Method for automatically measuring extinction angle of mineral under polarizing microscope

Abstract

The invention discloses a method for automatically measuring the extinction angle of a mineral under a polarizing microscope, and the method comprises the steps: providing a polarizing microscope which comprises a microscope main body and a rotating mechanism, and the microscope main body comprises a microscope seat, a microscope arm, a lens barrel, a light-emitting mechanism, a lower polaroid, an upper polaroid, a camera part and a display. The device has the beneficial effects that the rotating mechanism can drive the rotating disc to rotate so as to drive the sheets to rotate, cleavage seams or double crystal seams are automatically identified through software so as to obtain a first azimuth angle of the rotating disc when the cleavage seams or the double crystal seams are parallel to the longitudinal cross wire, and an extinction position is automatically identified through the software so as to obtain the extinction effect. The absolute value of the difference between the first azimuth angle and the second azimuth angle is the extinction angle of the mineral, the extinction angle of the target mineral can be automatically measured, the identification efficiency of mineral flakes can be improved, and the labor intensity can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polarizing microscopes, and in particular to an automatic measurement method for the extinction angle of minerals under a polarizing microscope. Background Art

[0002] A polarizing microscope is an optical microscope specially used to study transparent and opaque anisotropic materials. It has a wide range of applications, especially in science and engineering disciplines such as geology, biology, and materials science. The working principle of a polarizing microscope is based on the polarization phenomenon and birefringence of light. When light passes through a substance, if the properties and path of light do not change due to the direction of irradiation, then the substance is optically "isotropic", also known as a single refraction body; if the speed, refractive index, absorptivity, polarization, amplitude, etc. of light are different due to the direction of irradiation, then the substance is optically "anisotropic", also known as a birefringence body. A polarizing microscope uses a polarizer and an analyzer to change ordinary light into polarized light, and identifies the optical properties of a substance by observing its performance under polarized light.

[0003] The extinction angle of a mineral is an important parameter in the optical properties of a mineral crystal, and it is of great significance for the identification of minerals. The extinction angle refers to the angle between the radius of the optical body ellipse of the mineral slice and the cleavage seam, twinning seam or crystal plane trace when the mineral slice is in the extinction position under an orthogonal microscope.

[0004] Under a polarizing microscope, the method for measuring the extinction angle of a mineral is usually as follows: place the mineral slice under the microscope, adjust it to the orthogonal polarization state, and then rotate the stage so that the cleavage or twinning seam of the mineral gradually moves from the position parallel to the vertical crosshairs of the eyepiece to the mineral extinction position. At this time, the degree of rotation of the stage is recorded as the extinction angle of the mineral on a specific crystal plane. The existing determination of the extinction angle of a mineral requires manual measurement, which takes a long time. When analyzing rock thin sections, a large number of mineral extinction angle measurements are often required, which will face the problems of long measurement time and high labor intensity. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies and propose a method for automatically measuring the extinction angle of minerals under a polarizing microscope, so as to solve the problem that a large number of mineral extinction angle measurements are often required when analyzing rock slices in the prior art, which will face the problems of long measurement time and high labor intensity.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: The present invention provides a method for automatically measuring the extinction angle of minerals under a polarizing microscope, comprising the following steps: S1. Provide a polarizing microscope, which includes a microscope body and a rotating mechanism. The microscope body includes a lens base, a lens arm, a lens barrel, a light-emitting mechanism, a lower polarizer, an upper polarizer, a camera and a display. The lens arm is fixed to the lens base, and the lens barrel is fixed to the lens arm. An objective lens is installed at the lower end of the lens barrel, and an eyepiece is installed at the upper end of the lens barrel. The light-emitting mechanism is arranged below the lens barrel and is used to emit light to the objective lens. The lower polarizer is arranged between the light-emitting mechanism and the objective lens. The upper polarizer is detachably inserted in the lens barrel. The upper polarizer allows the vibration of light passing through The direction is parallel to the crosshairs of the eyepiece and perpendicular to the vibration direction of the light allowed to pass through by the lower polarizer. The rotating mechanism includes a stage, a turntable and a rotating driving member. The stage is fixed to the mirror arm and is located between the lower polarizer and the objective lens. The stage is provided with a first through hole. The turntable is rotatably arranged on the stage. The turntable is provided with a second through hole. The turntable is used to place a thin sheet. The rotating driving member is used to drive the turntable to rotate and can measure the azimuth of the turntable. The camera is used to capture the field of view of the eyepiece. The display is used to display the field of view of the eyepiece captured by the camera. S2, placing the sheet on the turntable, moving the sheet so that the target mineral is located in the center of the field of view, and then inserting the upper polarizer into the lens barrel; S3, obtaining the target mineral area in the field of view, driving the turntable to rotate by rotating the driving member, thereby driving the thin section to rotate, identifying the cleavage seam or twin seam in the target mineral area, and when the cleavage seam or twin seam is parallel to the longitudinal crosshairs, recording the first azimuth angle of the turntable at this time; S4, continue to drive the turntable to rotate by rotating the driving member, thereby driving the thin slice to rotate, and intercept an image of the target mineral area once for each unit angle of rotation, convert the image into a grayscale image, and then obtain the average grayscale of the grayscale image. If the average grayscale is less than the preset grayscale, it indicates that the extinction position is reached, and the second azimuth angle of the turntable at this time is recorded; S5. The absolute value of the difference between the first azimuth and the second azimuth is the mineral extinction angle.

