How to use and protect the oil lens of optical microscope
Due to the small size of bacteria, in the morphological study of bacteria, it is often necessary to use a microscope oil lens to observe clearly. Therefore, students must be proficient in the use and protection of oil mirrors.
1. Identification of oil lens:
The magnification of each objective lens can be identified by its shape. The larger the lens length, the smaller the lens diameter and the larger the magnification; otherwise, the smaller the magnification. The oil lens is longer than the low and high magnification lenses, and the lower edge of the lens is generally engraved with a circle of black or white lines, and engraved with words such as 100×, 1.25 or oil.
2. How to use the oil lens:
1. When using the microscope oil mirror, the microscope must be upright on the table, and the arm of the mirror must not be bent to tilt the stage, so as to prevent the cedar oil from overflowing, affecting the observation and polluting the table.
2. To the light:
When natural light is used as the light source, it is advisable to use a flat reflector; if artificial light is used, a concave mirror is used. First open the aperture, turn the reflector to focus the light on the light collector. The collector can be moved up and down and the aperture zoomed to get the best luminosity as needed. Generally, when observing objects with a low-power lens or a high-power lens or checking unstained specimens with an oil immersion lens, the light collector needs to be lowered and the aperture should be appropriately narrowed to reduce the luminosity; if the oil immersion immersion lens is used to examine stained samples, the luminosity should be strong. The brightness switch of the microscope should be adjusted to the brightest, the aperture is fully opened, and the light collector rises to be level with the stage.
3. Focus adjustment:
(1) Put the specimen piece on the stage, fix it with the specimen pusher, and move the part to be examined under the objective lens. First use a low-magnification lens to find out the position of the specimen, then raise the lens barrel, drop a drop of immersion oil on the part of the specimen to be inspected, and then change the oil lens to observe.
(2) Turn the coarse adjuster to raise the stage slowly (or lower the lens barrel gradually) until the oil lens is submerged in the oil. At this time, the eyes should be observed from the side, so as not to crush the specimen and damage the lens.
(3) Then move your eyes to the eyepiece, observe from the eyepiece, and slowly turn the coarse adjuster in the opposite direction (lower the stage, or raise the lens barrel). When blurred objects appear, use the fine adjuster and turn until the image is clear.
(4) After the observation, the lens barrel should be raised first, and the oil lens should be twisted to one side, and then the specimen should be removed. After the oil lens is used, the oil on the lens should be wiped off immediately with lens cleaning paper. If the lens oil is viscous and dry on the lens, use a lens cleaning paper dipped in a little xylene to wipe the lens, and then wipe off the remaining xylene with a dry lens paper to prevent the xylene from penetrating and dissolving the colloid used to fix the lens , causing the lens to shift or fall off.
3. The principle of using the oil mirror:
The lens of the oil lens is very small. When the 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, so that the light entering the lens is reduced and the object image is not clear. 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 slide glass, 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.
Fourth, the maintenance of the microscope:
1. The microscope is a precision instrument, please take good care of it when using it, and do not disassemble or collide it at will.
2. Strong acids, strong alkalis, chloroform, alcohol, ether, etc. can remove paint or damage parts, so be careful not to touch the microscope.
3. The fine adjuster is the most delicate and fragile mechanical part of the microscope. Each rotation makes the lens barrel rise or fall by 0.1mm, and it can only turn backwards, that is, when turning in one direction for several weeks and encountering resistance, it should turn in the opposite direction.
4. When not in use, turn the objective lens into a "eight" shape, lower the stage to the lowest point, lower the light collector, close the aperture, put on the protective cover, and return it with both hands.
During the use of the microscope, if any problem is found, it should be reported to the teacher in time and registered for maintenance.
