Light path system for water quality analyzer and water quality analyzer comprising light path system

Abstract

The invention discloses a light path system for a water quality analyzer and the water quality analyzer comprising the light path system.The light path system comprises a preceding-stage light path, a light splitting piece, a reference light path detection assembly and a detection light path detection assembly; the front-stage light path comprises a light source, a light filter, a first lens, a light homogenizing column, a second diaphragm and a second lens which are collinear with the optical axis and are sequentially arranged; the peripheral surface of the light uniformizing column is a frosted surface; the second diaphragm is a spiral step diaphragm and is provided with a light through hole, the inner wall of the light through hole is provided with an extinction channel which spirally extends in the axial direction, and the extinction channel is used for eliminating stray light. The light path system uses the first lens to converge light beams into the uniform light column, so that all light source emergent points are normalized in a standard mode and then reach the second lens through the second diaphragm. The frosted design of the outer side wall of the light uniformizing column, the threaded extinction design of the diaphragm and the double-lens design are combined, so that stray light and the interference effect of the stray light are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of water quality testing equipment, and more specifically to an optical path system for a water quality analyzer and a water quality analyzer including the optical path system. Background Technology

[0002] A water quality analyzer is an instrument that can rapidly and quantitatively analyze the concentration of various pollutants in water. For example, patent document CN 113418880 A discloses an ultraviolet-visible light water quality analyzer, including a housing with a display screen, a light shield, and a printer; a light source chamber located inside the housing, which generates incident light through the display screen; a monochromator located inside the housing to receive the incident light generated by the light source chamber, and to form outgoing light through reflection, converging, and grating diffraction; and a sample chamber located inside the housing to receive the outgoing light generated by the monochromator. By applying the outgoing light to the sample holder in the sample chamber, the content of the measured sample can be displayed on the display screen. A multi-parameter water quality analyzer is an analyzer that can quantitatively or qualitatively analyze multiple pollutants in water, such as ammonia nitrogen, heavy metals, and COD.

[0003] The optical path structure is a crucial component of a water quality analyzer, determining the accuracy of the analytical results. For example, patent document CN116087120 A discloses an optical system for improving the accuracy of water quality detection, including a pre-stage optical path, a beam splitter, a reference detection optical path, and a transmission detection optical path. The light in the pre-stage optical path is split by the beam splitter into a first beam for reflection into the reference detection optical path and a second beam for forward transmission into the transmission detection optical path. The first beam and the second beam are mirror-symmetrical through the beam splitter, and the exit pupils of the light in the pre-stage optical path are smaller than the entrance pupils of the light in the reference detection optical path and the transmission detection optical path, so that the first beam and the second beam form a mapping relationship.

[0004] However, in practical applications, it has been found that the optical path structure of existing water quality analyzers is difficult to effectively overcome stray light and its interference effect, and the detection accuracy needs to be further improved. Summary of the Invention

[0005] This application provides an optical path system for a water quality analyzer, which can effectively reduce stray light and stray light interference effects, thereby improving detection accuracy.

[0006] The optical path system for a water quality analyzer includes a pre-amplifier optical path, a beam splitter, a reference optical path detection component, and a detection optical path detection component. The pre-amplifier optical path includes a light source, a filter, a first lens, a light-diffusing column, a second aperture, and a second lens arranged sequentially along the optical axis. The outer peripheral surface of the light-diffusing column is frosted. The second aperture is a spiral stepped aperture with a light-passing hole. The inner wall of the light-passing hole has an extinction channel extending spirally along the axial direction, which is used to eliminate stray light.

[0007] In this application, the outer peripheral surface of the uniform light column is frosted to prevent stray light from entering the uniform light column; the aperture is a spiral stepped aperture with a spiral stepped extinction channel formed on the inner wall of the light passage. The light beam emitted from the uniform light column enters the light passage of the aperture, and most of the light beam passes parallel through the light passage to reach the second lens. A small portion of the stray light beam is eliminated in the extinction channel through reflection, diffuse reflection, scattering, absorption, etc., thus achieving the purpose of eliminating stray light.

