Flow cell and particle measurement device

Abstract

A flow cell is provided, the flow cell comprising: a body formed by blocks made of a uniaxial crystal material and bonded together; and a flow channel formed inside the body, such that the flow cell is configured to measure particles by receiving scattered light generated by particles passing through the flow channel; wherein the c-axis of a crystal in a predetermined portion of the body is configured to be substantially perpendicular to the receiving direction and polarization direction of the scattered light.

Description

Technical Field

[0001] The present invention relates to a flow cell into which a sample fluid is injected, and a particle measuring device using the flow cell to measure particles contained in the sample fluid. Background Technology

[0002] In the background art, flow cells are commonly used to detect light in order to count particles contained in chemical solutions. Flow cells are made of crystalline materials, such as chemically resistant synthetic corundum. Flow cells in which the flow channels are arranged along the c-axis of the synthetic corundum are known, such as this type of flow cell (see PTL 1).

[0003] Citation List

[0004] Patent documents

[0005] PTL1: JP-A-2004-053580 Summary of the Invention

[0006] Based on the aforementioned background technology, it is believed that a flow cell with the desired optical properties and mechanical strength can be manufactured using a relatively simple process. In particle measurement equipment using a flow cell, scattered light generated due to the interaction between the irradiating light and the particles is detected from outside a transparent plate. Due to the anisotropy of the crystalline material with an optical axis, birefringence occurs when the scattered light passes through the transparent plate. In this case, one polarized light component perpendicular to a plane including the c-axis and the direction of travel of the scattered light is used as the ordinary light, while another polarized light component parallel to the same plane is used as the extraordinary light. Typically, the polarization direction of the irradiating light is set perpendicular to the receiving direction of the scattered light. Therefore, in the case of detecting side-scattered light, the polarization direction of the irradiating light is set in the direction in which the flow channel extends. The polarization direction of the scattered light is consistent with the polarization direction of the irradiating light. In this case, the polarization direction of the scattered light is therefore consistent with the direction in which the flow channel extends, i.e., the c-axis direction of the transparent plate, which is like the polarization direction of the irradiating light. Therefore, due to birefringence, the scattered light polarized in the c-axis direction is used as the extraordinary light.

[0007] Here, the refractive index of ordinary light is constant and independent of its angle relative to the c-axis, while the refractive index of extraordinary light varies depending on its angle relative to the c-axis. Therefore, astigmatism occurs in the extraordinary light when scattered light passes through the light-transmitting plate. Astigmatism leads to an increase in spot size or a phase rotation. As a result, the light-converging performance of the optical system after passing through the light-transmitting plate is reduced, thus decreasing the SN ratio in photodetection or particle measurement.

[0008] The effect of this unusual light is particularly pronounced in interferometric systems in particle measurement devices (e.g., the particle counter described in Japanese Patent No. 5859154). However, for high-precision detection of scattered light, it is desirable to avoid the presence of unusual light even in typical light-receiving systems that are not interferometric systems.

[0009] Therefore, the objective of this invention is to provide a technique for suppressing the generation of unusual light due to birefringence.

[0010] To address the aforementioned problems, the present invention utilizes the following flow cell and the following particle measurement device. The terms in parentheses are merely exemplary, and the present invention is not limited thereto.

[0011] The flow cell according to the invention comprises: a body formed of blocks made of a uniaxial crystalline material and connected to each other; and a flow channel formed inside the body, such that the flow cell is configured to measure particles passing through the flow channel by receiving scattered light generated from particles; wherein: the crystal c-axis in a predetermined portion of the body is configured to be substantially perpendicular to the receiving direction and polarization direction of the scattered light. Preferably, the direction of the crystal c-axis in the predetermined portion of the body is substantially the same as the direction of the crystal c-axis in another portion of the body. More preferably, the body is formed by connecting a type of crystal facet from one of the plurality of blocks to a crystal facet of the same type in another block.

