Filter cloth mesh number measuring method and light diffraction measuring instrument

Abstract

The invention discloses a method for measuring the mesh number of filter cloth, which comprises the following steps: laser is emitted to the filter cloth to obtain a diffraction image of the filter cloth, the diffraction image comprises a plurality of diffraction bright spots which are periodically distributed, and each diffraction bright spot corresponds to one hole in the filter cloth; measuring a first distance between adjacent diffraction bright spots; the number of the filter cloth is calculated based on the first distance, a preset second distance and the wavelength of the laser through a preset target formula, the target formula is used for representing the function relation between the number of the filter cloth and the second distance and the function relation between the first distance and the wavelength of the laser, and the second distance is the distance between a receiving screen for receiving the diffraction image and the filter cloth. According to the method, the naked eye identification error caused by too small aperture in the filter cloth in a traditional visual inspection method is avoided, namely, the deviation between the mesh number of the filter cloth and the actual mesh number of the filter cloth is reduced, and the measurement accuracy of the mesh number of the filter cloth is improved.

Description

Technical Field

[0001] The invention belongs to the field of measurement technology, and in particular relates to a method for measuring the mesh count of a filter cloth and a light diffraction measuring instrument. Background Art

[0002] Filter cloth is a filter medium woven from natural or synthetic fibers. Common materials include cotton, linen, wool, silk, asbestos fiber, glass fiber, and certain synthetic fibers. Broadly speaking, filter cloth also includes metal mesh or nylon filter screens. The filter cloth industry has flourished in recent years, playing an increasingly important role in many fields, particularly environmental protection. The key parameter of filter cloth is mesh count, which is the number of holes per inch. The larger the mesh count, the smaller the pore size.

[0003] Currently, there are two methods for measuring the mesh count of filter cloth: (1) Densitometer method: Use a magnifying glass or microscope to observe with the naked eye how many grids there are within a length of 2.54 cm (i.e., one inch). The total number of grids is the mesh count of the filter cloth; (2) Direct observation method: Determine the mesh count of the filter cloth by directly observing the number and size of the holes in the screen with the naked eye. In other words, both of the above methods require the measurer to obtain the mesh count of the filter cloth through visual inspection. However, for filter cloth with a larger mesh count, that is, filter cloth with a smaller pore size, the visual inspection method can easily lead to a large deviation between the mesh count of the filter cloth obtained and the actual mesh count of the filter cloth.

[0004] Therefore, for filter cloths with larger mesh numbers, how to reduce the deviation between the measured mesh number of the filter cloth and the actual mesh number of the filter cloth is a problem that needs to be solved urgently. Summary of the Invention

[0005] To address the problem that visual inspection of filter cloth with a large mesh number may result in a large deviation between the mesh number of the filter cloth obtained and the actual mesh number of the filter cloth, the present invention provides a method for measuring the mesh number of the filter cloth. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for measuring the mesh count of a filter cloth, comprising: emitting a laser to the filter cloth to obtain a diffraction image of the filter cloth, wherein the diffraction image includes a plurality of periodically distributed diffraction bright spots, and each diffraction bright spot corresponds to a hole in the filter cloth;

[0007] measuring a first distance between adjacent diffraction spots;

[0008] Using a preset target formula, the mesh count of the filter cloth is calculated based on the first distance, the preset second distance and the wavelength of the laser. The target formula is used to characterize the functional relationship between the mesh count of the filter cloth and the second distance, the first distance and the laser wavelength. The second distance is the distance between the diffraction image and the filter cloth.

[0009] In one embodiment of the present invention, emitting laser light to a filter cloth to obtain a diffraction image of the filter cloth includes:

[0010] The laser emitter of the optical diffraction measuring instrument is used to emit laser light to the filter cloth, so that the laser light diffracts after passing through the filter cloth and forms a diffraction image on the receiving screen of the optical diffraction measuring instrument.

