WO2019116802A1

WO2019116802A1 - Particle analyzing device

Info

Publication number: WO2019116802A1
Application number: PCT/JP2018/041753
Authority: WO
Inventors: 長岡　英一; 久秋山; 正章鉤; 淳一青山; 慎作日浦
Original assignee: 株式会社堀場製作所
Priority date: 2017-12-15
Filing date: 2018-11-09
Publication date: 2019-06-20
Also published as: JPWO2019116802A1

Abstract

The present invention provides a particle analyzing device 100 which measures particles displaced in the direction of an optical axis, and which analyzes particles P by capturing images of a sample in which the particles P are dispersed in a dispersion medium, wherein the particle analyzing device 100 is provided with an image capturing unit 3 which captures images of the sample, and an image processing unit 4 which processes image data obtained by the image capturing unit 3, and wherein the image capturing unit 3 comprises: an imaging lens 31; a first light receiving element 321 which receives light in a first wavelength range, from among light image-formed by the imaging lens 31; a second light receiving element 322 which receives light in a second wavelength range, from among the light image-formed by the imaging lens 31; and an optical element 33 which enlarges an axial chromatic aberration, between an image-forming system for the first wavelength range and an image-forming system for the second wavelength range.

Description

Particle analyzer

The present invention relates to a particle analyzer that analyzes particles by imaging the particles.

Conventionally, as an apparatus for measuring the particle size distribution, particle shape and the like of particles, as shown in Patent Document 1, a device for imaging a sample flowing in a flow path with a camera and analyzing and processing the image is considered.

In this particle analyzer, in order to measure particles with a small particle diameter, it is conceivable to increase the optical magnification of the imaging lens of the camera.

However, if the optical magnification of the imaging lens is increased, the depth of field of the imaging lens becomes shallow (small), and particles at a position deviated in the optical axis direction with respect to the focusing plane of the imaging lens There is a problem that it can not measure.

Japanese Patent Application Laid-Open No. 11-316184

Therefore, the present invention has been made to solve the above-mentioned problems, and its main object is to measure particles shifted in the optical axis direction.

That is, the particle analysis device according to the present invention is a particle analysis device for imaging a sample in which particles are dispersed in a dispersion medium to analyze the particles, and an imaging unit for imaging the sample, and the imaging unit An image processing unit configured to process the obtained image data, wherein the imaging unit includes an imaging lens, and a first light receiving element configured to receive light of a first wavelength range of light imaged by the imaging lens; An axis is formed between a second light receiving element for receiving light of a second wavelength range in the light imaged by the imaging lens, an imaging system according to the first wavelength range, and an imaging system according to the second wavelength range And an optical element for enlarging the upper chromatic aberration.

In such a case, the axial chromatic aberration is expanded between the imaging system in the first wavelength range and the imaging system in the second wavelength range by the optical element. The focal length of the imaging lens is different for light in the two wavelength range. By receiving these by the first light receiving element and the second light receiving element, it is possible to measure particles at a position shifted in the optical axis direction of the imaging lens. In addition, by combining the images obtained by the respective light receiving elements into one image by processing such as depth combination, the depth of field of the imaging unit can be deepened, and particles at positions shifted in the optical axis direction can be obtained. Can be measured.

In the case where the optical element of the present invention is not used, if the optical magnification is low, the outline of small particles can not be obtained, and the measurement accuracy is degraded. In addition, when the magnification is increased, not only the field of view becomes narrow, but also the depth of field becomes shallow, so the number of particles that can be shot at one time decreases, and the number of shots that only satisfy statistical conditions is required. turn into. That is, it takes time to perform measurement with high accuracy, and shortening the time will deteriorate the measurement accuracy. On the other hand, by using the optical element of the present invention, particles in a position shifted in the optical axis direction of the imaging lens can be measured, so that not only measurement can be performed with high accuracy, but also the measurement time can be shortened.

The particle analysis device is provided between the imaging lens and each of the light receiving elements, and is a spectral element that separates light imaged in the imaging lens into light in the first wavelength range and light in the second wavelength range. It is possible to further provide. For example, it is conceivable to use a dichroic prism as the spectral element.
Compared to the case where a color filter is provided in front of a light receiving element to receive light in a desired wavelength range by using such a spectral element, the color separation accuracy is high and the light can be easily obtained. Have the advantages of high durability and high resistance to aging.