[0012] Furthermore, the particle measurement device according to the invention is a particle measurement device comprising: a flow cell according to any of the foregoing aspects; a light source configured to emit illumination light; an illumination optical system configured to allow the illumination light to pass through a portion of the flow cell other than a predetermined portion, such that a sample solution poured into a flow channel is irradiated by the illumination light; a converging optical system configured to converge scattered light generated by particles due to the illumination light and then transmitted through the predetermined portion, the particles being contained in the sample solution and passing through a detection region formed inside the flow channel; a light receiving element configured to receive the converged scattered light and output a signal having an amplitude corresponding to the intensity of the scattered light; and a measurement system configured to measure particles based on the output signal; wherein: the flow cell is oriented such that: the c-axis of a crystal in the predetermined portion of the flow cell is perpendicular to the receiving direction and polarization direction of the scattered light. The illumination light can pass through a wall of the flow cell other than the wall partially formed by the predetermined portion, such that the illumination light radiates onto the sample fluid.

[0013] When light is shone into a flow cell made of a uniaxial crystal material, and scattered light generated from particles passing through a detection region formed inside the flow channel is received, birefringence occurs because the scattered light passes through the walls of the flow cell. In this case, one polarized light component perpendicular to the plane that includes the crystal c-axis in the wall through which the scattered light passes and the direction of travel (receiving direction) of the scattered light is used as ordinary light, while the other polarized light component parallel to the same plane is used as extraordinary light.

[0014] Here, in the particle measurement apparatus according to the aforementioned aspect, the flow cell is oriented such that the c-axis (X-direction) of the crystal in a predetermined portion of the flow cell is perpendicular to the direction of travel (Z-direction) and polarization direction (Y-direction) of the scattered light, so that the scattered light transmitted through the predetermined portion is received. That is, the polarization direction (Y-direction) of the scattered light is perpendicular to the plane (ZX plane) including the c-axis in the wall (predetermined portion) through which the scattered light passes and the direction of travel of the scattered light. Therefore, according to the aforementioned aspect, the scattered light incident on the predetermined portion of the flow cell can be used as ordinary light. Therefore, the generation of unusual light can be suppressed, and the occurrence of astigmatism can be reduced. Therefore, the detection of scattered light and the SN ratio in particle measurement can be improved.

[0015] According to the present invention, as described above, the generation of extraordinary light due to birefringence can be suppressed. Attached Figure Description

[0016] Figure 1 This is a perspective view showing a flow cell in one embodiment.

[0017] Figure 2 This is a view showing the relationship between the c-axis and crystal planes in a unit crystal of synthetic corundum.

[0018] Figure 3 This is an exploded perspective view of the flow cell.

[0019] Figure 4 This is a block diagram illustrating the construction of a particle measuring device according to one embodiment.

[0020] Figure 5 This is a view showing the relationship between the direction of travel of the scattered light and a portion of the flow cell.

[0021] Figure 6A and 6B This is a view used to illustrate embodiments and comparative examples to explain the polarization direction of scattered light in the embodiments and comparative examples.

[0022] Figure 7 It is a view used to examine the energy of light rays when the c-axis orientation is set in the X direction.

[0023] Figure 8This is a view showing the size of the reference light spot.

[0024] Figure 9A and 9B This is a view showing the size of the scattered light spot.

[0025] Figure 10 This is a view showing the phase distribution of the reference light.

[0026] Figure 11A and 11B This is a view showing the phase distribution of the scattered light.

[0027] Figure 12A and 12B This is a view showing the experimental results when the c-axis orientation is set in the X direction (Example).

[0028] Figure 13A and 13B This illustrates the case where the c-axis orientation is set in the Y direction (comparative example).

[0029] A view of the experimental results. Detailed Implementation

[0030] Embodiments of the present invention will now be described with reference to the accompanying drawings. These embodiments are preferred examples. However, the present invention is not limited to these examples.

[0031] [Construction of a flow cell]

[0032] Figure 1 This is a perspective view showing a flow cell 10 in one embodiment.

