Several questions about microscope oil lens
Why use an oil immersion lens at 100x?
When the microscope needs to use the 100X objective lens, it needs to use the oil lens. Why? Let me introduce you to the optical principle
The magnification of the oil lens is high, and the lens is small, so the amount of light passing through is small; when the light passes through medium objects of different densities (transmission process: glass slide-air-lens), part of the light will be refracted and lost, which leads to The light entering the lens barrel is less, the field of view is darker, and the specimen cannot be observed clearly.
To solve this problem, it is necessary to drop a medium similar to glass refractive index (refractive index: n=1.52) between the lens and the glass to compensate for the problem of light loss. The refractive index of traditional cedar oil is 1.515, while C14H12O2 benzyl formate The refractive index of the ester compound can reach 1.5175, which is closer to the refractive index of glass, and the vision is clear. In this way, the light entering the oil lens increases to achieve the effect of enhancing the brightness of the field of view and clearing the object image. That is, drop a drop of lens oil on the slide, so that the images such as cells on the slide can be seen clearly.
When to use oil mirror?
The magnification of the object is the magnification of the eyepiece multiplied by the magnification of the objective lens, while the oil lens is the 100X objective lens, and the eyepiece is mostly 10X. So when you need 1000X magnification, you should choose an oil lens!
Generally, microorganisms such as fungi and yeast are relatively large (parasite eggs are even larger), and good results can be obtained with low-power objective lenses and high-power objective lenses. However, to see the morphology of stained bacteria and the morphological structure of eukaryotic cells, such as chlamydia, bacteria, blood cells, organelles and other finer structures, it is best to use oil immersion lenses when staining slides with body cavity fluids and secretions (oil immersion immersion lenses) The resolution can reach about 0.2μm), so as to observe more clearly.
How to use the oil mirror?
(1) Before using the oil lens, you must first observe through the low and high power lens, and then move the observation target part 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 objective lens converter so that the high-magnification lens leaves the light hole, drop a drop of cedar oil or BASO lens oil on the slide to be observed, then slowly turn the oil lens, and watch horizontally from the side when switching the oil lens The distance between the lens and the glass slide, so that the lens can be immersed in the oil without crushing the glass slide.
(4) Observe the eyepiece with the left eye, and slowly turn the fine focus screw until the object image is clear. If there is no object image or the target is not ideal, you need to search again. When refinding outside the refueling area, you should follow the procedure: low magnification→high magnification→oil lens. When re-finding in the refueling area, you should follow the procedure: low magnification → oil lens, and do not go through the high magnification lens to prevent oil from contaminating the lens.
(PS: Do not put the high-magnification lens in contact with the oil of the microscope lens, and wipe it clean with detergent in time after contact; after the observation, first convert the oil lens to a low-power lens, and then remove the glass slide to avoid damage to the lens, and use it in time Wipe the lens with lens tissue;)
(5) After the oil lens is used, if you use cedar oil, you need to wipe off the cedar oil on the lens and the specimen with a little xylene on the lens tissue, and then wipe it with dry lens tissue; while BASO advanced microscope oil lens The oil can be wiped off with ordinary lens cleaning paper~
