Method and device for adjusting two back-to-back gratings to be parallel to each other

Abstract

The present invention provides a method and device for adjusting two back-to-back gratings to be parallel to each other, including adjusting the parallelism of the grating surfaces of the two gratings and adjusting the parallelism of the grating lines of the two gratings. The adjustment device comprises a first grating A, a second grating B, a red light source, a receiving screen, a grating mounting plate, a pinhole diaphragm, a collimated light source, threaded structures respectively provided at the four corners of the gratings, and a telescopic slot rotation mechanism for connecting and mounting the gratings to the grating mounting plate. The parallelism of the grating surfaces of the two gratings is achieved by adjusting the first grating A and the second grating B, which are respectively provided on the front and back sides of the grating mounting plate, to be perpendicular to the same horizontal collimated light source. The red light source emits light, and the receiving screen displays the diffraction patterns formed by the two gratings in sequence. After marking two or more diffraction spots, the connecting line is marked. The first grating A is adjusted so that the marked connecting line is parallel to the marked connecting line of the second grating B, thereby completing the parallelism of the grating lines of the two gratings.

Description

Technical Field

[0001] The present invention relates to a grating measurement system component, and in particular discloses a method and an adjusting device for adjusting two back-to-back gratings to be parallel to each other, which are applied to a grating period measurement system. Background Art

[0002] In the process of measuring the period of an ordinary grating using a standard grating of known period, in order to reduce the error, two gratings need to be placed back to back and in parallel on the same sample plate.

[0003] In the prior art, most of the research focuses on how to adjust the parallelism of face-to-face grating pairs. Figure 1 As shown, by using a collimated light source 6 and a right-angle prism 12, a right-angle prism 12 is used to adjust the mutual parallelism of the grating pair. The first step is to place the collimated light source 6 at the dotted line position in the figure, adjust the collimated light source 6 so that the light passes through the pinhole aperture 5 and enters the first grating A and returns to the pinhole aperture 5, that is, adjust the collimated light source 6 and the first grating A to be perpendicular to each other, and make a height mark 13 for the height of the light emitted by the collimated light source 6 after passing through the pinhole aperture 5; the second step is to place a right-angle prism 12 between the collimated light source 6 and the first grating A (the dotted line position in the figure), and adjust it so that the light emitted by the collimated light source 6 is reflected by the first right-angle surface of the right-angle prism 12 and returns to the pinhole aperture 5, that is, adjust the light emitted by the collimated light source 6 to be perpendicular to the first right-angle surface of the right-angle prism 12, and fine-tune the right-angle prism 12 horizontally so that the height of the light beam emitted from the second right-angle surface of the right-angle prism 12 is strictly consistent with the height specified by the height mark 13; the third step is to move the collimated light source 6 and the pinhole aperture 5 and straighten them. Next, the second right-angled surface of the right-angle prism 12 (the dotted line position in the figure) is illuminated, and the collimated light source 6 is adjusted so that the light from the collimated light source 6 is reflected by the second right-angled surface of the right-angle prism 12 and then returns to the small hole of the aperture stop 5. That is, the direction of the light emitted by the collimated light source 6 is adjusted to be parallel to the first grating A. Fourth, the right-angle prism 12 is translated toward the collimated light source 6 so that the light emitted from the first right-angled surface of the right-angle prism 12 can illuminate the second grating B (the right-angle prism 12 is now located at the solid line position in the figure), while at the same time, it is always ensured that the light emitted by the collimated light source 6 is reflected by the second right-angled surface of the right-angle prism 12 and then returns to the small hole of the aperture stop 5. Fifth, the second grating B is adjusted so that the light emitted by the collimated light source 6 is refracted by the right-angle prism 12 and then illuminates the second grating B and then reflects from the right-angle prism 12 and then returns to the small hole of the aperture stop 5. At this point, the first grating A and the second grating B are parallel.