As a specific embodiment of the optical element, it is conceivable that the optical element is an approximately afocal system (an optical system with an infinite focal distance) as a whole. For example, it is conceivable that the optical element is a flat plate made of a high dispersion glass material. Further, it is conceivable that the optical element is a lens system including a first lens having at least a positive refractive power and a second lens having a negative refractive power. Here, it is considered that at least one of the first lens and the second lens is made of a high dispersion glass material. Further, it is desirable that the absolute values of the focal lengths of the first lens and the second lens be substantially the same. For example, the first lens having positive refractive power is a plano-convex lens, and the second lens having negative refractive power is a plano-concave lens. Furthermore, it is conceivable that the optical element is a diffractive optical element that expands chromatic aberration using a diffraction phenomenon. The diffractive optical element is considered to be a lens system including a diffractive optical element in which a diffraction grating is formed on the surface or in the inside.

It is preferable to further include a light irradiator that irradiates the light of the first wavelength range and the second wavelength range to the sample.
Thus, by irradiating the light of the first wavelength range and the second wavelength range, the wavelength purity can be increased by arbitrarily selecting the wavelength range on the light source side, so that a clearer image can be obtained. Can. In addition, chromatic aberration of magnification, distortion and the like can be easily corrected by image processing.

It is conceivable that the particle analysis device has a flow path through which the sample flows, and the imaging unit images the sample flowing through the flow path. At this time, if there is a possibility that the distribution is not uniform in the flow channel, particles shifted in the depth direction can not be measured, and the particle size distribution becomes insufficient. Also, if the depth of field is narrow, only particles in some distribution areas can be measured.
In order to solve this problem, it is desirable that the focal plane of the imaging unit be disposed to be inclined with respect to the flow path.
With this configuration, particles shifted in the depth direction orthogonal to the flow channel direction of the flow channel can be measured.

It is desirable that the imaging unit has a tilt lens, and the focusing surface of the imaging unit be inclined by the tilt lens.
With this configuration, there is no need to incline the entire imaging unit with respect to the flow path, and the entire particle analysis device can be miniaturized.

In the case where the focusing surface of the imaging unit has a substantially rectangular shape, it is preferable that the focusing surface be inclined at a predetermined angle with an axis substantially parallel to the short side of the focusing surface as a rotation center.
With this configuration, the long side of the focusing surface is inclined with respect to the flow direction, so that the inclination angle of the focusing surface can be reduced.

As the inclination mode of the focusing surface of the imaging unit, the focusing surface is inclined with respect to the flow channel direction of the flow channel, or the focusing surface is inclined with the flow channel direction of the flow channel as a rotation center It is thought that you are doing.
In the case where the focusing surface is inclined with respect to the flow channel direction of the flow channel, it is preferable that the imaging interval t of the image pickup unit satisfy the following.
t ≦ (d / sin θ) / v
Here, d is the depth of field by the imaging lens, θ is the inclination angle of the focusing surface, and v is the flow velocity of the sample.
With this configuration, it is possible to image and measure the particles in the sample flowing in the flow path without leaking.

It is conceivable that the particle analysis device can select the optical magnification of the imaging lens according to the size of the particle. In this case, the depth of field changes according to the optical magnification of the imaging lens. Therefore, it is desirable that the inclination angle of the focusing surface be adjustable in accordance with the depth of field of the imaging lens.
With this configuration, highly accurate measurement can be performed regardless of the particle size.

According to the present invention described above, axial chromatic aberration is generated between the light of the first wavelength range and the light of the second wavelength range by the optical element, and these are received by the first light receiving element and the second light receiving element. Therefore, it is possible to measure particles at a position shifted in the optical axis direction of the imaging lens.

It is a whole schematic diagram of a particle analysis device concerning a 1st embodiment. It is a schematic diagram which shows the structural example of the image pick-up element of 1st Embodiment. It is a graph which shows the spectral sensitivity of an image pick-up element, and a graph which shows the spectral transmission factor of the transmission filter of a light irradiation part. It is a figure showing depth composition of a 1st embodiment. It is a whole schematic diagram of the particle analyzer which concerns on the modification of 1st Embodiment. It is a schematic diagram which shows the structural example of a spectroscopy element (dichroic prism). It is a whole schematic diagram of the particle analyzer which concerns on the modification of 1st Embodiment. It is a whole schematic diagram of the particle analyzer which concerns on the modification of 1st Embodiment. It is a whole schematic diagram of the particle analyzer which concerns on 2nd Embodiment. It is a schematic diagram which shows the relationship of the observation distance C of 2nd Embodiment, the flow velocity v, and the depth of field d etc. FIG. It is a whole schematic diagram of the particle analyzer which concerns on the modification of 2nd Embodiment. It is a whole schematic diagram of the particle analyzer which concerns on modification embodiment. It is a whole schematic diagram of the particle analyzer which concerns on modification embodiment. It is a figure for demonstrating the function of particle | grain discrimination | determination in a modification embodiment.