[0033] The flow cell 10 is formed, for example, from synthetic corundum such as sapphire, and is substantially shaped as a cuboid. The flow cell 10 has an approximately linear flow channel 13 inside. Specifically, the flow channel 13, shaped as an approximately rectangular shape in cross-section, is formed to extend between a lower opening 11 and an upper opening 12, to penetrate the flow cell 10 substantially linearly. The lower opening 11 is located at the center portion of the bottom surface of the flow cell 10. The upper opening 12 is located at the center portion of the upper surface of the flow cell 10. The material of the flow cell 10 is not limited to synthetic corundum (hexagonal crystal system). Alternatively, any other uniaxial crystal material can be used as the material of the flow cell 10. Furthermore, the shape of the flow channel 13 is not limited to a linear shape. For example, the shape of the flow channel 13 can be a curved shape similar to an L-shape or a U-shape. Moreover, the cross-sectional shape of the flow cell 13 and the shape or position of the openings 11 and 12 are not limited to the above-described configuration. For example, the cross-sectional shape of the flow channel 13 can be formed as an approximately circular shape instead of an approximately rectangular shape.

[0034] From an external perspective, the flow cell 10 appears to be a single, monolithic body with a seamless, continuous surface. However, the flow cell 10 is actually formed from multiple blocks made of synthetic corundum and precisely connected to each other. The manner in which these blocks are connected will be further described later with reference to another accompanying drawing.

[0035] In the following figures, when light is detected using the flow cell 10, the direction of light travel (along the optical axis of the converging optical system, i.e., the light receiving direction) will be described as the Z direction, the direction in which the flow channel 13 extends will be described as the Y direction, and the direction perpendicular to the Y and Z directions will be described as the X direction.

[0036] Figure 2 This is a view showing the relationship between the c-axis (optical axis) and crystal planes in a unit crystal of synthetic corundum.

[0037] like Figure 2 As shown, the unit crystal of synthetic corundum has a c-plane orthogonal to the c-axis and an m-plane parallel to the c-axis. Furthermore, the crystal plane generated by cutting the unit crystal and orthogonal to the c-plane and m-plane is the a-plane. Each of the blocks constituting the flow cell 10 is obtained by cutting a block-shaped single-crystal material made from this unit crystal along the corresponding direction of the crystal plane. Therefore, each of the blocks constituting the flow cell 10 has a c-plane, an a-plane, and an m-plane.

[0038] Figure 3 This is an exploded perspective view of flow cell 10, showing the positional relationship between multiple blocks when they are connected to each other to form flow cell 10.

[0039] The flow cell 10 is made of, for example, four blocks: two first light-transmitting plates 14 and two second light-transmitting plates 15. The two first light-transmitting plates 14 are parallel to each other. The two second light-transmitting plates 15 are sandwiched between the first light-transmitting plates 14 in their thickness direction, facing the first light-transmitting plates 14. In each first light-transmitting plate 14, a c-plane is taken in the plane 14x perpendicular to the X direction, a m-plane is taken in the plane 14y perpendicular to the Y direction, and a-plane is taken in the plane 14z perpendicular to the Z direction. In each second light-transmitting plate 15, a c-plane is taken in the plane 15x perpendicular to the X direction, a m-plane is taken in the plane 15y perpendicular to the Y direction, and a-plane is taken in the plane 15z perpendicular to the Z direction. Then, the planes 14z and 15z, i.e., the a-planes of the blocks facing each other, are connected to each other. Therefore, the flow cell 10 is formed to have a flow channel 13 at the location surrounded by the four blocks.

[0040] In other words, the flow cell 10 is formed of interconnected blocks such that the crystallization c-axis in each portion of the flow cell 10 corresponds to the X direction. For the detection light, the light that travels in the Z direction through the first light-transmitting plate 14 is the target to be detected, generated by the interaction between the particles and the illumination light entering the flow cell 10 through either the first light-transmitting plate 14 (plane 14z) or the second light-transmitting plate 15 (plane 15x). As described with respect to the c-axis in the first light-transmitting plate 14 (through which the light to be detected passes), this c-axis is substantially perpendicular to the thickness direction of the first light-transmitting plate 14 and also substantially perpendicular to the direction in which the flow channel 13 extends.

