Hello classmates!
Everyone is very familiar with the Leica microscope, but what are the seven observation methods and how to use them? Not everyone has used them or is very clear. Therefore, today we will popularize the seven observation methods and their principles of the Leica microscope.
1. Mingchang
Mingchang is a familiar observation method widely used in pathology and examination, and all microscopes have this function.
2. Dark field
The dark field is actually a dark field illumination method, which differs from the bright field in that it does not directly observe the illuminated light, but instead observes the reflected or diffracted light of the object being tested. Therefore, the field of view becomes a dark background, while the object being tested presents a bright image.
The principle of the dark field is based on the optical Tindall phenomenon, where dust cannot be observed by the human eye when directly illuminated by strong light. This is caused by the diffraction of strong light. If the light is angled at it, the particles appear to increase in volume due to the reflection of light, making them visible to the human eye.
The special accessory required for dark field observation is a dark field condenser, which is characterized by not allowing the beam of light to pass through the tested object from bottom to top, but by changing the path of the light, making it slant towards the tested object, so that the illumination light does not directly enter the objective lens. By utilizing the bright patterns formed by the reflected or diffracted light on the surface of the tested object, the observation resolution of the dark field is much higher than that of the bright field. For example, the dark field of Leica DM4 M-type upright microscope in our metallographic microscope is quite typical.

3. Polarized light
Polarizing microscope is a kind of microscope to identify the optical properties of the fine structure of substances. All substances with birefringence can be clearly distinguished under the polarizing microscope. Of course, these substances can also be observed by staining method, but some are impossible, and must use the polarizing microscope.
The characteristic of a polarizing microscope is the method of changing ordinary light to polarized light for detection, in order to identify whether a substance is single or birefringent.
Birefringence is a fundamental characteristic of crystals, so polarizing microscopy is widely used in fields such as minerals and chemistry, as well as in biology and botany. A typical example is the Leica DM750 P professional polarizing microscope.

Alright, that's all for the students today, and we will introduce the other four observation methods in the next issue.

If you want to learn more knowledge, please feel free to call, write to us, or add WeChat to inquire about the engineers of Chain Metallography. The contact information can be found on the official website of Chain Metallography.