[0007] In some embodiments, in step S3, the method of identifying the cleavage seam or twin seam in the region of the target mineral is: capturing an image of an area of ​​target mineral; Grayscale the image; In the grayscale processed image, the lines in the grayscale image are found through the built-in function cv2.HoughLines of the OpenCV software, and then the angle between each found line and the x-axis is calculated. If the difference between the angles of at least two lines and the x-axis is less than the preset difference, it indicates that these lines are twinning seams or cleavage seams.

[0008] In some embodiments, when the cleavage seam or the twinning seam is parallel to the longitudinal crosshairs, the first azimuth angle of the turntable at this time is recorded, specifically: Obtain the angle between the twin seam or cleavage seam and the x-axis. When the angle between the twin seam or cleavage seam and the x-axis is equal to 90°, record the first azimuth angle of the turntable at this time.

[0009] In some embodiments, the light emitting mechanism includes a light source and a reflector, the reflector is disposed below the objective lens, and the light source is used to emit a light beam toward the reflector.

[0010] In some embodiments, the rotating mechanism further includes an aperture ring, wherein the aperture ring is fixed to the mirror arm, and the stage is fixed above the aperture ring.

[0011] In some embodiments, the aperture is fixed to the mirror arm via a connecting rod.

[0012] In some embodiments, the rotating mechanism further includes a bearing, an inner ring of the bearing is fixedly sleeved on the turntable, and an outer ring of the bearing is fixedly connected to the stage.

[0013] In some embodiments, the rotating driving component includes a rotating driving motor, a driving gear and a driven gear. The housing of the rotating driving motor is fixed to the loading platform, the driving gear is fixedly mounted on the output shaft of the rotating driving motor, and the driven gear is fixedly mounted on the turntable and meshes with the driving gear.

[0014] In some embodiments, the rotary drive motor is a Hall motor.

[0015] In some embodiments, a clearance hole is opened on the loading platform, and the output shaft of the rotary drive motor passes through the clearance hole.

[0016] Compared with the prior art, the method for automatically measuring the extinction angle of minerals under a polarizing microscope provided by the present invention has the following beneficial effects: the rotating mechanism can drive the turntable to rotate, thereby driving the thin slice to rotate, the cleavage seam or the twin seam is automatically identified by the software, thereby obtaining the first azimuth angle of the turntable when the cleavage seam or the twin seam is parallel to the longitudinal crosshairs, the extinction position is automatically identified by the software, thereby obtaining the second azimuth angle of the turntable in the extinction position, and the absolute value of the difference between the first azimuth angle and the second azimuth angle is the extinction angle of the mineral. The present invention can automatically measure the extinction angle of the target mineral, improve the efficiency of mineral thin slice identification, and reduce labor intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a polarizing microscope provided by one embodiment of the present invention.

[0018] Figure 2 yes Figure 1 Schematic diagram of the structure of the rotating mechanism.

[0019] Figure 3 yes Figure 1 Schematic diagram of the three-dimensional structure of the rotating mechanism.

[0020] Figure markings: 1-microscope body, 11-mirror base, 12-mirror arm, 13-lens barrel, 131-objective lens, 132-eyepiece, 14-light-emitting mechanism, 141-light source, 142-reflector, 15-lower polarizer, 16-upper polarizer, 2-rotation mechanism, 21-stage, 211-first through hole, 22-turntable, 221-second through hole, 23-rotation driving member, 231-rotation driving motor, 232-driving gear, 233-driven gear, 24-aperture block, 25-connecting rod, 26-bearing, 3-thin sheet. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] In order to solve the problem that a large number of mineral extinction angle measurements are often required in rock thin section analysis, which will face the problems of long measurement time and high labor intensity, the present invention provides an automatic measurement method for mineral extinction angle under a polarizing microscope, which can automatically measure the extinction angle of minerals, improve the efficiency of mineral thin section identification, and reduce labor intensity.

