photometer

Abstract

The present invention discloses a photometer, which is mainly used in the field of experimental instrument technology. The purpose of the present invention is to provide a photometer that can effectively reduce the concentricity error of the corresponding optical fiber heads on the measuring arm and the measuring platform, and improve the measurement accuracy. Solution: The photometer comprises: a measuring platform, on which a first optical fiber head connected to a light source and a fourth optical fiber head connected to a detection analyzer are provided; a measuring arm, which is hinged on the measuring platform and can rotate around its hinge axis between a first position and a second position; a second optical fiber head and a third optical fiber head connected by optical fibers are provided along the length direction thereof, and when in the first position, the first optical fiber head and the fourth optical fiber head are arranged opposite to the second optical fiber head and the third optical fiber head respectively; the hinge axis of the measuring arm and the measuring platform is parallel to the line connecting the second optical fiber head and the third optical fiber head.

Description

Technical Field

[0001] The present invention relates to the technical field of experimental instruments, in particular to a photometer. Background Art

[0002] A photometer, also known as a spectrometer, is a scientific instrument that decomposes complex light into spectral lines. Photometers have become a common instrument in modern molecular biology laboratories, often used for nucleic acid and protein quantification, as well as quantification of bacterial growth concentrations.

[0003] Chinese invention patent No. 201510108765.1 discloses a micro-spectrophotometer comprising an upper and lower measuring platform positioned relative to each other and adjustable in distance. The upper and lower measuring platforms are provided with a projecting fiber holder and a receiving fiber holder, respectively, aligned vertically. An adjustment lever, driven by a drive device, is used to adjust the distance between the upper and lower measuring platforms. The adjustment lever also includes a distance sensing mechanism for controlling the distance between the upper and lower measuring platforms. The sensing mechanism comprises a sensing device and a sensing element. The sensing device comprises a transmitter capable of emitting signals and a receiver capable of receiving signals in an unobstructed manner. The sensing element is capable of moving in and out between the transmitter and receiver. A disadvantage of this device is that while the adjustment lever can be used to adjust the distance between the upper and lower measuring platforms and correct the optical path length, the rotation of the measuring arm (upper measuring platform) relative to the lower measuring platform inevitably reduces the concentricity of the corresponding optical fiber tips on the upper and lower measuring platforms during adjustment. In particular, the longer measuring arm (upper measuring platform) further amplifies this concentricity error, causing deviations in the light transmission between the two optical fiber tips, thereby affecting the measurement results. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a photometer that can effectively reduce the concentricity error of the measuring arm and the corresponding optical fiber head on the measuring platform, thereby improving the measurement accuracy.

[0005] A photometer comprising:

[0006] A measuring platform, on which a first optical fiber head connected to a light source and a fourth optical fiber head connected to a detection analyzer are provided;

[0007] The measuring arm is hinged to the measuring platform and can rotate about its hinge axis between a first position and a second position; a second optical fiber head and a third optical fiber head connected by an optical fiber are provided on the measuring arm along its length, and when in the first position, the first optical fiber head and the fourth optical fiber head are arranged to face the second optical fiber head and the third optical fiber head respectively;

[0008] The hinge axis of the measuring arm and the measuring platform is parallel to the line connecting the second and third optical fiber heads, which greatly reduces the vertical distance between each optical fiber head and the hinge axis. Under the premise that the flip angle of the measuring arm is the same, compared with the existing technology, the concentricity error of the corresponding two optical fiber heads (the concentricity between the first and second optical fiber heads, or between the third and fourth optical fiber heads) can be effectively reduced, thereby improving measurement accuracy.