[0041] Incidentally, errors may occur during the fabrication of the flow cell 10 (when blocks are cut from bulk single-crystal material or when blocks are joined together). Therefore, the orientation of the c-axis between blocks may not be perfectly aligned, but slight differences are permissible. Furthermore, the explanation regarding the c-axis and c-plane has already been described above. However, the a-plane and m-plane may not have the same configuration as described above. That is, planes 14y and 15y perpendicular to the Y-direction can be set to correspond to the a-plane, and planes 14z and 15z perpendicular to the Z-direction can be set to correspond to the m-plane. In this case, the m-planes of blocks facing each other are joined together to form the flow cell 10.

[0042] [Structure of Particle Measurement Equipment]

[0043] Figure 4 This is a block diagram illustrating the construction of a particle measuring device 1 in one embodiment.

[0044] like Figure 4 As shown, the particle measuring device 1 includes a detection system 2 and a measuring system 3. The detection system 2 is a portion that irradiates light onto the sample solution poured into the flow cell 10 and detects the light generated due to the interaction between the particles contained in the sample solution and the irradiated light. The measuring system 3 measures the particles based on the light detected by the detection system 2.

[0045] The detection system 2 is composed of, for example, a flow cell 10, a light source 20, a beam splitter 30, an illumination lens 31, a light converging lens 32, a beam damper 33, a beam attenuator 34, a reflector 35, a beam expander 36, a beam splitter 40, light converging lenses 41 and 43, and light receiving elements 42 and 44.

[0046] In detection system 2, the first light emitted from light source 20 is split into two paths by beam splitter 30. One of the two paths ("illumination light") enters flow cell 10 via illumination lens 31 to form a detection area within the flow channel. Scattered light generated in the detection area is incident on the incident surface of beam splitter 40 via light converging lens 32. Furthermore, the illumination light that has passed through flow cell 10 is absorbed by beam damper 33. On the other hand, the intensity of the other split beam ("reference light") is attenuated by beam attenuator 34. The reference light is then reflected by mirror 35 and expanded in beam diameter by beam expander 36, and incident on the other incident surface of beam splitter 40. The scattered light and reference light incident on beam splitter 40 are spatially superimposed on each other, causing two interference beams to be emitted from different emission surfaces. The two interference beams are incident on light receiving elements 42 and 44 via light converging lenses 41 and 43, and are received (detected) accordingly by light receiving elements 42 and 44.

[0047] In addition, the measurement system 3 is composed of, for example, a signal processing unit 50, an analysis unit 60, an output unit 70, etc.

[0048] When the detection system 2 (light receiving elements 42 and 44) ​​receives the interference light, it outputs an electrical signal with an amplitude corresponding to the intensity of the interference light. After the signal processing unit 50 amplifies the output electrical signal V1 corresponding to the first interference light and the output electrical signal V2 corresponding to the second interference light (if necessary) and further applies predetermined processing to the electrical signals V1 and V2, the signal processing unit 50 generates a detection signal based on the processed electrical signals V1 and V2. Furthermore, the analysis unit 60 performs analysis based on the detection signal generated by the signal processing unit 50 and performs particle measurements (such as counting the number of particles or measuring each size of the particles). The output unit 70 outputs the results measured by the analysis unit 60.

[0049] The construction of particle measuring device 1 is merely an example. However, this embodiment is not limited to this. For example, although a Mach-Zehnder type interferometric optical system is used in the detection system 2 described above, any other interferometric optical system (such as a Michelson type interferometric optical system) can be used instead.

