Particle measuring device and particle measurement method

Abstract

To provide a technique for efficiently detecting particles.SOLUTION: Lenses 152, 154 and a beam splitter 156 are arranged so that an intersection point of an exit pupil and an optical axis of the lens 154 through which scattered light LS from particles passes and a condensing point of reference light LR emitted from the lens 152 are in a conjugate relation to each other. The lens 152 adjusts its expansion so that the reference light LR covers a wide range of a light reception surface. For such a particle measuring device, in light combination by the beam splitter 156, wave fronts of the scattered light LS and the reference light LR do not coincide with each other, and the optical axis becomes parallel and enters a detector 160. On a light receiving element 162, the wave front of the scattered light LS is constantly substantially parallel to the wave front of the reference light LR within a beam diameter range. An intensity variation in interaction between the scattered light LS and the reference light LR can be effectively obtained, thereby allowing effective detection of particles. As wave front shapes need not be made coincide in light combination of the scattered light LS and the reference light LR, high degree of freedom in design can be obtained.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for measuring the number, particle size, refractive index, etc. of particles contained in a fluid. [Background technology]

[0002] One method for measuring particles contained in a fluid involves irradiating the fluid with light and receiving scattered light generated when the irradiated light strikes particles (hereinafter referred to as "scattered light from particles"). In this type of measurement, in order to detect particles with smaller diameters, a known method is to separate light from a light source into irradiated light and reference light, cause the scattered light from the particles to interfere with the reference light, and count the particles by diameter based on the interference light incident on a detector (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5859154 [Patent Document 2] Patent No. 6030740 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to efficiently obtain the intensity change due to the interference between the scattered light from the particle and the reference light, it is desirable that the optical axes of the scattered light and the reference light beam are parallel to each other and that they are incident on the detector in an overlapping manner. If the optical axes of the scattered light and the reference light are deviated from the parallel state, the detection sensitivity will decrease.

[0005] In addition, in order to increase detection sensitivity, the wavefront of the scattered light and the wavefront of the reference light are generally made to roughly coincide. In this case, the total power of the light beam formed by combining the scattered light and the reference light is constant at any position along the optical axis, but if the spot size of the scattered light is reduced, the size of the light-receiving surface can also be reduced, resulting in reduced noise. For this reason, the detector (light-receiving element) is often placed near the beam waist of the scattered light (see Figure 3).

[0006] In the two prior art technologies described above, as shown in (A) in Figure 8, both the scattered light and the reference light are adjusted to become plane waves when combined, and the light receiving element is positioned near the beam waist. However, because the scattered light and the reference light are focused at the same position on the light receiving element in the detector, the interference between the scattered light and the reference light forms a small spot, and as shown in (B-1) in Figure 8, only a portion of the entire light receiving surface of the light receiving element is used, making it impossible to use the light receiving element efficiently.

[0007] Furthermore, in the two prior arts described above, the optical axes of the scattered light and reference light may deviate from parallel depending on the position of the particle being observed. When the scattered light is no longer parallel to the reference light and the wavefront of the scattered light is tilted, the overlap with the reference light decreases, weakening the interference between the scattered light and the reference light, as shown in (B-2) in Fig. 8. Furthermore, in a configuration in which multiple light-receiving elements are aligned in a row or two-dimensionally on the same surface, there are slight gaps between the light-receiving elements. If the reference light is incident at a position shifted from the center of each light-receiving element and the reference light spot extends into the gap, it becomes difficult to form an interference spot with the scattered light on the light-receiving surface, as shown in (B-3) in Fig. 8, which also leads to a decrease in detection sensitivity.

[0008] The present invention has been made in view of these problems, and an object of the present invention is to provide a technique for efficiently detecting particles. [Means for solving the problem]

[0009] To solve the above problems, the present invention employs the following particle measurement device and method implemented by this particle measurement device. Note that the following words in parentheses are merely examples, and the present invention is not limited thereto.

