Optical Microscope Dimming Procedure
An optical microscope is a precision optical instrument. The currently used microscope is matched with a set of lenses, so different magnifications can be selected to magnify and observe the fine structure of the object. Ordinary optical microscopes can usually magnify objects by 1500 to 2000 times (the maximum resolution is 0.2 μm).
(1) Eyepiece
It usually consists of two sets of lenses, the upper set is also called "eyepiece", and the lower set is called "field lens". A field diaphragm (metal ring device) is installed between the two or below the field lens, and the intermediate image enlarged by the objective lens falls on the plane of the field diaphragm, so an eyepiece micrometer can be added on it. The magnification is engraved on the top of the eyepiece, such as 10×, 20×, etc. According to the size of the field of view, eyepieces can be divided into ordinary eyepieces and wide-angle eyepieces. Some microscope eyepieces are also equipped with a diopter adjustment mechanism, and the operator can adjust the diopter for the left and right eyes respectively. Another camera eyepiece (NFK) can be used for shooting.
(2) Objective lens
Composed of an array of lenses, installed on the converter, also known as the objective lens. Usually each microscope is equipped with a set of objective lenses with different magnifications, including:
①Low magnification objective lens: refers to 1×～6×;
②Medium magnification objective lens: refers to 6×～25×;
③High magnification objective lens: refers to 25×～63×;
④Oil immersion objective lens: refers to 90×～100×.
Among them, when the oil immersion objective lens is used, it needs to fill the liquid with a refractive index of about 1.5 (such as cedar oil, etc.) between the lower surface of the objective lens and the upper surface of the cover glass, which can significantly improve the resolution of microscopic observation. Other objectives were used directly. During the observation process, the selection of objective lenses generally follows the order from low to high, because the field of view of the low-power lens is large, and it is easy to find the specific part to be inspected. The magnification of a microscope can be roughly regarded as the product of the magnification of the eyepiece and the magnification of the objective lens.
(3) Concentrator
Composed of a condenser lens and an iridescent aperture, it is located under the stage. The function of the condenser lens is to focus the light in the field of view; the iridescent aperture under the lens group can be opened or closed to control the light transmission range of the condenser, adjust the light intensity, and affect the imaging resolution and contrast. When using, it should be adjusted according to the purpose of observation and the intensity of the light source to obtain the best imaging effect.
(4) Light source
The earlier ordinary optical microscope used the reflector on the mirror base to reflect natural light or light to the center of the condenser lens as a light source for microscope inspection. Reflectors are composed of a mirror with a flat surface and another concave surface. Use a concave mirror when no concentrator is used or when the light is strong, and the concave mirror can play the role of converging light; when a concentrator is used or the light is weak, a plane mirror is generally used. The newly produced microscopes generally install the light source directly on the mirror base, and have a current adjustment screw for adjusting the light intensity. The light source types include halogen lamps, tungsten lamps, mercury lamps, fluorescent lamps, metal halide lamps, etc.
There are two types of light source illumination methods for microscopes: transmission type and reflection (episode) type. The former refers to the light source passing through the transparent microscope object from bottom to top; the reflection microscope uses the top of the objective lens to illuminate (epi-illumination) opaque objects.
2
Mechanical part
Including mirror base, mirror column, mirror wall, mirror barrel, nosepiece converter, stage and collimating helix, etc.
(1) mirror holder
The base part is used to support the stability of the whole microscope.
(2) mirror column
The upright short column between the mirror base and the mirror arm plays the role of connection and support.
(3) mirror arm
The bow-shaped part at the back of the microscope is the part to hold when moving the microscope. Some microscopes have a movable tilt joint between the mirror arm and the mirror column, which can adjust the backward tilt angle of the mirror barrel for easy observation.
(4) lens barrel
The cylindrical structure installed at the tip of the mirror arm connects the eyepiece on the top and the objective lens converter on the bottom. The international standard barrel length of the microscope is 160 mm, and this number is marked on the casing of the objective lens.
(5) Objective lens changer
The freely rotatable disc at the lower end of the lens barrel is used to install the objective lens. During observation, the objective lens with different magnifications can be exchanged by turning the converter.
(6) Stage
There is a circular light hole in the center of the platform below the lens barrel. For placing slides. The stage is equipped with a spring clamp to fix the specimen, and there is a pusher on one side to move the position of the specimen. Some pushers are also equipped with scales, which can directly calculate the distance moved by the specimen and determine the position of the specimen.
(7) Quasi-focus helix
There are two types of screw, large and small, mounted on the mirror arm or mirror column. When rotating, the mirror barrel or stage can move up and down, thereby adjusting the focal length of the imaging system. The large one is called the coarse quasi-focus spiral, and the lens barrel rises and falls by 10mm every time it rotates; the small one is the fine quasi-focus spiral, and the lens barrel only rises and falls by 0.1mm after one turn. Generally, when observing an object under a low magnification lens, quickly adjust the object image with a coarse quasi-focus spiral so that it is in the field of view. On this basis, or when using a high-power lens, fine-tune with the fine-focus screw. It must be noted that the general microscope is equipped with left and right alignment spirals, which have the same function, but do not rotate the spirals on both sides at the same time, to prevent torsion due to uneven strength of both hands, resulting in spiral slippage.
