(a) oblique method The light source is obliquely illuminated from the side on the surface of the light sheet so that the reflected light is symmetrically tilted and reflected without entering the objective lens (Fig. 2-9-6). When the light is obliquely reflected to the surface of the transparent or translucent mineral, except for being partially reflected obliquely The rest of the light penetrates into the interior of the mineral, encounters an interface with a proper inclination, and reflects from the inside of the mineral into the objective lens, so that the microscope field has a certain brightness, and has a transparent visual sense, that is, an internal reflection phenomenon. The color indicates that the mineral has an internal reflection color. The observation of the internal reflection of minerals by oblique illumination is less sensitive, and only the internal reflection of minerals with significant internal reflection can be observed. Therefore, do not think that the minerals that are black under the mirror when obliquely illuminated must have no internal reflection. In order to improve the observation effect, it is possible to observe the mineral powder by oblique illumination because the light transmittance of the powder is better than that of the bulk mineral. Mineral powder can be obtained by scoring the surface of the light sheet under a microscope with a steel needle or a diamond pen. Figure 2-9-6 oblique diagram (two) orthogonal polarization method The method is to observe the internal reflection phenomenon of minerals under orthogonal polarization. When the incident plane linear polarization is reflected by the mineral surface, the reflected light is substantially linearly polarized, so that it cannot pass through the upper polarizer, and the field of view is dark. However, the case where the linear polarized light incident inside the mineral is reflected is different, because the light waves reflected by the interface inside the mineral are often elliptically polarized or reflected and rotated, that is, a part of the internally reflected light can pass through the upper polarizer. To make the field of view show a certain brightness, which is the phenomenon of internal reflection under orthogonal polarized light. It is better to observe the mineral powder under orthogonal mirrors. For minerals with very weak internal reflection, oil can also be used as a medium to observe the mineral powder. This is the most effective way to observe internal reflection, because the reflectivity of minerals in oil immersion will be greatly reduced, and the amount of light penetrated into the interior of mineral powder. Greatly increased, making the internal reflection phenomenon more visible. Grippers For Robots,Pneumatic Grippers For Robots,Pneumatic Grippers,Cylinder Gripper SHINYEE TECHNOLOGY (NINGBO) CO., LTD , https://www.pneuvalve.com
Determination of internal reflection
Two types of internal reflection are commonly used, oblique measurement and orthogonal polarization. The results of the measurement can be divided into three levels: “obvious, visible and non-existentâ€. For minerals with internal reflection, the internal reflection color should be further observed and described in parentheses. For example, the internal reflection phenomenon of cinnabar can be recorded as: obvious [red red]