[0010] That is, the particle measuring device of the present invention includes a light source that emits light, a first beam splitter that splits the light from the light source into two, directing one light, the illumination light, toward a flow path into which a fluid flows and the other light, the reference light, in a direction different from the flow path, an optical system that adjusts the cross-sectional shape and spread angle of the reference light so that it covers a wide range or the entire light receiving portion of the detector, a second beam splitter that combines scattered light from particles contained in the fluid generated in a detection region formed within the flow path by irradiating the illumination light onto the flow path and the reference light that has passed through the optical system, with the wavefronts not coinciding, and a detector that has one or more light receiving elements that receive interference light between the scattered light and the reference light combined by the second beam splitter and output a signal corresponding to the intensity of the interference light. Note that if the light emitted by the light source has a spread in its cross section (i.e., the cross section is not a tiny dot but has a spread shape such as a line, a band, a square, a circle, etc.), an optical system that adjusts the spread of the reference light or the light from the light source may not be provided.

[0011] According to the particle measuring device of this aspect, the reference light can cover a wide range of the light receiving element, so even if the incident position of the scattered light on the detector changes depending on the position of the particle in the detection area, the scattered light and the reference light can interfere well, making it possible to detect particles efficiently. Furthermore, in the particle measuring device of this aspect, when the scattered light and the reference light are combined by the second beam splitter, it is not necessary to match the wavefronts of the two (match the wavefront shapes), so the degree of freedom in installing components can be increased compared to particle measuring devices that match the wavefront shapes and combine the lights.

[0012] Preferably, in the particle measuring device of the above-described aspect, the second beam splitter is arranged so that the direction of the chief ray of the scattered light generated at an arbitrary position in the detection region substantially coincides with the direction of the ray of the reference light passing through the same location as the chief ray of the scattered light.

[0013] According to this aspect of the particle measuring device, the scattered light and the reference light overlap and enter the detector, so that the intensity change of the interference between the scattered light and the reference light can be obtained effectively on the light receiving element, making it possible to more efficiently detect particles.

[0014] More preferably, the particle measuring device of the above-described aspect further comprises a telecentric optical system into which scattered light generated in the detection region is incident and which emits its chief ray parallel to the optical axis in image space, and the second beam splitter combines the reference light and the scattered light emitted from the telecentric optical system so that their optical axes are parallel.

[0015] According to this aspect of the particle measuring device, the scattered light heading toward the detector is parallel to the optical axis of the telecentric optical system regardless of the position of the particle in the detection region, and therefore it is easy to make the wavefronts of the scattered light and the reference light on the light-receiving element coincide with each other, thereby enabling the scattered light and the reference light to interfere more effectively on the light-receiving element and enabling more efficient particle detection.

[0016] More preferably, in the particle measuring device of the above aspect, the detector is disposed in the vicinity of the beam waist of the scattered light.

[0017] According to this aspect of the particle measuring device, the wavefront of the scattered light from the particles is generally flat on the light receiving element of the detector, and the wavefront of the scattered light and the wavefront of the reference light are generally parallel, so that the change in intensity of the interference between the scattered light and the reference light can be obtained effectively, making it possible to detect particles even more efficiently. [Effects of the Invention]

[0018] As described above, the particle measuring device of the present invention can efficiently detect particles contained in a fluid. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a block diagram showing the configuration of a particle measuring device 100 according to a first embodiment. [Figure 2] 10 is a diagram showing the detailed positional relationship between components in the beam combining and focusing optical system 150. FIG. [Figure 3] FIG. 10 is a diagram illustrating a beam waist. [Figure 4] 10 is a diagram showing an example of the manner in which scattered light and reference light are incident on a light receiving element 162. FIG. [Figure 5] FIG. 2 is a block diagram showing the configuration of a particle measuring device 200 according to a second embodiment. [Figure 6] 10 is a diagram showing how scattered light and reference light travel in a beam combining / collecting optical system 250. FIG. [Figure 7] FIG. 10 is a diagram showing a modified example of the beam combining and focusing optical system. [Figure 8] FIG. 1 is a diagram illustrating a conventional technique. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For ease of explanation, the components constituting the particle measurement device and the shape of the wavefront of light are shown in simplified form in the drawings. Furthermore, to facilitate understanding of the invention, in the block diagrams (FIGS. 1 and 5), the direction of light traveling between components is indicated by dashed arrows, and the direction of signals is indicated by solid arrows.

[0021] [First embodiment] FIG. 1 is a block diagram showing the configuration of a particle measuring device 100 according to the first embodiment.

[0022] The particle measuring device 100 mainly includes a light source 110 and a reference light L R and irradiation light L A and a beam splitter 120 that splits the reference light L R A mirror 130 that changes the direction of the light L A A flow cell 140 through which light passes, and a particle P contained in the fluid is irradiated with light L A Scattered light L generated by theS While collecting scattered light L S and reference beam L R and a beam combining / condensing optical system 150 that combines the beams and guides them to a detector 160.