[0004] However, the above technology can only prove that the two grating planes are parallel, but it cannot guarantee that the grating lines of the two gratings are parallel. The measurement principle of the grating period is based on the vector displacement in the periodic direction of the standard grating and the ordinary grating. Only by ensuring that the vector displacement of the two gratings is the same can the measurement results be more accurate. Therefore, it is particularly important to ensure that the pitch angle, yaw angle and rotation angle of the two gratings are the same, that is, the two gratings are completely parallel, which is particularly important for the accuracy of the measurement system. Summary of the Invention

[0005] The purpose of the present invention is to solve the defects of the prior art and design a method and an adjustment device for adjusting two back-to-back gratings to be parallel to each other. The method and the adjustment device complete the parallelism adjustment of the grating surfaces and the parallelism adjustment of the grating lines of the grating pair in two steps. The method is suitable for adjusting the parallelism of two back-to-back gratings, with small error, high precision and strong reliability. The above two steps can also be performed by two people at the same time, shortening the adjustment working time.

[0006] The present invention is achieved as follows: a method for adjusting two back-to-back gratings to be parallel to each other, characterized in that the method for adjusting the two back-to-back gratings to be parallel to each other includes adjusting the parallelism of the grating surfaces of the two back-to-back gratings and adjusting the parallelism of the grating lines of the two back-to-back gratings, and the adjustment device used includes a first grating A, a second grating B, a red light source, a receiving screen, a grating mounting plate, a pinhole diaphragm, a collimated light source, threaded structures respectively provided at the four corners of the gratings, and a telescopic slot rotation mechanism for connecting and installing the gratings to the grating mounting plate, and the pinhole diaphragm, the collimated light source, and the threaded structure are used to adjust the first grating A and the second grating B respectively provided on the front and back sides of the grating mounting plate to be parallel to the same horizontal collimated light source. To achieve vertical parallelism between the grating surfaces of the first grating A and the second grating B, the red light source, receiving screen, and telescopic slot rotation mechanism are used to adjust the parallelism of the two back-to-back grating lines. The red light source is directed perpendicularly to the first grating A and the second grating B, and two or more diffraction spots displayed by the first grating A and the second grating B on the receiving screen are marked. The marks on the corresponding gratings are connected to form two lines. The first grating A is rotated around the telescopic slot rotation mechanism until the line connecting the marks of the diffraction spots formed by the first grating A on the receiving screen is parallel to the line connecting the marks of the diffraction spots formed by the second grating B, thereby achieving parallelism between the grating lines of the first grating A and the second grating B. During the adjustment process, the position of the collimated light source is fixed, and the direction of its emitted light is also fixed.

[0007] The adjustment device for performing the aforementioned parallel adjustment of the grating surfaces of the two back-to-back gratings further includes a rotating control console. First, a collimated light source is adjusted to a horizontal light emission state, and the position of the collimated light source is fixed. The two gratings are then mounted on the front and back sides of a grating mounting plate. The collimated light source passes through a pinhole diaphragm and is incident on the first grating A. The yaw angle or pitch angle of the first grating A is adjusted using the threaded structures at the four corners of the first grating A so that the reflected light returns through the pinhole diaphragm. At this point, the first grating A is perpendicular to the horizontal collimated light source. The rotating control console is then rotated 180°. The collimated light source passes through the pinhole diaphragm and is incident on the second grating B. The yaw angle or pitch angle of the second grating B is adjusted using the threaded structures at the four corners of the second grating B so that the reflected light returns through the pinhole diaphragm. At this point, the second grating B is also perpendicular to the horizontal collimated light source, completing the parallel adjustment of the grating surfaces of the two gratings.

[0008] The adjustment device for performing the aforementioned back-to-back grating line parallel adjustment also includes a rotating control console. First, the angle of the incident light from the red light source is fixed and adjusted so that it strikes the second grating B, resulting in a diffraction pattern displayed on the receiving screen. Two or more diffraction spots are marked and connected to form a line. The rotating control console is then rotated 180°, and the light from the red light source strikes the first grating A. The diffraction pattern is also displayed on the receiving screen. Two or more diffraction spots are then marked and connected to form a second line. The first grating A is rotated using the telescopic slot rotation mechanism until the line connecting the two marks displayed on the receiving screen becomes parallel, completing the parallel adjustment of the grating lines.