100 ... particle analysis device P ... particle 2 ... light irradiation unit 3 ... imaging unit 4 ... image processing unit 31 ... imaging lens F1 to F3 ... focus plane 321 ... ... First light receiving element 322 ··· Second light receiving element 33 ··· Optical element 34 ··· Spectroscopic element 311 · · · Tilt lens

First Embodiment
Hereinafter, a particle analysis device according to a first embodiment of the present invention will be described with reference to the drawings.

The particle analysis device 100 according to the present embodiment analyzes the particles P by imaging a sample in which the particles P are dispersed in a dispersion medium. In the present embodiment, the particles P are analyzed by causing the particles to spontaneously fall into the atmosphere from the particle feeder 6 in which the particles P are stored, and imaging the particles P that naturally fall. In this case, the air in the space (flow path) S where the particles P fall spontaneously becomes the dispersion medium for dispersing the particles P, and the air and the particles P in the space become the sample.

Specifically, the particle analysis device 100 includes a light irradiation unit 2 that irradiates light to a sample, an imaging unit 3 that images a sample, and an image processing unit 4 that processes image data obtained by the imaging unit 3. Have. Here, the light irradiation unit 2 and the imaging unit 3 are disposed to face each other so as to sandwich a space (flow path) S in which the particles P fall naturally. Specifically, the light emitting unit 2 and the imaging unit 3 are disposed to face each other in the horizontal direction orthogonal to the flow channel direction (vertical direction).

The light irradiation part 2 irradiates light to the predetermined range of a sample, and is a surface emitting type thing using a light emitting diode, for example. Specifically, the light irradiation unit 2 includes a light source 21 formed of a light emitting diode, and a transmission filter 22 provided on the light emission side of the light source 21 and transmitting light of a predetermined wavelength. The transmission filter 22 of the present embodiment transmits the wavelengths (first, second and third wavelengths) received by the imaging unit 3. In addition, parallel illumination is preferable to obtain an accurate shadow picture. Although telecentric illumination is optimal, it may be a combination of an LED light source and a condenser lens.

The imaging unit 3 includes an imaging lens 31 and an imaging element 32 that receives light focused by the imaging lens 31.

The imaging lens 31 has a focal plane (focal plane) in a space (flow path) S where the particles P fall naturally. The imaging lens 31 of the present embodiment uses a telecentric lens. By using a telecentric lens, it is possible to capture an image without distortion and without being affected by parallax.

The imaging device 32 receives a plurality of first light receiving elements 321 that receive light in a first wavelength range, a plurality of second light receiving elements 322 that receive light in a second wavelength range, and light that receives light in a third wavelength range. A plurality of third light receiving elements 323 are provided. In the present embodiment, the light in the first wavelength range is red light (R), the light in the second wavelength range is green light (G), and the light in the third wavelength range is blue light (B) It is. Further, as shown in FIG. 2, the plurality of first to third

light receiving elements

321, 322, and 323 of the present embodiment are arranged in a matrix on a single substrate, and each of the imaging elements 32 is provided. In front of the

light receiving elements

321, 322, and 323, a transmission filter (not shown) for transmitting light in the corresponding wavelength range is provided. In addition, the transmission filter 22 of the light emitting unit 2 described above is an RGB transmission filter that transmits red light, green light, and blue light.

Here, in the spectral sensitivity of the imaging device 32, as shown in FIG. 3, the wavelength ranges of R, G, and B overlap each other. On the other hand, in the spectral transmittance of the transmission filter 22 of the light irradiation unit 2, the wavelength ranges of R, G, and B are separated from each other. Therefore, the light (R) in the first wavelength range is set to 630 nm, the light (G) in the second wavelength range is set to 530 nm, and the light (B) in the third wavelength range is set to 460 nm.