[0050] [The relationship between the direction of scattered light travel and the orientation of the C-axis]

[0051] Figure 5 This is a view showing the relationship between the direction of travel of the scattered light and a portion of the flow cell 10, illustrating the configuration related to the reception of the scattered light extracted from the configuration of the detection system 2. Figure 5 The text shows along Figure 1 The horizontal cross-sectional view of the flow cell 10 is taken by the cutting line VV.

[0052] like Figure 5 As shown, the converging optical system is configured such that its optical axis is perpendicular to the surface 14z of the first light-transmitting plate 14, which forms a portion of the flow cell 10 in this embodiment. In other words, the flow cell 10 is configured such that surface 14z is perpendicular to the direction of travel of the scattered light. Furthermore, in this embodiment, the illumination light is incident on the flow cell 10 from the X direction (not shown). Therefore, the detection region M is formed inside the flow channel 13.

[0053] When particles P contained in the sample fluid injected into the flow channel 13 pass through the detection area M, scattered light is generated due to the interaction between particles P and the irradiated light, resulting in scattered light traveling in the Z direction, i.e., side-scattered light L. S The light is transmitted through the first light-transmitting plate 14 and incident on the incident surface of the beam splitter 40. On the other hand, the reference light L... R It is incident on another incident surface of the beam splitter 40. The scattered light L... S The transmission component and the reference light L R The reflected components have already interfered with each other in the first interference beam L I1 The light is emitted from the emitting surface of the beam splitter 40 and ultimately received by the light receiving element 42. On the other hand, the scattered light L... S The reflected component and the reference light L R The transmitted components have already interfered with each other in the second interference light L I2 The light is emitted from another emitting surface of the beam splitter 40 and ultimately received by the light receiving element 44. Therefore, the side-scattered light L is received in the detection system 2 according to this embodiment. S and reference light L R The light has already interfered with each other.

[0054] As described above, the c-axis is set to the X-direction in the flow cell 10. Therefore, the direction of travel of the scattered light (Z-direction) is perpendicular to the c-axis. In this embodiment of the receiving-side scattered light, the irradiation light is incident on the flow cell 10 from the X-direction, such that the polarization direction of the irradiation light corresponds to the Y-direction. Therefore, the polarization direction of the scattered light also corresponds to the Y-direction. Since a slight tilt may occur in the incident direction of the irradiation light, the polarization direction is not completely parallel to the Y-direction, i.e., a slight tilt may occur.

[0055] [The relationship between the polarization direction of scattered light and the orientation of the C-axis]

[0056] Figure 6A and 6B This is a view used to illustrate embodiments and comparative examples to explain the polarization direction of scattered light in the embodiments and comparative examples. Figure 6A The relationship between the polarization direction of the scattered light and the c-axis orientation is shown in the embodiment. Figure 6BThe relationship between the polarization direction and c-axis orientation of the scattered light is shown when the synthetic corundum cell (flow cell 10') described in PTL 1 above is used as a comparative example.

[0057] Figure 6A In the portion of the flow cell 10 wall formed on the side receiving the scattered light (the first light-transmitting plate 14, which is not yet connected), the c-axis is set in the X direction. Furthermore, the direction of travel of the scattered light corresponds to the Z direction, and the polarization direction of the scattered light corresponds to the Y direction. The polarization direction (Y direction) of the scattered light is perpendicular to a plane (ZX plane) that includes the direction of travel of the scattered light (Z direction) and the c-axis (X direction). Therefore, the scattered light incident on the portion of the wall formed on the side receiving the scattered light is used as ordinary light. Therefore, in this embodiment, when the scattered light passes through the first light-transmitting plate 14, the generation of extraordinary light can be suppressed due to birefringence. Therefore, for the reception of scattered light, the influence of extraordinary light can be reduced.

[0058] Figure 6B On the other hand, in the comparative example, the c-axis in the portion of the wall forming the flow cell 10' on the side receiving the scattered light is set in the Y direction. The direction of travel and polarization of the scattered light are the same as in the embodiment. In this case, the polarization direction (Y direction) of the scattered light is parallel to a plane (YZ plane) that includes the direction of travel (Z direction) of the scattered light and the c-axis (Y direction). Therefore, the scattered light incident on the portion of the wall forming on the side receiving the scattered light is used as a superfluous light. Therefore, in the comparative example, when the scattered light passes through the first light-transmitting plate 14, superfluous light is easily generated due to birefringence. Therefore, the reception of the scattered light is easily affected by superfluous light.

