Analysis of Basic Principles and Characteristics of Polar Microscopes in China
First, the characteristics of polarized light microscope <br> Polarized light microscopy is a microscope to identify the optical properties of the fine structure of matter. Any substance with birefringence can be clearly distinguished under a polarizing microscope. Of course, these substances can also be observed by dyeing, but some are impossible, and a polarizing microscope must be used.
The characteristic of a polarizing microscope is to change the ordinary light into polarized light for microscopic examination to identify whether a substance is monorefractory (isotropic) or birefringent (anisotropic).
Birefringence is a fundamental feature of crystals. Therefore, polarized light microscopes are widely used in the fields of minerals, chemistry, and the like. In biology, many structures also have birefringence, which requires differentiation using a polarizing microscope. In botany, such as identification of fibers, chromosomes, spindles, starch granules, cell walls, and whether cells and tissues contain crystals. In plant pathology, the invasion of pathogens often causes changes in the chemical properties of tissues, which can be identified by polarized light microscopy. In human and zoology, polarized light microscopy is often used to identify epiphyses, teeth, cholesterol, nerve fibers, tumor cells, striated muscles and hair.
Second, the basic principle of polarized light microscopy (1) single refraction and birefringence: when light passes through a substance, such as the nature of light and the way the light does not change due to the direction of illumination, this substance has optical Same-sex", also known as single-refractors, such as ordinary gases, liquids, and amorphous solids; if light passes through another substance, the speed, refractive index, absorbency, and vibration, amplitude, etc. of the light are due to the direction of illumination. Differently, this substance is optically "anisotropic", also known as birefringent, such as crystals, fibers, and the like.
(2) Polarization of light: Light waves can be classified into natural light and polarized light according to the characteristics of vibration. The vibration characteristic of natural light is that there are many vibration planes on the vertical light wave transmission axis, the amplitude of the vibration on each plane is the same, and the frequency is the same; the natural light can be vibrated in only one direction by reflection, refraction, birefringence and absorption. Light waves, which are called "polarized light" or "polarized light."
The simplest is linearly polarized light that vibrates only in a straight line. When the light enters the birefringent body, it is divided into A and B linear plane polarized lights as shown in the figure. The vibration directions of the two are perpendicular to each other, and the speed, refractive index and wavelength are different.
(3) The generation and effect of polarized light: The most important components of polarized light microscopes are polarizing devices - polarizers and analyzers. In the past, both were made of Nicola prisms, which were made of natural calcite. However, due to the large size of the crystal, it is difficult to obtain a large area of ​​polarization. Recently, polarized microscopes use artificial polarizers. To replace the Nicole shuttle.
The artificial polarizer is made of crystals of quinoline sulfate, also known as Herapathite, which is green olive. When ordinary light passes through it, linearly polarized light that vibrates only in a straight line can be obtained.
The polarizing microscope has two polarizers, one called “polarizer†between the light source and the object to be inspected; the other device is called “analyzer†between the objective lens and the eyepiece, and the handle extends into the lens barrel or the middle. The outside of the attachment is operated for a scale with a rotation angle.
When the light emitted from the light source passes through the two polarizers, if the vibration directions of the polarizer and the analyzer are parallel to each other, that is, in the case of "parallel detection and deviation", the field of view is the brightest. Conversely, if the two are perpendicular to each other, that is, in the case of "orthogonal misalignment," the field of view is completely dark, and if the two are tilted, the field of view indicates a moderate degree of brightness. It can be seen that the linearly polarized light formed by the polarizer can pass completely if its vibration direction is parallel to the vibration direction of the analyzer; if it is skewed, it passes only a part; if it is vertical, it cannot pass at all.
Therefore, in the case of using a polarized light microscope, in principle, the polarizer and the analyzer are in a state of being orthogonally detected.
The vibration characteristics of natural light and polarized light The polarization of the birefringent and the light (4) The birefringence under the quadrature detection: In the case of orthogonality, the field of view is dark, if the object under inspection is optically Isotropic (single refractor), no matter how the stage is rotated, the field of view is still dark, because the direction of vibration of the linearly polarized light formed by the polarizer does not change, still with the vibration direction of the analyzer Vertical sake. If the object to be inspected contains a birefringent substance, this part will emit light. This is because the linearly polarized light emitted from the polarizer enters the birefringent body, and two kinds of linearly polarized light whose vibration directions are perpendicular to each other are generated. When the two kinds of light pass through the analyzer, they can see the bright image because they are perpendicular to each other and more or less transparent to the analyzer. When the light passes through the birefringent body, the vibration directions of the two polarized lights are different depending on the type of the object.
