A metallurgical microscope uses a different lighting method than a conventional microscope and can illuminate solid specimens to identify, inspect, and measure them. They are like other optical microscopes with the exception of the lighting orientation. Some industries use inverted metallurgical microscopes, which observe the specimen from below the stage or table. Electronic parts manufacturers, forensic laboratories, and metal foundries all use this type of instrument.
A conventional microscope illuminates a transparent specimen from below the stage, making it visible through the eyepiece. Since light cannot penetrate opaque or solid objects, this is not a suitable method for observing these samples under magnification. Metallurgical microscopes illuminate objects from above, either with an external light source or with that light travels through the magnification objectives using beam splitters. This lighting technique illuminates the entire object without creating distracting or unnecessary reflections.
The illumination technology may include color filters or filters designed to change polarization and light intensity. These options allow viewing objects in bright or dark field applications. The filters may be contained in a removable cartridge within the microscope body.
The eyepiece on a metallurgical microscope may be singular or binocular, and most microscopes can link directly to a computer for specimen observation on a screen. Field of view (FOV) varies with microscope brand and model with some offering FOVs of up to 0.787 inches (20 millimeters) in diameter. The microscopes may have three to four objective lenses with a range of magnifying capacity. Some versions are capable of magnifying up to 1,250 times.
Another type of microscope used for industrial purposes is the inverted metallurgical microscope. This type of instrument has the objective under the stage, which allows viewing of specimens that vary in size. As individuals typically use a metallurgical microscope for observing surface structure, large items can be placed on the stage without anyone coming into contact with the objectives. Researchers also place flasks or bottles on the stage, observing microorganisms within a liquid environment.
Electronics manufacturers often use a metallurgical microscope as a quality control instrument, inspecting parts for microscopic defects. Forensic labs use the instrument for identifying firing patterns on bullets and casings or for analyzing the surface area of bones and other material. Metal foundries use metallurgic optical microscopes for grain analysis and to determine the structure of manufactured metals. Scientists use the microscopes for analyzing and identifying metal components.