[0011] In one embodiment of the present invention, a target scale is pre-calibrated on the receiving screen of the optical diffraction measuring instrument;

[0012] Measuring the first distance between adjacent diffraction spots includes:

[0013] The first distance between adjacent diffraction bright spots is measured using the target scale on the receiving screen of the optical diffraction measuring instrument.

[0014] In one embodiment of the present invention, the target formula is expressed as:

[0015]

[0016] Wherein, M is the mesh number of the filter cloth, Δl is the first distance, λ is the wavelength of the laser, and L is the second distance.

[0017] In one embodiment of the present invention, the process of obtaining the target formula includes the following steps:

[0018] Based on the period length of the filter cloth and the mesh number of the filter cloth, a first formula is constructed, where the first formula is used to characterize the functional relationship between the period length of the filter cloth and the mesh number of the filter cloth;

[0019] Based on the second distance, the wavelength of the laser, the first distance, and the period length of the filter cloth, a second formula is constructed, where the second formula is used to characterize the functional relationship between the period length of the filter cloth and the second distance, the wavelength of the laser, and the first distance;

[0020] Based on the first formula and the second formula, a target formula is obtained.

[0021] In one embodiment of the present invention, obtaining a target formula based on the first formula and the second formula includes:

[0022] Combine the first formula and the second formula to obtain the target formula;

[0023] The expression of the first formula is:

[0024]

[0025] Where, d is the period length of the filter cloth, and M is the mesh number of the filter cloth;

[0026] The expression of the second formula is:

[0027]

[0028] Wherein, λ is the wavelength of the laser, L is the second distance, and Δl is the first distance;

[0029] The expression of the target formula is:

[0030]

[0031] Where M is the mesh size of the filter cloth.

[0032] Another aspect of the present invention provides a light diffraction measuring instrument, which is applied to the above-mentioned method for measuring the mesh count of filter cloth. The light diffraction measuring instrument comprises: a laser emitter, a lens group, a card slot and a receiving screen arranged in sequence along the optical path;

[0033] A laser emitter, used to emit laser light to the filter cloth, so that the laser light diffracts after passing through the filter cloth;

[0034] A lens group, used for shaping the laser light emitted by the laser transmitter into parallel light;

[0035] A slot for setting the filter cloth;

[0036] The receiving screen is used to receive the diffraction image formed by the laser diffraction after passing through the filter cloth and to measure the second distance between adjacent diffraction bright spots in the diffraction image.

[0037] In one embodiment of the present invention, the lens group includes a first short-focus lens and a second short-focus lens, and the first short-focus lens and the second short-focus lens have the same focal length.

[0038] In one embodiment of the present invention, the shape of the slot is annular.

[0039] In one embodiment of the present invention, the light diffraction measuring instrument further includes a lens barrel and a base;

[0040] The lens group, the card slot and the receiving screen are sequentially arranged inside the lens barrel;

[0041] The base is arranged below the lens barrel and is used for supporting the lens barrel.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The method for measuring the mesh number of the filter cloth provided in an embodiment of the present invention emits a laser to the filter cloth to obtain a diffraction image of the filter cloth, then measures the first distance between adjacent diffraction spots in the diffraction image, and finally uses a preset target formula to calculate the mesh number of the filter cloth based on the first distance, a preset second distance (i.e., the distance between the diffraction image and the filter cloth), and the wavelength of the laser. This avoids the naked eye recognition error caused by the small aperture in the filter cloth in the traditional visual inspection method, that is, reduces the deviation between the mesh number of the filter cloth and the actual mesh number of the filter cloth, and improves the measurement accuracy of the mesh number of the filter cloth.

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 1 is a schematic structural diagram of a light diffraction measuring instrument provided by an embodiment of the present invention;

[0046] Figure 2 This is a structural diagram of a card slot provided by an embodiment of the present invention;

[0047] Figure 3 It is a structural schematic diagram of a receiving screen provided by an embodiment of the present invention.