[0008] This optical system uses a first lens to focus the light beam into a uniform light column, thus standardizing the emission points of all light sources. The beam then enters the aperture of the second aperture and reaches the second lens. The combination of the frosted design of the outer wall of the uniform light column, the spiral extinction design of the aperture, and the double-lens design effectively reduces stray light and its interference effects.

[0009] When the instrument's status changes, the light source status also changes. This application utilizes beam splitter technology to further improve system stability and measurement accuracy. The light rays converged by the second lens are split into two paths by the beam splitter. One path, transmitted light, directly enters the measurement chamber as the measuring light, while the other path, refracted light, enters the reference chamber as the reference light. The light entering the reference chamber serves as the light energy reference, allowing for real-time adjustment of the instrument's zeroing state and thus real-time correction of the built-in ammonia nitrogen calibration line, ensuring the accuracy of each measurement. This can be used for real-time monitoring of the instrument's status and to compensate for the influence of light source changes due to instrument status and environmental conditions.

[0010] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0011] Optionally, the beam splitter is installed at a 45° angle. The light beam from the second lens reaches the beam splitter, with the transmitted beam serving as the detection beam and the reflected beam serving as the reference beam. The optical axes of the detection beam and the reference beam are perpendicular to each other. The measurement chamber or sample chamber is located in the optical path of the detection beam.

[0012] Optionally, the detection optical path detection component includes a third lens and a detection optical sensor.

[0013] Optionally, the reference optical path detection component includes a fourth lens and a reference optical sensor.

[0014] As an alternative to the spiral stepped aperture, the inner wall of the light-transmitting hole is machined into a threaded hole, and the gap between adjacent threads is the extinction channel.

[0015] As another alternative to the spiral stepped aperture, a coaxially extending spiral ring is embedded in close to the inner wall of the light-transmitting hole, and the gap between adjacent rings is the extinction channel.

[0016] Optionally, the optical path system further includes an assembly sleeve, in which the first lens and the second lens are respectively fixedly installed at both axial ends of the assembly sleeve; the beam leveling column and the second aperture are coaxially distributed within the assembly sleeve. The first lens, the beam leveling column, the second aperture, and the second lens are integrated and assembled within the assembly sleeve to form an independent assembly, which facilitates processing and assembly.

[0017] Optionally, the assembly sleeve is a two-section combined sleeve, including a first sleeve and a second sleeve. The first sleeve and the second sleeve have a free end and a connecting end, respectively, and are assembled and connected by their respective connecting sections. The first lens is fixed to the free end port of the first sleeve, and the second lens is fixed to the free end port of the second sleeve. The light-transmitting hole is distributed inside the second sleeve and near one end of the second lens, and the second aperture is integrated inside the second sleeve.

[0018] Optionally, the connecting ends of the first sleeve and the second sleeve are threaded together.

[0019] Optionally, the free end of the second sleeve also has a radial flange for assembly.

[0020] Optionally, the first lens is a biconvex lens. This reduces planar interference noise.

[0021] Optionally, it also includes a first aperture collinear with the optical axis and disposed between the filter and the first lens, wherein the first aperture is the spiral stepped aperture. That is, the first aperture also adopts a spiral stepped aperture, and the second aperture has a light-transmitting hole, the inner wall of which has an extinction channel extending spirally along the axial direction. The extinction channel is used to eliminate stray light, and the implementation of the extinction channel is the same as that of the first aperture.

[0022] Optionally, the light-transmitting holes of the first and second apertures are both extended holes of equal diameter.

[0023] The first and second apertures are preferably constructed by directly machining the inner wall of the light-transmitting hole into a threaded hole.

