The steps of changing the microscope low-power lens to high-power lens
As we all know, in the process of using the microscope, it is generally observed with a low magnification lens, and then the sample to be magnified and observed is moved to the center of the field of view, and finally the high magnification lens is replaced for observation, so there is a conversion between low magnification and high magnification during use. , that is, we often say that the low-power mirror finds the field of view, and the high-power mirror observes the sample. This is also the most basic common sense used by microscopes, but the methods used are different. The following will introduce the low-power mirror and high-power mirror and oil How to use between mirrors.
How to use the low magnification lens
When observing any specimen, a low magnification lens must be used first, because its large field of view makes it easy to find the target and determine the part to be observed.
(1) Mirror taking and placement
The microscope is a high-precision optical experimental instrument. When it is not in use, it is usually packed and placed in a box. When it is used, it is taken out and opened. Stay upright to prevent mirrors and eyepieces from slipping out. Place the microscope lightly on the laboratory table, usually on the left side, 3 to 4 cm away from the edge of the table, with the mirror arm facing your chest for easy observation.
(2) Cleaning
Check whether the microscope is faulty and clean. If there is dust and dirt on the metal part, wipe it with a clean soft cloth. If the lens is dirty, it should be wiped with lens tissue, never with a handkerchief. If there is glue or sticky dirt, use a small amount of xylene to clean it.
(3) Alignment step
Raise the lens barrel to a distance of 1-2 cm from the stage, rotate the nosepiece, turn the low magnification lens toward the stage, and align with the light hole in the center. The rotation process should be slow. When you hear the click sound, open the aperture, raise the light collector, turn the reflector to the light source, observe on the eyepiece with the left eye (do not close the right eye), and adjust the reflector at the same time. direction until the light in the field of view is uniform and bright.
(4) Place the slide specimen
Take a slide specimen and place it on the stage. Note that the side with the cover glass must be facing up, otherwise the focus cannot be adjusted when observed with a high-power microscope, and the slide specimen is easily damaged. Then clamp the glass slide with the slicing clip, turn the screw of the platform mover, and align the part to be observed in the center of the light-transmitting hole.
(5) Adjust the focal length
Rotate the coarse adjuster counterclockwise with your left hand, so that the stage slowly rises to about 5 mm from the objective lens to the specimen. Note that when the stage is raised, do not observe on the eyepiece. Be sure to watch the stage rise from the right side, so as not to rise too much and cause damage to the lens or specimen. Then, open both eyes at the same time, observe with the left eye on the eyepiece, slowly turn the coarse adjuster clockwise with the left hand, and slowly lower the stage until a clear object image appears in the field of view.
Note: If the object image is not in the center of the field of view, you can adjust the slide pusher to adjust it to the center (note that the direction of moving the slide is opposite to that of the object image in the field of view). If the brightness in the field of view is not suitable, it can be adjusted by raising and lowering the position of the concentrator or opening and closing the aperture. If this operation fails, you should re-operate, and do not raise the stage blindly and impatiently.
2 How to use the high magnification lens
When the object needs to be further magnified and observed, it can be observed with high magnification.
(1) High magnification lens focusing
After adjusting with the low-power lens, you can replace the high-power objective lens for observation. First, turn the converter. When converting the high-power lens, the rotation speed should be slow, and observe from the side (to prevent the high-power lens from colliding with the glass), such as a high-power lens. If the glass slide is touched, it means that the focal length of the low-power lens is not adjusted properly, and the operation should be repeated.
(2) Adjust the focal length
After converting the high magnification lens, observe with the left eye on the eyepiece. At this time, you can generally see a not very clear object image. You can move the screw of the fine adjuster counterclockwise about 0.5-1 circle to obtain a clear object image. If the brightness of the field of view is not suitable, use the concentrator and aperture to adjust it. If you need to replace the slide specimen, you must turn the coarse adjuster clockwise (do not turn the wrong direction) to lower the stage before removing the slide specimen.
3 How to use the oil mirror
The multiples of the objective lens are divided into many types, but when the objective lens reaches 100, cedar oil or fir oil is needed as the objective lens, so the objective lens with more than 100 times is oily objective lens, which is generally marked with "oil". The principle of oily objective lens is between the objective lens and the specimen. The medium is not air but cedar oil or fir oil, because the refractive index of oil is higher than that of air, which improves the resolution of the lens, but we should pay attention to the method when using the oil lens, otherwise the effect will be counterproductive.
(1) Before using the oil mirror, you must first find the inspected object through the low-power mirror, and then use the high-power mirror to adjust the focus. After the inspected object is adjusted to the center of the field of view, change the oil mirror for observation.
(2) When using the oil lens, be sure to add a drop of cedar oil (mirror oil) to the cover glass before use. Rotate the objective lens so that the oil lens is on the optical axis and then adjust the thickness and focal screw, so that the objective lens moves down slowly until it comes into contact with the cedar oil on the cover glass. Be careful in this process, and try to avoid the lens from crushing the cover glass or the specimen. . At this time, observe the eyepiece and rotate the fine focus screw until a clear specimen image can be seen in the field of view. The condenser can be adjusted to change the intensity of the light. When observing the specimen with the oil lens, it is not allowed to use the coarse adjustment wheel, and only the fine adjustment wheel can be used to adjust the focus. If the cover glass is too thick, it cannot be focused and needs to be replaced, otherwise it will crush the glass or damage the lens.
(3) After the observation, the oil on the lens should be wiped off in time. The method is to lower the stage to separate the specimen from the objective lens, first absorb the oil on the lens with dry lens paper, and then use the lens paper soaked in xylene. Wipe clean, and then wipe with dry lens tissue.
