What is the principle of the oil lens in an optical microscope?
Oil lens is one of the optical microscopes. When used, the lens is immersed in oil (usually cedar oil) to observe finer structures. It is one of the microscopes commonly used in laboratories. The clarity is slightly higher than that of ordinary optical microscopes. It is used for Observe chlamydia, bacteria, cell organelles, and more.
The lens of the oil lens is very small. When light passes through the air between the glass slide and the oil lens, refraction or total reflection occurs due to the different density of the medium, which reduces the light entering the lens and makes the object image unclear. If cedar oil (n=1.515), which is similar to the refractive index of glass (n=1.52), is added between the oil lens and the glass slide, the light entering the lens will increase, the brightness of the field of view will be enhanced, and the object image will be bright and clear. Due to the small size of bacteria, in morphological studies of bacteria, it is often necessary to use a microscope oil lens to observe them more clearly. Therefore, you must be proficient in the use and protection of oil lenses.
Notes on using oil lens:
(1) Before using the oil lens, you must first observe through low and high magnification lenses, and then move the part that needs further magnification to the center of the field of view.
(2) Raise the light collector to the highest position and open the aperture to the maximum.
(3) Turn the converter to move the high-magnification lens away from the light aperture, add a drop of cedar oil to the glass slide in the area to be observed, and then slowly turn the oil lens. When changing the oil lens, look at the lens and glass lens horizontally from the side. The distance is such that the lens is immersed in the oil without crushing the slide.
(4) Observe with your left eye
Eyepiece, and slowly turn the fine adjuster until the object image is clear.
If there is no object image or the target is not ideal and it is necessary to search again, follow the procedure of low magnification → high magnification → oil lens when searching again outside the refueling area. When re-searching in the refueling area, follow the procedure: low magnification → oil lens. High magnification lens is not allowed to avoid oil contamination of the lens.
(5) After using the oil lens, first use lens cleaning paper dipped in a little xylene to wipe off the cedar oil on the lens and specimen, and then wipe it clean with dry erasing lens paper.