[0023] See also Figure 1 , Figure 1 The schematic diagram of the structure of the method for automatically measuring the extinction angle of minerals under a polarizing microscope in an embodiment of the present invention comprises the following steps: S1. Provide a polarizing microscope, please refer to Figure 1-Figure 3The polarizing microscope comprises a microscope body 1 and a rotating mechanism 2. The microscope body 1 comprises a lens base 11, a lens arm 12, a lens barrel 13, a light-emitting mechanism 14, a lower polarizer 15, an upper polarizer 16, a camera and a display (not shown). The lens arm 12 is fixed to the lens base 11, the lens barrel 13 is fixed to the lens arm 12, an objective lens 131 is installed at the lower end of the lens barrel 13, an eyepiece 132 is installed at the upper end of the lens barrel 13, the light-emitting mechanism 14 is arranged below the lens barrel 13, and is used to emit light to the objective lens 131, the lower polarizer 15 is arranged between the light-emitting mechanism 14 and the objective lens 131, the upper polarizer 16 is detachably inserted in the lens barrel 13, and the vibration direction of the light allowed to pass through by the upper polarizer 16 is consistent with the eyepiece The longitudinal crosshairs of the mirror 132 are parallel and perpendicular to the vibration direction of the light allowed to pass through by the lower polarizer 15. The rotating mechanism 2 includes a stage 21, a turntable 22 and a rotating driving member 23. The stage 21 is fixed to the mirror arm 12 and is located between the lower polarizer 15 and the objective lens 131. The stage 21 is provided with a first through hole 211 for light to pass through. The turntable 22 is rotatably arranged on the stage 21. The turntable 22 is provided with a second through hole 221. The turntable 22 is used to place a thin film 3. The rotating driving member 23 is used to drive the turntable 22 to rotate and can measure the azimuth angle of the turntable 22. The camera is used to capture the field of view of the eyepiece 132, and the display is used to display the field of view of the eyepiece captured by the camera. S2, placing the sheet 3 on the turntable 22, moving the sheet 3 so that the target mineral is located in the middle of the field of view, and then inserting the upper polarizer 16 into the lens barrel 13; S3, obtaining the target mineral area in the field of view, driving the turntable 22 to rotate by rotating the driving member 23, thereby driving the thin slice 3 to rotate, identifying the cleavage seam or twin seam in the target mineral area, and when the cleavage seam or twin seam is parallel to the longitudinal crosshairs, recording the first azimuth angle of the turntable 22 at this time; In the step S3, the method for identifying the cleavage seams or twin seams in the region of the target mineral is as follows.

[0024] (1) Capturing an image of the target mineral area; in this embodiment, the target mineral area is selected by the user. On the system operation interface, a circular or directional selection box can be provided for the user to select the target mineral area. The position and size of the selection box can be adjusted. The selection box should ensure that it is completely within the area covered by the target mineral.

[0025] (2) Grayscale processing of the image: Grayscale processing of the image is a basic step in image processing. It converts a color image into a grayscale image, that is, each pixel in the image is represented by a grayscale between black and white, rather than three color channels of red, green, and blue. This process helps to reduce the complexity of image processing because grayscale images only involve one color channel, rather than three. In this embodiment, OpenCV software is used to complete the image grayscale processing task.

[0026] (3) In the grayscale processed image, the lines in the grayscale image are searched by the built-in function cv2.HoughLines of the OpenCV software, and then the angle between each found line and the x-axis is calculated. If the difference between the angles between at least two lines and the x-axis is less than the preset difference, it indicates that these lines are twin seams or cleavage seams. The principle is: if at least two lines are approximately parallel, it indicates that these lines are twin seams or cleavage seams. The reason why at least two lines are required is to prevent the crosshairs from being mistakenly identified as twin seams or cleavage seams. In this embodiment, the x-axis is defined as an infinitely long straight line starting from the origin (0,0) and extending to the right along the horizontal direction.

[0027] In step S3, when the cleavage seam or the twin seam is parallel to the longitudinal crosshairs, the first azimuth angle of the turntable at this time is recorded, specifically: Obtain the angle between the twin seam or cleavage seam and the x-axis. When the angle between the twin seam or cleavage seam and the x-axis is 90°, record the first azimuth of the turntable at this time. When the angle between the twin seam or cleavage seam and the x-axis is 90°, it indicates that it is parallel to the longitudinal crosshairs.