[0009] Preferably, in the first position, the distance between the first optical fiber head and the second optical fiber head is 0.1-1 mm, which is used to measure low-concentration solutions; the distance between the third optical fiber head and the fourth optical fiber head is 0.02-0.1 mm, which is used to measure high-concentration solutions. In actual applications, if a low-concentration solution is measured, the low-concentration solution is dropped between the first optical fiber head and the second optical fiber head (actually dropped on the liquid bead bearing surface of the first optical fiber head), and no solution is added between the third optical fiber head and the fourth optical fiber head; if a high-concentration solution is measured, the high-concentration solution is dropped between the third optical fiber head and the fourth optical fiber head (actually dropped on the liquid bead bearing surface of the fourth optical fiber head), and no solution is added between the first optical fiber head and the second optical fiber head; compared with the photometer with fixed optical path in the prior art, high-concentration solution and low-concentration solution can be measured by one machine, and compared with the photometer with adjustable optical path in the prior art, the present invention does not need to adjust the optical path, does not need to be recalibrated, and does not need to be separately determined in the program whether it is a high-concentration solution or a low-concentration solution. The measurement time is short, and whether it is a low-concentration solution or a high-concentration solution, the angle between the measuring arm and the measuring platform remains unchanged, that is, the concentricity of the measuring arm and the corresponding optical fiber head on the measuring platform does not change, and the measurement accuracy is fixed and higher.

[0010] Preferably, a lower top block is provided on the upper surface of the measuring platform, and the lower top block is located in the middle of the line connecting the first optical fiber head and the fourth optical fiber head.

[0011] Preferably, the measuring arm is provided with an upper top column opposite to the lower top block. When in the first position, the lower top block and the upper top column are against each other, and the distance between the corresponding two optical fiber heads can be fine-tuned by replacing the lower top blocks of different heights.

[0012] Preferably, a convex portion is formed on the measuring arm, and the convex portion and the second optical fiber head and the third optical fiber head are respectively located on both sides of the hinge axis; a limiting groove matching the convex portion is formed on the measuring platform; when in the second position, the convex portion is limited in the limiting groove, and at this time, the measuring arm is stationary in the second position under the combined action of its own gravity and the limiting groove.

[0013] Preferably, the measuring platform is provided with a first mounting wall and a second mounting wall having mounting holes, wherein first and second bearings are mounted in the mounting holes of the two mounting walls, respectively. A rotating shaft is tightly mounted in the axial hole of the measuring arm, and the ends of the rotating shaft are supported by the first and second bearings, respectively. Since the ends of the rotating shaft are mounted on the first and second mounting walls, respectively, via the first and second bearings, the use of two supporting positions improves the stability of the rotating shaft and the measuring arm tightly fitted therewith, reduces shaking during the measurement arm's rotation, and ensures measurement accuracy.

[0014] Preferably, a flange is formed at one end of the rotating shaft, and a threaded hole is processed at the other end; the end of the rotating shaft processed with the threaded hole passes through the axial holes of the second bearing and the measuring arm in sequence and is inserted into the first bearing, and is threadedly connected to the set screw through the threaded hole, so that the flange is limited to the outer end surface of the second bearing, and the head of the set screw is limited to the outer end surface of the first bearing, thereby ensuring effective fastening and installation of the measuring arm and the rotating shaft, and convenient installation and disassembly.

[0015] Preferably, a first limiting portion is provided at one end of the mounting hole of the first mounting wall, and a first bearing pressure plate is detachably installed at the other end, the inner end face of the first bearing abuts against the first limiting portion, and the outer end face abuts against the first bearing pressure plate; a second limiting portion is provided at one end of the mounting hole of the second mounting wall, and a second bearing pressure plate is detachably installed at the other end, the inner end face of the second bearing abuts against the second limiting portion, and the outer end face abuts against the second bearing pressure plate.

[0016] Preferably, the second optical fiber head includes a main body, an optical fiber mounting hole located in the main body, and a liquid bead stretching portion formed at the end of the main body; wherein the liquid bead stretching portion includes a liquid bead stretching surface formed at the end, and the diameter of the liquid bead stretching surface is smaller than the diameter of the liquid bead bearing surface of the first optical fiber head; on the one hand, since the diameters of the two opposite end faces of the first optical fiber head and the second optical fiber head are different, it can reduce or even avoid the mechanical interference between the end face of the second optical fiber head and the end face of the first optical fiber head due to installation process, optical fiber eccentricity, skewness, etc. under high precision requirements, so that the actual distance between the two cannot meet the measurement requirements (that is, the optical path does not meet the measurement requirements); on the other hand, the diameter of the liquid bead stretching surface becomes smaller, and less sample liquid can be used for measurement, with a smaller contact area, relying on the surface tension of the liquid bead, contact stretching to form a liquid column to complete the measurement.