[0024] Optionally, it also includes a light source mounting base and a filter mounting base, which are rotating bases that can be driven synchronously; light sources of different wavelengths are mounted in a circular array around the rotation axis of the light source mounting base, and the filters are mounted in a one-to-one correspondence with the light sources in the filter mounting base; rotating the light source mounting base and the filter mounting base allows selection of any one of the light sources and the corresponding filter for use in the pre-stage optical path.

[0025] Optionally, the light source mounting base and the filter mounting base are coaxially and fixedly connected.

[0026] Optionally, the light source mounting base and the filter mounting base are driven by the same motor, which can be a stepper motor.

[0027] Optionally, the filter mounting base has axial through holes arranged in a ring array with its rotation axis as the center, the filter is installed in the corresponding axial through hole, and the light source paired with the filter extends into the axial through hole.

[0028] Optionally, the axial through hole is divided into small hole segments and large hole segments with different diameters along the axial direction, and a limiting step surface is formed at the junction; the light source extends into the small hole segment, the filter is placed at the limiting step surface, and the first aperture is tightly fitted with the large hole segment and limits the filter.

[0029] In this scheme, light sources of different wavelengths are paired with corresponding filters in a fixed manner. The wavelength transmitted by the filter is consistent with the wavelength of the corresponding light source. By selecting different light sources, different wavelengths of detection light can be obtained, which can meet the needs of multi-parameter detection of multi-water quality analyzers.

[0030] Optionally, it also includes a light source mounting base and a filter mounting base, wherein the light source mounting base is a fixed base and the filter mounting base is a rotating base; the light source is a full-spectrum light source, which is mounted on the light source mounting base and can transmit filters of different wavelengths, which are mounted in a ring array around the rotation axis of the filter mounting base; the filter mounting base is rotated to select any filter to be paired with the light source and used in the pre-stage optical path.

[0031] In this scheme, the light source is a full-spectrum light source. Different filters can transmit different wavelengths. By selecting the filters, different wavelengths of detection light can be obtained to achieve the purpose of multi-parameter detection of water quality analyzer.

[0032] In this application, the light source and filter are fixedly installed with 0-angle incident light, which improves the wavelength blue shift problem caused by installation.

[0033] This application also provides a water quality analyzer including the aforementioned optical path system. Apart from the optical path system, other components of the water quality analyzer can be components from existing water quality analyzer models sold by the applicant.

[0034] Compared with the prior art, this application has at least one of the following beneficial effects: (1) The optical path system uses a first convex lens to focus the light beam into a uniform light column of a specific size, so that the emission points of all light sources are standardized and then enter the self-developed threaded stepped aperture to reach the second convex lens. The combination of the frosted design of the outer wall of the uniform light column, the threaded stepped aperture design, and the double convex lens technology effectively reduces stray light and the interference effect of stray light.

[0035] (2) The light source and filter are fixedly installed with 0-angle incident, which improves the wavelength blue shift problem caused by installation.

[0036] (3) The beam splitter technology effectively improves system stability and measurement accuracy. The light rays passing through the first set of biconvex lenses are split into two beams by the beam splitter. One beam enters the measurement chamber directly as the measurement light, while the other beam enters the reference chamber as the reference light. This reference light is used to monitor the instrument status in real time and to compensate for the influence of the light source on the instrument status and environmental conditions. Since the light state changes when the instrument status changes, the light entering the reference chamber serves as the light energy reference. This allows for real-time adjustment of the instrument's zeroing state and real-time correction of the built-in ammonia nitrogen caliper, ensuring the accuracy of each measurement.

[0037] After optimization through the above combination of technologies, the instrument's measurement accuracy error is less than 3%, and the data repeatability is less than 2%. Furthermore, because the optical path system of this application reduces stray light, maintains a fixed spot size, and eliminates blue shift in the output wavelength compared to previous systems, the production efficiency of the detector is increased fourfold, and the pass rate rises from 80% to over 95%. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the planar structure of an optical path system according to one embodiment of this application.

[0039] Figure 2 for Figure 1 The optical path diagram of the optical path system shown is shown.

