How to use the objective lens and focus of the microscope well
When using a microscope, adopt the focusing principle of low magnification first and then high magnification. Focusing under low magnification objective lens is equivalent to doing preliminary focus adjustment for high magnification objective lens. The focal length is preliminarily adjusted through the operation of the low magnification lens), and the tissue can be observed under the high magnification lens only with slight adjustment or even without adjustment. However, the specific meaning of "low-magnification objective lens" is avoided in many operating instructions.
During the use of the microscope, the 10x objective lens is the standard common objective lens in focusing work. The reason is that changing from a 10x objective lens to a lower magnification objective lens, or from a 10x objective lens to a higher magnification objective lens, will not change drastically. Another reason is that the focal depth of the lower magnification objective lens is long, and the naked eye vision of the observer is not easy to focus well, and the contact between the sample and the lens is easy to occur when directly converting to the high magnification objective lens.
At the same time, the 10x objective lens is not only a standard common objective lens in focusing work, but also involves a lot in actual work. For example, in many relevant national standards for metallographic inspection, it is the most common to compare the reference standard spectrum under the 100X observation condition, and the 100X acquisition is obtained by combining a 10X objective lens with a 10X eyepiece. From the actual operation, as long as it is not random or malicious, the previous operation should be to make the objective lens near the focal plane. Under the condition of 10x objective lens, after the sample is placed correctly, there should be a blurred image, or even a relatively clear, slightly Just adjust the fine-tuning.
⑵About entry and exit
There is a big difference between our experience and the introduction in other literatures on the problem of focusing after the conversion of low-magnification objective lens to high-magnification objective lens. Due to the improvement of the current microscope manufacturing process, the parfocal performance of different objective lenses of the microscope is relatively good, especially for foreign products. In this way, after the low-power focus is clear, when switching to high-power observation, sometimes the image is already clear without refocusing; or, Just slightly increase the object distance, and the degree of adjustment is definitely not the concept of 1 to 3 turns, that is, the concept of 1 to 3 degrees (angle), an extremely small adjustment amount.
⑶About the nosepiece
When changing the objective lens, do not push the objective lens directly by hand, otherwise, the screw thread fixing the objective lens may become loose and slippery, and the optical axis may be skewed. The objective lens of the microscope and the microscopic digital camera system are screwed on the objective lens converter. When changing different objective lenses, rotate the objective lens converter until the ear hears a slight "click" sound and the resistance increases sharply. At this time, the objective lens is in the normal working position: perpendicular to the plane of the stage.
⑷The relationship between "forward and reverse" and "object distance"
The rotation direction of the coarse adjustment and fine adjustment knobs of the microscope is closely related to the increase and decrease of the object distance. The so-called clockwise and counterclockwise are also relative. Generally, the effect is seen from the right side of the microscope; different types of microscopes require different rotation directions of the focus knob when the object distance is reduced or increased. clearly stated in the guidance process. In the case of ambiguity, the relationship between the focus knob and the object distance must be understood in advance when officially operating the microscope; never blindly follow certain instructions for clockwise and counterclockwise special occasions.