Therefore, the imaging unit 3 of this embodiment is an optical element 33 that generates axial chromatic aberration between the imaging system with the first wavelength range, the imaging system with the second wavelength range, and the imaging system with the third wavelength range. have.

The optical element 33 is a flat plate made of, for example, a high dispersion glass material provided between the imaging lens 31 and each of the

light receiving elements

321, 322, and 323. As the high dispersion glass material, one having an Abbe number smaller than 30 can be used.

The position of the focal plane by the imaging lens 31 is shifted in the optical axis direction by the optical element 33. Specifically, from the object side to the imaging lens 31 side, the focusing surface F1 of the light of the first wavelength range (red light), the focusing surface F2 of the light of the second wavelength range (green light), and the third wavelength range Light (blue light) is shifted in the order of the focal plane F3. Each of the focal planes F1, F2, and F3 has the depth of field of the imaging lens 31.

Thus, the area (focusing plane F1) captured by the first light receiving element 321, the area (focusing plane F2) captured by the second light receiving element 322, and the area (focusing plane F3) captured by the third light receiving element 323. ) Are mutually different positions along the optical axis direction.

Each image data obtained by the

light receiving elements

321, 322, 323 is analyzed by the image processing unit 4.

The image processing unit 4 is a general-purpose to special-purpose computer having a CPU, a memory, an input / output interface, an AD converter, and an input unit such as a keyboard and a mouse as a structure. Further, a display 5 is connected to the image processing unit 4. Then, the image processing unit 4 performs image processing by operating the CPU and its peripheral devices based on the program stored in the memory, and performs various calculations for obtaining measurement items of the particles P.

Specifically, as shown in FIG. 4, the image processing unit 4 uses the first image obtained from the first light receiving element 321, the second image obtained from the second light receiving element 322, and the third light receiving element 323. Image processing such as depth synthesis is performed using the obtained third image to synthesize one image. More specifically, the image processing unit 4 forms first to third images without performing Bayer conversion on the light intensity signals obtained by the light receiving elements 321 to 323. Then, the image processing unit 4 complements the pixel omission outside the respective wavelength regions for each of the first image, the second image, and the third image. Thereafter, the image processing unit 4 performs depth combination using the complemented image and combines it into one image. Then, the image processing unit 4 displays the composite image on the display 5 (see FIG. 1).

Further, the image processing unit 4 calculates the particle size distribution of the particles P, the circle equivalent diameter, the major diameter, the minor diameter, the peripheral length, the aspect ratio, the degree of circularity, the degree of unevenness, etc. The image processing unit 4 also displays the calculated numerical values on the display 5 together with the composite image.

<Effect of First Embodiment>
According to the particle analysis device 100 of the present embodiment, axial chromatic aberration is generated in each of the light of the first to third wavelength regions by the optical element 33, and these are represented by the first to third

light receiving elements

321, 322, 323. By receiving light, it is possible to measure the particles P at a position shifted in the optical axis direction of the imaging lens 31. In addition, by combining the images obtained by the

light receiving elements

321, 322, and 323 into one image by processing such as depth combination, the depth of field of the imaging unit 31 can be extended, and displacement in the optical axis direction Particles P at different positions can be measured.

In addition, the areas imaged by the

light receiving elements

321, 322, and 323, that is, the focus planes F1, F2, and F3 do not necessarily have to be continuous areas. The depths of field of the

light receiving elements

321, 322, 323 may overlap with each other, or may be separated as shown in FIG. The particles in the region exceeding the depth of field are photographed somewhat blurred, but can be easily restored by performing well-known sharpening processing by the image processing unit 4. At this time, if a telecentric lens is used as the imaging lens 31, the particle size, aspect ratio, and the like can be correctly measured. The optical element 33 may be selected as needed so that the distance between the focusing planes F1, F2, and F3 (the distance in the optical axis direction) can be arbitrarily set according to the size and specific gravity of the particles to be measured. Alternatively, an optical element 33 capable of adjusting the amount of axial chromatic aberration (the distance between the focal planes F1, F2, and F3) may be used.

Modification of First Embodiment
As shown in FIG. 5, between the imaging lens 31 and the imaging device 32, the light focused by the imaging lens 31 is separated into light of a first wavelength range, light of a second wavelength range, and light of a third wavelength range. A spectral element 34 may be provided. As this spectral element 34, as shown in FIG. 6, for example, a dichroic prism can be used. The dichroic prism is for separating the incident light into red light, green light and blue light, and the first imaging element 32a comprising a plurality of first light receiving elements 321 on the light emission surface of each light, A second imaging element 32 b including a plurality of second light receiving elements 322 and a third imaging element 32 c including a plurality of third light receiving elements 323 are provided. In this case, the optical element 33 is provided between the imaging lens 31 and the spectral element 34.