[0028] S4. Continue to rotate the turntable 22 by rotating the driving member 23, thereby driving the thin sheet 3 to rotate. For each unit angle of rotation, capture the image of the target mineral area once, convert the image into a grayscale image, and then obtain the average grayscale of the grayscale image. If the average grayscale is less than the preset grayscale, it indicates that the image darkness is very low, indicating that the extinction position is reached, and record the second azimuth angle of the turntable 22 at this time.

[0029] S5. The absolute value of the difference between the first azimuth and the second azimuth is the mineral extinction angle.

[0030] The technical solution provided by the present invention can drive the turntable 22 to rotate through the rotating mechanism 23, thereby driving the thin slice 3 to rotate, and automatically identifying the cleavage seam or the twin seam through the software, thereby obtaining the first azimuth angle of the turntable 22 when the cleavage seam or the twin seam is parallel to the longitudinal crosshairs, and automatically identifying the extinction position through the software, thereby obtaining the second azimuth angle of the turntable 22 in the extinction position, and the absolute value of the difference between the first azimuth angle and the second azimuth angle is the mineral extinction angle. The present invention can automatically measure the extinction angle of the target mineral, which can improve the efficiency of mineral thin slice identification and reduce labor intensity.

[0031] For details, please refer to Figure 1 The light emitting mechanism 14 includes a light source 141 and a reflector 142 . The reflector 142 is disposed below the objective lens 131 . The light source 141 is used to emit a light beam toward the reflector 142 .

[0032] It should be understood that the microscope body 1 includes not only the above-mentioned components but also other components such as a focusing mechanism. The structures and installation methods of these components are all prior arts and will not be described in detail in the present invention.

[0033] For details, please refer to Figure 1 and Figure 2 The rotating mechanism 2 further includes an aperture ring 24, which is fixed to the mirror arm 12, and the stage 21 is fixed above the aperture ring 24. The aperture ring 24 is fixed to the mirror arm 12 via a connecting rod 25.

[0034] For details, please refer to Figure 1 and Figure 2 The rotating mechanism 2 further includes a bearing 26 , an inner ring of the bearing 26 is fixedly sleeved on the turntable 22 , and an outer ring of the bearing 26 is fixedly connected to the stage 21 , thereby improving the stability of the turntable 22 during rotation.

[0035] For details, please refer to Figure 1-Figure 3 The rotating driving member 23 includes a rotating driving motor 231, a driving gear 232 and a driven gear 233. The housing of the rotating driving motor 231 is fixed to the stage 21. The driving gear 232 is fixedly sleeved on the output shaft of the rotating driving motor 231. The driven gear 233 is fixedly sleeved on the turntable 22 and meshes with the driving gear 232. When in use, the rotating driving motor 231 drives the driving gear 232 to rotate, the driving gear 232 drives the driven gear 233 to rotate, the driven gear 233 drives the turntable 22 to rotate, and the turntable 22 drives the thin sheet 3 to rotate. Since the rotation rate is very low, the thin sheet 3 does not need to be fixed and can be directly placed on the turntable 22.

[0036] For details, please refer to Figure 1-Figure 3 The rotating drive motor is a Hall motor. A Hall motor is a motor with a Hall sensor: it can detect the position of the rotor, achieve smooth start-up and precise control; it can start at zero speed; during the operation of the motor, the angle of rotation of the motor's rotor can be monitored, so that the angle of rotation of the turntable 22 can be calculated, and the azimuth angle of the turntable 22 can be obtained.

[0037] For details, please refer to Figure 1-Figure 3A clearance hole is provided on the loading platform 21, and the output shaft of the rotation driving motor 231 passes through the clearance hole.

[0038] The technical solution provided by the present invention can drive the turntable 22 to rotate through the rotating mechanism 23, thereby driving the thin slice 3 to rotate, and automatically identifying the cleavage seam or the twin seam through the software, thereby obtaining the first azimuth angle of the turntable 22 when the cleavage seam or the twin seam is parallel to the longitudinal crosshairs, and automatically identifying the extinction position through the software, thereby obtaining the second azimuth angle of the turntable 22 in the extinction position, and the absolute value of the difference between the first azimuth angle and the second azimuth angle is the mineral extinction angle. The present invention can automatically measure the extinction angle of the target mineral, which can improve the efficiency of mineral thin slice identification and reduce labor intensity.