[0017] Preferably, the third optical fiber head includes a main body, an optical fiber mounting hole located in the main body, and a liquid bead stretching portion formed at the end of the main body; wherein the liquid bead stretching portion includes a liquid bead stretching surface formed at the end, and the diameter of the liquid bead stretching surface is smaller than the diameter of the liquid bead bearing surface of the fourth optical fiber head; on the one hand, since the diameters of the two opposite end faces of the third optical fiber head and the fourth optical fiber head are different, it can reduce or even avoid mechanical interference between the end face of the fourth optical fiber head and the end face of the third optical fiber head due to installation process, optical fiber eccentricity, skewness, etc. under high precision requirements, so that the actual distance between the two cannot meet the measurement requirements (that is, the optical path does not meet the measurement requirements); on the other hand, the diameter of the liquid bead stretching surface becomes smaller, and less sample liquid can be used for measurement, and a smaller contact area can be used, relying on the surface tension of the liquid bead to contact and stretch to form a liquid column to complete the measurement.

[0018] Preferably, the liquid bead stretching portion is in the shape of a spherical head, one end of which is connected to the main body and has a diameter equal to that of the main body, and the other end is processed with a flat surface to form the liquid bead stretching surface, and the spherical side forms a liquid bead stop surface, so that the liquid beads are only distributed on the liquid bead stretching surface; at the same time, the structure is easy to wipe and clean without residue, and will not affect the next measurement.

[0019] Alternatively, the liquid bead stretching portion is in a truncated cone shape, the lower end face of which is connected to the main body and has a diameter equal to the diameter of the main body, the upper end face is the liquid bead stretching surface, and the side surface forms a liquid bead stop surface, so that the liquid beads are only distributed on the liquid bead stretching surface; at the same time, this structure is easy to wipe and clean, without residue, and will not affect the next measurement.

[0020] Alternatively, the bead stretching portion comprises a first truncated cone portion, a cylindrical portion, and a second truncated cone portion coaxially connected in sequence. The lower end surface of the second truncated cone portion is connected to the main body and has a diameter equal to that of the main body. The upper end surface of the first truncated cone portion serves as the bead stretching surface, and the side surface of the first truncated cone portion forms a bead stop surface, ensuring that the bead is distributed only on the bead stretching surface. Furthermore, this structure is easy to wipe and clean, leaving no residue and preventing interference with subsequent measurements.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The hinge axis between the measuring arm and the measuring platform is parallel to the line connecting the second and third fiber optic heads, which greatly reduces the vertical distance between each fiber optic head and the hinge axis. Under the premise that the flip angle of the measuring arm is the same, compared with the existing technology, it can effectively reduce the concentricity error of the corresponding two fiber optic heads (between the first and second fiber optic heads, or between the third and fourth fiber optic heads) and improve measurement accuracy.

[0023] 2. In the first position, the distance between the first and second fiber optic heads is 0.7 mm, which is used for measuring low-concentration solutions; the distance between the third and fourth fiber optic heads is 0.05 mm, which is used for measuring high-concentration solutions. Compared with the fixed optical path photometers in the prior art, this device can measure both high-concentration and low-concentration solutions with a single device. Compared with the adjustable optical path photometers in the prior art, the present invention does not require optical path adjustment or recalibration, and the program does not need to separately determine whether the solution is a high-concentration or low-concentration solution. The measurement time is short, and the angle between the measuring arm and the measuring platform remains unchanged, whether measuring low-concentration or high-concentration solutions. That is, the concentricity of the measuring arm and the corresponding fiber optic head on the measuring platform does not change, resulting in fixed and higher measurement accuracy.

[0024] 3. By tightening the set screw, the flange is limited to the outer end face of the second bearing, and the head of the set screw is limited to the outer end face of the first bearing, ensuring the effective fastening and installation of the measuring arm and the rotating shaft. At the same time, the set screw is sunk into the first mounting wall (the end face of the set screw head is flush with the surface of the first mounting wall, or even lower than the surface of the first mounting wall), which does not increase the horizontal width, does not affect the appearance, and is also convenient for installation and disassembly.