As described above, in the configuration in which three imaging elements 32a to 32c are provided using dichroic prisms, consideration of overlapping influence of spectral sensitivity becomes unnecessary as compared with a color CCD. In this case, by using the transmission filter 22 in the light irradiation unit 2, the light (B) of the third wavelength range is positively shortened and the light (G) of the second wavelength range is reduced to the light of the third wavelength range ( B) If the light (R) in the first wavelength range is moved to the near infrared side by moving the light closer, the aberration can be further expanded. In the case of a color CCD (one CCD), the difference in axial chromatic aberration between R and G is small, but if the imaging device 32 is divided into three sheets (first to third imaging devices 32a to 32c), the wavelength is as described above The chromatic aberration can be further expanded by selecting.

Further, as the optical element 33, in addition to a flat plate made of a high dispersion glass material, a diffractive optical element may be used which expands the chromatic aberration using a diffraction phenomenon. Moreover, you may use them together. Here, the diffractive optical element may be a lens system including a diffractive optical element in which a diffraction grating is formed on the surface or in the inside.

Furthermore, the light irradiation unit 2 may not have the transmission filter 22. In this case, the light source may be a combination of a red LED, a green LED and a blue LED. Further, the light source may emit light in the near infrared region or light in the ultraviolet region.

Moreover, as shown in FIG. 7, the optical element 33 may be provided in front of the imaging lens 31. A flat plate made of a high dispersion glass material may be used as the optical element 33. Here, when the imaging lens 31 is a magnifying optical system, the position of the optical element 33 is preferably in front of the imaging lens 31. As a result, even if the optical magnification (lateral magnification) is increased, the longitudinal chromatic aberration can be increased without being affected by the longitudinal magnification which is the square of the lateral magnification. When the imaging lens 31 is a reduction optical system, the position of the optical element 33 is preferably behind the imaging lens 31.

Further, as shown in FIG. 8, the optical element 33 may be constituted by a lens system including a first lens 33a having at least positive refractive power and a second lens 33b having negative refractive power. Here, the first lens 33a is a plano-convex lens, and the second lens 33b is a plano-concave lens. The optical element 33 is configured such that the plano-convex lens 33a and the plano-concave lens 33b are disposed close to each other. In this case, it is preferable to use a high dispersion glass material for the plano-concave lens 33b and a low dispersion glass material for the plano-convex lens 33a, and it is preferable to make the absolute values of the focal distances of the two equal. The order and orientation of the plano-convex lens 33a and the plano-concave lens 33b (order of the concavo-convex surface and the plane) does not matter. A plano-concave, plano-convex lens in which the surface on one side is a plane is advantageous in order to ensure the perpendicularity to the optical axis as the assembly accuracy. As the optical specification, a biconvex lens having positive refractive power or a biconcave lens having negative refractive power may be used, and the same performance can be achieved using a meniscus lens having positive or negative refractive power. In addition, a cemented lens in which these lenses (plano-concave, plano-convex, biconcave, biconvex, meniscus) are pasted together by adhesion or the like may be used. Further, a high dispersion glass material may be used for the plano-convex lens 33a, or a high dispersion glass material may be used for both the plano-convex lens 33a and the plano-concave lens 33b.

Second Embodiment
Next, a particle analysis device according to a second embodiment of the present invention will be described with reference to the drawings.

The particle analysis device 100 of the present embodiment differs from the above embodiment in the configuration of the imaging unit 3. The other configuration is the same as that of the first embodiment, so the description will be omitted.

As shown in FIG. 9, the imaging unit 3 of the present embodiment is disposed such that its focal planes F1 to F3 are inclined with respect to the flow path S. The flow channel direction in the present embodiment is the vertical direction, and the focus planes F1 to F3 are inclined with respect to the vertical direction. Further, in the present embodiment, the light irradiation unit 2 is also disposed to be inclined with respect to the flow path S and is opposed to the imaging unit 3.

Specifically, the focus planes F1 to F3 of the imaging unit 3 have a substantially rectangular shape, and the focus planes F1 to F3 are inclined at a predetermined angle with respect to an axis substantially parallel to the short sides of the focus planes F1 to F3. ing.