[0040] Figure 3 for Figure 1 The diagram shows a three-dimensional structure of the optical path system.

[0041] Figure 4 This is a schematic diagram of the planar structure of the optical path system according to another embodiment of this application.

[0042] Figure 5 for Figure 4 The diagram shows a three-dimensional structure of the optical path system.

[0043] Figure 6 This is a schematic diagram of the assembly between the first lens, the light-diffusing column, the second aperture, and the second lens.

[0044] Figure 7 for Figure 6 Assembly diagram with the uniform light column removed.

[0045] Figure 8 This is a schematic diagram illustrating the parameters related to the aperture.

[0046] Figure 9 The image shows the 420nm light spot before the optical path improvement.

[0047] Figure 10 The image shows the 420nm light spot result after the optical path improvement.

[0048] Figure 11 The image shows the 620nm light spot before the optical path improvement.

[0049] Figure 12 The image shows the 620nm light spot result after the optical path improvement.

[0050] Figure 13 This is a comparison chart of test data from the old and new platforms at a wavelength of 420nm.

[0051] Figure 14 This is a comparison chart of test data from the old and new platforms at a wavelength of 470nm.

[0052] Figure 15 This is a comparison chart of test data from the old and new platforms at a wavelength of 620nm.

[0053] The reference numerals in the figure are as follows: 1. Light source mounting base; 2. Filter mounting base; 3. Light source; 4. Filter; 5. First aperture; 6. First lens; 7. Beam leveling column; 8. Second aperture; 9. Second lens; 10. Beam splitter; 11. Third lens; 12. Detection light sensor; 13. Measurement chamber; 14. Fourth lens; 15. Reference light sensor; 16. Motor; 17. First support; 18. Sample tube; 19. Assembly sleeves (19a. First sleeve, 19b. Second sleeve, 19c. Axial hole, 19d. First limiting step, 19e. Light passage hole, 19f. Second limiting step, 19g. Radial flange); 20. Second support. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0056] like Figures 1-5 As shown, an optical path system for a water quality analyzer includes a pre-amplifier optical path, a beam splitter, a reference optical path detection component, and a detection optical path detection component. The pre-amplifier optical path includes a light source 3, a filter 4, a first lens 6, a uniform beam 7, a second aperture 8, and a second lens 9 arranged sequentially and coaxially. The uniform beam 7 is a solid uniform beam with a frosted outer surface. The second aperture 8 is a spiral stepped aperture. Specifically, the second aperture 8 has a light-passing hole, and the inner wall of the light-passing hole has an extinction channel extending spirally along the axial direction. The extinction channel is used to eliminate stray light. The outer surface of the uniform beam is frosted, preventing external stray light from entering the uniform beam. The light beam emitted from the uniform beam enters the light-passing hole of the aperture. Most of the light passes parallel through the hole to reach the second lens, while a small portion of the stray beam is eliminated through reflection, diffuse reflection, scattering, and absorption within the spirally extending extinction channel, thus achieving the purpose of eliminating stray light.

[0057] Beam splitter 10 is installed at a 45° angle in the output optical path of the second lens. The light beam from the second lens 8 is transmitted and reflected after reaching beam splitter 10. The transmitted beam serves as the detection beam, and the reflected beam serves as the reference beam. The optical axes of the detection beam and the reference beam are perpendicular to each other. Measurement chamber 13 is located in the optical path of the detection beam. The detection optical path detection assembly includes a third lens 11 and a detection optical sensor 12; the reference optical path detection assembly includes a fourth lens 14 and a reference optical sensor 15.

[0058] In some embodiments, the optical path system further includes a first aperture 5, which is disposed between the filter 4 and the first lens 5. The first aperture 5 has a light-transmitting hole, and the inner wall of the light-transmitting hole has an extinction channel extending spirally along the axial direction. The extinction channel is used to eliminate stray light. The light beam filtered by the filter enters the first aperture for initial extinction.