[0009] An adjustment device used in the method for adjusting two back-to-back gratings to be parallel to each other is characterized in that the adjustment device includes a first grating A, a second grating B, a red light source, a receiving screen, a grating mounting plate, a pinhole diaphragm, a collimated light source, threaded structures respectively provided at the four corners of the gratings, and a telescopic slot rotation mechanism for connecting and mounting the gratings to the grating mounting plate. The red light source and the grating mounting plate are placed on a work surface. The telescopic slot rotation mechanism is a two-section sleeve structure, wherein one section of the tube is fixed to the area of ​​the grating mounting plate for mounting the gratings, and the other section of the tube is adhered to the gratings. The two sections of the tube are respectively provided with mutually cooperating snap-fitting structures. The first grating A and the second grating B are respectively mounted on the front and back sides of the grating mounting plate via the corresponding snap-fitting structures of the two sections of the telescopic slot rotation mechanism. The collimated light source and pinhole diaphragm are located on one side of the grating mounting plate, and the receiving screen is located on the other side of the grating mounting plate.

[0010] The adjusting device further comprises a rotating console, which is placed on a work surface, and the grating mounting plate is vertically placed on the flat top surface of the rotating console. The receiving screen is a wall or a screen capable of receiving light spots.

[0011] Both the first grating A and the second grating B are detachable gratings, and are angularly rotated via their respective telescopic slot rotation mechanisms, and their respective yaw or pitch angles are adjusted via threaded structures provided at the four corners. The two sections of the telescopic slot rotation mechanism are connected by a snap-fit ​​structure. The snap-fit ​​structure comprises a plurality of snap-fit ​​bosses provided on the inner wall of the outer section of the tube, which are matched with a plurality of snap-fit ​​bosses provided on the outer circumference of the inner section of the tube. The two sections of the tube are connected by a ring after the positions of the snap-fit ​​bosses correspond. The snap-fit ​​bosses provided on the outer circumference of the inner section of the tube are closely attached to the inner wall of the outer section of the tube, allowing relative rotation under the action of external force. At the same time, after the two sections of the tube are connected, there is still space for mutual telescopic movement.

[0012] The beneficial effects of the present invention are: the present invention is suitable for adjusting the parallelism between two back-to-back gratings, the device structure is simple, the principle is easy to understand, and the parallelism adjustment of the grating is achieved by completing the parallelism adjustment of the grating surfaces and the parallelism adjustment of the grating lines. It is easy to implement and easy to operate, and the above two steps can be performed by two people at the same time, which is time-saving and efficient. The device of the present invention has low environmental requirements, small errors, and strong reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a schematic diagram of an adjustment device and an adjustment method for achieving parallel adjustment of two face-to-face gratings in the prior art.

[0014] Figure 2 It is a schematic structural diagram of the regulating device of the present invention.

[0015] Figure 3 This is a schematic diagram showing the distribution of the thread structure and telescopic slot rotation mechanism for adjusting the grating angle of the present invention.

[0016] Figure 4 This is a schematic diagram of the components and adjustment method for adjusting the parallelism of the grating surfaces of two back-to-back gratings of the present invention.

[0017] Figure 5 This is a schematic diagram of the components and adjustment method for adjusting the parallelism of the grating lines of two back-to-back gratings of the present invention.

[0018] Figure 6 It is a schematic diagram of the diffraction spot displayed on the receiving screen of the present invention.

[0019] Figure 7 This is a schematic diagram showing the distribution of light of various wavelength bands in the linear array CCD when the grating lines are parallel to the line light source.

[0020] Figure 8 This is a schematic diagram showing the distribution of light of different wavelength bands in the linear array CCD when the grating lines are not parallel to the line light source.

[0021] Figure 9 It is a schematic structural diagram of the telescopic slot rotation mechanism of the present invention.

[0022] In the figure: A, first grating; B, second grating;