Schematic diagram of parallel detection (A) and quadrature detection (B). In the case of orthogonality, when the stage is rotated, the image of the birefractor changes four times in the 360° rotation. Darken every 90°. The darkened position is the position where the two vibration directions of the birefringent body coincide with the vibration directions of the two polarizers, and the "extinction position" is rotated by 45° from the extinction position, and the object to be inspected becomes the brightest, which is " Diagonal position", because when the polarized light reaches the object when it deviates from 45°, part of the light is decomposed and can pass through the analyzer, so it is bright. According to the above basic principle, it is possible to judge isotropic (single-refractive) and anisotropic (birefringent) substances by using polarized light microscopy.
Birefringent under quadrature detection (5) Interference color: In the case of quadrature detection, the birefringence is observed by using mixed light of different wavelengths as the light source. When rotating the stage, in the field of view Not only the brightest diagonal position, but also the color. The reason for the appearance of color is mainly caused by the interference color (of course, the object to be inspected is not colorless and transparent). The distribution characteristics of the interference color are determined by the type of the birefringer and its thickness, which is due to the corresponding delay in the dependence of the wavelength of the light of different colors. If the delay of one region of the object to be inspected is different from the delay of the other region, then The color of the light passing through the analyzer is different.
Third, some requirements of the polarizing microscope on the device (a) light source: preferably using monochromatic light, because the speed of light, refractive index, absorption and interference phenomena vary due to different wavelengths. General light can be used for general microscopy.
(2) Stage: For the round shape, use a stage that can adjust the center and the edge is angled (360°) to rotate.
(C) and mirror: should use the achromatic target, because the apochromatic and semi-apochromatic objectives themselves often polarized.
(4) Eyepiece: It must have a crosshair mirror.
(5) Condenser: In order to obtain parallel polarized light, a shake-out condenser that can push out the upper lens should be used.
(6) Compensation film: When performing fine polarizing microscopy, it is necessary to use compensation tablets, such as gypsum, mica and quartz compensation tablets.
Fourth, the requirements of polarized light microscopy (1) the optical axis and the light passing center of the stage must be in a straight line, otherwise the object to be inspected will deviate from the center of the field of view when moving the object, and even move to the field of view, and Affect the microscopic examination.
(2) Both the polarizer and the analyzer are marked with the sign of the vibration direction. When in the orthogonal state, it is customary to make the vibration direction of the polarizer coincide with the horizontal line of the crosshair in the eyepiece, and the analyzer The direction of vibration is the same as the vertical line of the crosshair.
(3) The film should not be too thin, otherwise the weak birefringence will easily disappear. At the same time, it should be observed in a fresh state (otherwise, the birefringence is often strengthened or disappeared due to the treatment of steps such as fixation and dyeing), and then observed.
First, the characteristics of polarized light microscope <br> Polarized light microscopy is a microscope to identify the optical properties of the fine structure of matter. Any substance with birefringence can be clearly distinguished under a polarizing microscope. Of course, these substances can also be observed by dyeing, but some are impossible, and a polarizing microscope must be used.
The characteristic of a polarizing microscope is to change the ordinary light into polarized light for microscopic examination to identify whether a substance is monorefractory (isotropic) or birefringent (anisotropic).
Birefringence is a fundamental feature of crystals. Therefore, polarized light microscopes are widely used in the fields of minerals, chemistry, and the like. In biology, many structures also have birefringence, which requires differentiation using a polarizing microscope. In botany, such as identification of fibers, chromosomes, spindles, starch granules, cell walls, and whether cells and tissues contain crystals. In plant pathology, the invasion of pathogens often causes changes in the chemical properties of tissues, which can be identified by polarized light microscopy. In human and zoology, polarized light microscopy is often used to identify epiphyses, teeth, cholesterol, nerve fibers, tumor cells, striated muscles and hair.
Second, the basic principle of polarized light microscopy (1) single refraction and birefringence: when light passes through a substance, such as the nature of light and the way the light does not change due to the direction of illumination, this substance has optical Same-sex", also known as single-refractors, such as ordinary gases, liquids, and amorphous solids; if light passes through another substance, the speed, refractive index, absorbency, and vibration, amplitude, etc. of the light are due to the direction of illumination. Differently, this substance is optically "anisotropic", also known as birefringent, such as crystals, fibers, and the like.
(2) Polarization of light: Light waves can be classified into natural light and polarized light according to the characteristics of vibration. The vibration characteristic of natural light is that there are many vibration planes on the vertical light wave transmission axis, the amplitude of the vibration on each plane is the same, and the frequency is the same; the natural light can be vibrated in only one direction by reflection, refraction, birefringence and absorption. Light waves, which are called "polarized light" or "polarized light."
The simplest is linearly polarized light that vibrates only in a straight line. When the light enters the birefringent body, it is divided into A and B linear plane polarized lights as shown in the figure. The vibration directions of the two are perpendicular to each other, and the speed, refractive index and wavelength are different.
(3) The generation and effect of polarized light: The most important components of polarized light microscopes are polarizing devices - polarizers and analyzers. In the past, both were made of Nicola prisms, which were made of natural calcite. However, due to the large size of the crystal, it is difficult to obtain a large area of ​​polarization. Recently, polarized microscopes use artificial polarizers. To replace the Nicole shuttle.