[0059] In one embodiment of the spiral stepped aperture, the inner wall of the aperture's light-transmitting hole is machined into a threaded hole, with the gap between adjacent threads forming an extinction channel. In another embodiment of the spiral stepped aperture, coaxially extending spiral rings are embedded close to the inner wall of the aperture's light-transmitting hole, with the gap between adjacent rings forming an extinction channel. Figures 1-5 In all the embodiments shown, the first method, namely the threaded through-hole form, is used. The light-passing hole of the first aperture 4 is a first threaded through-hole, allowing light from the filter to pass through, and the first threaded through-hole is collinear with the optical axis. The light-passing hole of the second aperture 8 is a second threaded through-hole, allowing light from the uniform light column to pass through, and the second threaded through-hole is collinear with the optical axis.

[0060] To facilitate the assembly of optical path components, in some embodiments, the optical path system further includes an assembly sleeve 19, see [link to documentation]. Figure 6 and Figure 7 The first lens 6 and the second lens 9 are respectively fixedly installed in the axial end ports of the assembly sleeve 19; the light-diffusing column 7 and the second aperture 8 are coaxially distributed in the assembly sleeve 19. After assembly, the first lens, the light-diffusing column, the second aperture, and the second lens are integrated into the assembly sleeve to form an independent assembly, which is convenient for processing and assembly.

[0061] In some embodiments, the mounting sleeve 19 is a two-section combined sleeve, including a first sleeve 19a and a second sleeve 19b. The first sleeve and the second sleeve each have a free end and a connecting end, and are assembled and connected through their respective connecting sections. The first lens 6 is fixedly mounted in the free end port of the first sleeve 19a, and the second lens 9 is fixedly mounted in the free end port of the second sleeve 19b. The second aperture 8 is integrated into the second sleeve 19b, that is, an axially penetrating threaded through hole (i.e., the second threaded through hole) is provided directly in the second sleeve and near the second lens 9. After assembly, the two ends of the threaded through hole respectively contact and engage with the light-diffusing column and the second lens. The connecting ends of the first sleeve and the second sleeve are threadedly connected, or an interference fit can be used.

[0062] To facilitate the assembly of the uniform light column, in some embodiments, the assembly sleeve 19 has an axial hole 19c for accommodating the uniform light column 7. The axial hole is a light-perforated hole coaxially connected to the second threaded through hole. Part of the axial hole 19c is located in the first sleeve, and part is located in the second sleeve. The diameter of the axial hole is larger than the diameter of the second threaded through hole, and a first limiting step 19d is formed at the connection. There is a light-passing hole 19e with a smaller diameter than the axial hole between the axial hole and the first lens 6, and a second limiting step 19f is formed at the connection. After the uniform light column is assembled into the assembly sleeve, the first limiting step and the second limiting step limit the axial ends of the uniform light column, respectively. To prevent the uniform light column from breaking due to hard collision between the components, a silicone gasket with a certain elasticity (not shown in the figure) can be set between the uniform light column and the second limiting step. The light converged by the first lens 6 reaches the uniform light column 7 through the light-passing hole 19e, then enters the spiral stepped aperture (second aperture 8) formed by the second threaded through hole, and finally exits through the second lens 9.

[0063] In some embodiments, the free end of the second sleeve 19b also has a radial flange 19g for assembly, facilitating the assembly and connection of the next-level components.

[0064] In some implementations, the first lens in the pre-amplifier optical path is a biconvex lens, the second lens is a plano-convex lens, and the third and fourth lenses are biconvex lenses in the detection optical path.