[0023] More specifically, the particle measuring device 100 includes, for example, a light source 110, various optical elements 120, 122, 124, 130, 152, 154, 156, a flow cell 140, and a detector 160 as components for detecting particles, and includes a counting unit 170 as a component for counting the detected particles.

[0024] Light source 110 emits light of a predetermined wavelength (e.g., laser light). Beam splitter 120 splits the light from light source 110 into transmitted light and reflected light at a predetermined ratio. Hereinafter, the light transmitted through beam splitter 120 will be referred to as "irradiation light," and the reflected light will be referred to as "reference light."

[0025] The irradiated light L emitted from the beam splitter 120 A The irradiated light L passes through the lens 122 and is directed to the flow cell 140. A The light is focused toward the flow cell 140, and the irradiated light L A The light collection area (irradiated light L A The degree of light collection onto the flow cell 140 is adjusted.

[0026] The flow cell 140 is made of a glass material such as synthetic quartz or optical glass, or a crystalline material such as synthetic corundum, and has a flow path formed therein through which a fluid flows. A detection area is set within the flow path, and irradiation light L is directed toward the detection area. A From another perspective, the irradiated light L A is incident on the flow cell 140, and the irradiated light L A When a particle P is present in the detection area, the irradiated light L A hits particle P and scatters light L S occurs.

[0027] The lens 154 reflects the scattered light L from the particle P. S The detector 160 is configured to focus the scattered light L S The scattered light L is approximately perpendicular to the optical axis direction. S The scattered light L that has passed through the lens 154 is S The irradiated light L transmitted through the beam splitter 156 is directed to the detector 160. A is absorbed by the beam damper 142.

[0028] On the other hand, the reference light L emitted from the beam splitter 120 R passes through lens 124 , mirror 130 , lens 152 and beam splitter 156 to detector 160 .

[0029] The mirror 130 reflects the reference beam L R The lens 124 located upstream of the mirror 130 and the lens 152 located downstream of the mirror 130 reflect the reference beam L toward the beam splitter 156. R The reference light L is incident on the detector 160 so as to cover a wide range of the light receiving surface formed inside the detector 160. R The beam splitter 156 adjusts the spreading of the reference light L R is reflected in the direction of the detector 160, while the reference light L R and the transmitted scattered light L S The beams are spatially superimposed (hereinafter referred to as "combined beams") and emitted.

[0030] In this manner, the combining and focusing optical system 150 includes the lenses 152 and 154 and the beam splitter 156 described above.

[0031] FIG. 2 shows the detailed positional relationships between components in the beam combining and focusing optical system 150.

[0032] In the combining and focusing optical system 150, the scattered light L S The intersection of the exit pupil of the lens 154 through which the reference light L passes and the optical axis, and the ... reference light LR The lenses 152 and 154 and the beam splitter 156 are arranged so that the focal points (beam waists) of the first and second light beams are conjugate with each other.

[0033] With this arrangement, the scattered light L S and reference light L R The optical axes of the scattered light L are parallel to each other and enter the detector 160. S and reference beam L R At the surface where the scattered light L and the scattered light L are combined, that is, at the reflecting surface (half mirror) 156a of the beam splitter 156, S and reference beam L R The wavefronts do not match.

[0034] 2) and the beam splitter 156. The mirror 130 (not shown in FIG. 2) and the beam splitter 156 also split the reference beam L R is scattered light L passing through lens 154 and directed to detector 160. S is arranged so as to be parallel to

[0035] For example, scattered light L S The distance between the exit pupil of the lens 154 through which the reference light L passes and the center of the beam splitter 156 is R and the center of the beam splitter 156 (both are distance D), and the scattered light L S The optical axis of the reference beam L R When the optical axis of the beam splitter 156 intersects with the optical axis of the beam splitter 156 at a right angle, the reflecting surface 156a of the beam splitter 156 reflects the scattered light L S The scattered light L is arranged at an angle of 45 degrees to the optical axis (θ = 45 degrees). S The optical axis of the reference beam L R When the optical axis of the reference light L does not intersect at a right angle, R The optical axis of the scattered light L S The reflecting surface 156a of the beam splitter 156 may be adjusted so that the light enters the detector 160 parallel to the optical axis of the beam splitter 156.

