A stray light detector based on a nested tube structure

Abstract

The present disclosure relates to a stray light detector based on a nested tube structure, which includes a light source, a photodetector, an optical lens, and a nested tube. It is characterized in that: the nested tube includes an inner tube and an outer tube, the inlet end extends out of the inlet end of the outer tube, and the outlet end of the inner tube extends out of the outlet end of the outer tube by a preset distance or the outlet end of the inner tube retracts into the outlet end of the outer tube by a preset distance; the light source is arranged near the inlet end of the inner tube, the photodetector is arranged near the inlet end of the outer tube, the optical lens is arranged between the photodetector and the inlet end of the outer tube, and the object to be measured is arranged at the outlet end of the outer tube; both the inner tube and the outer tube are made of non-light-transmitting materials. The stray light detector provided by the present disclosure can improve the excitation and collection efficiency of stray light, reduce the interference of the excitation light, and thus improve the detection sensitivity.

Description

Technical Field

[0001] The present disclosure relates to the technical field of stray light detection, and in particular, to a stray light detector based on a nested tube structure. Background Art

[0002] When an excitation beam encounters a sample to be measured, scattering, absorption, or fluorescence effects will occur, thereby generating light with a chaotic propagation direction (i.e., stray light). By analyzing the stray light, the composition of the sample to be measured can be obtained.

[0003] Detection principle of a fluorometer: Use short-wavelength "excitation light" to excite the sample to be measured, so that the sample to be measured emits long-wavelength fluorescence; among them, the radiation direction of the fluorescence is chaotic and can be regarded as a kind of stray light. Detection principle of a turbidimeter: When the excitation light encounters a sample to be measured containing particles or having uneven components, the excitation light is scattered, and its scattering direction is also chaotic (such as Mie scattering and Rayleigh scattering). Therefore, the scattered light can be regarded as another kind of stray light. Therefore, fluorescence and scattered light are collectively referred to as stray light (i.e., light with a chaotic propagation direction).

[0004] For a turbidimeter and a fluorometer, the intensity of the excitation light (>mW) is much greater than the intensity of the stray light (fW~nW). Therefore, the interference of the excitation light on the stray light becomes the main factor restricting the detection accuracy.

[0005] In order to reduce the interference of the excitation light, a transparent capillary is usually used as the sample cell - the incident direction of the excitation light is perpendicular to the axial direction of the capillary (i.e., the excitation beam is perpendicularly incident on the side wall of the capillary), and the stray light is detected in another direction perpendicular to both the excitation light and the axial direction of the capillary. At this time, the detection direction of the stray light, the incident direction of the excitation light, and the axial direction of the capillary are perpendicular to each other, so as to minimize the interference of the excitation light on the stray light to the greatest extent. However, the transmission optical path of the excitation light in the sample to be measured is very short, the excitation efficiency is very low, and the collection efficiency of the scattered light (or fluorescence) is also low; in addition, the sample to be measured needs to be introduced into the capillary, and the inside of the capillary is easily contaminated (Optics and Lasers in Engineering, 2021, 139, 106488).

[0006] Therefore, exploring a new structure to improve the collection efficiency of stray light, reduce the interference of the excitation light, thereby improving the detection sensitivity and reducing the volume of the instrument is the problem currently faced. Summary of the Invention

[0007] The present invention provides a stray light detector, which can improve the excitation and collection efficiency of stray light, and can reduce the interference of the excitation light, so as to improve the detection sensitivity while reducing the volume of the stray light detector.

[0008] According to the first aspect of the embodiments of the present disclosure, a stray light detector based on a nested tube structure is provided. The stray light detector includes a light source, a photodetector, an optical lens, and a nested tube. The nested tube includes an inner tube and an outer tube. The inlet end of the inner tube extends out of the inlet end of the outer tube, and the outlet end of the inner tube extends out of the outlet end of the outer tube by a preset distance or the outlet end of the inner tube is retracted into the outlet end of the outer tube by a preset distance;

[0009] The light source is arranged near the inlet end of the inner tube, the photodetector is arranged near the inlet end of the outer tube, the optical lens is arranged between the photodetector and the inlet end of the outer tube, and the object to be measured is arranged at the outlet end of the outer tube;

[0010] Both the inner tube and the outer tube are made of non-light-transmitting materials.