[0065] To facilitate the installation of the light source and filter, the optical path system also includes a light source mounting base 1 and a filter mounting base 2. In a first embodiment, the light source mounting base 1 and the filter mounting base 2 are synchronously driven rotating bases, see [link to relevant documentation]. Figures 1-3 Light sources 3 of different wavelengths are arranged in a circular array around the rotation axis of the light source mounting base 1. Filters 4 are mounted in a one-to-one correspondence with the light sources 3 on filter mounting base 2, and the wavelengths that the filters can transmit are consistent with the wavelengths of the corresponding light sources. By rotating the light source mounting base 1 and the filter mounting base 2, any light source and its corresponding filter can be selected for use in the pre-amplifier optical path. The light source mounting base 1 and the filter mounting base 2 are coaxially and fixedly connected. The light source mounting base and the filter mounting base are driven by the same motor 16. In this scheme, light sources of different wavelengths and their corresponding filters form a fixed pair, and different wavelengths of detection light can be obtained by selecting different light sources, which can meet the needs of multi-parameter detection in multi-water quality analyzers.

[0066] In some embodiments, the filter mounting base 2 has axial through holes arranged in a ring array around its rotation axis. The filter 4 is correspondingly installed within these axial through holes, and a light source paired with the filter also extends into these axial through holes. The axial through holes are divided into small-diameter segments and large-diameter segments along the axial direction, and a limiting step surface is formed at the junction. The filter is placed at the limiting step surface, and the light source extends into the small-diameter segment from one side of the filter. The first aperture 5 is tightly fitted to the large-diameter segment from the other side of the filter via its mounting hardware. One side of the axial end face of the filter is limited by the limiting step surface, and the other side is limited by the mounting hardware of the assembled first aperture. Figure 1 and Figure 2 In this configuration, to facilitate the display of the filter, the first aperture is not fully installed. The mounting hardware for the first aperture can be a cylindrical structure, with a first threaded through-hole axially penetrating the cylindrical structure. The outer circumferential surface of the cylindrical structure is threadedly connected to the axial through-hole of the filter rotating seat. The diameter of the first threaded through-hole is smaller than the diameter or side length of the filter. The cylindrical structure mounting hardware has two axial end faces, one of which mates with the filter, and the other end face is close to the end face of the mounting sleeve 19.

[0067] To facilitate the assembly of the mounting sleeve, light source mounting base, filter mounting base, and other structures, a first bracket 17 is also included. See some embodiments for details. Figure 3 The bracket has a vertical mounting plate. The motor 16 is fixedly mounted on the mounting plate of the bracket through a motor mount. Its output shaft passes vertically through the mounting plate and is fixedly connected to the axis of the filter mounting base and the light source mounting base. The first aperture 5 is mounted in the axial through hole of the filter mounting base 2. The bracket 17 has a through hole for passing through and fixing the mounting sleeve 19. The first lens, the light-diffusing column, the second aperture, and the second lens are assembled into an integrated accessory through the mounting sleeve, pass through the through hole on the bracket, and are arranged coaxially with the threaded through hole of the first aperture.

[0068] The second implementation of the light source mounting base 1 and the filter mounting base 2 is shown in Figure 4 and Figure 5 , the light source mounting base 1 is a fixed base, and the filter mounting base 2 is a rotating base. The light source is a full-spectrum light source and is installed inside the light source mounting base. The filters are arranged in an annular array centered on the rotation axis of the filter mounting base. Different filters can transmit different wavelengths. Rotate the filter mounting base to select any filter to be paired with the light source and used in the front-stage optical path. In this solution, the light source is a full-spectrum light source, and detection light of different wavelengths is obtained by selecting filters, so as to achieve the purpose of multi-parameter detection of the water quality analyzer.

[0069] Figure 4 and Figure 5 In the implementation shown in, the overall structure of the filter mounting base can adopt the structure of the filter mounting base in the first implementation, and the overall thickness is less than that of the first method because the light source does not need to extend into the filter mounting base again. The light source mounting base can adopt a cylindrical structure. The light source mounting base is fixed on the axial extension line of the mating sleeve 19 and adjacent to the filter mounting base through the second bracket 20. The light source 3 is assembled in the cylindrical base and is incident perpendicularly to the filter.