[0036] When the components of the beam combining / collecting optical system 150 are arranged in the above-described relationship, the scattered light LS The chief ray of a certain reference beam L R The light incident on the detector 160 is received by the light receiving element 162.

[0037] The lenses 152 and 154 may each be configured as a single lens, or may be configured as a plurality of optical elements (lenses, mirrors, diffractive optical elements, etc.), or one or both of the lenses 152 and 154 may be eliminated. S The intersection of the exit pupil and the optical axis and the reference light L R It is also possible to design the beam waist at other positions. For example, the scattered light L S The intersection of the exit pupil and the optical axis and the reference beam L R The beam waists of the scattered light L may be aligned on the reflecting surface 156a of the beam splitter 156. S Exit pupil and reference beam L R The beam waists of the reference light L may be made to coincide with each other, or may be made to coincide virtually downstream of the detector 160. Furthermore, for example, the lenses 124 and 152 may be configured to include lenses with different curvatures in the vertical and horizontal directions, such as cylindrical lenses, toroidal lenses, or ellipsoidal lenses, to obtain the reference light L. R is given astigmatism, and the reference light L seen from a certain direction is R beam waist and scattered light L S The intersection of the exit pupil and the optical axis is in a conjugate relationship, and the reference light L seen from a direction perpendicular to this is R beam waist and scattered light L S It is also possible to design the beam waists of the two beams to match.

[0038] Returning to FIG. 1, the configuration of the particle measuring device 100, particularly the configuration downstream of the combining and focusing optical system 150, will be further described.

[0039] The detector 160 outputs a signal whose magnitude corresponds to the intensity of light received by the light-receiving element. The light-receiving element of the detector 160 can be a photodiode, a phototransistor, an image sensor, a photomultiplier tube, or the like. The detector 160 may have a single light-receiving element forming a continuous light-receiving surface, or may have a light-receiving surface divided into a grid pattern by arranging multiple light-receiving elements in a row or two-dimensionally, such as a segmented photodiode. Alternatively, multiple detectors 160 can be used in an array.

[0040] The counting unit 170 calculates the particle size from the magnitude of the signal output from the detector 160, and counts the number of particles from the number of signals.

[0041] In such a particle measuring device 100, scattered light L directed toward the detector 160 is scattered depending on the position of the particle P in the detection region. S The angle of the reference beam L R The scattered light L is incident on the detector 160 so as to cover a wide range of the light receiving surface. S 3, the wavefront of the light is substantially flat at the beam waist. S The wavefront of the light becomes almost flat, and the minute scattered light L S Within the beam diameter range of R Since the wavefront of the scattered light L S The change in intensity of scattered light L S and reference beam L R Therefore, it is possible to effectively obtain the intensity change of the interference light with the particle P, and it is possible to efficiently receive the interference light and thereby detect the particle P.

[0042] In addition, in the particle measuring device 100, the scattered light L S and reference beam L R Since there is no need to match the wavefront shapes when combining the two, there is a high degree of freedom in installing the components.

[0043] In the particle measuring device 100, as shown in FIG. R The reference beam L covers a wide area of ​​the light receiving surface. R The spread of the scattered light L is adjusted depending on the position of the particle P. S Even if the incident position of the reference light L changes, R In addition, the reference light L R The horizontal extent of the reference light L is greater than the horizontal width of the aligned light receiving elements 162 (in the illustrated example, four light receiving elements 162 are aligned in a row). R Even if the incident position of the light receiving element is slightly shifted in the horizontal direction, the light receiving element can be sufficiently covered. S and can be effectively interfered with.

[0044] The number and arrangement of the light receiving elements 162 shown in FIG. R For example, the reference light L may be spread so as to cover almost the entire or a part (for example, 50 out of 100 light receiving elements) of a light receiving surface formed by arranging a plurality of light receiving elements in a row or two-dimensionally. R The spreading (cross-sectional shape) of the reference light L R However, instead of this, or in addition to this, a margin may be provided in the vertical direction. R It is possible to cope with the case where the incident position of the light beam is shifted in the vertical direction.