[0023] 1. Red light source; 2. Receiving screen; 3. Rotating control console; 4. Grating mounting plate; 5. Pinhole diaphragm; 6. Collimated light source; 7. First thread structure; 8. Second thread structure; 9. Third thread structure; 10. Fourth thread structure; 11. Telescopic slot rotation mechanism; 12. Right-angle prism; 13. Height mark; 14. Snap-on boss. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0025] like Figure 2 and Figure 3As shown, the present invention is a method and an adjustment device for adjusting two back-to-back gratings to be parallel to each other. The adjustment device of the present invention includes a first grating A, a second grating B, a red light source 1, a receiving screen 2, a rotating control console 3, a grating mounting plate 4, a pinhole diaphragm 5, a collimated light source 6, a first thread structure 7, a second thread structure 8, a third thread structure 9, a fourth thread structure 10 and a telescopic slot rotating mechanism 11. The red light source 1 and the rotating control console 3 are respectively placed on a work surface, and the grating mounting plate 4 is vertically placed on the rotating control console. On the flat top surface of the table 3, the rotating console 3 can be rotated horizontally on the work platform. The telescopic slot rotating mechanism 11 is a two-section sleeve structure. One section of the tube is fixed in the area of ​​the grating mounting plate 4 for mounting the grating, and the other section of the tube is glued to the grating. The two sections of the tube are respectively provided with mutually cooperating clamping structures. The first grating A and the second grating B are respectively mounted on the front and back sides of the grating mounting plate 4 through the corresponding two sections of the telescopic slot rotating mechanism. The two sections of the tube of the telescopic slot rotating mechanism are sleeved. The clamping structure is a plurality of clamping bosses 14 provided on the inner wall of a section of the tube body placed on the outside and a plurality of clamping bosses 14 provided on the outer periphery of the tube body placed on the inside. The two sections of the tube body are connected in a ring after the positions of the plurality of clamping bosses 14 are matched. The clamping bosses 14 provided on the outer periphery of the inner tube body are close to the inner wall of the outer tube body and can rotate relative to each other under the action of external force. At the same time, after the two sections of the tube body are sleeved, there is still space for mutual telescopic movement, so the first grating A and the second grating B can be respectively revolved around the telescopic clamping bosses 14. A slot rotation mechanism 11 is used to adjust the rotation angle. Both gratings are detachable. The four corners of the first grating A and the second grating B are also provided with four threaded structures (i.e., a first threaded structure 7, a second threaded structure 8, a third threaded structure 9, and a fourth threaded structure 10). The yaw angle or pitch angle of the first grating A and the second grating B can be adjusted by tightening or loosening the nuts on the threaded structures. The collimated light source 6 and the pinhole aperture 5 are located on one side of the grating mounting plate 4, and the receiving screen 2 is located on the other side of the grating mounting plate 4.

[0026] The method for adjusting the parallelism of two back-to-back gratings described in the present invention achieves parallelism between the grating planes of first grating A and second grating B by adjusting them to be perpendicular to a horizontal collimated light source 6. During the adjustment process, the collimated light source is fixed in position and its emitted light direction is also fixed. A red light source 1 is perpendicularly incident on each of the first grating A and second grating B, and two or more diffraction spots displayed by the first grating A and second grating B on a receiving screen 2 are marked. The marks on the corresponding gratings are connected to form two lines. The first grating A is rotated around the telescopic slot rotation mechanism 11 until the line connecting the marks of the diffraction spots formed by the first grating A on the receiving screen 2 is parallel to the line connecting the marks of the diffraction spots formed by the second grating B, thereby achieving parallelism between the grating lines of the first grating A and the second grating B.

[0027] The adjustment method of the present invention is specifically as follows:

[0028] like Figure 4 As shown, the module for adjusting the parallelism of two back-to-back gratings of the present invention comprises a first grating A, a second grating B, a rotation console 3, a grating mounting plate 4, an aperture stop 5, and a collimated light source 6. First, the collimated light source is adjusted so that its emitted light is horizontal, and the position of the collimated light source 6 is fixed. The two gratings are then mounted on the front and back sides of the grating mounting plate 4. The collimated light source 6 is incident on the first grating A through the aperture stop 5. The yaw or pitch angle of the first grating A is adjusted so that the reflected light returns through the aperture stop 5, i.e., the first grating A is perpendicular to the horizontal collimated light source 6. Next, the rotation console 3 is rotated 180°. The collimated light source 6 is incident on the second grating B through the aperture stop 5. The yaw or pitch angle of the second grating B is adjusted so that the reflected light returns through the aperture stop 5, i.e., the second grating B is perpendicular to the horizontal collimated light source 6, thus completing the adjustment of the parallelism of the two gratings.

