The difference between stereo microscope and metallographic microscope
1. Lighting system
1. Metallographic microscopes generally have a special reflected light illumination path (because the observed sample is opaque), and the illumination light passes through the semi-reflective lens and then irradiates the surface of the sample through the objective lens. Imaging in the eye, so the objective lens replaces 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.
2. Stereo microscopes generally use external light sources, such as side halogen lamps for oblique illumination, and ring LED lights for illumination, but these illumination methods are not coaxial illumination, and their illumination light is obliquely emitted from the side, which is in line with the main optical axis. A certain angle, in principle, is a bit like the dark field illumination of a metallographic microscope. In addition, some stereo microscopes also have coaxial lighting sources, but the coaxial lighting of stereo microscopes has certain limitations. If the design is not proper, glare will occur, which requires special accessories or lenses to eliminate it.
2. Magnification
1. The magnification of the metallographic microscope objective lens is above 1.25 times and below 100 times, and the magnification of the eyepiece is between 10X and 20X. Therefore, the total magnification of the metallographic microscope is between 12.5X and 2000 times.
2. The magnification of the stereo microscope varies greatly. If it is a stereo microscope for general inspection, the magnification is generally between 0.5 times and 100 times. If it is a research-grade microscope, the magnification will increase while improving the optical quality. Increase to about 200 times to 400 times.
3. Rack and focusing mechanism
1. The frame of the metallographic microscope 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 surface of the sample is generally required to be relatively flat, and the sample needs to be ground, polished and corroded. Except for the inverted metallographic microscope, although sample preparation is also required, it has almost no limitation on the size of the sample. A good inverted metallographic microscope can hold samples weighing about 10 kg. In addition, the focusing mechanism of the upright metallographic microscope is to lift the stage (there are also a few upright microscopes and measuring microscopes that lift the objective lens through special accessories), and the focusing mechanism of the inverted metallographic microscope is to lift the objective lens.
2. The size of the stereo microscope frame is generally small, but if it is used 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 requirements for samples and does not Special sample preparation is required, as long as the surface of the sample preparation is roughly flat. Because the stereo mirror is relatively light, the focusing method of the stereo microscope is generally to lift the entire optical path host.