[0025] 4. The end face diameters of the two optical fiber heads (the second optical fiber head and the third optical fiber head) located on the measuring arm are smaller than the end face diameters of the two corresponding optical fiber heads (the first optical fiber head and the fourth optical fiber head). This can reduce or even avoid mechanical interference between the two corresponding optical fiber heads due to installation process, optical fiber non-concentricity, skewness, etc. under high-precision requirements, making it impossible for the actual distance between the two to meet the measurement requirements (i.e., the optical path does not meet the measurement requirements); on the other hand, the diameter of the liquid bead stretching surface becomes smaller, so less sample liquid can be used for measurement, and a smaller contact area can be used. The measurement is completed by relying on the surface tension of the liquid bead and contact stretching to form a liquid column. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of the photometer of the present invention (the measuring arm is in the first position).

[0027] Figure 2 for Figure 1 Schematic diagram of the structure from another perspective.

[0028] Figure 3 Schematic diagram of the structure of the photometer of the present invention (the measuring arm is in the second position).

[0029] Figure 4 for Figure 3 Schematic diagram of the structure from another perspective.

[0030] Figure 5 FIG. 4 is a top view of the photometer of the present invention (the measuring arm is in the second position).

[0031] Figure 6 for Figure 5 CC section view.

[0032] Figure 7 FIG. 1 is a top view of the photometer of the present invention (the measuring arm is in the first position).

[0033] Figure 8 for Figure 7 AA section view.

[0034] Figure 9 for Figure 7 BB cross-sectional view.

[0035] Figure 10 for Figure 9 Magnified view of part A.

[0036] Figure 11 for Figure 9 Enlarged view of part B.

[0037] Figure 12 This is an enlarged view of the assembly structure of the rotating shaft and measuring arm.

[0038] Figure 13 for Figure 8 Enlarged view of part C.

[0039] Figure 14 for Figure 8 Enlarged view of part D. DETAILED DESCRIPTION

[0040] In order to facilitate understanding of the technical solution of the present invention, the following is a detailed description with reference to the accompanying drawings and specific embodiments.

[0041] like Figures 1-14 As shown, a photometer in this embodiment includes:

[0042] A measuring platform 5 is provided with a first optical fiber head 1 connected to a light source via an optical fiber, and a fourth optical fiber head 4 connected to a detection analyzer via an optical fiber;

[0043] A measuring arm 6 is hingedly connected to the measuring platform 5 and is capable of rotating about its hinge axis between a first position and a second position. A second optical fiber head 2 and a third optical fiber head 3 are disposed along the length of the measuring arm 6, connected by optical fibers. In the first position, the first optical fiber head 1 and the fourth optical fiber head 4 are arranged opposite the second optical fiber head 2 and the third optical fiber head 3, respectively.

[0044] like Figure 1-Figure 7As shown, the hinge axis between the measuring arm 6 and the measuring platform 5 is parallel to the line connecting the second optical fiber head 2 and the third optical fiber head 3, which greatly reduces the vertical distance between each optical fiber head and the hinge axis. Under the premise that the flip angle of the measuring arm 6 is the same, compared with the existing technology, the concentricity error of the corresponding two optical fiber heads (the concentricity between the first optical fiber head and the second optical fiber head, or the concentricity between the third optical fiber head and the fourth optical fiber head) can be effectively reduced, thereby improving the measurement accuracy.

