Operating Method of the Microscope Oil Immersion Objective
The oil immersion objective is a type of microscope objective. It is named so because it must be immersed in cedarwood oil during use.
Basic Principle
The refractive index of light in cedarwood oil (n=1.515) is close to that of glass (n=1.52). This reduces the light refracted out of the lens and increases the brightness of the field of view.
Operating Procedures
(1) Light adjustment: Raise the condenser to the highest position, open the diaphragm to the maximum, and adjust the concave mirror to obtain the strongest incident light for the lens.
(2) Slide loading: Place a drop of cedarwood oil on the area to be examined of the stained specimen slide. Secure the slide on the stage with the spring clip, and move the target area above the condenser. First locate the suitable field of view with the low-power objective, then switch to the oil immersion objective for observation.
(3) Focusing: Use the coarse focusing knob to raise the stage or lower the oil immersion objective until the objective nearly touches the specimen slide. While looking through the eyepiece, slowly turn the fine focusing knob in the opposite direction until a completely clear image is obtained.
(4) Maintenance: After use, lower the stage or raise the oil immersion objective with the coarse focusing knob and remove the specimen slide.Use lens tissue to blot up cedarwood oil. If the oil dries out or the view is blurred, apply 1–2 drops of xylene or absolute ethanol on the lens tissue to remove cedarwood oil on the slide, and immediately wipe off the xylene with dry lens tissue. Clean the oil immersion objective in the same way.Then rotate the low-power objective to the center or turn the objectives into a "figure-eight" position. Turn the coarse focusing knob to bring the objective lens close to the stage, and lower the condenser. Cover the microscope with silk cloth, place it into the microscope cabinet, and store it in a cool and dry place.