[0070] The light-passing holes of the first aperture and the second aperture are both equal-diameter extension holes. The parameters of the threaded through-holes of the first aperture and the second aperture are preferably set as follows (for the meaning of related parameters, see Figure 8 ): The axial length l satisfies: L / 2 ≤ l < l - 5(h)(L) / 2(D), where L is the back focal length of the corresponding lens; the pitch d satisfies d < hL / D, where L is the back focal length of the corresponding lens, D is the spot diameter on the corresponding lens, and h is the thread depth and satisfies h < 1 / 5 D. Among them, on the premise of being machinable, the smaller the pitch d within the foregoing range, the better the extinction effect.

[0071] The back focal length L generally refers to the distance from the vertex of the last optical surface of the lens to the rear focal plane. When the size of the outgoing light spot is determined, according to the focusing requirements of the matching lens, the size of the light spot from the light source to the lens is a determined quantity, which can be defined as D (spot diameter).

[0072] Specifically for the first aperture: The axial length l1 of the threaded through-hole of the first aperture satisfies: L1 / 2 ≤ l1 < L1 - 5(h1)(L1) / 2(D1), and the pitch d1 satisfies d1 < h1L1 / D1, where L1 is the back focal length of the first lens; D1 is the spot diameter on the first lens, and h1 is the thread depth of the threaded through-hole and satisfies h1 < 1 / 5 D1. For example, taking h1 as 1 / 6D1, d1 < 1 / 6 L1, and L1 / 2 ≤ l1 < 7 / 12 L1.

[0073] Specifically for the second aperture: The axial length l2 of the threaded through-hole of the second aperture satisfies: (L2) / 2 < l2 < L2 - 5(h2)(L2) / 2(D2), and the pitch d2 satisfies d2 < h2L2 / D2, where L2 is the back focal length of the second lens, D2 is the spot diameter on the second lens, and h2 is the depth of the thread hole and satisfies h2 < 1 / 5 D2. For example, taking h2 as 1 / 6D2, d2 < 1 / 6 L2, and L2 / 2 ≤ l2 < 7 / 12 L2.

[0074] A water quality analyzer can improve its optical path system based on the multi-parameter analyzer LH-725, that is, replace its optical path system with the optical path system of the present application to construct a new water quality analysis and detection platform.

[0075] For the water quality analyzer using the optical path system of the present application, the optical path system first uses a double convex lens (to reduce plane interference light noise) to converge the light beam passing through the filter into a uniform light column, uses a uniform light column of a certain size to unify all the light source emission points into object points of the same size, and at the same time uses the extinction thread, the reflection and matte characteristics of the side wall of the uniform light column to eliminate stray light. Then a plano-convex lens is used to collimate the outgoing light, and the optical path is divided into two paths by a beam splitter: one path is used as the main measurement light, and the other path is used as the reference light (for real-time monitoring and compensating for the influence of the light source with the environment and usage cycle). The main measurement light emitted by the beam splitter enters the measurement chamber, passes through the measurement vessel and then is converged onto the measurement sensor by a double convex lens.

[0076] Under the same measurement conditions, the comparison results of the 420nm spots in the measurement chamber before and after the improvement of the optical path are as Figure 9 and Figure 10 shown, Figure 9 is the spot of LH-725, that is, before the improvement of the optical path, Figure 10 is the spot after using the optical path of the present application. Under the same measurement conditions, the comparison results of the 620nm spots are as Figure 11 and Figure 12 shown, Figure 11 is the spot of LH-725, that is, before the improvement of the optical path, Figure 12 is the spot after using the optical path of the present application. It can be seen from the figure that before the improvement, the sizes and shapes of the spots at the two wavelengths are inconsistent, and there are obvious halos around the spots, while after the improvement, the sizes of the spots are basically the same and the halos are basically faded. At the same time, the light source and the filter are fixedly installed at a 0-degree incidence angle, which improves the wavelength blue shift problem caused by the installation.