[0059] Figure 7 This is a diagram used to check the energy of light when the c-axis orientation is set in the X direction. Figure 7 The diagram shows the unit direction vector OP = (cosφcosθ,cosφsinθ,sinφ). With the optical axis direction (direction of light propagation) set to (0, 0, 1) and the polarization direction on the optical axis set to (0, 1, 0), the light rays in the direction vector OP are examined as follows.

[0060] When the c-axis orientation is set to (1, 0, 0), the normal to the plane formed by the c-axis and the ray can be expressed by the following direction vector.

[0061] (1,0,0)×(cosφcosθ,cosφsinθ,sinφ)

[0062] =(0,-sinφ,cosφsinθ)...(1)

[0063] Furthermore, a plane that uses light rays as normals, i.e., a plane perpendicular to light rays, can be expressed by the following expression.

[0064] (cosφcosθ)x+(cosφsinθ)y+(sinφ)z=0

[0065] Furthermore, since it is assumed that the polarization direction of a ray has a vector with an X-direction component of 0 in a plane perpendicular to the ray, the polarization direction of a ray can be represented by the following direction vector.

[0066] (0,1,-cosφsinθ / sinφ)...(2)

[0067] Here, the direction vectors expressed by the aforementioned expressions (1) and (2) are parallel to each other. Therefore, the full energy of the ray expressed by the direction vector OP is used as ordinary light. Therefore, when the ray is scattered light, the full energy of the scattered light is used as ordinary light.

[0068] The inspection results show that the c-axis is set in the X direction, the direction of travel of the scattered light is set in the Z direction, and the polarization direction of the scattered light is set in the Y direction. In other words, the c-axis is set perpendicular to both the direction of travel and the polarization direction of the scattered light. Therefore, theoretically, it is clear that the scattered light can be used as ordinary light, thus suppressing the generation of extraordinary light due to birefringence.

[0069] [Spot Size]

[0070] Figure 8 This is a view showing the size of the reference light spot in the image plane.

[0071] Figure 8 The area shown is 20 square μm in size, and each scale mark is 2 μm in size. It can be determined that the reference light spot falls within a 12 square μm area.

[0072] Figure 9A and 9B This is a view showing the size of the scattered light spot in the image plane. Figure 9A The image shows the spot size of the scattered light received by the flow cell 10 according to the foregoing embodiment, i.e., the scattered light (ordinary scattered light) under the condition of suppressing the generation of extraordinary light. Figure 9B The spot size of the scattered light received by using the flow cell 10' in the aforementioned comparative example is shown, i.e., the scattered light (extra-scattered light) without suppressing the generation of extra-light.

[0073] Figure 9A Ordinary scattered light spots fall within a 20 square μm region, which is almost the same as... Figure 8The spot size of the reference light shown is the same. This demonstrates that, by suppressing the generation of extraneous light, the energy of the scattered light can be used effectively because when the scattered light and the reference light are superimposed, most of the scattered light overlaps with the reference light.

[0074] Figure 9B On the other hand, the spot size of the highly scattered light expands to a region of 200 square μm, which is about 10 times larger than the spot size of the reference light or the ordinary scattered light. This indicates that, without suppressing the generation of highly scattered light, most of the energy of the scattered light is wasted because when the scattered light and the reference light are superimposed, most of the scattered light does not overlap with the reference light.

[0075] [Phase Distribution]

[0076] Figure 10 It is a view showing the phase distribution of the reference light when the reference light forms an image on the light receiving element. Figure 11A and 11B These are views showing the phase distribution of the scattered light as it forms an image on the light-receiving element. Figure 11A The phase distribution of ordinary scattered light is shown. Figure 11B The phase distribution of highly scattered light is shown. Both phase distributions were derived through simulation.