[0048] Figure 4 This is a flow chart of a method for measuring the mesh count of a filter cloth provided by an embodiment of the present invention;

[0049] Figure 5 Schematic diagram of a two-dimensional orthogonal grid of a filter cloth provided by an embodiment of the present invention;

[0050] Figure 6 Schematic diagram of a diffraction image of a filter cloth provided by an embodiment of the present invention;

[0051] Figure 7 This is a schematic diagram of a diffraction optical path of a laser provided by an embodiment of the present invention.

[0052] Reference numerals:

[0053] 100-Light diffraction measuring instrument;

[0054] 110-Laser transmitter; 1101-Laser transmitter power supply

[0055] 120-lens group; 1201-first short-focus lens, 1202-second short-focus lens;

[0056] 130-card slot;

[0057] 140-receiving screen

[0058] 150-lens tube;

[0059] 160-base. DETAILED DESCRIPTION

[0060] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a method for measuring the mesh number of a filter cloth proposed in accordance with the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] The aforementioned and other technical contents, features, and effects of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.

[0062] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0063] Before introducing the method for measuring the mesh number of the filter cloth provided by the present invention, the light diffraction measuring instrument provided by the embodiment of the present invention is first introduced. Figure 1 , Figure 1 It is a structural schematic diagram of a light diffraction measuring instrument provided by the invention.

[0064] like Figure 1 As shown, the optical diffraction measuring instrument 100 includes a laser emitter 110, a lens group 120, a card slot 130 and a receiving screen 140 arranged in sequence along the laser light path.

[0065] The laser emitter 110 is used to emit laser light toward the filter cloth, causing the laser light to diffract after passing through the filter cloth. It should be noted that based on the principle of laser diffraction, when the laser emitter power supply 1101 is turned on and the laser light 1101 emitted by the laser emitter 110 perpendicularly illuminates the filter cloth, the laser light 1101 undergoes Fraunhofer diffraction (i.e., far-field diffraction) due to the filter cloth's periodic structure. This ultimately forms a periodic diffraction image consisting of alternating light and dark patterns on the receiving screen 140 of the optical diffraction measuring instrument 100. The spacing of the diffraction spots in the diffraction image corresponds to the spacing and arrangement of the holes in the filter cloth; that is, each diffraction spot corresponds to a hole in the filter cloth.

[0066] The lens group 120 is used to shape the laser light emitted by the laser emitter into parallel light, which can also be understood as collimating the laser light 1101 emitted by the laser emitter.

[0067] It should be noted that although lasers are highly coherent and directional, the laser light 1101 emitted by most laser emitters still has a certain divergence angle. In other words, even if the initial beam of laser light 1101 appears straight, it will gradually diffuse into a non-parallel beam during propagation. Therefore, in order to improve the quality of the laser light 1101 beam and ensure a uniform light field irradiated on the filter cloth, thereby ensuring the clarity and measurability of the diffraction image of the filter cloth, a lens assembly 120 is required in front of the filter cloth to eliminate the divergence angle of laser light 1101 and shape the laser light 1101 into parallel light. This ensures that the light intensity and angle received by each hole in the filter cloth are consistent, thus avoiding distortion of the diffraction image caused by uneven light intensity distribution or differences in incident angle.

[0068] The lens group 120 includes a first short-focus lens 1201 and a second short-focus lens 1202 . The focal lengths of the first short-focus lens 1201 and the second short-focus lens 1202 are the same. For example, the focal lengths F of the first short-focus lens 1201 and the second short-focus lens 1202 are both equal to 4.5 cm.

[0069] Furthermore, in order to ensure that the beam of laser light 1101 passing through the first short-focus lens 1201 and the second short-focus lens 1202 is neither magnified nor reduced, but only the divergence angle of laser light 1101 is changed, in an embodiment of the present invention, in addition to requiring the first and second short-focus lenses 1201 to have the same focal length, the distance between the first and second short-focus lenses 1201, 1202 must also be equal to the sum of their focal lengths, thereby constructing the lens assembly 120 into a 1:1 collimation system. For example, when the focal lengths F of the first and second short-focus lenses 1201, 1202 are both 4.5 cm, the distance between the first and second short-focus lenses 1201, 1202 is 4.5 cm + 4.5 cm = 9 cm.