[0045] On the other hand, in FIG. 4, the reference light L is projected so as to cover only a portion of the vertical direction of the light receiving element. R In this case, the spread of the reference light L R and scattered light L S Although the ability to deal with vertical deviations in the incident position of the reference light L is limited, it is possible to increase the particle detection sensitivity instead. R If the vertical direction is shortened without changing the total light amount of the reference light L R The higher the energy density of the reference light L, the higher the particle detection sensitivity. RWithout changing the energy density of the reference light L R By shortening the vertical direction of the light receiving element 162, the amount of light incident on the light receiving element 162 is reduced, and the output noise of the light receiving element 162 is reduced, thereby increasing the particle detection sensitivity. R Considering the amount of vertical shift of the incident position of the reference light L R It is desirable to keep the vertical length of the board to the minimum necessary.

[0046] When the light emitted by the light source 110 has a spread such as a line, a strip, a square, a circle, or the like in a cross section perpendicular to the direction of propagation (for example, when the light source 110 emits light with a spread angle within a range that can be considered parallel, the cross section of the light immediately after being emitted from the light source 110 has a certain area, or the cross section has a shape exceeding a predetermined size), the reference light L R Since the detector 160 can cover a wide range of the light receiving surface, the range of particles that can be detected in the detection area formed within the flow cell 140 is widened, making it possible to more efficiently detect particles P contained in the fluid.

[0047] Alternatively, the reference light L R The lens placed in the optical path of the reference light L R For example, if the lenses 124 and 152 are configured to include lenses with different curvatures in the vertical and horizontal directions, such as cylindrical lenses, toroidal lenses, or ellipsoidal lenses, the reference light L R The cross section of the can be expanded and shaped into a flattened shape as shown in FIG.

[0048] In FIG. 2, the reference light L R is incident as diffused light that covers a wide range of the light receiving surface, but instead, the reference light L R By adjusting the optical elements arranged on the optical path of the reference light L R Alternatively, the light may be incident as a convergent beam that covers a wide area of ​​the light receiving surface.

[0049] In the above example, the light receiving surface of the detector 160 receives the scattered light L S The light receiving surface is located near the beam waist and is approximately perpendicular to the optical axis of the S The direction of the optical axis of the scattered light L S The detector may be placed at a position other than the beam waist position. Even with such a placement, it is possible to ensure a certain degree of particle detection accuracy.

[0050] The split ratio of the transmitted light (illumination light) to the reflected light (reference light) in the beam splitter 120 can be set according to the expected intensity of the scattered light, i.e., the size of the particles expected to be detected. For example, the illumination light may be 95% and the reference light may be 5%, or the illumination light may be 99% and the reference light may be 1%, or both may be 50% and 50%.

[0051] Similarly to the above-described lenses 152 and 154, the lenses 122 and 124 may each be configured as a single lens, or may each be configured as a plurality of optical elements (lenses, mirrors, diffractive optical elements, etc.). Alternatively, one or both of the lenses 122 and 124 may be eliminated.

[0052] Second Embodiment FIG. 5 is a block diagram showing the configuration of a particle measuring device 200 according to the second embodiment.

[0053] The particle measuring device 200 measures scattered light L from particles P. S A telecentric optical system 254 (for example, an image-side telecentric lens) is used as an optical element for collecting the reference light L R and the scattered light L emitted from the telecentric optical system 254 S are combined by a beam splitter 156, in other words, the combining / focusing optical system 250 has a telecentric optical system 254 and the above-mentioned lens 152 and beam splitter 156, which is particularly different from the particle measuring device 100 of the first embodiment (FIG. 1).

[0054] In the particle measuring device 200, similarly to the particle measuring device 100, the scattered light L S and reference beam L R When these are combined, the scattered light L S and reference beam L R The wavefronts of the scattered light L S The intersection of the exit pupil and the optical axis and the reference beam L R The components of the beam combining and focusing optical system 250 are arranged so that the beam waists of the reference light L incident on the beam splitter 156 and the detector 160 are in a conjugate relationship. R becomes parallel light. Below, a description of the points common to the particle measuring device 100 will be omitted.

[0055] FIG. 6 shows the scattered light L in the combining / collecting optical system 250. S and reference light L R This shows the progression of the above.