[0029] like Figure 5 As shown, the module for adjusting the parallelism of the grating lines of two back-to-back gratings of the present invention includes a first grating A, a second grating B, a red light source 1, a receiving screen 2, a rotating control console 3 and a grating mounting plate 4. First, the angle of the incident light from the red light source 1 is fixed and adjusted so that it is incident on the second grating B, and a diffraction pattern is displayed on the receiving screen 2. Two or more diffraction spots are marked and the marks are connected to form a line. Then the rotating control console 3 is rotated 180°, and the light emitted by the red light source 1 is incident on the first grating A. The diffraction pattern is also displayed on the receiving screen 2. Two or more diffraction spots are marked and the marks are connected to form a second line. If the grating lines of the first grating A and the second grating B are parallel, the lines connecting the two marks are also parallel. If the two lines marked twice are not parallel, the first grating A is rotated by the telescopic slot rotating mechanism 11 until the lines connecting the two marks displayed on the receiving screen 2 are parallel, thereby completing the adjustment of the parallelism of the grating lines of the two gratings.

[0030] like Figure 6 As shown in the figure, A1OA2 is the diffraction pattern of the first grating A, and B1O1B2 is the diffraction pattern of the second grating B. The incident light is incident vertically on the grating surface. When the grating lines are not parallel to the line light source, the position of the 0th order diffraction spectrum line remains unchanged, and the +1st and -1st order diffraction spots are offset upward and downward respectively, with unequal heights, and slightly move closer to the central zeroth order diffraction spot. When the angle between the grating lines and the line light source increases, the upward and downward offset distances of the +1st and -1st order diffraction spots increase significantly. The optical signal is collected and analyzed by a linear array CCD, which is composed of multiple pixel arrangements, such as Figure 7 and Figure 8 As shown in the figure, the arrows indicate the incident direction of the diffracted light of each band. The small rectangle in the middle is the pixel, and the large rectangle on the periphery is the diffracted light area of ​​each band. Each pixel will receive the light of each band diffracted by the grating. When the grating lines are parallel to the line light source, the distribution of the light of each band in the linear array CCD is as follows Figure 7 As shown in the figure, the shaded area marked by the oblique lines is the light area received by the pixel. When the grating lines are not parallel to the line light source, the light of each band is distributed in the linear array CCD as shown in the figure. Figure 8 As shown in , a pixel will receive optical signals of two or more bands at the same time, and as Figure 8 As shown, the light area ratio received by each pixel is Figure 7 The area of ​​light received is reduced, resulting in a decrease in the intensity of received light.

[0031] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for adjusting two back-to-back gratings to be parallel to each other, characterized by: The method for adjusting the parallelism of two back-to-back gratings includes adjusting the parallelism of the grating surfaces of the two back-to-back gratings and adjusting the parallelism of the grating lines of the two back-to-back gratings. The adjustment device used includes a first grating A, a second grating B, a red light source, a receiving screen, a grating mounting plate, a pinhole diaphragm, a collimated light source, threaded structures respectively arranged at the four corners of the grating, and a telescopic slot rotation mechanism for connecting and installing the grating and the grating mounting plate. The pinhole diaphragm, the collimated light source, and the threaded structure are used to adjust the first grating A and the second grating B respectively arranged on the front and back sides of the grating mounting plate to be perpendicular to the same horizontal collimated light source to achieve the parallelism of the grating surfaces of the first grating A and the second grating B. The red light source, the receiving screen, the grating mounting plate, the pinhole diaphragm, the collimated light source, and the threaded structure are used to adjust the first grating A and the second grating B respectively arranged on the front and back sides of the grating mounting plate to be perpendicular to the same horizontal collimated light source. The screen and the telescopic card slot rotation mechanism adjust the grating lines of the two back-to-back gratings to be parallel, and the red light source is vertically incident on the first grating A and the second grating B respectively. Two or more diffraction spots displayed by the first grating A and the second grating B on the receiving screen are marked, and the marks of the corresponding gratings are connected to form two lines. The first grating A is rotated with the telescopic card slot rotation mechanism as the center until the marked line connecting the diffraction spots formed by the first grating A on the receiving screen is parallel to the marked line connecting the diffraction spots formed by the second grating B, thereby achieving parallelism between the grating lines of the first grating A and the second grating B. During the adjustment process, the position of the collimated light source and the direction of the emitted light remain fixed.

