens of the objective lens to the cover glass of the specimen when the specimen being observed is the clearest. The working distance of the objective lens is related to its focal length. The longer the focal length of the objective lens, the lower the magnification, and the longer its working distance.
The function of the objective lens is to magnify the specimen for the first time, and it is the most important component that determines the performance of the microscope - the level of resolution. Resolution is also known as resolution or resolving power. The magnitude of resolution is expressed by the numerical value of the resolution distance (the minimum distance between two object points that can be distinguished).
At a clear distance of 25cm, two objects with a distance of 0.073mm can be clearly seen by the normal human eye. This value of 0.073mm is the resolution distance of the normal human eye. The smaller the resolution distance of a microscope, the higher its resolution and better its performance.
The magnification of an optical microscope is smaller than that of an electron microscope. An optical microscope can only observe microscopic structures such as cells and chloroplasts, while an electron microscope can observe submicroscopic structures, that is, the structure of organelles, viruses, bacteria, etc
An electron microscope projects an accelerated and aggregated electron beam onto a very thin sample, where electrons collide with atoms in the sample to change direction, resulting in three-dimensional angular scattering. The size of the scattering angle is related to the density and thickness of the sample, so it can form images with different shades. The images will be displayed on imaging devices (such as fluorescent screens, films, and photosensitive coupling components) after amplification and focusing.
Due to the very short de Broglie wavelength of electrons, the resolution of a transmission electron microscope is much higher than that of an optical microscope, reaching 0.1-0.2nm and magnification of tens of thousands to millions of times. Therefore, the use of transmission electron microscopy can be used to observe the fine structure of samples, and even to observe the structure of only one row of atoms, which is tens of thousands of times smaller than the smallest structure observed by optical microscopy. TEM is an important analytical method in many scientific fields related to physics and biology, such as cancer research, virology, materials science, as well as nanotechnology, semiconductor research, and so on.
The highest resolution of an optical microscope
200 nanometers. The resolution of an optical microscope (with visible light wavelengths ranging from 770 to 390 nanometers) is closely related to the focusing range of the illuminating beam. In the 1870s, German physicist Ernst Abbe discovered.
Visible light, due to its wave characteristics, undergoes diffraction, making the beam unable to focus infinitely. According to this Abbe's law, the minimum diameter for focusing visible light is one-third of the wavelength of the light wave.
That's 200 nanometers. For over a century, the "Abbe limit" of 200 nanometers has been considered the theoretical resolution limit of optical microscopes, and objects smaller than this size must be observed using an electron microscope or tunnel scanning microscope.
Numerical aperture, also known as aperture ratio, abbreviated as NA or A, is the main parameter of the objective lens and condenser, and is directly proportional to the resolution of the microscope. The numerical aperture of the dry objective is 0.05-0.95, and the numerical aperture of the oil immersed objective (cedar oil) is 1.25.
Working distance refers to the distance from the front lens of the objective lens to the cover glass of the specimen when the specimen being observed is the clearest. The working distance of the objective lens is related to its focal length. The longer the focal length of the objective lens, the lower the magnification, and the longer its working distance.
The function of the objective lens is to magnify the specimen for the first time, and it is the most important component that determines the performance of the microscope - the level of resolution. Resolution is also known as resolution or resolving power. The magnitude of resolution is expressed by the numerical value of the resolution distance (the minimum distance between two object points that can be distinguished).
At a clear distance of 25cm, two objects with a distance of 0.073mm can be clearly seen by the normal human eye. This value of 0.073mm is the resolution distance of the normal human eye. The smaller the resolution distance of a microscope, the higher its resolution and better its performance.
