How to Use and Protect Oil Lenses for Optical Microscopes
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 it more 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 length of the oil lens is longer than that of 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 the words 100×, 1.25 or oil are engraved.
Second, the use of oil mirror:
1. When using the microscope oil lens, the microscope must be upright on the table, and the mirror arm must not be bent to tilt the stage, so as to avoid the overflow of cedar oil, affecting the observation and contaminating the table.
2. To light:
When natural light is used as the light source, a flat reflector should be used; if artificial light is used, a concave mirror should be used. First open the aperture and turn the mirror to focus the light on the collector. The collector can be moved up and down and the iris can be zoomed to obtain the best luminosity as needed. Generally, when observing the image with a low-power or high-power lens or checking unstained specimens with an oil lens, it is necessary to lower the concentrator and reduce the aperture appropriately to reduce the luminosity; if the stained specimen is examined with an oil lens, the luminosity should be strong. The microscope brightness switch should be set to maximum brightness, the aperture should be fully open, and the collector should be raised to level with the stage.
3. Focusing distance:
(1) Put the specimen sheet 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 the position of the specimen, then raise the lens barrel, drop a drop of lens oil on the part to be inspected of the sample, and then change the oil lens for observation.
(2) Turn the coarse adjuster to make the stage rise slowly (or make the lens barrel descend gradually) until the oil lens is immersed in the oil. The eye should be viewed from the side at this point to avoid crushing the specimen and damaging the lens.
(3) Then move both eyes to the eyepiece, while observing from the eyepiece, slowly turn the coarse adjuster (lower the stage, or raise the lens barrel) in the opposite direction. until the image is clear.
(4) After the observation, the lens barrel should be raised first, the oil lens should be twisted to one side, and then the specimen should be removed. After using the oil lens, wipe the oil off the lens with lens tissue immediately. If the lens oil is sticky and dry on the lens, you can wipe the lens with a lens paper dipped in a little xylene, and then wipe off the remaining xylene with dry lens paper to prevent the xylene from infiltrating and dissolving the glue used to fix the lens. , causing the lens to shift or fall off.
3. The use principle of 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, 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.
Fourth, the maintenance of the microscope:
1. The microscope is a precision instrument, you should pay attention to it when using it, and do not disassemble and collide at will.
2. Strong acids, strong alkalis, chloroform, alcohol, ether, etc. can remove paint or damage the parts, so be careful not to contact the microscope.
3. The fine adjuster is the most delicate and fragile mechanical part of the microscope. It raises or lowers the lens barrel by 0.1 mm per rotation, and can only rotate back and forth, that is, when it rotates in one direction for several weeks and encounters resistance, it should rotate in the opposite direction.
4. When not in use, turn the objective lens into an "eight" shape, lower the stage to the low point, lower the light collector, close the aperture, put on the protective cover, and send it back with both hands flat.
During the use of the microscope, if any problem is found, it should be reported to the teacher and registered in time for maintenance.