[0011] In the stray light detector provided by the present disclosure, the excitation light emitted by the light source enters the inner tube along the inlet end of the inner tube and is transmitted along the inner tube, so as to excite the object to be measured located at the outlet end of the inner tube; the stray light generated after the object to be measured is irradiated by the excitation light is collected by the outer tube and is transmitted along the gap between the inner tube and the outer tube to the photodetector at the inlet end of the outer tube; the photodetector can know the components of the object to be measured by testing information such as the intensity and spectrum of the stray light. Among them, since both the outer tube and the inside are made of light-impermeable materials, which require the ability to reflect light and not transmit light, the outer tube can not only collect and transmit stray light, but also shield the interference of external ambient light. The inner tube can not only transmit excitation light, but also separate the excitation light from the stray light, avoiding the leakage of excitation light into the outer tube, thereby reducing the interference of excitation light on the stray light.

[0012] Further, in the stray light detector provided by the present disclosure, the excitation light at the outlet end of the inner tube is transmitted outward and is difficult to return to the inner tube. The transmission directions of the excitation light and the stray light are opposite, so as to most effectively reduce the interference of the excitation light.

[0013] In one embodiment, the stray light detector further includes a light trap, and the light trap is connected to the outlet end of the outer tube;

[0014] The light trap is used to conduct away and / or absorb the excitation light.

[0015] In one embodiment, the inner tube includes a first inner tube section, a second inner tube section, and a third inner tube section that are sequentially connected. The first inner tube section and the third inner tube section are horizontally arranged, and the second inner tube section is inclined;

[0016] A first through hole is provided on the side wall of the outer tube. The third inner tube section is arranged in the outer tube through the first through hole. One end of the second inner tube section is arranged in the outer tube through the first through hole, and the other end is arranged outside the outer tube. The first inner tube section is arranged outside the outer tube.

[0017] In one embodiment, the outer tube includes a first section of the outer tube, a second section of the outer tube, and a third section of the outer tube that are connected in sequence. The first section of the outer tube and the third section of the outer tube are horizontally arranged, and the second section of the outer tube is inclined.

[0018] A second through hole is provided on the side wall of the second section of the outer tube. One end of the inner tube is disposed inside the outer tube through the second through hole, and the other end is disposed inside the outer tube and extends out of the outlet end of the outer tube.

[0019] In one embodiment, a reflecting mirror that is inclined is provided at the inlet end of the outer tube. A third through hole is provided on the inclined reflecting mirror. One end of the inner tube is disposed inside the outer tube through the third through hole.

[0020] In one embodiment, an absorbent material layer is provided on the inner wall of the outer tube. The absorbent material layer is made of one or any several combinations of titanium dioxide, titanium nitride, zinc oxide, zirconium oxide, or anodized aluminum.

[0021] In one embodiment, a filter or an absorbent sheet is provided at the inlet end or inside the outer tube for attenuating the excitation light and transmitting the stray light.

[0022] In one embodiment, the preset distance is greater than 1 mm, the inner diameter of the inner tube is 0.05 - 20 cm, and the inner diameter of the outer tube is 0.1 - 50 cm.

[0023] In one embodiment, both the outer tube and the inner tube are made of an antioxidant metal material or a metal material that does not emit fluorescence after oxidation, and their cross-sectional shapes are circular, oval, triangular, square, rectangular, or polygonal.

[0024] In one embodiment, the light trapping cell is a U-shaped tube made of black anodized aluminum.

[0025] A stray light detector provided by the present disclosure has the following technical effects:

[0026] (1) The excitation light and the stray light are both transmitted in the nested tube. Compared with the existing structure where the excitation light and the stray light are perpendicular to each other, the structure of the present disclosure is more compact and is easier to align and excite the object to be measured; (2) The excitation light is transmitted in the inner tube, and the stray light is transmitted in the outer tube. The excitation light and the stray light are isolated from each other through the wall of the inner tube - the walls of the inner tube and the outer tube are both light-impermeable, and their transmission directions are opposite. Therefore, the excitation light entering the stray light channel can be maximally avoided, thereby reducing the interference of the excitation light on the stray light; (3) The structural design that the outlet end of the inner tube is spaced from the outlet end of the outer tube by a preset distance can improve the collection efficiency of the stray light without increasing the volume and complexity of the instrument.