2. The method for adjusting two back-to-back gratings to be parallel to each other according to claim 1, characterized in that: The device for adjusting the parallelism of the grating surfaces of the two back-to-back gratings further includes a rotating control console. First, the collimated light source is adjusted to a horizontal light emission state and the position of the collimated light source is fixed. The two gratings are then mounted on the front and back sides of the grating mounting plate. The collimated light source passes through the pinhole diaphragm and is incident on the first grating A. The yaw angle or pitch angle of the first grating A is adjusted using the threaded structures at the four corners of the first grating A so that the reflected light returns through the pinhole diaphragm. At this time, the first grating A is perpendicular to the horizontal collimated light source. The rotating control console is then rotated 180°. The collimated light source passes through the pinhole diaphragm and is incident on the second grating B. The yaw angle or pitch angle of the second grating B is adjusted using the threaded structures at the four corners of the second grating B so that the reflected light returns through the pinhole diaphragm. At this time, the second grating B is also perpendicular to the horizontal collimated light source, thereby completing the adjustment of the parallelism of the grating surfaces of the two gratings.

3. The method for adjusting two back-to-back gratings to be parallel to each other according to claim 1, characterized in that: The adjustment device for adjusting the parallelism of the grating lines of the two back-to-back gratings also includes a rotating console. First, the angle of the incident light from the red light source is fixed and adjusted so that it is incident on the second grating B. The diffraction pattern is displayed on the receiving screen. Two or more diffraction spots are marked and the marks are connected to form a line. Then, the rotating console is rotated 180°. The light emitted by the red light source is incident on the first grating A. The diffraction pattern is also displayed on the receiving screen. Two or more diffraction spots are continuously marked and the marks are connected to form a second line. The first grating A is rotated by the telescopic slot rotation mechanism until the line connecting the two marks displayed on the receiving screen is parallel, thereby completing the adjustment of the parallelism of the grating lines of the two gratings.

4. An adjusting device for use in the method for adjusting two back-to-back gratings to be parallel to each other as claimed in any one of claims 1 to 3, characterized in that: The adjustment device includes a first grating A, a second grating B, a red light source, a receiving screen, a grating mounting plate, a pinhole diaphragm, a collimated light source, threaded structures respectively provided at the four corners of the grating, and a telescopic slot rotation mechanism for connecting and installing the grating and the grating mounting plate. The red light source and the grating mounting plate are placed on a work surface. The telescopic slot rotation mechanism is a two-section sleeve structure, one section of the tube body is fixed in the area of ​​the grating mounting plate for mounting the grating, and the other section of the tube body is adhered to the grating. The two sections of the tube body are respectively provided with mutually cooperating clamping structures. The first grating A and the second grating B are respectively mounted on the front and back sides of the grating mounting plate through the corresponding clamping structures of the two sections of the tube body of their respective telescopic slot rotation mechanisms. The collimated light source and pinhole diaphragm are located on one side of the grating mounting plate, and the receiving screen is located on the other side of the grating mounting plate.

5. The adjusting device used in the method for adjusting two back-to-back gratings to be parallel to each other according to claim 4, characterized in that: The adjusting device further comprises a rotating console, which is placed on a work surface, and the grating mounting plate is vertically placed on the flat top surface of the rotating console.

6. The adjusting device used in the method for adjusting two back-to-back gratings to be parallel to each other according to claim 4, characterized in that: The first grating A and the second grating B are both detachable gratings, and their angle rotation is achieved through their respective telescopic slot rotation mechanisms, and their respective yaw angles or pitch angles are adjusted through thread structures provided at the four corners.

7. The adjusting device used in the method for adjusting two back-to-back gratings to be parallel to each other according to claim 4 or 6, characterized in that: The two sections of the tube body of the telescopic slot rotation mechanism are sleeved by a clamping structure. The clamping structure is a plurality of clamping bosses provided on the inner wall of the tube section placed on the outer side and a plurality of clamping bosses provided on the outer periphery of the tube section placed on the inner side. The two sections of the tube body are connected in a ring after the positions of the plurality of clamping bosses correspond to each other. The clamping bosses provided on the outer periphery of the inner tube body are tightly attached to the inner wall of the outer tube body, and perform relative rotation under the action of external force. At the same time, after the two sections of the tube body are sleeved, there is still space for mutual telescopic movement.

8. The adjusting device used in the method for adjusting two back-to-back gratings to be parallel to each other according to claim 4, characterized in that: The receiving screen is a wall or a screen that can receive light spots.

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