A Brief Discussion on Common Illumination Technologies for Metallographic Microscopes
At present, there are hundreds of microscope brands in China, and different brands of microscopes have numerous different types of microscopes. Among these microscopes, there are many differences in lighting technology. This article mainly introduces the lighting techniques commonly used in metallographic microscopes.
The first type is direct lighting: When observing objects that require high contrast light, this type of lighting is usually used. The direct lighting is directly directed at the object and has a relatively bright brightness. However, this type of lighting also has a disadvantage, that is, using direct lighting on objects with strong reflectivity may cause reflection.
The second type, dark field microscope: Dark field microscope is mainly used to observe objects related to structure and refractive index changes, such as diatoms, radiolarians, and other single cells with regular structures, as well as linear structures in cells such as flagella and fibers. The light in the dark field shines on the surface of the object at an angle set by humans. The characteristic of this light is that it is usually used on the surface of the object without color difference, so the visual system cannot return anything. These two observation methods are usually equipped in metallographic microscopes.
The third type is back lighting: This lighting technology is usually used to measure the size and sense the direction of objects. The principle is to shine light from the back of the object being measured. The light of this lighting is relatively uniform, and the side profile of the object can be seen through the camera.
The fourth type is scattered lighting: Outdoor scattering is a form of natural light that emits light without a clear focus direction. The light is not dazzling and is relatively soft, making it suitable for highly reflective objects.
The fifth type, coaxial lighting: The formation of coaxial light is a uniform surface light source that emits in a vertical direction. Through a 45 degree semi transparent mirror, the light source illuminates the surface of the object in a vertical downward direction. This type of light source is particularly helpful for detecting highly reflective flat objects.
In the illumination techniques used in metallographic microscopes, the above five are mainly used.
