Explanation of common usage problems of student microscopes
Problems with the use of student microscope lenses
When using a high-power lens, the focus can be adjusted directly with a high-power lens without first using a low-power lens. The field of view of a high-power lens is small and relatively dark, and it is difficult to find the target, making focusing relatively difficult. So, the correct operation to use a high-power lens is to first use a low-power lens to find the object to be observed, then move the object to the center of the field of view, and then switch to a high-power lens. Then, adjust the fine focusing spiral to focus and clear the object image. At the same time, adjust the aperture to increase the luminous flux.
2. Unable to proficiently recognize the numbers engraved on the objective lens of a high and low magnification microscope, indicating the main performance parameters of the lens. For example, the numbers on a 10x lens include "10/0.25" and "160/0.17". Their meaning is: "10" represents magnification; 0.25 "represents the aperture rate; 160 "is the length of the lens tube (mm); 0.17 "is the required thickness of the cover glass. Many students cannot understand the meaning of these numbers and mistakenly believe that '160' is 160 × Lens. Generally speaking, low magnification lenses are shorter and high magnification lenses are longer. This method can be used to teach students to distinguish, which is both time-saving and effective.
When using a high-power lens, only changing the eyepiece without changing the objective lens usually refers to a high-power objective lens. When using a high-power lens, the eyepiece can remain unchanged, as long as the high-power objective is converted. As before, using 10 × Objective lens, now using 40 × An objective lens is sufficient.
When switching lenses, directly pushing the lens often causes deviation of the optical axis or even loosening of screws, which affects imaging. The converter should be rotated.
The Problem of Focusing Students' Microscopes
1. Focusing in the process of lowering the objective lens can easily cause the object lens to collide with the mounting and damage the mounting and lens.
2. Focusing with excessive force can easily wear the gears and cause tripping.
3. When using a coarse focusing spiral for high magnification mirrors, it is difficult to simply focus the high magnification mirror and reduce operational efficiency.
The issue of using light for students' microscopes
1. For materials with strong refractive index, if the field of view is too bright, it often makes it difficult to see the structure clearly, which can easily cause eye fatigue and affect experimental efficiency. When observing the structure of onion epidermal cells, due to the thin protoplast layer, a dark field should be used to achieve good results.
2. If the field of view is too dark, it can also make it difficult to see the object clearly, affecting the effect. For thicker materials or darker colored materials, the luminous flux should be increased. The observation field of view should be blue and white, and the eyes should feel comfortable. Summary: In the process of cultivating students to use student microscopes, good usage habits should be gradually formed according to good methods, so as to achieve both convenience and simplicity in daily experimental learning.
