Five problems of using optical microscope correctly

1、 Problems with proper installation

Before using the microscope, first install the eyepiece and objective lens of the microscope. The installation of the eyepiece is relatively simple. The main problem lies in the installation of the objective lens. Due to the high value of the objective lens, in case the thread is not closed properly, it is easy to fall to the ground and cause damage to the lens. Therefore, for the sake of safety, it is emphasized to hold the objective lens with the left index finger and middle finger, and then install the objective lens with the right hand, so that even if it is not installed properly, it will not fall to the ground 。

2、 The problem of correct light alignment

Light alignment is a very important step in the use of a microscope. Some users turn an objective to the through-hole at random, instead of using a low-power lens to aim at the light as required. I like to use one hand when turning the mirror. I often pull it down. Therefore, when guiding students, teachers must emphasize the use of low power mirror for light. When the light is strong, use small aperture and flat mirror, and when the light is weak, use large aperture and concave mirror. The reflector should be rotated with both hands until you see a uniform and bright circular field of vision. After the light is aligned, do not move the microscope casually, so as to avoid that the light can not pass through the reflector accurately and enter the light hole.

3、 The correct use of quasi spiral focus

It can be said that the most important step in the use of microscope and the most difficult step for users is to adjust the focal length and find the object image. Users are prone to the following errors in the process of operation: first, focus directly under the high-power mirror; second, the eye is always looking at the field of vision in the eyeglass regardless of whether the tube is up or down; third, they do not know the critical value of object distance, when the object distance is adjusted to 2 ~ 3cm, it is still up-regulated, and the speed of turning the focusing spiral is very fast. The first two errors often cause the objective lens to collide with the film loading and damage the film or lens, while the third error is the most common phenomenon when using a microscope. In view of the above errors, it must be emphasized to the user that the focus must be adjusted at the low power mirror. First, turn the coarse focusing screw to make the lens barrel slowly drop and the objective lens close to the slide. In this process, the eye should look at the objective lens from the side, then look into the eyepiece with the left eye, and slowly adjust the coarse focusing screw to make the lens tube slowly up If the object distance is more than 1 cm, but the object image is still not seen, it may be that the specimen is not in the field of vision or the spiral speed of coarse focusing is too fast. At this time, the loading position should be adjusted, and then the above steps should be repeated. When the blurred object image appears in the field of vision, it is necessary to use the fine one Only in this way can we narrow the search range and improve the speed of finding the object image.

4、 The problem of objective lens conversion

When a low power lens is used, a high-power mirror is replaced. Users often like to use their fingers to directly push the objective lens, which is labor-saving. However, it is easy to cause the optical axis of the objective lens to skew. The reason is that the material of the converter is soft, the accuracy is high, and the thread is uneven, which is easy to loosen. Once the thread is broken, the whole converter will be scrapped. The teacher should instruct the students to hold the lower rotating plate of the converter to change the objective lens.

5、 Correct use of eyes

When observing objects with a microscope, both eyes should be opened at the same time, and the left eye should look into the eyepiece. But many users often can"t do this. They like to cover their right eyes with their hands or simply close their right eyes. This is not in line with the observation requirements of the experiment. This bad habit will cause fatigue in the left eye, and at the same time, they can"t draw pictures while observing. The left eye should be close to the eyepiece as much as possible, and the right eye should try to gaze into the field of vision, so that repeated training can meet the requirements of both eyes open for observation at the same time. Or you can do the following exercises: open your eyes, stand between your eyes with a piece of paper or palm, in front of your nose, so that the left and right eyes can"t look at each other on the opposite side, and then consciously look at the left side, and then look at the right side, such 3 ~ 5 times, do it in the morning and evening every day, and you can learn it within one star period.

The use or operation error of microscope is a common phenomenon in use. As long as we take it seriously, consciously correct it, overcome it, and skillfully and correctly use the microscope, we can do it.