[0045] When in the first position, the distance between the first optical fiber head 1 and the second optical fiber head 2 is 0.1-1mm, and in this example the distance between the two is 0.7mm, which is used to measure low-concentration solutions; the distance between the third optical fiber head 3 and the fourth optical fiber head 4 is 0.02-0.1mm, and in this example the distance between the two is 0.05mm, which is used to measure high-concentration solutions; taking the distances of 0.05mm and 0.7mm in this example as an example, the corresponding high and low concentrations are high and low concentration measurement intervals divided by the conventional 1500ng / ul (dsDNA), that is, when the distance between the first optical fiber head 1 and the second optical fiber head 2 is 0.7mm, solutions below 1500ng / ul (dsDNA) are measured; when the distance between the third optical fiber head 3 and the fourth optical fiber head 4 is 0.05mm, solutions above 1500ng / ul (dsDNA) are measured. In actual applications, if a low-concentration solution is measured, the low-concentration solution is dropped between the first optical fiber head 1 and the second optical fiber head 2 (actually dropped on the liquid bead bearing surface of the first optical fiber head), and no solution is added between the third optical fiber head 3 and the fourth optical fiber head 4; if a high-concentration solution is measured, the high-concentration solution is dropped between the third optical fiber head 3 and the fourth optical fiber head 4 (actually dropped on the liquid bead bearing surface of the fourth optical fiber head), and no solution is added between the first optical fiber head 1 and the second optical fiber head 2; compared with the fixed optical path photometer in the prior art, high-concentration solution and low-concentration solution can be measured by one machine, and compared with the adjustable optical path photometer in the prior art, the present invention does not need to adjust the optical path, does not need to be recalibrated, and does not need to be separately determined in the program whether it is a high-concentration solution or a low-concentration solution. The measurement time is short, and whether it is a low-concentration solution or a high-concentration solution, the angle between the measuring arm 6 and the measuring platform 5 remains unchanged, that is, the concentricity of the measuring arm 6 and the corresponding optical fiber head on the measuring platform 5 does not change, and the measurement accuracy is fixed and higher.

[0046] A lower top block 7 is provided on the upper surface of the measuring platform 5, and the lower top block is located in the middle of the line connecting the first optical fiber head 1 and the fourth optical fiber head 4; an upper top column 8 is provided on the measuring arm 6, which is opposite to the lower top block 7. When in the first position, the lower top block 7 and the upper top column 8 are at odds with each other, and the distance between the corresponding two optical fiber heads can be fine-tuned by replacing the lower top block 7 with different heights.

[0047] like Figure 3-Figure 6 As shown, a protrusion 9 is formed on the measuring arm 6, and the protrusion and the second optical fiber head 2 and the third optical fiber head 3 are respectively located on either side of the hinge axis; a limiting groove 10 is formed on the measuring platform 5 to match the protrusion; when in the second position, the protrusion 9 is confined within the limiting groove 10, and the measuring arm 6 is stationary in the second position under the combined action of its own gravity and the limiting groove 10.

[0048] like Figures 8-12 As shown, the measuring platform 5 is provided with a first mounting wall 11 and a second mounting wall 12 with mounting holes, and a first bearing 13 and a second bearing 14 are respectively installed in the mounting holes of the two mounting walls. A rotating shaft 15 is tightly installed in the axial hole of the measuring arm 6, and both ends of the rotating shaft are respectively supported on the first bearing 13 and the second bearing 14. Specifically, a flange 15-1 is formed at one end of the rotating shaft 15, and a threaded hole 15-2 is processed at the other end; the end of the rotating shaft processed with the threaded hole 15-2 passes through the second bearing 14 and the axial hole of the measuring arm 6 in sequence and is inserted into the first bearing 13, and is threadedly connected with a set screw 16 through the threaded hole 15-2, so that the flange 15-1 is limited to the outer end surface of the second bearing 14, and the head of the set screw 16 is limited to the outer end surface of the first bearing 13, ensuring that the rotating shaft 15 is effectively fastened and installed on the first bearing 13 and the second bearing 14.

[0049] Because the ends of the rotating shaft 15 are mounted on the first mounting wall 11 and the second mounting wall 12 via the first bearing 13 and the second bearing 14, respectively, the use of two support points enhances the stability of the rotating shaft 15 and the measuring arm 6, which is tightly fitted to the rotating shaft, reduces shaking during the turning process of the measuring arm 6, and ensures measurement accuracy. Furthermore, the set screw 16 is recessed into the first mounting wall 11 (the end surface of the set screw head is flush with the surface of the first mounting wall, or even lower than it, similar to a countersunk screw). This does not increase the lateral width, does not affect the aesthetics, and facilitates installation and removal (for removal, simply remove the set screw from the threaded hole and then pull out the rotating shaft). In this example, the end of the rotating shaft 15 with the flange 15-1 and the head of the set screw 16 are both provided with screwdriver fastening slots 20. During installation and removal, two screwdrivers are inserted into the two screwdriver fastening slots 20 and twisted in opposite directions to install or remove the measuring arm 6 and rotating shaft 15, making it simple and convenient.