Here, the inclination angle θ of the focus planes F1 to F3, the depth dimension D of the flow path S, the length L of the measurement area (long sides of the focus planes F1 to F3), and the depth of field d of the imaging lens 31 The relationship with is the following equation.
sin θ ≒ (D−d) / L
The depth of field d of the imaging lens 31 is the depth of field in a single light receiving element (for example, the first light receiving element 321).

Further, as shown in FIG. 10, the observation distance C in one frame of the imaging unit 3 is as follows.
C = d / sin θ
When the imaging interval t of the imaging unit 3 satisfies the following equation, imaging can be performed without leaking the particles P in the sample flowing through the flow path S.
t ≦ C / v
t ≦ (d / sin θ) / v
Here, v is the flow velocity (dropping velocity) of the sample.

<Effect of Second Embodiment>
According to the particle analysis device 100 of the present embodiment, the particles P shifted in the depth direction orthogonal to the flow channel direction of the flow channel S can be measured. Thereby, measurement can be performed over a wider range in the optical axis direction than in the first embodiment.

Modification of Second Embodiment
As shown in FIG. 11, the imaging lens 31 of the imaging unit 3 may have a tilt lens 311, and the focusing surfaces F1 to F3 may be inclined by the tilt lens 311. As a result, there is no need to incline the entire imaging unit 3 with respect to the flow path S, and the entire particle analysis device 100 can be miniaturized.

Further, the optical magnification of the imaging lens 31 may be selectable according to the size of the particle size. In this case, the depth of field d changes in accordance with the optical magnification of the imaging lens 31. Therefore, it is desirable that the inclination angle θ of the focus planes F1 to F3 be adjustable in accordance with the depth of field d of the imaging lens 31. With this configuration, highly accurate measurement can be performed regardless of the particle size.

<Other Modified Embodiments>
The present invention is not limited to the above embodiments.

For example, although light in three wavelength ranges of RGB is used in the above embodiment, measurement may be performed using other different wavelength ranges. Moreover, it is not restricted to three types of wavelength ranges, It may measure using two types of wavelength ranges, and may measure using four or more types of wavelength ranges.

Further, the second embodiment may be configured not on the premise of the first embodiment.
That is, as shown in FIG. 12, the imaging unit 3 of the particle analysis device 100 does not have the optical element 33 of the first embodiment, and the focal plane F of the imaging unit 3 is inclined with respect to the flow path S It is arranged to be. The other configuration is the same as that of the second embodiment. With this particle analyzer 100, it is possible to measure particles P shifted in the depth direction orthogonal to the flow channel direction of the flow channel S.

In the particle analysis device 100 shown in FIG. 12, the imaging device 32 of the imaging unit 3 may not be provided with a transmission filter or the like that transmits light of a specific wavelength. The imaging unit 3 having such a configuration is generally referred to as a monochrome camera, and a transmission filter is not necessary, so the imaging sensitivity is increased. Further, since each pixel can be photographed under the same condition, more accurate measurement becomes possible.

The sample in each of the above embodiments is a sample using air as a dispersion medium, but may be a dispersion medium other than a gas, for example, a sample in which particles are dispersed in a liquid or gel. In this case, the particle analysis apparatus may be configured to flow the sample through the flow cell, or may be configured to be accommodated in a batch-type cell.

As a configuration for circulating the sample through the flow cell, one shown in FIG. 13 can be considered. That is, for example, a measurement cell 7 for storing a sample in which particles are dispersed in a liquid, and a circulation path 8 having a storage tank 81 for introducing the sample into and out of the measurement cell 7 and a circulation pump 82 are provided. And the light irradiation part 2 is provided in one side of the measurement cell 7, and the imaging part 3 is provided in the other side of the measurement cell. Here, the measurement cell 7 and the optical element 33 may be integrally configured by using a high dispersion glass material on the side wall on the imaging unit 3 side of the measurement cell.

In addition to the glass material, the optical element of each of the above embodiments may be made of a resin having a transmittance of about 30 Abbe number such as PC (polycarbonate) or PS (polystyrene).