[0056] The telecentric optical system 254 scatters the scattered light L from the incident particle P. S The telecentric optical system 254 emits the chief ray parallel to the optical axis of the telecentric optical system 254. Generally, a telecentric optical system refers to a configuration in which the chief ray is parallel to the optical axis of the lens in both object space and image space, and a configuration in which the chief ray is parallel to the optical axis only in object space is called object-side telecentric, and a configuration in which the chief ray is parallel to the optical axis only in image space is called image-side telecentric. However, in this embodiment, the telecentric optical system 254 is configured so that the chief ray is parallel to the optical axis at least in image space. In other words, in the telecentric optical system 254, the chief ray may or may not be parallel to the optical axis in object space.

[0057] The telecentric optical system 254 is disposed so that its optical axis coincides with the direction of maximum sensitivity of the light receiving element 162. For example, the optical axis of the telecentric optical system 254 may be disposed so as to be approximately perpendicular to the light receiving surface of the light receiving element 162, prioritizing the density of incident light, or may be disposed in a manner other than approximately perpendicular, taking into account various factors that affect the wavelength dependency of the sensitivity of the light receiving element 162. Note that, in the illustrated example, the telecentric optical system 254 is composed of two lenses, but the telecentric optical system 254 may be composed of a single lens or multiple optical elements.

[0058] The mirror 130 (not shown in FIG. 6) and the beam splitter 156 reflect the reference light L from its reflecting surface 156 a toward the detector 160 . R is arranged so that the reference light L R is emitted as parallel light.

[0059] In the particle measuring device 200 in which the beam combining and focusing optical system 250 is arranged in this manner, scattered light L from the particle P generated in the detection region S is incident on the telecentric optical system 254. The telecentric optical system 254 S The scattered light L is adjusted so that the chief ray is parallel to the optical axis of the telecentric optical system 254, regardless of the incident direction of the S The scattered light L emitted from the telecentric optical system 254 S is transmitted through the beam splitter 156. On the other hand, the reference light L R is reflected by the beam splitter 156 towards the detector 160 .

[0060] At this time, since the components of the beam combining and focusing optical system 250 are arranged in the above-described relationship, the scattered light L emitted from the beam splitter 156 S and reference light L R The principal rays of the two beams are parallel to each other and enter the detector 160.

[0061] More specifically, scattered light L from a particle P occurring at an arbitrary position within the field of view (within the detection region of the flow cell 140) S The scattered light L S Reference light L passing through the same place as the chief ray of R Therefore, the scattered light L passing through the same place on the half mirror 156a coincides with the light direction of the scattered light L after the combination. S The chief ray and reference ray L R The light beam also enters the detector 160 (light receiving element 162) at the same position.

[0062] Even in the configuration of the particle measuring device 200 of the second embodiment, the scattered light L S and reference beam L R Although the wavefront of the reference light L R The wavefront of the scattered light L S The chief ray of the reference beam L R At the beam waist, the scattered light L S The wavefront of the scattered light L on the light receiving element 162 in the particle measuring device 200 is also flat, compared to the particle measuring device 100 of the first embodiment. S and reference beam L R Therefore, the wavefront of the reference light L R and scattered light L S This allows for better interference between the particles P and the light, making it possible to detect the particles P more efficiently.

[0063] [Advantages of the present invention] As described above, the particle measuring device of each of the above-described embodiments provides the following effects.

[0064] (1) In the particle measuring device 100, scattered light L directed toward the detector 160 depending on the position of the particle P in the detection region. S The angle of the scattered light L changes, but on the light receiving element 162 of the detector 160, SThe wavefront of the reference beam L is always R Since the wavefront of the scattered light L S This makes it possible to effectively obtain the intensity change of the particle, thereby enabling efficient particle detection.

[0065] (2) In the particle measuring device 200, the reference light L R The entire wavefront is flat, and the scattered light L is directed toward the detector 160 regardless of the position of the particle P in the detection area. S Since the chief ray of the scattered light L on the light receiving element 162 is perpendicular to the wavefront of the reference light, S and reference beam L R Since it is easy to make the wavefront of the reference light L coincide with that of the reference light L on the light receiving element 162, R and scattered light L S This allows for better interference between the two and allows for more effective detection of the intensity change, thereby enabling more efficient detection of the particles P.

[0066] (3) In the particle measurement devices 100 and 200, the reference light L R The reference light L is adjusted by adjusting the optical elements 124 and 152 provided on the optical path of the reference light L and the shape of the light emitted from the light source 110. R covers a wide range of the light receiving surface, the scattered light L varies depending on the position of the particle P in the detection area. S Even if the incident position of the reference light L changes, R and can be effectively interfered with.