[0077] like Figure 10 and Figure 11A As shown, the phase distribution of the reference light and the phase distribution of the ordinary scattered light are roughly consistent. Therefore, the following considerations can be made: That is, when the generation of unusual light can be suppressed, the phases of the reference light and the scattered light are easily aligned, thus producing good interference between them. Therefore, the signal intensity during light reception can be increased, and the signal-to-noise ratio (SN ratio) can be improved.

[0078] On the other hand, such as Figure 11B As shown, the phase distribution of the highly scattered light has a very complex shape, completely different from that of the reference light. Therefore, the following considerations can be made: In other words, if the generation of highly scattered light cannot be suppressed, it is difficult to align the phases of the scattered and reference lights, making it difficult to produce good interference between them. Consequently, the signal intensity naturally decreases during light reception, and thus the signal-to-noise ratio (SN) naturally decreases as well.

[0079] [Changes in interference fringes due to changes in C-axis orientation]

[0080] Figure 12A and 12B as well as Figure 13A and 13BThis is a view used to interpret the results. In each result, the change in the appearance of the interference fringes caused by the change in c-axis orientation is confirmed experimentally. Figure 12A and 12B The experimental results from the examples are shown. Figure 13A and 13B The experimental results are shown in the comparative example.

[0081] In the experiment, the pinhole was positioned within the flow cell at the location where the scattered light was supposed to be emitted, and the screen was positioned between the beam splitter 40 and the light converging lens 41 (specifically, in...). Figure 5 (The location is indicated by the double dashed line SC). Through the beam splitter 40, the light diffracted by the pinhole and the reference light interfere with each other. The interference light reflected on the screen is imaged, thereby confirming the appearance of the interference fringes. Figure 12A and Figure 13A The simulation results of the phase distribution of scattered light at the screen location are shown, and Figure 12B and Figure 13B A photograph is shown that captures an image of the state of light at a screen location.

[0082] Figure 12A and 12B Experimental results are shown when using the flow cell 10 according to this embodiment, specifically when the c-axis orientation is set in the X direction. From Figure 12A Based on the phase distribution, it is assumed that no phase rotation of the scattered light occurred in this embodiment. Furthermore, to support the simulation results, no interference fringes appeared, and the diffracted light and the reference light almost perfectly superimposed on each other, thus... Figure 12B A strong light is generated in the photograph. In this embodiment, such light is ultimately received. Therefore, the intensity of the output signal is high.

[0083] Figure 13A and 13B Experimental results are shown when using the flow cell 10 according to the comparative example, specifically when the c-axis orientation is set in the Y direction. From Figure 13A Based on the phase distribution, it is believed that phase rotation of the scattered light occurred in the comparative example. As mentioned above, when the scattered light passes through the flow cell 10', due to birefringence, the scattered light is used as a superfluous beam, thus causing astigmatism in the comparative example. Therefore, it can be said that the phase rotation is caused by the superfluous beam. Furthermore, to support the simulation results, the phase rotation of the scattered light caused by astigmatism is reflected, and... Figure 13B Hyperbolic interference fringes appear in the photograph. During light reception, a signal with an intensity corresponding to the intensity integrated over the entire light beam is output. Therefore, the intensity of the output signal in the comparative example is low.

[0084] [Advantages of the Invention]

[0085] Based on the above embodiments, the following effects can be obtained.

[0086] (1) When light passes through the flow cell 10, birefringence occurs. However, the c-axis of the crystal in the portion forming a wall on the side receiving the light (one of the first light-transmitting plates 14 that is not yet connected) is perpendicular to both the direction of light travel and the polarization direction. Therefore, when scattered light passes through the flow cell 10 (the first light-transmitting plate 14 that is not yet connected), the scattered light generated due to the interaction between the particles P contained in the sample fluid injected into the flow channel 13 and the irradiating light can be used as ordinary light. Thus, the generation of extraordinary light can be suppressed.