[0070] Specifically, the laser 1101 is first focused by the first short-focus lens 1201 and then shaped into parallel light by the second short-focus lens 1202 .

[0071] The card slot 130 is used to set the filter cloth.

[0072] It should be noted that since the filter cloth is a soft material and is prone to wrinkles or loosening, in order to avoid the diffraction image distortion caused by local bending or unevenness of the filter cloth, in the embodiment of the present invention, the filter cloth can be set in the annular groove 130 (the annular groove 130 can be seen in FIG. Figure 2Specifically, an annular clamping groove 130 can be used to flatten the filter cloth by clamping, thereby preventing distortion of the diffraction image caused by local bending or unevenness of the filter cloth. Furthermore, because the annular clamping groove 130 exhibits excellent axial symmetry, it facilitates alignment with the laser 1101, thereby reducing optical path deviations caused by eccentricity or tilt, thereby improving the measurability of the filter cloth mesh count. Furthermore, since the filter cloth has a two-dimensional periodic structure (i.e., holes are arranged in both the horizontal and vertical directions), the annular clamping groove 130 does not restrict the filter cloth's placement direction. Therefore, the use of the annular clamping groove 130 can accommodate the acquisition of diffraction images in any direction.

[0073] The receiving screen 140 is used to receive a diffraction image formed by the laser light diffracting after passing through the filter cloth and to measure a second distance between adjacent diffraction spots in the diffraction image.

[0074] In order to facilitate the measurement of the second distance between adjacent diffraction spots in the diffraction image, in an embodiment of the present invention, a target scale can be pre-calibrated on the receiving screen 140, so that when it is necessary to measure the second distance between adjacent diffraction spots in the diffraction image, the diffraction image is directly compared with the target scale to obtain the second distance between adjacent diffraction spots.

[0075] For example, see Figure 3 , Figure 3 This is a schematic diagram of the structure of a receiving screen provided by the invention. Figure 3 It can be seen that the receiving screen 140 is pre-calibrated with target scales of 300, 200 and 100.

[0076] In one possible embodiment, the target scale can be a set of reference scale lines calibrated based on the spacing of the diffraction spots corresponding to the known filter cloth mesh number, that is, when the spacing of the diffraction spots is read out through the target scale on the receiving screen 140, the corresponding filter cloth mesh number can be obtained.

[0077] In order to effectively prevent the influence of external vibration and air flow disturbance on the optical path, in the embodiment of the present invention, Figure 1 As shown, the optical diffraction measuring instrument 100 may further include a lens barrel 150 and a base 160 . The base 160 is disposed below the lens barrel 150 to support the lens barrel 150 .

[0078] Specifically, lens assembly 120, card slot 130, and receiving screen 140 are all enclosed in a lens barrel 150, thereby reducing diffraction image drift or distortion caused by environmental factors. Furthermore, because lens barrel 150 effectively blocks external stray light from entering the area of receiving screen 140, it also prevents external stray light from affecting the diffraction image, ensuring the accuracy of diffraction image measurement.

[0079] Furthermore, considering that the lens barrel 150 itself is long and heavy, in order to ensure the stability of the lens barrel 150, a base 160 needs to be provided under the lens barrel 150 to provide a stable support therefor.

[0080] After introducing the structure of the optical diffraction measuring instrument provided by the embodiment of the present invention, Figure 4 , introduces the method for measuring the mesh number of the filter cloth provided by the embodiment of the present invention, please refer to Figure 4 , the method comprises the following steps:

[0081] S1: emitting laser light to the filter cloth to obtain a diffraction image of the filter cloth. The diffraction image includes a plurality of periodically distributed diffraction spots, and each diffraction spot corresponds to a hole in the filter cloth.