[0067] (4) In the particle measuring device 100, 200, the scattered light L S and reference beam L R Since there is no need to match the wavefront shapes of the two when combining them, there is a high degree of freedom in installing the components.

[0068] The present invention is not limited to the above-described embodiment, and can be practiced in various modified forms.

[0069] In the above-described embodiment, the scattered light L transmitted through the beam splitter 156 Sand the reflected reference light L R Alternatively, or in addition to this, a detector 160 may be provided to detect scattered light L reflected by the beam splitter 156, as in the modified example shown in FIG. S and the transmitted reference light L R The detector 160 may be arranged in the direction of travel of the beam.

[0070] In the above-described embodiment, the light emitted from light source 110 is incident directly on beam splitter 120, but an optical element (lens, mirror, diffractive optical element, etc.) that adjusts the beam diameter or shape of the light emitted from light source 110 may be disposed between light source 110 and beam splitter 120. Furthermore, the light emitted from beam splitter 156 is incident directly on detector 160, but an adjustment lens may be disposed between beam splitter 156 and detector 160.

[0071] In the above-described embodiment, the mirror that changes the direction of travel of the reference light L R Only one mirror (mirror 130) is arranged on the optical path of the irradiated light L A and scattered light L S A mirror may be placed on the optical path of the first light source 10, or mirrors may be placed at multiple locations on each optical path.

[0072] Furthermore, the configurations and numerical values ​​given in the course of the explanation of the particle measuring devices 100 and 200 are merely examples, and it goes without saying that they can be modified as appropriate when implementing the present invention. [Explanation of symbols]

[0073] 100 Particle measurement device 110 Light source 120 Beam Splitter 130 Mirror 140 flow cell 150 Combining and focusing optical system 160 detectors 170 Counting Department

Claims

1. a light source that emits light; a first beam splitter that splits the light from the light source into two beams, directing one beam, which is an illumination beam, toward a flow path into which a fluid is introduced, and directing the other beam, which is a reference beam, in a direction different from the direction of the flow path; a second beam splitter that combines the reference light and scattered light from particles contained in the fluid, which is generated in a detection region formed in the flow channel by irradiating the flow channel with the illumination light, in a state where the wavefronts do not coincide with each other; a detector having one or more light-receiving elements, which receives interference light between the scattered light and the reference light combined by the second beam splitter with the light-receiving elements and outputs a signal according to the intensity of the interference light; A particle measurement device equipped with

2. 2. The particle measuring device according to claim 1, The particle measuring device further comprises an optical system for adjusting the spread of the reference light or the light from the light source.

3. 3. The particle measuring device according to claim 1, The second beam splitter comprises: a particle measuring device arranged so that the direction of a chief ray of the scattered light generated at an arbitrary position in the detection area substantially coincides with the direction of a ray of the reference light passing through the same location as the chief ray of the scattered light.

4. 4. The particle measuring device according to claim 3, a telecentric optical system into which the scattered light generated in the detection area is incident and which emits a chief ray of the scattered light parallel to an optical axis in an image space; The second beam splitter comprises: a particle measuring device that combines the reference light and the scattered light emitted from the telecentric optical system so that their optical axes are parallel to each other;

5. 3. The particle measuring device according to claim 1, The detector comprises: A particle measuring device characterized in that it is disposed in the vicinity of the beam waist of the scattered light.

6. 3. The particle measuring device according to claim 2, The optical system comprises: an asymmetric lens that generates astigmatism, wherein a beam waist of the reference light as viewed from a predetermined direction is conjugate with an intersection point between an exit pupil of the scattered light and an optical axis; The detector comprises: a particle measuring device disposed at a position where the beam waist of the reference light and the beam waist of the scattered light substantially coincide with each other when viewed from a direction perpendicular to the predetermined direction;

7. a splitting step of splitting light emitted from a light source into two beams, directing one beam, which is an illumination beam, toward a flow path into which a fluid is introduced, and directing the other beam, which is a reference beam, in a direction different from the flow path; a combining step of combining the reference light and scattered light from particles contained in the fluid, which is generated in a detection region formed in the flow channel by irradiating the flow channel with the illumination light, in a state where the wavefronts do not coincide with each other; a detection step of receiving interference light between the scattered light and the reference light combined in the combining step and outputting a signal corresponding to the intensity of the interference light; A particle measurement method comprising:

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