[0039] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for automatically measuring the extinction angle of minerals under a polarizing microscope, characterized in that: The steps include: S1. Provide a polarizing microscope, which includes a microscope body and a rotating mechanism. The microscope body includes a lens base, a lens arm, a lens barrel, a light-emitting mechanism, a lower polarizer, an upper polarizer, a camera and a display. The lens arm is fixed to the lens base, and the lens barrel is fixed to the lens arm. An objective lens is installed at the lower end of the lens barrel, and an eyepiece is installed at the upper end of the lens barrel. The light-emitting mechanism is arranged below the lens barrel and is used to emit light to the objective lens. The lower polarizer is arranged between the light-emitting mechanism and the objective lens. The upper polarizer is detachably inserted in the lens barrel. The upper polarizer allows the vibration of light passing through The direction is parallel to the crosshairs of the eyepiece and perpendicular to the vibration direction of the light allowed to pass through by the lower polarizer. The rotating mechanism includes a stage, a turntable and a rotating driving member. The stage is fixed to the mirror arm and is located between the lower polarizer and the objective lens. The stage is provided with a first through hole. The turntable is rotatably arranged on the stage. The turntable is provided with a second through hole. The turntable is used to place a thin sheet. The rotating driving member is used to drive the turntable to rotate and can measure the azimuth of the turntable. The camera is used to capture the field of view of the eyepiece. The display is used to display the field of view of the eyepiece captured by the camera. S2, placing the sheet on the turntable, moving the sheet so that the target mineral is located in the center of the field of view, and then inserting the upper polarizer into the lens barrel; S3, obtaining the target mineral area in the field of view, driving the turntable to rotate by rotating the driving member, thereby driving the thin section to rotate, identifying the cleavage seam or twin seam in the target mineral area, and when the cleavage seam or twin seam is parallel to the longitudinal crosshairs, recording the first azimuth angle of the turntable at this time; S4, continue to drive the turntable to rotate by rotating the driving member, thereby driving the thin slice to rotate, and intercept an image of the target mineral area once for each unit angle of rotation, convert the image into a grayscale image, and then obtain the average grayscale of the grayscale image. If the average grayscale is less than the preset grayscale, it indicates that the extinction position is reached, and the second azimuth angle of the turntable at this time is recorded; S5. The absolute value of the difference between the first azimuth and the second azimuth is the mineral extinction angle.

2. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 1, characterized in that: In step S3, the method for identifying the cleavage seam or twin seam in the region of the target mineral is: capturing an image of an area of ​​target mineral; Grayscale the image; In the grayscale processed image, the lines in the grayscale image are found through the built-in function cv2.HoughLines of the OpenCV software, and then the angle between each found line and the x-axis is calculated. If the difference between the angles of at least two lines and the x-axis is less than the preset difference, it indicates that these lines are twinning seams or cleavage seams.

3. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 2, characterized in that: When the cleavage seam or twin seam is parallel to the longitudinal crosshairs, record the first azimuth of the turntable at this time, specifically: Obtain the angle between the twin seam or cleavage seam and the x-axis. When the angle between the twin seam or cleavage seam and the x-axis is equal to 90°, record the first azimuth angle of the turntable at this time.

4. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 1, characterized in that: The light emitting mechanism comprises a light source and a reflector, wherein the reflector is arranged below the objective lens, and the light source is used for emitting a light beam toward the reflector.

5. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 1, characterized in that: The rotating mechanism also includes an aperture ring, which is fixed to the mirror arm, and the stage is fixed above the aperture ring.

6. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 5, characterized in that: The light blocking ring is fixed to the mirror arm via a connecting rod.

7. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 1, characterized in that: The rotating mechanism further comprises a bearing, wherein an inner ring of the bearing is fixedly sleeved on the turntable, and an outer ring of the bearing is fixedly connected to the loading platform.

8. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 1, characterized in that: The rotary drive member includes a rotary drive motor, a driving gear and a driven gear. The housing of the rotary drive motor is fixed to the stage. The driving gear is fixedly sleeved on the output shaft of the rotary drive motor. The driven gear is fixedly sleeved on the turntable and meshes with the driving gear.

9. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 8, characterized in that: The rotary drive motor is a Hall motor.

10. The method for automatically measuring the extinction angle of minerals under a polarizing microscope according to claim 1, characterized in that: The loading platform is provided with a clearance hole, and the output shaft of the rotary drive motor passes through the clearance hole.

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