[0027] In addition, compared with optical fibers, the sleeve in this application has a higher collection efficiency for stray light. This is because the collection angle of an optical fiber is limited by the numerical aperture, while there is no such limitation for the embedded sleeve. Moreover, compared with the structure of multiple tubes arranged side by side, the embedded sleeve structure is simpler and more compact. It only requires two tubes and has a higher collection efficiency - the stray light is confined within the outer tube and will not spread outside the outer tube.

[0028] In summary, the stray light detector provided by this disclosure has the advantages of a compact structure, low excitation light interference, high stray light collection efficiency, and high detection sensitivity. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the stray light detector in Embodiment 1 of this disclosure.

[0030] Figure 2 It is a schematic structural diagram of the stray light detector in Embodiment 2 of this disclosure.

[0031] Figure 3 It is a schematic structural diagram of the stray light detector in Embodiment 3 of this disclosure.

[0032] Figure 4 It is a schematic structural diagram of the connection between the outer tube and the light trap of the stray light detector in Embodiment 4 of this disclosure.

[0033] In the figure, 1 - light source; 2 - excitation beam; 3 - inner tube of the embedded sleeve; 4 - outer tube of the embedded sleeve; 5 - object to be measured; 6 - stray light; 7 - filter; 8 - optical lens; 9 - photodetector; 10 - optical mirror; 11 - light trap; 12 - liquid level. Detailed Description of the Embodiments

[0034] The following will describe this disclosure in detail in combination with the embodiments and the drawings. It should be noted that the described embodiments are only for facilitating the understanding of this disclosure and do not impose any limitations on it.

[0035] As Figures 1 - 3 shown, a stray light detector provided by this disclosure includes a light source 1, a photodetector 9, an optical lens 8, and an embedded sleeve. The embedded sleeve includes an inner tube 3 and an outer tube 4. The inlet end of the inner tube 3 extends out of the inlet end of the outer tube 4, and the outlet end of the inner tube 3 extends out of the outlet end of the outer tube 4 by a preset distance or the outlet end of the inner tube 3 retracts to a preset distance L from the outlet end of the outer tube 4;

[0036] The light source is arranged near the inlet end of the inner tube 3, the photodetector is arranged near the inlet end of the outer tube 4, the optical lens is arranged between the photodetector and the inlet end of the outer tube 4, and the object to be measured 5 is arranged at the outlet end of the outer tube 4;

[0037] Both the inner tube 3 and the outer tube 4 are made of non-light-transmitting materials. Preferably, both the outer tube 4 and the inner tube 3 are made of metal materials that are antioxidant or do not emit fluorescence after oxidation, such as gold, platinum, or aluminum, etc. Their cross-sectional shapes are circular, oval, triangular, square, rectangular, or polygonal. The inner tube 3 and the outer tube 4 can be a coaxial structure or a non-coaxial structure. For example, the inner tube is closer to one side wall of the outer tube.

[0038] It should be noted that in this embodiment, the outlet end of the inner tube 3 extends a preset distance beyond the outlet end of the outer tube 4 or the outlet end of the inner tube 3 retracts into the outlet end of the outer tube 4 by a preset distance L. It can be understood as follows:

[0039] The inner tube at the outlet end is shorter than the outer tube, that is, the inner tube is retracted inside the outer tube, which is simply called "retraction". At this time, the stray light excited at the outlet end of the inner tube originates from the inside of the outer tube or the port close to the outer tube. Therefore, it is easy to be collected by the outer tube, that is, the collection efficiency is high, which is beneficial to improving the signal intensity of the stray light. And the excitation light at the outlet end is transmitted outward and is difficult to return to the metal tube because the transmission directions of the excitation light and the stray light are opposite. Therefore, it can most effectively reduce the excitation light interference.

[0040] The inner tube at the outlet end is longer than the outer tube, that is, the inner tube extends outside the outer tube, which is simply called "extension". At this time, the stray light excited at the outlet end of the inner tube originates from the outside of the outer tube, so the collection efficiency will be reduced, that is, the signal intensity is reduced; however, at this time, the excitation light emitted from the inner tube is located outside the port of the outer tube, so the efficiency of the outer tube collecting the excitation light is reduced, which is beneficial to reducing the excitation light interference, that is, the noise is reduced.