[0087] (2) By using the flow cell 10, the generation of birefringent light is suppressed, thereby reducing astigmatism and also reducing the increase in spot size or the occurrence of phase rotation. Therefore, good interference can be generated between the scattered light and the reference light, thereby increasing the intensity of the output electrical signal during light reception. As a result, the SN ratio in optical detection and particle measurement can be improved.

[0088] The present invention is not limited to the foregoing embodiments, but can be modified and implemented in various ways.

[0089] In the above embodiment, the flow cell 10 consists of a total of four blocks: two first light-transmitting plates 14 and two second light-transmitting plates 15. However, the number of blocks is not limited to this. In the portion forming the flow cell, the crystal c-axis in the part through which the received scattered light is transmitted can be set in the X direction, i.e., the X-axis is perpendicular to the direction of travel and polarization of the scattered light, and this portion can be composed of a single block. Any other portion can be formed by connecting multiple blocks to each other.

[0090] In the above embodiment, a linear shape was used as the shape of the flow channel 13. However, any other shape (such as an L-shape or a U-shape) can be used instead. In this case, in the portion forming the flow cell, the c-axis of the crystal in the portion through which the received scattered light passes can be set in a direction perpendicular to the direction of travel and polarization of the scattered light, and this portion can be composed of a single block. Even with this construction, similar to the case using the aforementioned flow cell 10, the generation of extraneous light can be suppressed.

[0091] In the foregoing embodiment, side-scattered light was received. However, the received scattered light is not limited to side-scattered light. Even when scattered light with any direction is received, the orientation or position of the optical axes of the illumination optics and the converging optics relative to the flow cell 10 can be adjusted so that the c-axis in the first light-transmitting plate 14 is perpendicular to the direction of travel and polarization of the scattered light.

[0092] In the foregoing embodiments, an interferometric optical system is used in detection system 2. However, a non-interferometric optical system can be used alternatively. By using the flow cell 10, the generation of extraneous light can be suppressed even when scattered light is received through a non-interferometric optical system. Therefore, the SN ratio in the detection system can be improved, thereby enabling accurate particle counting in measurement system element 3.

[0093] Furthermore, the materials, values, etc., mentioned as examples of the construction of the flow cell 10 and the particle measuring device 1 are merely examples. It is important, of course, that the invention can be appropriately modified when it is implemented.

Claims

1. A flow cell, comprising: The main body is formed by blocks made of uniaxial crystalline material and connected to each other; as well as, A flow channel is formed inside the body, such that the flow cell is configured to measure the particles by receiving scattered light generated by the particles passing through the flow channel; In this embodiment, the crystal c-axis of the main body in the predetermined portion through which the received scattered light passes is configured to be substantially perpendicular to the receiving direction and polarization direction of the scattered light.

2. The flow cell according to claim 1, wherein, The direction of the crystal c-axis in a predetermined portion of the main body is substantially the same as the direction of the crystal c-axis in another portion of the main body.

3. The flow cell according to claim 1 or 2, wherein, The body is formed by connecting a crystal facet of one type in one of the plurality of blocks to a crystal facet of the same type in another block.

4. A particle measuring device, comprising: The flow cell according to any one of claims 1 to 3; A light source, configured to emit illumination light; An illumination optical system configured to allow illumination light to pass through a portion of the flow cell other than a predetermined portion, such that the sample solution poured into the flow channel is irradiated by the illumination light; A converging optical system configured to converge scattered light generated by particles due to irradiation by the irradiating light and then transmitted through the predetermined portion, the particles being contained in the sample solution and passing through a detection area formed inside the flow channel; A light receiving element configured to receive converged scattered light and output a signal having an amplitude corresponding to the intensity of the scattered light; as well as A measurement system configured to measure the particles based on an output signal; Wherein: the direction of the flow cell is set such that: the c-axis of the crystal in a predetermined portion of the flow cell is perpendicular to the receiving direction and polarization direction of the scattered light.

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