What is a Compound Light Microscope?

Optical microscope (English Optical Microscope, abbreviated as OM) is an optical instrument that uses the principle of optics to enlarge and image tiny objects that cannot be distinguished by the human eye, so that people can extract microstructure information.

Optical microscope

Optical microscope (English Optical Microscope, abbreviated as OM) is an optical instrument that uses the principle of optics to enlarge and image tiny objects that cannot be distinguished by the human eye, so that people can extract microstructure information.

Chinese name

Optical microscope

Foreign name

Optical Microscope

Principle

Optical principle

Purpose

For people to extract microstructure information

The microscope is a

As early as the first century BC, people have discovered that when observing small objects through spherical transparent objects, they can be enlarged and imaged. Sphere

The microscope uses the principle of magnification of convex lenses to enlarge small objects that cannot be distinguished by the human eye to a size that can be resolved by the human eye. It is mainly to increase the opening angle of nearby small objects to the eye (objects with large viewing angles are larger on the retina). ), Their magnification ability is expressed by the angular magnification M. Because the opening angle of the same object to the eye is related to the distance of the object from the eye, the distance between the image and the eye is generally specified as 25 cm (

With the development of modern biotechnology and the increase of people's requirements for microscopes, a single optical microscopy imaging system is far from meeting people's microphotographs.

There are many ways to classify light microscopes

Adjustment of lighting light path system

In order for the microscope's field of view to be uniformly and sufficiently illuminated, the illumination light path system must be adjusted when the microscope is first installed and debugged. This is an important means and the most basic to use the microscope correctly and obtain correct and reliable results Requirements. In addition, correctly grasping the adjustment of the illumination light path system is a necessary step after replacing the light source bulb in the process of using the microscope, and it is also a necessary means to check the performance of the microscope from time to time during daily use. The adjustment of the microscope illumination light path system mainly includes the following 4 items:

1. Preliminary adjustment of the light source lamp room outside the microscope

First open the housing of the lamp room.

(1) During the experiment, the microscope should be placed slightly to the left on the table, and the lens holder should be about 6 to 7 cm from the edge of the table.

(2) Turn on the light source switch and adjust the light intensity to a suitable level.

(3) Turn the objective lens converter so that the low-power lens faces the light-passing hole on the stage. First adjust the lens to about 1-2cm away from the stage, then look into the eyepiece with your left eye, then adjust the height of the condenser, adjust the aperture stop to the maximum, and let the light enter the lens barrel through the condenser Inside, the field of vision is now bright.

(4) Place the slide to be observed on the stage so that the part under observation is located in the center of the clear hole, and then clamp the slide with a specimen holder.

(5) Observe with low-power lens first (objective lens 10X, eyepiece 10x). Before observing, first turn the coarse focus focusing handwheel so that

(1) Must be proficient in and strictly implement the use rules, operate the microscope in accordance with strict procedures and instructions.

(2) Be sure to hold the curved arm with one hand and support the base with the other hand when removing the microscope. The microscope cannot be tilted to prevent the eyepiece from sliding out of the upper end of the lens barrel. Handle the microscope with care.

(3) During observation, the position of the microscope cannot be moved at will.

(4) All the optical parts of the microscope can only be wiped with special lens-wiping paper, and can not be wiped with other things, or touch the lens with fingers, so as not to stain the lens with sweat.

(5) Keep the microscope dry and clean to avoid contamination by dust, water and chemical reagents.

(6) When changing the objective lens, do not carry the animal lens, only rotate the converter.

(7) Do not turn the focusing handwheel at will. When using the micro-focusing knob, use light force and slow rotation, and do not turn hard when you cannot turn.

(8) Do not arbitrarily disassemble the parts on the microscope, and it is strictly forbidden to disassemble the objective lens arbitrarily, so as not to damage the screw of the converter, or to make the low and high magnification objective lens out of focus after the screw is loose.

(9) When using a high magnification objective lens, do not use the coarse focus adjustment handwheel to adjust the focal length, otherwise the moving distance will be too large, which will damage the objective lens and the glass.

(10) Before returning it, you must check whether the objective lens is contaminated with water or reagents. If it is, wipe it off, and wipe the stage clean, then put the microscope in the box, and pay attention to the lock box.

(11) It is best to keep the microscope in a dry and clean environment to avoid dust and chemical contamination.

