What Are the Detection Technologies of Metallographic Microscopes?
1, Bright field observation
Bright field microscopy is a commonly used method for pathological examination, examination, and visualization of stained sections. All microscopes are capable of performing this function. I will not elaborate further here.
2, Dark field observation
Dark field practice is dark field illumination. Its characteristics differ from the bright field of view. Metallographic microscopes do not directly observe the illuminated light, but rather the reflected or diffracted light of the object being inspected. Therefore, the field of view becomes a gloomy backdrop, while the inspected object appears as a bright image. The principle of dark field is based on the optical Tyndall phenomenon, where dust particles cannot be observed by the human eye when exposed to strong light, due to the diffraction of strong light. If the light is obliquely projected onto it, the particles appear to increase in volume due to the reflection of light, making them visible to the human eye. The extraordinary accessory required for dark field viewing is a dark field spotlight. The characteristic of this observation method of metallographic microscope is that it does not allow the light beam to pass through the object being inspected from bottom to top, but changes the path of the light beam to be obliquely directed towards the object being inspected, so that the illumination light does not directly enter the objective lens, and uses the light reflected or diffracted from the surface of the object being inspected to form a bright image. The resolution of dark field observation is much higher than that of bright field observation, reaching 0.02-0.004mm.
3, Phase contrast inspection method
The successful creation of phase contrast microscopy in the development of optical microscopes is a major achievement in modern microscopy skills. We know that the human eye can only distinguish the wavelength (color) and amplitude (brightness) of light waves. For colorless and transparent biological specimens, when light passes through, the wavelength and amplitude do not change much, making it difficult to observe the specimen in a bright field.
The phase contrast microscope uses the difference in optical path length of the object being examined for mirror inspection, which means using light to intervene in the image in a favorable way, turning the phase difference that the human eye cannot distinguish into a distinguishable amplitude difference. Even colorless and transparent substances can become clearly visible. This large stool is used for observing living cells, so phase contrast microscopy is commonly used for inverted microscopy.
