5 Considerations for Using an Optical Microscope
1. Installation problem
Before using the optical microscope, the eyepiece and objective lens of the microscope must first be installed. The installation of the eyepiece is relatively simple, but the main problem lies in the installation of the objective lens. Since the objective lens is more expensive, if the screw is not closed properly when the student installs it, it is easy to drop it on the ground and cause damage to the lens. Hold the objective lens with the index finger and middle finger of your left hand, and then install the objective lens with your right hand, so that even if it is not installed properly, it will not fall to the ground.
2. Problems with light
Aiming at the light is a very important step when using a microscope. Some students just turn an objective lens to face the light hole when they are at the light, instead of using a low-power lens to align with the light as required. I like to use one hand when turning the mirror, and it often turns the mirror down. Therefore, when teachers instruct students, they must emphasize the use of low-power mirrors to face the light. When the light is strong, use small apertures and flat mirrors, and when the light is weak, use large apertures and concave mirrors. Until a uniformly bright circular field of view. After the light is aligned, do not move the microscope casually, so as to prevent the light from entering the light hole accurately through the mirror.
3. The problem of using the quasi-focus helix correctly
Using the quasi-focus screw to adjust the focal length and finding the object image can be said to be the most important step in the use of the microscope, and it is also the most difficult step for students. Students are prone to make the following mistakes during operation:
a. Direct focus under high magnification lens;
b. Regardless of whether the lens barrel is raised or lowered, the eyes are always looking at the field of view in the eyepiece;
c. I don’t know the critical value of the object distance. When the object distance is adjusted to 2-3 cm, it is still increasing, and the speed of turning the quasi-focus spiral is very fast.
The first two kinds of error results often cause the objective lens to interfere with the mounting film and damage the mounting film or lens, while the third error is the most common phenomenon when students use the microscope.
4. The problem of objective lens conversion
After using a low magnification lens and switching to a high magnification lens, students often prefer to push and turn the objective lens directly with their fingers, thinking that this is more labor-saving, but it is easy to deflect the optical axis of the objective lens because the material of the converter is softer and the precision is higher. , the thread is uneven and easy to loosen. Once the threads are broken, the entire converter is scrapped. The teacher should instruct the students to hold the lower layer of the converter and turn the plate to convert 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 stare into the eyepiece. However, many students often fail to do this. They like to cover their right eyes with their hands or simply close their right eyes. This does not meet the observation requirements of the experiment. This bad habit will cause fatigue to the left eye, and they cannot To observe and draw pictures. While pointing out this shortcoming of the students, the teacher should demonstrate in detail, telling the students that the left eye should be as close to the eyepiece as possible, and the right eye should try to look into the field of vision. Repeated training in this way will meet the requirement of opening both eyes at the same time.
The use or operation error of the microscope is a common phenomenon in biological experiments. As long as we take it seriously, correct it consciously, overcome it, and use the microscope skillfully and correctly, it is completely possible.