[0050] A first stopper 11-1 is provided at one end of the mounting hole of the first mounting wall 11, and a first bearing pressure plate 17 is removably mounted on the other end. The inner end surface of the first bearing 13 abuts the first stopper 11-1, while the outer end surface abuts the first bearing pressure plate 17. During installation, the first bearing 13 is placed into the mounting hole of the first mounting wall 11, with its inner end surface abutting the first stopper 11-1. The first bearing pressure plate 17 is then screwed onto the first mounting wall 11, pressing the first bearing 13 firmly into the mounting hole. During disassembly, the first bearing 13 can be removed from the mounting hole after removing the first bearing pressure plate 17. Both installation and disassembly are simple and convenient, facilitating the replacement of wearing parts.

[0051] One end of the mounting hole of the second mounting wall 12 is provided with a second limiting portion 12-1, and the other end is detachably mounted with a second bearing pressure plate 18. The inner end surface of the second bearing 14 abuts the second limiting portion 12-1, and the outer end surface abuts the second bearing pressure plate 18. Similarly, during installation, the second bearing 14 is placed into the mounting hole of the second mounting wall 12, with its inner end surface abutting the second limiting portion 12-1. The second bearing pressure plate 18 is then screwed onto the second mounting wall 12, pressing the second bearing 14 tightly into the mounting hole. During disassembly, after removing the second bearing pressure plate 18, the second bearing 14 can be removed from the mounting hole. Both installation and disassembly are simple and convenient, facilitating the replacement of wearing parts.

[0052] like Figure 12 As shown, as a preferred embodiment of this embodiment, a recessed portion is formed on the outer surface of the central portion of the rotating shaft 15, so that the ends of the rotating shaft 15 are tightly connected with the axial hole of the measuring arm 6. A gap 19 is formed between the recessed portion and the wall of the axial hole of the measuring arm 6. Since only the ends of the rotating shaft 15 are tightly connected with the axial hole of the measuring arm 6, and not the entire rotating shaft 15, it is more convenient to install and remove the rotating shaft 15.

[0053] As a preferred solution of this embodiment, both first bearing 13 and second bearing 14 are constructed from at least two coaxially joined bearings. The multiple bearings provide a more precise fit with more balls, tightly clasping the rotating shaft 15 and further reducing play while ensuring the flexible movement of the measuring arm 6.

[0054] like Figure 13 、 Figure 14 As shown, in this example,

[0055] The first optical fiber head 1 and the fourth optical fiber head 4 are both SMA905 with a diameter of 3 mm, and a liquid bead bearing surface 26 is formed on the end surface thereof;

[0056] The second optical fiber head 2 includes a body 21, an optical fiber mounting hole 22 located in the body 21, and a liquid bead stretching portion 23 formed at the end of the body 21; wherein the liquid bead stretching portion 23 includes a first truncated cone portion 23-1, a cylindrical portion 23-2, and a second truncated cone portion 23-3 that are coaxially connected and integrally formed in sequence, wherein the lower end surface (the end with a slightly larger diameter) of the second truncated cone portion 23-3 is connected to the body 21 and has a diameter equal to that of the body 21, the upper end surface of the first truncated cone portion 23-1 forms a liquid bead stretching surface 24, and the side surface of the first truncated cone portion 23-1 forms a liquid bead stopping surface 25. The diameter of the liquid bead stretching surface 24 is smaller than the diameter of the liquid bead bearing surface 26 of the first optical fiber head 1. On the one hand, since the diameters of the two opposite end faces of the first optical fiber head 1 and the second optical fiber head 2 are different, it can reduce or even avoid the mechanical interference between the end face of the second optical fiber head 2 and the end face of the first optical fiber head 1 due to installation process, optical fiber non-concentricity, skewness, etc. under high precision requirements, so that the actual distance between the two cannot meet the measurement requirements (that is, the optical path does not meet the measurement requirements); on the other hand, the diameter of the liquid bead stretching surface 24 becomes smaller, and less sample liquid can be used for measurement, with a smaller contact area, relying on the surface tension of the liquid bead, contact stretching to form a liquid column to complete the measurement.