First, the problem of correct installation

Before using the microscope, you must first install the eyepiece and objective lens of the microscope. The installation of the eyepiece is extremely simple. The main problem is the installation of the objective lens. Because the objective lens is more expensive, in case the screw is not properly closed when the student is installed, it is easy to fall to the ground and cause the lens to be damaged. Hold the objective lens with your index finger in your left hand and the middle finger, and then mount the objective lens with your right hand so that you will not fall to the ground even if it is not installed properly.

Second, the problem of correct light

Aligning the light is an important step when using a microscope. Some students will randomly turn an objective lens toward the clear hole when aligning the light, instead of using a low-power lens to align the light as required. I like to use one hand when turning the mirror, and often pull the mirror down. Therefore, when instructing students, teachers must emphasize the use of low-power mirrors for light. When the light is strong, use a small aperture and a flat mirror, and when the light is weak, use a large aperture, a concave mirror, and a mirror with both hands. To a uniform and 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 clear aperture through the reflector accurately.

Third, the correct use of quasi-focus helix

Using the quasi-focus helix to adjust the focal length and find the object image can be said to be the most important step in the use of the microscope, but also the most difficult step for students. Students are prone to the following errors during operation: one is to focus directly under a high-power lens; the other is that the eye always looks in the eyepiece field of view regardless of the lens barrel rising or falling; the third is not knowing the critical value of the object distance and the object distance adjustment Up to 2 to 3 cm, it is still adjusted upward, and the speed of turning the quasi-focusing spiral is very fast. The first two types of error results often cause the objective lens to interfere with the mounting film and damage the mounting film or the lens, while the third error is the most common phenomenon when students use the microscope. In response to the above errors, the teacher must emphasize to the students that the focal length must be adjusted under a low magnification lens. First, turn the coarse quasi-focus helix to slowly lower the lens barrel and the objective lens close to the glass slide, but be careful not to let the objective lens touch the glass slide. In this process, the eye should look at the objective lens from the side, then use the left eye to look inside the eyepiece, and slowly adjust the coarse focus focus spiral in reverse, so that the lens barrel slowly rises until the object image is seen, and at the same time to the student This shows that the object distance of a general microscope is about 1 cm, so if the object distance is far more than 1 cm, but the object image is still not seen, it may be that the specimen is not in the field of view or the coarse quasi-focus helix is rotated too fast. Loading position, and then repeat the above steps, when blurry objects appear in the field of vision, you must use the fine quasi-focus helix adjustment, only in this way can narrow the search range and increase the speed of finding objects.

Fourth, the problem of objective lens conversion

After using a low-power lens and switching to a high-power lens, students often like to push the objective lens directly with their fingers, which is considered to be more labor-saving, but this will easily skew the optical axis of the objective lens because the material of the converter is softer and has higher accuracy , Uneven threads are easily loosened. Once the thread is broken, the entire converter is scrapped. Teachers should instruct students to turn the conversion objective by holding the lower part of the converter.

Five, the problem of optical glass cleaning

Optical glass is used for the lens, prism, lens, etc. of the instrument. It is easy to be stained with oil, water wet dirt, fingerprints, etc. during manufacture and use, which affects imaging and light transmittance. According to the characteristics of dirt, different structures, different cleaning agents, different cleaning tools, and different cleaning methods should be used to clean optical glass. Lenses with antireflection coatings, such as those of cameras, slide projectors, and microscopes, can be cleaned with about 20% alcohol and about 80% ether in a cleaning agent. When cleaning, use a soft brush or a cotton ball with a small amount of cleaning agent to make a circular motion from the center of the lens outwards. Do not immerse such lenses in the cleaning agent to clean them. Do not wipe hard when cleaning the lens, otherwise the AR coating will be damaged and the lens will be damaged.

The method of cleaning prisms and plane mirrors can be performed according to the method of cleaning lenses.

The above-mentioned cleaning agent can also be used to clean grease mist, water-moisture mist, and oil-water mixed mist on the optical glass. The cleaning method is similar to the method of cleaning the lens.

Mold on the surface of optical glass is a common phenomenon. When the optical glass is moldy, light is scattered on its surface, making the imaging blurry. In severe cases, the instrument will be scrapped. Most of the causes of mold growth of optical glass are microbial spores attached to the surface. When the temperature and humidity are suitable and the required "nutrients" are available, they will grow rapidly and form mold spots. It is especially important to prevent mildew and stain on the optical glass, and it should be cleaned immediately if mildew is generated. Pay attention to drying.