[0082] Specifically, the laser emitter 110 of the optical diffraction measuring instrument 100 may be used to emit laser light to the filter cloth, so that the laser light is diffracted after passing through the filter cloth, and a diffraction image is formed on the receiving screen 140 of the optical diffraction measuring instrument 100 .

[0083] It should be noted that this step is based on the principle of laser diffraction. When laser light is vertically irradiated on the filter cloth, due to the filter cloth's periodic structure, the laser light undergoes Fraunhofer diffraction (i.e., far-field diffraction), forming a periodic diffraction pattern of alternating light and dark on the receiving screen of the optical diffraction measuring instrument. The spacing of the diffraction spots in the diffraction image corresponds to the spacing and arrangement of the holes in the filter cloth, meaning each diffraction spot corresponds to a hole in the filter cloth.

[0084] It should be noted that the filter cloth can be viewed as a two-dimensional orthogonal grid, for example Figure 5 As shown, Figure 5 Schematic diagram of a two-dimensional orthogonal grid of a filter cloth provided by an embodiment of the present invention, such as Figure 5 As shown, each unit is a rectangular hole with a period length of d1 along the x-direction, with a total of N1 columns; a period length of d2 along the y-direction, with a total of N2 columns. The period length of the filter cloth is also called the grid spacing or spatial period, which refers to the distance between the centers of two adjacent holes on the filter cloth. Further, when a beam of parallel light with a wavelength of λ is incident on Figure 5 When the diffraction pattern is on a two-dimensional orthogonal grid in the image, the Fraunhofer principle shows that the diffraction pattern can be as follows: Figure 6 The two-dimensional diffraction image is shown.

[0085] In addition, since the filter cloth has an identical structure in the x-direction and the y-direction, that is, the filter cloth has the same spacing (periodic structure) in the two orthogonal directions (i.e., the transverse and longitudinal directions) in its plane, the period length d1 in the x-direction is the same as the period length d2 in the y-direction, that is, in the present invention, the period length of the filter cloth can be uniformly expressed as d. It can be understood that since the two-dimensional diffraction image is obtained based on the filter cloth, then Figure 6Each diffraction spot in the two-dimensional diffraction image corresponds to Figure 5 A hole in the filter cloth.

[0086] S2: Measure the first distance between adjacent diffraction spots.

[0087] Specifically, the first distance between adjacent diffraction bright spots is measured using the target scale on the receiving screen 140 of the optical diffraction measuring instrument 100 .

[0088] S3: Using a preset target formula, the mesh count of the filter cloth is calculated based on the first distance, the preset second distance, and the wavelength of the laser. The target formula is used to characterize the functional relationship between the mesh count of the filter cloth and the second distance, the first distance, and the laser wavelength. The second distance is the distance between the diffraction image and the filter cloth.

[0089] It is understood that the distance between the diffraction image and the filter cloth, i.e., the second distance, is the same as the distance between the card slot and the receiving screen of the optical diffraction measuring instrument. Specifically, when measuring the mesh count of the filter cloth using the optical diffraction measuring instrument, the second distance is known and does not need to be measured. It should be noted that after adjusting the distance between the card slot and the receiving screen of the optical diffraction measuring instrument, it is necessary to remeasure the distance between the card slot and the receiving screen when measuring the mesh count of the filter cloth using the optical diffraction measuring instrument. This re-determined distance between the card slot and the receiving screen will be used as the second distance.

[0090] Among them, the expression of the target formula is:

[0091]

[0092] Wherein, M is the mesh number of the filter cloth, Δl is the first distance, λ is the wavelength of the laser, L is the second distance, and the unit of 0.0254 is mm, which means the unit length is one inch.

[0093] Specifically, after obtaining the first distance between adjacent diffraction spots, the first distance, the known laser wavelength, and the second distance are substituted into the above target formula to calculate the mesh count M of the filter cloth.

