Basic specification for the use of optical microscopes in middle schools

The microscope is a necessary experimental instrument in the middle school biology laboratory. Whether the microscope is used correctly and skillfully is often the key to the success or failure of the experiment. Therefore, it is necessary to put forward standardized requirements for using microscopes in teaching. According to teaching practice, the author believes that the use of microscopes should mainly include the following aspects:

1. Take the microscope. Hold the mirror arm with your right hand and hold the mirror base with your left hand, and place it in front of your chest. The purpose of this is mainly to prevent the microscope from being dropped off during the delivery of the microscope.

2. The microscope is placed with the lens barrel facing forward and the mirror arm facing backward; placed on the table in front of the observer's seat, biased to the left side of the body to facilitate the observation of the left eye into the eyepiece; placed on the inside of the table, about 5 cm from the edge of the table.

3. Use of tilted joints Generally, tilted joints cannot be used in biological experiments in middle schools. Because tilted joints are generally used for long-term observation of non-water-sealed slides, the temporary slides observed in the middle school biological laboratory are all water-sealed slides, and the observation of water-sealed slides is generally shorter, so no tilt joints are used. Necessary. If you use a tilt joint, you should pay attention to the following two points: (1) hold the mirror arm with your right hand, and hold the lens base with your left hand, gently bend down; (2) the angle between the lens barrel and the vertical direction does not exceed 40 degrees to avoid the microscope Dumped.

4. To the light (1) Turn the coarse quasi-focus spiral to make the lens barrel rise slowly, then turn the converter to align the low-magnification objective lens with the through hole; (2) Use your fingers to turn the shutter (or diaphragm), yes The maximum aperture is aligned with the clear aperture; (3) The left eye is looking into the eyepiece, and at the same time, turning the mirror to make it look towards the light source, so that the brightness in the field of view is uniform and appropriate. After aligning the light, the position of the microscope is generally no longer moved. If the microscope is moved, the light needs to be re-aligned.

5. Use of low magnification objective lens (1) Turn the coarse quasi-focusing screw by hand to slowly lower the lens barrel, while looking at the objective lens from the side with both eyes, when the objective lens and the slide specimen on the stage are separated by 2 ~ 3mm stop. (2) Look into the eyepiece with your left eye (note that the right eye is open at the same time), and turn the coarse quasi-focus screw to make the lens barrel rise slowly until you see the object image. If it is not clear, you can adjust the fine quasi-focus spiral until it is clear.

6. Use of high power objective lens Before using high power objective lens, you must first use low power objective lens to find the object image to be observed. Because the field of view of high power objectives is small and dark. If the microscope function is intact, when switching to a high-power objective, simply move the part to be further magnified under the low-power lens to the center of the field of view, and then turn the converter so that the high-power objective is directly facing the clear aperture, and the left eye is directed into the eyepiece Look, turn the fine quasi-focus screw counterclockwise to make the lens barrel rise slightly, and turn it about half a turn to see clearly. If the field of view is blurred, it should be lowered and turned slowly in a clockwise direction, so that the lens barrel is slowly lowered. Generally, it will be clear when it rotates once. After switching to a high-power objective lens, the brightness in the field of view becomes darker, so generally choose a larger aperture and use the concave surface of the mirror.

7. Use of mirrors Mirrors are used in conjunction with shutters (or diaphragms) to adjust the brightness of the field of view. The reflector has a flat surface and a concave surface. For light, if the light in the field of view is too strong, use the plane of the mirror. If the light is still too strong, use a smaller aperture; conversely, if the light in the field of view is weak, use a larger aperture or use a reflector The concave surface of the mirror.

8. Wiping the lens After the lens is contaminated, the observation effect is often affected, so it needs to be wiped frequently. Please pay attention to the lens cleaning: (1) Use special lens cleaning paper; (2) Fold the lens cleaning paper several times when wiping the lens, and then wipe it in one direction. For oil pollution, a few drops of xylene can be dripped on the lens paper, and then wiped as above.

9. Placement of the microscope after the experiment After the microscope is used, the slide should be removed, and its mechanical part should be wiped clean with white gauze. In addition, it is necessary to: (1) turn the converter so that the two objective lenses are on both sides; (2) turn the coarse quasi-focus screw to lower the lens barrel to the lowest point to prevent the lens barrel from descending due to gravity Cause slip wire; (3) Erect the mirror, cover it with red silk cloth, and then lock the microscope into the box.



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