How to use a high-power microscope:

Take the mirror and place it: Hold the mirror arm with your right hand and drag the mirror holder with your left hand. Place the microscope on the experimental platform about 7 cm from the edge, slightly to the left. Install the eyepiece and objective lens.

Focusing: Turn the converter to align the low-power objective lens with the light hole (the front end of the objective lens and the stage should be kept at a distance of 5 to 10 mm). Align a larger aperture at the light hole. One eye is looking at the eyepiece, and the other eye is open. Turn the mirror to make the light reflect through the light hole into the lens barrel. Through the eyepiece, you can see the white and bright circle Vision.

Observation: Put the slide specimen to be observed on the stage and press it with the press clamp, and the specimen should be directly facing the center of the light hole. Rotate the coarse collimation screw to slowly lower the lens barrel until the objective lens is close to the slide specimen. Look inside the eyepiece with one eye, and at the same time turn the coarse collimating screw counterclockwise to make the lens barrel rise slowly until the object is seen clearly. Then turn the fine collimating screw slightly to make the image more clear.

Note for high magnification microscope: First observe with a low magnification lens, find the object image to be magnified, move it to the center of the field of view, and then replace it with a high magnification objective lens. After replacing the high magnification objective lens, the coarse collimating screw can no longer be turned, but only the fine collimating screw can be used to adjust.

High power optical microscope

1. Lens use problem

1. Cannot skillfully identify the numbers engraved on the microscope objectives of high and low magnification lenses, indicating the main performance parameters of the lens. For example, the numbers on a 10x lens are: "10/0.25" and "160/0.17". Their meanings are: "10" means the magnification; "0.25" means the lens aperture ratio; "160" means the length of the lens barrel (mm); "0.17" means the required cover glass thickness. Many students do not understand the meaning of these numbers and mistakenly think that "160" is a 160× lens. Generally speaking, low-power lenses are shorter and high-power lenses are longer. This method can be used to teach students to distinguish, which saves time and has good results.

2. When using a high-power lens, only change the eyepiece without changing the objective lens. The high-power lens usually refers to the objective lens. When using a high magnification lens, the eyepiece can be unchanged, as long as the high magnification objective lens is changed. If you used a 10× objective lens, you can now use a 40× objective lens.

3. When using a high-power lens, instead of using a low-power lens, you can directly use a high-power lens to adjust the focal length. A high-power lens has a small field of view and is relatively dark, and it is not easy to find a target, and it is relatively difficult to adjust the focus. Therefore, the correct operation of using a high-power lens is: first use a low-power lens to find the object image to be observed, then move the object image to the center of the field of view, and finally switch to a high-power lens, then adjust the fine focus screw to focus, and adjust the object image. At the same time, the iris should be adjusted to increase the amount of light.

4. When switching the lens, pushing the lens directly will often cause the optical axis to deviate or even the screw to loosen, which affects the imaging. The converter should be turned.

2. Focusing problem

1. Adjusting the focus while the objective lens is descending can easily cause the object lens to interfere with the mounting lens and damage the mounting film and the lens.

2. Excessive focus adjustment will easily wear the gears and cause tripping.

3. Coarse focusing screw for high magnification lens. When using coarse focusing screw, it is more difficult to adjust the focus of high magnification lens and reduce the operating efficiency.

Third, the problem of running out

1. The field of view is too bright. For materials with strong refractive index, the observation field of view is too bright, and the structure is often unclear, and it is very easy to cause eye fatigue, which affects the efficiency of the experiment. For example, when observing the cell structure of onion epidermis, due to the thin protoplasm layer, dark field can be used to obtain good results.

2. If the field of view is too dark, if the observation field is too dark, the image of the object will not be seen clearly, which will affect the effect. For thicker scanning electron microscope materials or darker colored materials, the amount of light should be increased. The observation field should be blue and white, and the eyes should feel comfortable.

Fourth, the problem of observation methods

1. The bad habit of opening one eye and closing one eye when observing will cause the left eye, which is often used, to be extremely fatigued, unable to look at and observe for a long time, and also unable to complete the drawing well. The corrective method is available: Keep the left eye close to the eyepiece, and try to look into the field of view for 1 to 2 minutes with the right eye. This practice several times can overcome the problem of invisible right eye when both eyes are opened at the same time, and one eye is closed.

2. The usual habit of using the right eye when observing should be: observing with the left eye, and matching the right hand with the right eye.

Common mistakes in the use of microscopes:

(1) Improper placement of the microscope prevents the operation of the microscope. The placement of the microscope is either to the front or back, or to the right, or even turn the lens barrel toward you. The microscope should be placed 125px from the edge of the table, the lens barrel forward, and the reason why the microscope position is slightly to the left should be explained (open both eyes for observation at the same time, and the eyes will not be fatigued and easy to draw.)

(2) The correct use of the reflector is often forgotten when you visit one and the other. You can’t choose a flat mirror or a concave mirror according to the intensity of the light; use a high-power lens for the light, and do not lower the position of the low-power mirror; When adjusting, the objective lens is not in place, the aperture is not adjusted properly, and the field of view is uneven and bright.

(3) Cannot quickly find the object to be observed without following concise and reasonable procedures. First use a low-power lens with a wide field of view, put the material to be observed in the center of the light hole, lower the lens barrel so that the distance between the lower end of the objective lens and the loading film is about 25px, slowly adjust the coarse collimation spiral in the counterclockwise direction, while watching the field of view with the left eye , Until you see the image clearly. If the specimen does not enter the field of view for the first time, the operation must be repeated. While adjusting the coarse focus screw, move the slide until the object image is seen. In the specific operation, the impurity or bubbles on the surface of the film can also be used as a reference. When the impurity appears, it indicates that the object distance is basically adjusted. Then move the film to find the object to be observed.

(4) The method of using the high-power objective lens is incorrect. Because the working distance of the high-power objective lens is small, some students are afraid of damaging the lens. After being a high magnification lens, it will never be found again. Therefore, in teaching, it is necessary to repeatedly emphasize to students that before using a high-power objective lens, replace the high-power eyepiece first, and then directly change the high-power objective lens, and widen the aperture.

(5) Ignore the use of the collimation screw. Some students still adjust the coarse collimation screw when using high magnification objectives. As a result, the objective lens is often damaged and the mounting is crushed.

(6) It is considered that the larger the magnification, the clearer. If the eyepiece magnification is too large, the enlarged virtual image obtained will be very unclear. Therefore, explain to students that the objects that can be seen clearly under a low power lens do not need to be observed with a scanning electron microscope.

(7) Ignore the maintenance of the microscope The microscope is a precise magnifying instrument, and students should be educated to take care of the microscope. Handle with care. Do not wipe the lens with your hands or cloth. When using tilt joints, the tilt angle must not be too large. After the experiment, close the lens cover, remove the glass slide on the stage, turn the converter to separate the two objective lenses on both sides, lower the lens barrel, and put it into the lens box.