[0094] It should be noted that, in the embodiment of the present invention, the target formula can be derived in the following way:

[0095] Step (1): Based on the period length of the filter cloth and the mesh number of the filter cloth, a first formula is constructed, where the first formula is used to characterize the functional relationship between the period length of the filter cloth and the mesh number of the filter cloth.

[0096] Specifically, the expression of the first formula is:

[0097]

[0098] Where d is the period length of the filter cloth, 0.0254 is in mm, which means the unit length is one inch, and M is the mesh size of the filter cloth.

[0099] It should be noted that since the mesh count of the filter cloth is defined as the number of holes on the filter cloth per inch of length, and the period length of the filter cloth refers to the distance between the holes on the filter cloth, the mesh count M of the filter cloth × the period length d of the filter cloth is equal to 1 inch.

[0100] Step (2): Based on the second distance, the wavelength of the laser, the first distance and the period length of the filter cloth, a second formula is constructed, and the second formula is used to characterize the functional relationship between the period length of the filter cloth and the second distance, the wavelength of the laser and the first distance.

[0101] Specifically, the expression of the second formula is:

[0102]

[0103] Wherein, λ is the wavelength of the laser, L is the second distance, and Δl is the first distance.

[0104] It should be noted that the second formula can be derived in the following way:

[0105] For example, Figure 7 As shown, taking the x direction of the two-dimensional grating as an example for derivation, the diffraction angle in the x direction of the grating equation satisfies the third formula:

[0106] Among them, the expression of the third formula is:

[0107] d1sinθ=mλ

[0108] Where m is a positive integer, representing the mth order diffraction spot, d1 is the period length of the filter cloth in the x direction, θ is the diffraction angle of the laser, and λ is the wavelength of the laser.

[0109] Since Fraunhofer diffraction is far-field diffraction, the distance between the diffraction image and the filter cloth, that is, the second distance L, is much larger than d1, and the fourth formula can be obtained:

[0110] Among them, x i is the position of the m-th order diffraction spot on the receiving screen.

[0111] Furthermore, by substituting the fourth formula into the third formula, we can get the fifth formula. Specifically, the expression of the fifth formula is

[0112] Similarly, for the m+1th order diffraction spot, the diffraction angle in the x-direction of the grating equation satisfies the sixth formula, which is expressed as follows:

[0113]

[0114] Among them, x i+1 is the position of the m+1th order diffraction spot on the receiving screen;

[0115] Finally, subtract the fifth formula from the sixth formula to get the second formula.

[0116] Step (3): Based on the first formula and the second formula, obtain the target formula.

[0117] Specifically, the first formula and the second formula are combined to obtain the target formula.

[0118] The expression of the second formula is:

[0119]

[0120] Wherein, λ is the wavelength of the laser, L is the second distance, and Δl is the first distance;

[0121] From the expressions of the first formula and the second formula above, we can know that after combining the first formula and the second formula, we can get The expression of the target formula is obtained as

[0122] To sum up, the light emission module provided by the embodiment of the present invention provides a method for measuring the mesh number of the filter cloth, which emits laser to the filter cloth to obtain a diffraction image of the filter cloth, and then measures the first distance between adjacent diffraction spots in the diffraction image. Finally, a preset target formula is used to calculate the mesh number of the filter cloth based on the first distance, the preset second distance (that is, the distance between the diffraction image and the filter cloth) and the wavelength of the laser, thereby avoiding the naked eye recognition error caused by the small aperture in the filter cloth in the traditional visual inspection method, that is, reducing the deviation between the mesh number of the filter cloth and the actual mesh number of the filter cloth, and improving the measurement accuracy of the mesh number of the filter cloth.

[0123] In the several embodiments provided herein, it should be understood that the apparatus and method disclosed herein can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the module division is merely a logical functional division. In actual implementation, other division methods may be used. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not implemented.

[0124] In addition, the functional modules in various embodiments of the present invention may be integrated into a single processing module, each module may exist physically separately, or two or more modules may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or hardware plus software functional modules.

