The use, principle and matters needing attention of microscope

Microscope can be divided into optical microscope, electron microscope and digital microscope according to microscopic principle.

optical microscope

Usually consists of optical part, lighting part and mechanical part. There is no doubt that the optical part is the most critical, consisting of eyepiece and objective lens. As early as 1590, glasses manufacturers in the Netherlands and Italy have made magnifying instruments similar to microscopes. There are many kinds of optical microscopes, mainly including bright-field microscope (ordinary optical microscope), dark-field microscope, fluorescence microscope, phase contrast microscope, laser scanning focusing microscope, polarizing microscope, differential interference difference microscope, inverted microscope and so on.

electron microscope

The electron microscope has similar basic structural characteristics to the optical microscope, but it has much higher magnification and resolution than the optical microscope. It uses electron flow as a new light source to image objects. Since ruska invented the first transmission electron microscope in 1938, many other types of electron microscopes have been developed besides the continuous improvement of transmission electron microscope itself. Such as scanning electron microscope, analytical electron microscope, ultra-high pressure electron microscope, etc. Combined with various electron microscope sample preparation techniques, we can study the structure of samples or the relationship between structure and function in many aspects. Microscopes are used to observe images of tiny objects. It is often used in biology, medicine and observation of tiny particles. An electron microscope can magnify an object 2 million times.

Desktop microscope, mainly refers to traditional microscope, is pure optical magnification, with high magnification and good imaging quality, but it is generally large and inconvenient to move, and is mostly used in laboratories, which is not convenient for going out or on-site detection.

How to use a microscope:

When using natural light source for microscopic examination, it is best to use a light source facing north instead of direct sunlight; When using artificial light source, fluorescent light source should be used.

During microscopic examination, the body should face the practice table, adopt a correct posture, open your eyes naturally, observe the specimen with your left eye, record and draw with your right eye, and adjust the focal length with your left hand to make the object image clear and move the visual field of the specimen. Right-handed recording and drawing.

During microscope inspection, the stage should not be tilted, because when the stage is tilted, liquid or oil will easily flow out, which will not only damage the specimen, but also pollute the stage and affect the inspection results.

During microscopic examination, the visual field of the specimen should be moved in a certain direction until the whole specimen is observed to avoid omission or repetition.

The heavy light of microscope is the conversion of light and objective lens and the adjustment of light. When observing parasite specimens, light regulation is very important. Because the observed specimens, such as eggs and cysts, are all objects under natural light, some are large, some are small, some are in shades of color, some are colorless and transparent, and the low-power and high-power objective lenses change a lot, so it is necessary to adjust the focal length and light at any time according to different specimens and requirements during microscopic examination to make the observed objects clear. In general, the light of dyed specimens is stronger, and the light of colorless or undyed specimens is weaker; The light observed by a low-power lens is weaker, while the light observed by a high-power lens is stronger.

Precautions:

(1) Before using the microscope, you should be familiar with the names of various parts of the microscope and how to use them, especially to identify the characteristics of three kinds of objective lenses.

(2) Most specimens observed in parasitology practice are colorless and light-colored, so we must pay attention to the adjustment of light.

(3) When observing fresh specimens, cover glass should be added to avoid drying deformation or pollution erosion of the objective lens due to evaporation. At the same time, it can make the surface of the specimen flat and the light concentrated, which is beneficial to observation.