[0041] It should be noted that according to different requirements, such as signal intensity or noise, the structure of the inner tube retraction or extension can be selected. For example:

[0042] When the parallelism of the excitation light beam emitted from the inner tube is low, that is, when the beam divergence angle is large, the excitation light beam is easy to be incident on the wall of the outer tube. Due to the diffuse reflection of the excitation light beam on the tube wall, the excitation light will be reflected backward, so that the excitation light is collected by the outer tube. Therefore, the structure of the inner tube extension needs to be adopted;

[0043] When the parallelism of the excitation light beam emitted from the inner tube is high, that is, when the beam divergence angle is small, the excitation light beam will not contact the wall of the outer tube and there is no side wall diffuse reflection. At this time, the structure of the inner tube retraction can be adopted.

[0044] In the stray light detector provided by the present disclosure, the excitation light emitted by the light source enters the inner tube 3 along the inlet end of the inner tube 3 and is transmitted along the inner tube 3, so as to excite the object to be measured 5 located at the outlet end of the inner tube 3; the stray light generated after the object to be measured 5 is irradiated by the excitation light is collected by the outer tube 4 and transmitted along the gap between the inner tube and the outer tube 4 to the photodetector at the inlet end of the outer tube 4; the photodetector can know the composition of the object to be measured 5 by testing information such as the intensity and spectrum of the stray light. Among them, since both the outer tube 4 and the inner tube 3 are made of light-impermeable materials, the outer tube 4 can not only collect and transmit the stray light, but also shield the interference of ambient light. The inner tube 3 can not only transmit the excitation light, but also separate the excitation light from the stray light, avoiding the leakage of the excitation light into the outer tube 4, thereby reducing the interference of the excitation light on the stray light.

[0045] Moreover, in the stray light detector provided by the present disclosure, since the outlet end of the inner tube 3 is at a preset distance from the outlet end of the outer tube 4 - the inner tube 3 is retracted into the outer tube 4, the stray light excited at the outlet end of the inner tube 3 is still inside the outer tube 4 or near the port of the outer tube 4. Therefore, the stray light excited at the outlet end of the inner tube 3 is easily collected by the outer tube 4, so that the collection efficiency of the stray light can be improved, and further it is beneficial to improve the signal intensity of the stray light.

[0046] Furthermore, in the stray light detector provided by the present disclosure, the excitation light at the outlet end of the inner tube 3 is transmitted outward and it is difficult to return to the inner tube 3. The transmission directions of the excitation light and the stray light are opposite, so that the interference of the excitation light can be reduced most effectively.

[0047] Finally, since the object to be measured 5 is placed inside the outer tube 4, the stray light 6 emitted by stimulated emission is also confined inside the outer tube 4, thus greatly improving the collection efficiency of the stray light 6. Its collection efficiency can be as high as 50%, because the stray light emitted to the left can be collected, that is, half of the stray light can be collected.

[0048] It should be noted that when the object to be measured 5 is a transparent liquid, the excitation light 2 can propagate inside the object to be measured 5. At this time, all the stray light 6 emitted by the object to be measured 5 in the whole propagation path is confined inside the outer tube 4, and thus is collected and detected, so the collection efficiency is greatly improved.

[0049] In contrast, the existing turbidimeter adopts a structure where the "excitation light and stray light" are perpendicular to each other, and only a very small part of the stray light can be collected, because only the stray light perpendicular to the direction of the excitation light can be collected by the existing turbidimeter.

[0050] It can be seen that in the present disclosure: (1) The excitation light and the stray light are transmitted in the nested tube. Compared with the existing structure where the excitation light and the stray light are perpendicular to each other, its structure is more compact and it is easier to align and excite the object to be measured; (2) The excitation light is transmitted in the inner tube, and the stray light is transmitted in the outer tube. The excitation light and the stray light are isolated from each other through the wall of the inner tube - the walls of the inner tube and the outer tube are both light-impermeable, and their transmission directions are opposite. Therefore, the excitation light can be maximally prevented from entering the stray light channel, thereby reducing the interference of the excitation light on the stray light; (3) The structural design in which the outlet end of the inner tube is at a preset distance from the outlet end of the outer tube can improve the collection efficiency of the stray light without increasing the volume and complexity of the instrument.