[0057] The third optical fiber head 3 includes a body 21, an optical fiber mounting hole 22 located in the body 21, and a liquid bead stretching portion 23 formed at the end of the body 21; wherein the liquid bead stretching portion 23 is in the shape of a spherical head, one end of which is connected to the body 21 and has a diameter equal to the diameter of the body 21, and the other end is processed with a plane to form a liquid bead stretching surface 24, and the spherical side surface forms a liquid bead stop surface 25; the diameter of the liquid bead stretching surface 24 is smaller than the diameter of the liquid bead bearing surface 26 of the fourth optical fiber head 4. On the one hand, since the diameters of the two opposite end faces of the third optical fiber head 3 and the fourth optical fiber head 4 are different, the mechanical interference between the end face of the fourth optical fiber head 4 and the end face of the third optical fiber head 3 due to installation process, optical fiber non-concentricity, skewness, etc. under high precision requirements can be reduced or even avoided, so that the actual distance between the two cannot meet the measurement requirements (that is, the optical path does not meet the measurement requirements); on the other hand, the diameter of the liquid bead stretching surface 24 becomes smaller, so that less sample liquid can be used for measurement, and a smaller contact area can be used to rely on the surface tension of the liquid bead to contact and stretch to form a liquid column to complete the measurement.

[0058] The bead-drawing portion 23 of the second optical fiber tip 2 and / or the third optical fiber tip 3 may also be truncated cone-shaped, with its lower end surface (the end with the larger diameter) connected to the body 21 and having a diameter equal to that of the body 21. The upper end surface forms a bead-drawing surface 24, and the side surface forms a bead-stopping surface 25. Of course, the bead-drawing portion 23 of the second optical fiber tip 2 and the third optical fiber tip 3 may also have the same structure, both being truncated cone-shaped or spherical.

[0059] In this example, in order to ensure a better bead stretching effect, the diameter of the bead stretching surface 24 is set to 1-1.5 mm.

[0060] The diameters of the optical fiber mounting holes 22 of the second optical fiber head 2 and the optical fiber mounting holes 22 of the third optical fiber head 3 are slightly smaller than those of the optical fiber mounting holes of the first optical fiber head 1 and the fourth optical fiber head 4. Even if there are certain errors in the concentricity of the first optical fiber head 1 and the second optical fiber head 2 and the concentricity of the third optical fiber head 3 and the fourth optical fiber head 4, the accuracy of the measurement can be guaranteed.

[0061] The above are only preferred embodiments of the present invention. The scope of protection of the present invention shall be based on the scope defined by the claims. Several improvements and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should also be regarded as the scope of protection of the present invention.

Claims

1. A photometer comprising: A measuring platform (5) is provided with a first optical fiber head (1) connected to a light source and a fourth optical fiber head (4) connected to a detection analyzer; A measuring arm (6) is hinged to the measuring platform (5) and is capable of rotating about its hinge axis between a first position and a second position; A second optical fiber head (2) and a third optical fiber head (3) connected by optical fibers are arranged along the length direction thereof; when in the first position, the first optical fiber head (1) and the fourth optical fiber head (4) are arranged facing the second optical fiber head (2) and the third optical fiber head (3) respectively; The invention is characterized in that: the hinge axis of the measuring arm (6) and the measuring platform (5) is parallel to the connecting line of the second optical fiber head (2) and the third optical fiber head (3); when the solution is added between the first optical fiber head and the second optical fiber head, no solution is added between the third optical fiber head and the fourth optical fiber head; when the solution is added between the third optical fiber head and the fourth optical fiber head, no solution is added between the first optical fiber head and the second optical fiber head; when in the first position, the distance between the first optical fiber head (1) and the second optical fiber head (2) is 0.1-1 mm, and the distance between the third optical fiber head (3) and the fourth optical fiber head (4) is 0.02-0.05 mm.