The artificial polarizer is made of crystals of quinoline sulfate, also known as Herapathite, which is green olive. When ordinary light passes through it, linearly polarized light that vibrates only in a straight line can be obtained.
The polarizing microscope has two polarizers, one called “polarizer†between the light source and the object to be inspected; the other device is called “analyzer†between the objective lens and the eyepiece, and the handle extends into the lens barrel or the middle. The outside of the attachment is operated for a scale with a rotation angle.
When the light emitted from the light source passes through the two polarizers, if the vibration directions of the polarizer and the analyzer are parallel to each other, that is, in the case of "parallel detection and deviation", the field of view is the brightest. Conversely, if the two are perpendicular to each other, that is, in the case of "orthogonal misalignment," the field of view is completely dark, and if the two are tilted, the field of view indicates a moderate degree of brightness. It can be seen that the linearly polarized light formed by the polarizer can pass completely if its vibration direction is parallel to the vibration direction of the analyzer; if it is skewed, it passes only a part; if it is vertical, it cannot pass at all.
Therefore, in the case of using a polarized light microscope, in principle, the polarizer and the analyzer are in a state of being orthogonally detected.
The vibration characteristics of natural light and polarized light The polarization of the birefringent and the light (4) The birefringence under the quadrature detection: In the case of orthogonality, the field of view is dark, if the object under inspection is optically Isotropic (single refractor), no matter how the stage is rotated, the field of view is still dark, because the direction of vibration of the linearly polarized light formed by the polarizer does not change, still with the vibration direction of the analyzer Vertical sake. If the object to be inspected contains a birefringent substance, this part will emit light. This is because the linearly polarized light emitted from the polarizer enters the birefringent body, and two kinds of linearly polarized light whose vibration directions are perpendicular to each other are generated. When the two kinds of light pass through the analyzer, they can see the bright image because they are perpendicular to each other and more or less transparent to the analyzer. When the light passes through the birefringent body, the vibration directions of the two polarized lights are different depending on the type of the object.
Schematic diagram of parallel detection (A) and quadrature detection (B). In the case of orthogonality, when the stage is rotated, the image of the birefractor changes four times in the 360° rotation. Darken every 90°. The darkened position is the position where the two vibration directions of the birefringent body coincide with the vibration directions of the two polarizers, and the "extinction position" is rotated by 45° from the extinction position, and the object to be inspected becomes the brightest, which is " Diagonal position", because when the polarized light reaches the object when it deviates from 45°, part of the light is decomposed and can pass through the analyzer, so it is bright. According to the above basic principle, it is possible to judge isotropic (single-refractive) and anisotropic (birefringent) substances by using polarized light microscopy.
Birefringent under quadrature detection (5) Interference color: In the case of quadrature detection, the birefringence is observed by using mixed light of different wavelengths as the light source. When rotating the stage, in the field of view Not only the brightest diagonal position, but also the color. The reason for the appearance of color is mainly caused by the interference color (of course, the object to be inspected is not colorless and transparent). The distribution characteristics of the interference color are determined by the type of the birefringer and its thickness, which is due to the corresponding delay in the dependence of the wavelength of the light of different colors. If the delay of one region of the object to be inspected is different from the delay of the other region, then The color of the light passing through the analyzer is different.
Third, some requirements of the polarizing microscope on the device (a) light source: preferably using monochromatic light, because the speed of light, refractive index, absorption and interference phenomena vary due to different wavelengths. General light can be used for general microscopy.
(2) Stage: For the round shape, use a stage that can adjust the center and the edge is angled (360°) to rotate.
(C) and mirror: should use the achromatic target, because the apochromatic and semi-apochromatic objectives themselves often polarized.
(4) Eyepiece: It must have a crosshair mirror.
(5) Condenser: In order to obtain parallel polarized light, a shake-out condenser that can push out the upper lens should be used.
(6) Compensation film: When performing fine polarizing microscopy, it is necessary to use compensation tablets, such as gypsum, mica and quartz compensation tablets.
Fourth, the requirements of polarized light microscopy (1) the optical axis and the light passing center of the stage must be in a straight line, otherwise the object to be inspected will deviate from the center of the field of view when moving the object, and even move to the field of view, and Affect the microscopic examination.
(2) Both the polarizer and the analyzer are marked with the sign of the vibration direction. When in the orthogonal state, it is customary to make the vibration direction of the polarizer coincide with the horizontal line of the crosshair in the eyepiece, and the analyzer The direction of vibration is the same as the vertical line of the crosshair.
(3) The film should not be too thin, otherwise the weak birefringence will easily disappear. At the same time, it should be observed in a fresh state (otherwise, the birefringence is often strengthened or disappeared due to the treatment of steps such as fixation and dyeing), and then observed.
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