[0051] In addition, compared with optical fibers, the nested tube in the present disclosure has a higher collection efficiency for stray light because the collection angle of optical fibers is limited by the numerical aperture, while the nested tube has no such limitation; and, compared with the structure of multiple tubes arranged side by side, the nested tube structure is simpler and more compact. It only requires two tubes and has a higher collection efficiency - the stray light is confined within the outer tube and will not diverge outside the outer tube.

[0052] In summary, the stray light detector provided by the present disclosure has the advantages of a compact structure, low excitation light interference, high stray light collection efficiency, and high detection sensitivity.

[0053] In one embodiment, as Figure 4 shown, the stray light detector further includes a light trap 11, and the light trap 11 is connected to the outlet end of the outer tube 4;

[0054] The light trap 11 is used to guide away and / or absorb the excitation light, and it is preferably a U-shaped tube made of black anodized aluminum.

[0055] The light trap in this embodiment is connected to the outer tube to prevent the excitation light from being reflected back into the outer tube and being collected and transmitted to the photodetector by the outer tube. As Figure 4 shown, the light trap preferably has a U-shaped elbow structure, so as to be able to guide away the excitation light beam to the greatest extent and reduce the beam return. Further, the inner diameter of the elbow structure is greater than or equal to the inner diameter of the outer tube.

[0056] It should be noted that an absorbent material, such as black anodized aluminum, is provided inside the U-shaped tube to absorb the excitation light.

[0057] Specifically, the light-trapping cell 11 is connected to the outer tube 4, and the U-shaped tube is sleeved outside the outer tube 4. Therefore, the light-trapping cell 11 can shield external light, that is, prevent external light from entering the outer tube 4. Moreover, since the inner wall of the U-shaped tube is made of black anodized aluminum material, which has a high light absorption rate and an absorption coefficient of up to 95%, it can absorb the excitation light to reduce the interference of the excitation light beam. The excitation light beam 2 enters the U-shaped tube and is reflected by the side wall and then travels forward along the U-shaped tube and cannot return to the outer tube 4. Therefore, the interference of the excitation light beam 2 can be minimized. Therefore, the U-shaped light-trapping cell has the functions of shielding external light, absorbing the excitation light beam, and preventing the excitation light beam from returning.

[0058] It should be noted that the side wall of the U-shaped tube in this embodiment can also be an arc-shaped reflecting surface, that is, Figure 4 the side wall reflecting surface in

[0059] is not limited to a plane; moreover, the side wall of the U-shaped tube in this embodiment is not limited to black and can also be shiny. In this case, the U-shaped tube is used to conduct the excitation light away instead of absorbing it.

[0060] In one implementation, as Figure 1 shown, the inner tube 3 includes a first inner tube section, a second inner tube section, and a third inner tube section connected in sequence. The first inner tube section and the third inner tube section are horizontally arranged, and the second inner tube section is inclined.

[0061] A first through hole is provided on the side wall of the outer tube 4, and the third inner tube section is arranged in the outer tube 4 through the first through hole. One end of the second inner tube section is arranged in the outer tube 4 through the first through hole, and the other end is arranged outside the outer tube 4. The outer wall of the inclined second inner tube section can reflect stray light.

[0062] In one implementation, as Figure 2 shown, the outer tube 4 includes a first outer tube section 4, a second outer tube section 4, and a third outer tube section 4 connected in sequence. The first outer tube section 4 and the third outer tube section 4 are horizontally arranged, and the second outer tube section 4 is inclined. The outer wall of the inclined second outer tube section can reflect stray light.

[0063] A second through hole is provided on the side wall of the second outer tube section 4, and one end of the inner tube 3 is arranged in the outer tube 4 through the second through hole.

[0064] In one implementation, as Figure 3As shown, a mirror is disposed at the inlet end of the outer tube 4 in an inclined manner. A third through hole is provided on the inclined mirror. One end of the inner tube 3 is disposed inside the outer tube 4 through the third through hole. The inclined mirror can reflect stray light.