An optical microscope is a precision optical instrument. The currently used microscope is matched with a set of lenses, so different magnifications can be selected to magnify and observe the fine structure of the object. Ordinary optical microscopes can usually magnify objects by 1500 to 2000 times (the maximum resolution is 0.2 μm).
(1) Eyepiece
the
It usually consists of two sets of lenses, the upper set is also called the "eyepiece" and the lower one is called the "field lens". A field diaphragm (metal ring device) is installed between the two or below the field lens, and the intermediate image enlarged by the objective lens falls on the plane of the field diaphragm, so an eyepiece micrometer can be added on it. The magnification is engraved on the top of the eyepiece, such as 10×, 20×, etc. According to the size of the field of view, eyepieces can be divided into ordinary eyepieces and wide-angle eyepieces. Some microscope eyepieces are also equipped with a diopter adjustment mechanism, and the operator can adjust the diopter for the left and right eyes respectively. Another camera eyepiece (NFK) can be used for shooting.
(2) Objective lens
It consists of an array of lenses and is installed on the converter, also known as the objective lens. Usually each microscope is equipped with a set of objective lenses with different magnifications, including:
①Low magnification objective lens: refers to 1×～6×;
②Medium magnification objective lens: refers to 6×～25×;
③High magnification objective lens: refers to 25×～63×;
④Oil immersion objective lens: refers to 90×～100×.
When the oil immersion objective lens is used, it is necessary to fill the liquid with a refractive index of about 1.5 (such as cedar oil, etc.) between the lower surface of the objective lens and the upper surface of the cover glass, which can significantly improve the resolution of microscopic observation. Other objectives were used directly. During the observation process, the selection of objective lenses generally follows the order from low to high, because the field of view of the low-power lens is large, and it is easy to find the specific part to be inspected. The magnification of a microscope can be roughly regarded as the product of the magnification of the eyepiece and the magnification of the objective lens.
(3) Concentrator
It consists of a condenser lens and an iridescent aperture, located under the stage. The function of the condenser lens is to focus the light in the field of view; the iridescent aperture under the lens group can be opened or closed to control the light transmission range of the condenser, adjust the light intensity, and affect the imaging resolution and contrast. When using, it should be adjusted according to the purpose of observation and the intensity of the light source to obtain the best imaging effect.
(4) Light source
The earlier ordinary optical microscope used the reflector on the mirror base to reflect natural light or light to the center of the condenser lens as a light source for mirror inspection. Reflectors are composed of a mirror with a flat surface and another concave surface. Use a concave mirror when no concentrator is used or when the light is strong, and the concave mirror can play the role of converging light; when a concentrator is used or the light is weak, a plane mirror is generally used. The newly produced microscopes generally install the light source directly on the mirror base, and have a current adjustment screw for adjusting the light intensity. The light source types include halogen lamps, tungsten lamps, mercury lamps, fluorescent lamps, metal halide lamps, etc.
There are two types of light source illumination methods for microscopes: transmission type and reflection (episode) type. The former refers to the light source passing through the transparent microscope object from bottom to top; the reflection microscope uses the top of the objective lens to illuminate (epi-illumination) opaque objects.
2
Mechanical part
Including mirror base, mirror column, mirror wall, mirror barrel, nosepiece converter, stage and collimating helix etc.
(1) mirror holder
The base part is used to support the stability of the whole microscope.
(2) mirror column
the
The upright short column between the mirror base and the mirror arm plays the role of connection and support.
(3) mirror arm
The bow-shaped part at the back of the microscope is the part to hold when moving the microscope. Some microscopes have a movable tilt joint between the mirror arm and the mirror column, which can adjust the backward tilt angle of the mirror barrel for easy observation.
(4) lens barrel
The cylindrical structure installed at the tip of the mirror arm connects the eyepiece on the top and the objective lens converter on the bottom. The international standard barrel length of the microscope is 160 mm, and this number is marked on the casing of the objective lens.
(5) Objective lens changer
The freely rotatable disc at the lower end of the lens barrel is used to mount the objective lens. During observation, the objective lens with different magnifications can be exchanged by turning the converter.
(6) Stage
The platform below the lens barrel has a circular light hole in the center. For placing slides. The stage is equipped with a spring clamp to fix the specimen, and there is a pusher on one side to move the position of the specimen. Some pushers are also equipped with scales, which can directly calculate the distance moved by the specimen and determine the position of the specimen.
(7) Quasi-focus spiral
There are two large and small spirals installed on the mirror arm or mirror column, which can move the mirror barrel or stage up and down when rotating, thereby adjusting the focal length of the imaging system. The large one is called the coarse quasi-focus spiral, and the lens barrel rises and falls by 10mm every time it rotates; the small one is the fine quasi-focus spiral, and the lens barrel only rises and falls by 0.1mm after one turn. Generally, when observing an object under a low magnification lens, quickly adjust the object image with a coarse quasi-focus spiral so that it is in the field of view. On this basis, or when using a high-power lens, fine-tune with the fine-focus screw. It must be noted that the general microscope is equipped with left and right alignment spirals, which have the same function, but do not rotate the spirals on both sides at the same time, to prevent torsion due to uneven strength of both hands, resulting in spiral slippage.
