Instructions for Using the Oil Immersion Objective of Metallographic Microscopes
① Locate the specimen to be observed under the high-power objective of the metallographic microscope, and move the area to be further magnified to the center of the field of view.
② Raise the condenser to its highest position and open the iris diaphragm fully.
③ Rotate the revolving nosepiece to move away the high-power objective. Place a drop of cedar oil on the coverslip of the area to be observed as the medium (the refractive index of cedar oil is roughly equal to that of glass).
④ Slightly raise the tube or lower the stage. Rotate the revolving nosepiece to align the oil immersion objective with the light aperture. Then observe the gap between the oil immersion objective and the specimen from the side. Slowly turn the coarse focus knob to bring the oil immersion objective into contact with the oil drop, and carefully bring it close to the coverslip surface.Special attention shall be paid during this operation; the adjustment speed must not be too fast. For some microscopes, you may directly switch to the oil immersion objective without raising the tube, and the lens can be immersed in the oil drop.
⑤ Look through the eyepiece. At the same time, gently turn the fine focus knob to slightly raise or lower the stage until a clear image is obtained.If switching directly to the oil immersion objective, only turn the fine focus knob and slightly lower the lens or raise the stage to clearly view the image.Do not use the coarse focus knob. If no blurred image is visible in the field of view, avoid continuously turning the fine focus knob in one direction to lower the lens, as this may crack the coverslip or damage the objective lens.
⑥ After finishing oil immersion observation, thoroughly clean the cedar oil on both the objective lens and specimen slide. First, wipe off most of the oil on the lens with lens paper moistened with a small amount of xylene. Then wipe with dry lens paper. Wipe along the diameter direction of the lens; do not wipe in a circular motion around the lens.