[0065] Preferably, an absorbent material layer is provided on the inner wall of the outer tube 4, and the absorbent material layer can absorb the excitation light inside the outer tube. Among them, the absorbent material layer is composed of one or any several combinations of titanium dioxide, titanium nitride, zinc oxide, zirconium oxide, or anodized aluminum.

[0066] In one implementation, as Figure 1 , 3 shown, a filter or an absorbent sheet is provided at the inlet end or inside the outer tube 4.

[0067] In this embodiment, in order to detect fluorescence, a filter or an absorbent sheet can be provided at the inlet end or inside the outer tube 4. The filter is a long-pass filter to block the short-wavelength excitation light 2 or a spectroscopic device such as a grating, a filter set, or a linear variable filter.

[0068] It should be noted that when detecting turbidity, the present disclosure does not require a filter or an absorbent sheet to be provided at the inlet end or inside the outer tube 4.

[0069] Preferably, the preset distance is greater than 1 mm, the inner diameter of the inner tube 3 is 0.05 - 20 cm, and the inner diameter of the outer tube 4 is 0.1 - 50 cm. More preferably, the preset distance is 5 - 20 mm, the inner diameter of the inner tube 3 is 2 - 5 mm, and the inner diameter of the outer tube 4 is 3 - 10 mm.

[0070] In this embodiment, the outlet end of the inner tube 3 is indented by a length L compared to the outlet end of the outer tube. L is called the indentation distance. When the object to be measured 5 is located in the indented area inside the outer tube 4, the stray light 6 emitted by it can be both constrained inside the outer tube 4 and transmitted along the gap between the inner tube 3 and the outer tube 4, that is, the stray light 6 enters the gap between the inner tube 3 and the outer tube 4. And, as L increases, the shielding angle range of the inner tube 3 for the stray light 6 will decrease, so the collection efficiency of the stray light 6 can be improved. However, it should be noted that although increasing L can improve the collection efficiency, when L increases, the transmission distance of the excitation light 2 inside the outer tube 4 also increases. At this time, the excitation light 2 is not in the inner tube 3, so the probability that the excitation light 2 enters the gap between the inner tube 3 and the outer tube 4 through scattering also increases, that is, the interference of the excitation light 2 on the stray light 6 increases. Therefore, the indentation distance L needs to be set to an optimal value. In this embodiment, L is preferably between 0.3 - 3D, where D is the inner diameter of the outer tube 4.

[0071] It can be understood that when the end faces of the inner tube 3 and the outer tube 4 are flush, i.e., L = 0, the analyte 5 can only be located outside the port of the outer tube 4, and most of the emitted stray light 6 cannot enter the outer tube 4.

[0072] Further, in this embodiment, the inner diameter D of the outer tube 4 is preferably between (2 - 20)d, where d is the inner diameter of the inner tube 3.

[0073] The following takes specific embodiments to elaborate in detail on the structure of the stray light detector provided by the present disclosure.

[0074] Embodiment 1

[0075] As Figure 1 shown, in this embodiment, the outer tube 4 is a silver tube with an inner diameter of 5 mm, and the inner tube 3 is a silver tube with an inner diameter of 2 mm and an outer diameter of 3 mm. A hole is opened on the side wall of the outer tube 4, the inner tube 3 is bent by 135 degrees and inserted into the outer tube 4 through the hole, and the inserted inner tube is coaxial with the outer tube; wherein, at the right port, the inner tube 3 retracts 10 mm compared to the outer tube 4, i.e., L = 10 mm.

[0076] The analyte 5 is placed in the retracted area of the inner tube 4, i.e., outside the right port of the inner tube 3 and inside the right port of the outer tube 4.

[0077] The light source 1, such as ultraviolet light emitted by an ultraviolet LED, serves as the excitation light 2. The excitation light 2 enters the inner tube 3 and travels rightward along the inner tube 3. The excitation light 2 irradiates the analyte 5 and causes the analyte 5 to emit fluorescence (which is a kind of stray light 6). The fluorescence travels leftward along the gap between the inner tube 3 and the outer tube 4, passes through the linear variable filter 7 and the lens 8, and is finally received by the photodetector 9. Among them, the linear variable filter 7 is used to test the fluorescence spectrum.

