Introduction to the three differences between metallographic microscopes and stereomicroscopes
An introduction to the three differences between metallographic microscopes and stereomicroscopes:
1. Lighting light path system:
Metallurgical microscopes generally have a special reflected light illumination path (because the sample being observed is opaque), and the illumination light passes through the semi-reflective lens and then is irradiated to the surface of the sample through the objective lens. After reflection, it passes through the objective lens and eyepiece and then enters the human eye. Imaging, so the objective lens replaces the role of the condenser lens in the Kohler illumination system. In principle, this kind of lighting belongs to coaxial lighting, that is, the illuminating light and the reflected light are in the same main light path.
Stereoscopic microscopes generally use external light sources, such as lateral halogen lamps for oblique illumination and ring-shaped LED lamps for illumination. However, these illumination methods are not coaxial illumination. Their illumination light is obliquely emitted from the side and has a certain distance from the main optical axis. The angle is, in principle, similar to the dark field illumination of a metallographic microscope. In addition, some stereomicroscopes also have coaxial illumination sources, but coaxial illumination of stereoscopes has certain limitations. If not designed properly, glare will occur, which requires special accessories or lenses to eliminate it.
2. Microscope frame and focusing mechanism?
The metallographic microscope frame is generally relatively large, but since the metallographic microscope is used for high-magnification inspection, the size of the sample it can place is generally relatively small, and the sample surface is generally required to be relatively flat, and the sample needs to be ground, polished and corroded. This is Except for the inverted metallographic microscope, although sample preparation is also required, it has almost no limit on the size of the sample. A good inverted metallographic microscope can place samples weighing about 10 kilograms. In addition, the focusing mechanism of the upright metallographic microscope is a lifting stage (there are also a few upright microscopes and measuring microscopes that lift the objective lens through special accessories), and the inverted metallographic focusing mechanism is a lifting objective lens.
The frame size of a stereo microscope is generally relatively small, but if it is matched with a large-size mobile frame, it can inspect samples of different sizes, including directly inspecting products on the production line, so it has very low sample requirements and does not require special For sample preparation, as long as the surface of the sample is roughly flat. Because stereoscopes are relatively light, the focusing method of stereomicroscopes is generally to raise and lower the entire optical path host.
3. Magnification
The magnification of the objective lens of a metallographic microscope is between 1.25x and 100x, and the magnification of the eyepiece is between 10X and 20X. Therefore, the total magnification of a metallographic microscope is between 12.5X and 2000x.
The magnification of stereo microscopes varies greatly. If it is a stereo microscope used for ordinary inspection, the magnification is generally between 0.5 times and 100 times. If it is a research-grade microscope, while improving the optical quality, the magnification will also be increased to About 200 times to 400 times.