[0077] Comparison of detection data: Using an absorptive neutral density filter as the standard fixture, comparative tests were conducted at wavelengths of 420nm, 470nm, and 620nm under the same conditions. The absorbance values ​​measured by the new platform's optical path were basically consistent with the standard absorbance data, thus resolving the absorbance deviation problem of the original platform. The test results are shown in Tables 1-3. Figures 13-15 The new platform uses the optical path system described in this application, while other components are the same as the original platform LH-725. (See Tables 1-3 and...) Figures 13-15 The results show that after adopting the optical path system of this application, the instrument measurement accuracy error and data repeatability are significantly reduced.

[0078] in, Figures 13-15 In the figure, the absorbance on the horizontal axis is the standard absorbance, and the absorbance on the vertical axis is the absorbance measured on the new and old platforms.

[0079] Table 1. Comparison of absorbance test results at 420nm wavelength

[0080] Table 2 Comparison of absorbance test results at 2470nm wavelength

[0081] Table 3. Comparison of absorbance test results at 620nm wavelength

[0082] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An optical path system for a water quality analyzer, comprising a pre-amplifier optical path, a beam splitter, a reference optical path detection component, and a detection optical path detection component, characterized in that, The pre-stage optical path includes a light source, a filter, a first lens, a light-diffusing column, a second aperture, and a second lens arranged in sequence along the optical axis; the outer peripheral surface of the light-diffusing column is a frosted surface; the second aperture is a spiral stepped aperture with a light-passing hole, and the inner wall of the light-passing hole has an extinction channel extending spirally along the axial direction, the extinction channel being used to eliminate stray light.

2. The optical path system according to claim 1, characterized in that, The inner wall of the light-transmitting hole is machined into a threaded hole, and the gap between adjacent threads is the matting groove.

3. The optical path system according to claim 1, characterized in that, A coaxially extending spiral ring is embedded in the inner wall of the light-transmitting hole, and the gap between adjacent rings is the extinction channel.

4. The optical path system according to claim 1, characterized in that, The optical path system also includes a mounting sleeve, in which the first lens and the second lens are respectively fixedly installed at both ends of the axial direction of the mounting sleeve; the uniform light column and the second aperture are coaxially distributed within the mounting sleeve.

5. The optical path system according to claim 4, characterized in that, The assembly sleeve is a two-section combined sleeve, including a first sleeve and a second sleeve. The first sleeve and the second sleeve have a free end and a connecting end, respectively, and are assembled and connected by their respective connecting sections. The first lens is fixed to the free end port of the first sleeve, and the second lens is fixed to the free end port of the second sleeve. The light-transmitting hole is distributed inside the second sleeve and is adjacent to one end of the second lens. The second aperture is integrated inside the second sleeve.

6. The optical path system according to claim 1, characterized in that, It also includes a first aperture stop that is collinear with the optical axis and disposed between the filter and the first lens, wherein the first aperture stop is the spiral stepped aperture stop.

7. The optical path system according to claim 1, characterized in that, The first lens is a biconvex lens.

8. The optical path system according to claim 1, characterized in that, It also includes a light source mounting base and a filter mounting base; the light source mounting base and the filter mounting base are rotating bases that can be driven synchronously; light sources of different wavelengths are mounted in a circular array around the rotation axis of the light source mounting base, and the filters are mounted in the filter mounting base in a one-to-one correspondence with the light sources; the light source mounting base and the filter mounting base can be rotated to select any one of the light sources and the corresponding filter for use in the pre-stage optical path.

9. The optical path system according to claim 1, characterized in that, It also includes a light source mounting base and a filter mounting base; the light source mounting base is a fixed base, and the filter mounting base is a rotating base; the light source is a full-spectrum light source, which is mounted on the light source mounting base and can transmit filters of different wavelengths. The filters are mounted in a ring array around the rotation axis of the filter mounting base; the filter mounting base can be rotated to select any filter to be paired with the light source and used in the pre-stage optical path.

10. A water quality analyzer comprising the optical path system as described in any one of claims 1 to 9.

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