[0078] By analyzing the fluorescence spectrum, the components and content of the analyte can be obtained.

[0079] Embodiment 2

[0080] As Figure 2 shown, the outer tube 4 is a stainless steel tube with an inner diameter of 10 mm, and the inner tube 3 is a quartz tube with an inner diameter of 3 mm, an outer diameter of 5 mm, and a gold-plated inner wall. The outer tube 4 is bent by 135 degrees, a hole is opened on the side wall of the outer tube 4, and then the inner tube 3 is inserted into the outer tube 4 through the hole. Among them, at the right port, the inner tube 3 retracts 5 mm compared to the outer tube 4, i.e., L = 5 mm.

[0081] The analyte 5 is located at the right end face of the outer tube 4, i.e., the right boundary of the retracted area L.

[0082] The light source 1, such as a red laser, emits red light as the excitation light 2. The excitation light 2 enters the inner tube 3 and travels rightward along the inner tube 3. The excitation light 2 irradiates the object to be measured 5, causing the object to emit stray light 6. The stray light 6 travels leftward along the gap between the inner tube 3 and the outer tube 4, passes through the lens 8, and is finally received by the photodetector 9.

[0083] By measuring the change in the light intensity received by the detector, the turbidity of the object to be measured can be obtained.

[0084] Example 3

[0085] As Figure 3 shown, the outer tube 4 is a stainless steel tube with an inner diameter of 10 mm, and the inner tube 3 is a stainless steel tube with an inner diameter of 3 mm and an outer diameter of 5 mm. A reflector 10 is placed at the left port of the outer tube 4. The reflecting surface of the reflector 10 makes an angle of 45 degrees with the axis of the outer tube 4, and a hole is opened in the middle of the reflector 10. Then, the inner tube 3 is inserted into the hole of the reflector 10 and then into the outer tube 4. At this time, the inner tube 3 and the outer tube 4 are coaxial. Among them, at the right port, the inner tube 3 is indented 10 mm compared to the outer tube 4, that is, L = 10 mm.

[0086] The object to be measured 5 is located in the indented area, that is, outside the right port of the inner tube 3 and inside the right port of the outer tube 4.

[0087] The light source 1, such as an ultraviolet laser, emits ultraviolet light as the excitation light 2. The excitation light 2 enters the inner tube 3 and travels rightward along the inner tube 3. The excitation light 2 irradiates the object to be measured 5, causing the object to emit fluorescence. The fluorescence travels leftward along the gap between the inner tube and the outer tube, passes through the light absorption sheet and the lens 8, and is finally received by the photodetector 9. Among them, the light absorption sheet is used to absorb the excitation light 2 and can transmit the fluorescence without absorbing it, thereby reducing the interference of the excitation light on the fluorescence.

[0088] By analyzing the fluorescence intensity, the components and content of the object to be measured can be obtained.

[0089] Example 4

[0090] As Figure 2 shown, the outer tube 4 is a stainless steel tube with an inner diameter of 10 mm and an outer diameter of 12 mm, and the inner tube 3 is a quartz tube with an inner diameter of 3 mm, an outer diameter of 5 mm, and a gold-plated inner wall. The outer tube 4 is bent 135 degrees, and a hole is opened on the side wall of the outer tube 4. Then, the inner tube 3 is inserted into the outer tube 4 through the hole. Among them, at the right port, the inner tube 3 extends 5 mm compared to the outer tube 4, that is, L = 5 mm.

[0091] The object to be measured 5 is a liquid, such as diesel dissolved in water. The object to be measured is placed in the light trap 11, as Figure 4As shown, the liquid level position of the analyte is 12. Among them, the light-trapping cell is a U-shaped tube 11 made of black anodized aluminum, and the inner diameter of the tube is 13 mm. Then, the nested metal tubes, including the inner tube 3 and the outer tube 4, are vertically erected and inserted into the U-shaped tube 11 so that the port of the inner tube 3 is below the liquid level 12.

[0092] The light source 1, such as an ultraviolet LED, emits an ultraviolet beam of 310 nm as the excitation light 2. The excitation light 2 enters the inner tube 3 and travels to the right along the inner tube 3. The excitation light 2 irradiates the analyte 5 from below the liquid level, preventing the excitation light 2 emitted from the liquid surface from entering the outer tube 4 and causing the analyte 5 to emit stray light 6. The stray light 6 travels to the left along the gap between the inner and outer tubes, passes through the lens 8, and is finally received by the photodetector 9.