[0125] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for measuring the mesh count of a filter cloth, characterized in that: include: emitting a laser to the filter cloth to obtain a diffraction image of the filter cloth, wherein the diffraction image includes a plurality of periodically distributed diffraction bright spots, each of which corresponds to a hole in the filter cloth; measuring a first distance between adjacent diffraction bright spots; The mesh count of the filter cloth is calculated based on the first distance, the preset second distance, and the wavelength of the laser using a preset target formula. The target formula is used to characterize the functional relationship between the mesh count of the filter cloth and the second distance, the first distance, and the laser wavelength. The second distance is the distance between the receiving screen that receives the diffraction image and the filter cloth.

2. The method for measuring the mesh number of filter cloth according to claim 1, characterized in that: The step of emitting laser light to the filter cloth to obtain a diffraction image of the filter cloth comprises: The laser emitter of the optical diffraction measuring instrument is used to emit laser light to the filter cloth, so that the laser light is diffracted after passing through the filter cloth, and the diffraction image is formed on the receiving screen of the optical diffraction measuring instrument.

3. The method for measuring the mesh number of filter cloth according to claim 2, characterized in that: The receiving screen of the optical diffraction measuring instrument is pre-calibrated with a target scale; Measuring a first distance between adjacent diffraction spots includes: The first distance between adjacent diffraction bright spots is measured using the target scale on the receiving screen of the light diffraction measuring instrument.

4. The method for measuring the mesh number of filter cloth according to claim 1, characterized in that: The expression of the target formula is: Wherein, M is the mesh number of the filter cloth, Δl is the first distance, λ is the wavelength of the laser, and L is the second distance.

5. The method for measuring the mesh number of filter cloth according to claim 1, characterized in that: The process of obtaining the target formula includes the following steps: Based on the period length of the filter cloth and the mesh number of the filter cloth, constructing a first formula for characterizing the functional relationship between the period length of the filter cloth and the mesh number of the filter cloth; Constructing a second formula based on the second distance, the wavelength of the laser, the first distance, and the period length of the filter cloth, wherein the second formula is used to characterize the functional relationship between the period length of the filter cloth and the second distance, the wavelength of the laser, and the first distance; The target formula is obtained based on the first formula and the second formula.

6. The method for measuring the mesh number of filter cloth according to claim 5, characterized in that: The step of obtaining the target formula based on the first formula and the second formula includes: Combining the first formula and the second formula to obtain the target formula; The expression of the first formula is: Wherein, d is the period length of the filter cloth, and M is the mesh number of the filter cloth; The expression of the second formula is: Wherein, λ is the wavelength of the laser, L is the second distance, and Δl is the first distance; The expression of the target formula is: Wherein, M is the mesh number of the filter cloth.

7. A light diffraction measuring instrument, characterized in that: A method for measuring the mesh count of a filter cloth according to any one of claims 1 to 6, comprising: a laser emitter, a lens group, a card slot, and a receiving screen arranged in sequence along an optical path; The laser emitter is used to emit laser light to the filter cloth, so that the laser light is diffracted after passing through the filter cloth; The lens group is used to shape the laser light emitted by the laser emitter into parallel light; The card slot is used to set the filter cloth; The receiving screen is used to receive a diffraction image formed by diffraction of the laser light after passing through the filter cloth and to measure a second distance between adjacent diffraction bright spots in the diffraction image.

8. The optical diffraction measuring instrument according to claim 7, characterized in that: The lens group includes a first short-focus lens and a second short-focus lens, and the first short-focus lens and the second short-focus lens have the same focal length.

9. The optical diffraction measuring instrument according to claim 7, characterized in that: The shape of the slot is annular.

10. The light diffraction measuring instrument according to claim 7, characterized in that: The light diffraction measuring instrument also includes a lens barrel and a base; The lens group, the card slot and the receiving screen are sequentially arranged inside the lens barrel; The base is arranged below the lens barrel and is used for supporting the lens barrel.

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