A few notes on the correct use of optical microscopes
I. The problem of correct installation
Before using the microscope, the first thing to do is to install the eyepiece and objective lens of the microscope. Eyepiece installation is extremely simple, the main problem lies in the installation of the objective lens, due to the objective lens lens is more expensive, in case the students installed thread did not close well, easy to fall to the ground, resulting in damage to the lens, so in order to insure that the students install the objective lens with the left index finger and middle finger to support the objective lens, and then use the right hand will be the objective lens up, so that even if it is not installed well, it will not fall to the ground.
Problems of correctly aligning the light
Light is a very important step in the use of microscopes, some students in the light, casually turn an objective lens to the through-hole, rather than according to the requirements of the light must be a low magnification mirror. When turning the reflector, they like to use one hand, often wrenching the reflector down. So the teacher in the guidance of the students, must emphasise the use of low magnification to the light, when the light is strong with a small aperture, plane mirror, and when the light is weak with a large aperture, concave mirror, the reflector to use both hands to rotate, when you see a uniformly bright round field of view until. Don't move the microscope casually after the light is right, so that the light can't accurately pass through the reflector into the light-through hole.
Third, the correct use of the focusing screw
The use of the focusing screw to adjust the focus and find the object can be said to be an important step in the use of microscopes, but also students feel that the * difficult step. Students are very likely to make the following mistakes in the operation: first, directly adjusting the focus at high magnification.
Secondly, regardless of the rise or fall of the barrel, the eyes are always in the eyepiece to see the field of view; thirdly, do not understand the critical value of the object distance, the object distance is adjusted to 2 ~ 3 cm and still adjusting upward.
3cm is still adjusted upwards, and the speed of turning the focusing screw is very fast. The first two errors often result in the objective lens against the mount, damage to the mount or lens, while the third error is a common phenomenon when students use microscopes. In response to the above errors, the teacher must emphasise to the students, adjust the focus must be adjusted at low magnification, first turn the coarse focusing spiral, so that the barrel of the microscope slowly down, the objective lens close to the slide, but be careful not to let the objective lens to touch the slide, in the process of the eyes from the side of the objective lens, and then use the left eye towards the eyepiece to gaze at the eyepiece, and slowly reverse the adjustment of the coarse focusing spiral, the barrel of the microscope to slowly rise until the object is seen until the object image, and so on. At the same time, explain to the students that the general microscope object distance in 1 cm or so, so if the object distance is far more than 1 cm, but still do not see the object image, it may be that the specimen is not in the field of view or turn the coarse focusing spiral too fast, at this time should be adjusted to the position of the mount, and then repeat the above steps, when there is a fuzzy image in the field of view, it is necessary to switch to the fine focusing spiral adjustments, only in this way can we narrow down the scope of the search to improve the speed of finding the object image. The speed of finding the object.
Problems of Objective Lens Conversion
The use of low-magnification mirror for high-magnification mirror, students often like to use their fingers to directly push the objective lens, that this is more energy-saving, but this is easy to make the optical axis of the objective lens skewed, the reason is that the converter of the material texture of the softer, more accurate, uneven threads are easy to loosen the force. Once the threads are damaged, the entire converter will be scrapped. Teachers should instruct students to hold the lower rotary spanner of the converter to convert the objective lens.