[0093] As Figure 4 As shown, after being reflected by the side wall of the U-shaped tube, the excitation light 2 travels forward along the U-shaped tube and exits from the other port of the U-shaped tube. Therefore, the excitation light 2 is effectively prevented from returning to the tube 4; moreover, with each side wall reflection, the inner wall of the U-shaped tube can significantly absorb the excitation light, and the absorption rate is greater than 95%. Therefore, in this embodiment, the dual effects of "preventing return" and "significant absorption" can minimize the interference of the excitation light 2 to the greatest extent.

[0094] By testing the received spectrum of the detector, the oil content in the water can be obtained.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than limiting the protection scope of the present disclosure. Although the present disclosure has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present disclosure can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present disclosure.

Claims

1. A stray light detector based on a nested tube structure, comprising a light source, a photodetector, an optical lens, and a nested tube, characterized in that: The nested tube includes an inner tube and an outer tube. The inlet end of the inner tube extends out of the inlet end of the outer tube, and the outlet end of the inner tube extends out of the outlet end of the outer tube by a preset distance or the outlet end of the inner tube retracts into the outlet end of the outer tube by a preset distance; The light source is arranged near the inlet end of the inner tube, the photodetector is arranged near the inlet end of the outer tube, the optical lens is arranged between the photodetector and the inlet end of the outer tube, and the object to be measured is arranged at the outlet end of the outer tube; Both the inner tube and the outer tube are made of light-tight materials.

2. The stray light detector based on the nested tube structure according to claim 1, wherein: The stray light detector further includes a light trap, and the light trap is connected to the outlet end of the outer tube; The light trap is used to guide away and / or absorb the excitation light.

3. The stray light detector based on the nested tube structure according to claim 1, characterized in that: The inner tube includes a first inner tube section, a second inner tube section, and a third inner tube section that are connected in sequence. The first inner tube section and the third inner tube section are arranged horizontally, and the second inner tube section is arranged obliquely; A first through hole is provided on the side wall of the outer tube. The third inner tube section is arranged in the outer tube through the first through hole. One end of the second inner tube section is arranged in the outer tube through the first through hole, and the other end is arranged outside the outer tube. The first inner tube section is arranged outside the outer tube.

4. A stray light detector based on a nested tube structure according to claim 1, characterized in that: The outer tube includes a first outer tube section, a second outer tube section, and a third outer tube section that are connected in sequence. The first outer tube section and the third outer tube section are arranged horizontally, and the second outer tube section is arranged obliquely; A second through hole is provided on the side wall of the second outer tube section. One end of the inner tube is arranged in the outer tube through the second through hole, and the other end is arranged in the outer tube and extends out of the outlet end of the outer tube.

5. A stray light detector based on a nested tube structure according to claim 1, characterized in that: An inclined mirror is provided at the inlet end of the outer tube. A third through hole is provided on the inclined mirror. One end of the inner tube is arranged in the outer tube through the third through hole.

6. A stray light detector based on a nested tube structure according to any one of claims 1 to 5, characterized in that: An absorbent material layer is provided on the inner wall of the outer tube.

7. A stray light detector based on a nested tube structure according to any one of claims 1 to 5, characterized in that: A filter or an absorbent sheet is provided at the inlet end or inside the outer tube for attenuating the excitation light and transmitting the stray light.

8. A stray light detector based on a nested tube structure according to any one of claims 1 to 5, characterized in that: The preset distance is greater than 1 mm. The inner diameter of the inner tube is 0.05 - 20 cm, and the inner diameter of the outer tube is 0.1 - 50 cm.

9. A stray light detector based on a nested tube structure according to any one of claims 1 to 4, characterized in that: Both the outer tube and the inner tube are made of metal, and their cross-sectional shapes are circular, oval, triangular, square, rectangular, or polygonal.

10. A stray light detector based on a nested tube structure according to claim 6, characterized in that: The absorbent material layer is composed of one or any combination of titanium dioxide, titanium nitride, zinc oxide, zirconium oxide, or anodized aluminum.

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