2. The photometer according to claim 1, wherein: A lower top block (7) is provided on the upper surface of the measuring platform (5), and the lower top block is located in the middle of the line connecting the first optical fiber head (1) and the fourth optical fiber head (4).

3. The photometer according to claim 2, wherein: An upper top column (8) opposite to the lower top block (7) is provided on the measuring arm (6).

4. The photometer according to claim 1, wherein: A convex portion (9) is formed on the measuring arm (6), and the convex portion and the second optical fiber head (2) and the third optical fiber head (3) are respectively located on both sides of the hinge axis; a limiting groove (10) matching the convex portion is formed on the measuring platform (5); when in the second position, the convex portion (9) is limited in the limiting groove (10).

5. The photometer according to claim 1, wherein: The measuring platform (5) is provided with a first mounting wall (11) and a second mounting wall (12) with mounting holes, and a first bearing (13) and a second bearing (14) are respectively installed in the mounting holes of the two mounting walls. A rotating shaft (15) is tightly installed in the axial hole of the measuring arm (6), and both ends of the rotating shaft are respectively supported on the first bearing (13) and the second bearing (14).

6. The photometer according to claim 5, wherein: A flange (15-1) is formed at one end of the rotating shaft (15), and a threaded hole (15-2) is processed at the other end; the end of the rotating shaft processed with the threaded hole (15-2) passes through the axial holes of the second bearing (14) and the measuring arm (6) in sequence, and is then inserted into the first bearing (13), and is threadedly connected to the set screw (16) through the threaded hole (15-2), so that the flange (15-1) is limited to the outer end surface of the second bearing (14), and the head of the set screw (16) is limited to the outer end surface of the first bearing (13).

7. The photometer according to claim 5, wherein: A first limiting portion (11-1) is provided at one end of the mounting hole of the first mounting wall (11), and a first bearing pressure plate (17) is detachably installed at the other end, wherein the inner end face of the first bearing (13) abuts against the first limiting portion (11-1), and the outer end face abuts against the first bearing pressure plate (17); a second limiting portion (12-1) is provided at one end of the mounting hole of the second mounting wall (12), and a second bearing pressure plate (18) is detachably installed at the other end, wherein the inner end face of the second bearing (14) abuts against the second limiting portion (12-1), and the outer end face abuts against the second bearing pressure plate (18).

8. The photometer according to claim 1, wherein: The second optical fiber head (2) comprises a body (21), an optical fiber mounting hole (22) located in the body (21), and a liquid bead stretching portion (23) formed at the end of the body (21); wherein the liquid bead stretching portion (23) comprises a liquid bead stretching surface (24) formed at the end, and the diameter of the liquid bead stretching surface (24) is smaller than the diameter of the liquid bead bearing surface of the first optical fiber head (1); Alternatively, the third optical fiber head (3) comprises a body (21), an optical fiber mounting hole (22) located in the body (21), and a liquid bead stretching portion (23) formed at the end of the body (21); wherein the liquid bead stretching portion (23) comprises a liquid bead stretching surface (24) formed at the end, and the diameter of the liquid bead stretching surface (24) is smaller than the diameter of the liquid bead bearing surface of the fourth optical fiber head (4).

9. The photometer according to claim 8, wherein: The bead stretching portion (23) is in the shape of a spherical head, one end of which is connected to the body (21) and has a diameter equal to that of the body (21), and the other end is processed with a plane to form the bead stretching surface (24), and the spherical side surface forms a bead stop surface (25); Alternatively, the bead stretching portion (23) is in a truncated cone shape, the lower end surface of which is connected to the body (21) and has a diameter equal to that of the body (21), the upper end surface of which is the bead stretching surface (24), and the side surface of which forms a bead stop surface (25); Alternatively, the liquid bead stretching portion (23) includes a first truncated cone portion (23-1), a cylindrical portion (23-2), and a second truncated cone portion (23-3) coaxially connected in sequence, wherein the lower end surface of the second truncated cone portion (23-3) is connected to the main body (21) and has a diameter equal to that of the main body (21), the upper end surface of the first truncated cone portion (23-1) is the liquid bead stretching surface (24), and the side surface of the first truncated cone portion (23-1) forms a liquid bead stop surface (25).

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