As particle P of the above-mentioned embodiment, there may be a case where the first particle X having translucency and the second particle Y different from the first particle X are mixed. Examples of light-transmitting particles that are the first particles X include air bubbles and particles made of resin, and the second particles Y may be light-transmitting particles or have light-transmitting properties. There may be no particles. The first particles X and the second particles Y are dispersed in the medium in the cell 7. The medium is a liquid such as water or a gas such as air.
In the following, the case where the first particle X is a measurement target X such as a pharmaceutical product, a food, a chemical product or the like, and the second particle Y is a bubble Y which is a particle not to be measured.

The light emitting unit 2 and the imaging unit 3 are disposed to face each other so as to sandwich the cell 7, and the light emitted from the light emitting unit 2 is a light transmitting particle as shown in FIG. 14 (a). It refracts when it passes. More specifically, when the refractive index of the particle is larger than the refractive index of the medium, as shown in the upper part of the figure, the light is refracted and condensed, and the refractive index of the particle is smaller than the refractive index of the medium In the case, as shown in the lower part of the figure, light is refracted and diverged. Thereby, a part of the light irradiated to the particles, specifically, the light irradiated to the central part of the particles reaches the imaging unit 3.
As a result, as shown in FIG. 14 (b), bright and dark regions caused by refraction of light passing through the particles appear in the image of the particles captured by the imaging unit 3. More specifically, the central part of the particles captured in the image is a bright area (hereinafter referred to as bright area S1), and the outer peripheral part is a dark area (hereinafter referred to as dark area S2). The dark area S2 is an identifiable area.

More specifically, as shown in FIG. 14A, when particles or bubbles Y to be measured X are regarded as a ball lens, the focal length EFL of these particles is the diameter D of the particles, the refraction of the particles It can be calculated by the following calculation formula using the ratio n1 and the refractive index n2 of the medium in which the particles are dispersed as parameters.
EFL = n1 · D / 4 (n1-n2)
From this, when imaging the measurement object X and the bubble Y whose diameters D are mutually equal, the ratio of the bright region S1 and the dark region S2 due to the difference between the refractive index of the measurement object X and the refractive index of the bubble Y, Changes in size, shape, contrast, etc.

Therefore, the particle discrimination unit of the image processing unit 4 determines whether the particle reflected in the obtained image is the first particle or the second particle based on the above-described bright and dark areas S1 and S2, that is, the measurement object X It is determined whether there is a certain bubble Y or not. Specifically, in the particle discrimination unit, particles reflected in the image are the measurement object X based on the image difference between the light and dark areas S1 and S2 appearing due to the difference between the refractive index of the measurement object X and the refractive index of the bubble Y. It is determined whether the air bubble Y or the air bubble Y. For example, the image difference described above is calculated by binarizing the image.

In addition, various modifications and combinations may be made without departing from the spirit of the present invention.

According to the present invention, axial chromatic aberration is generated in the light of the first wavelength range and the light of the second wavelength range by the optical element, and these are received by the first light receiving element and the second light receiving element. It is possible to measure particles at a position shifted in the optical axis direction of the imaging lens.

Claims

A particle analysis apparatus for imaging a sample in which particles are dispersed in a dispersion medium to analyze the particles,
An imaging unit configured to image the sample;
An image processing unit that processes image data obtained by the imaging unit;
The imaging unit is
An imaging lens,
A first light receiving element that receives light in a first wavelength range among light beams imaged by the imaging lens;
A second light receiving element that receives light in a second wavelength range among the light imaged by the imaging lens;
A particle analysis apparatus comprising: an optical element for expanding axial chromatic aberration between an imaging system according to the first wavelength range and an imaging system according to the second wavelength range.
It further comprises a spectral element provided between the imaging lens and each of the light receiving elements, for separating the light focused by the imaging lens into light of the first wavelength range and light of the second wavelength range.
The particle analyzer according to claim 1, wherein the optical element is provided between the imaging lens and the spectral element.
The particle analyzer according to claim 1, wherein the optical element is an optical element that is substantially afocal system as a whole.
The particle analyzer according to claim 1, wherein the optical element is a flat plate made of a high dispersion glass material.
The optical element is a lens system including a first lens having at least a positive refractive power and a second lens having a negative refractive power,
The particle analysis device according to claim 1, wherein at least one of the first lens and the second lens is made of a high dispersion glass material.
The particle analysis device according to claim 1, wherein the optical element is a diffractive optical element that expands chromatic aberration using a diffraction phenomenon.
The particle analysis device according to claim 6, wherein the diffractive optical element is a lens system including a diffractive optical element in which a diffraction grating is formed on the surface or in the inside.
The particle analysis device according to claim 1, further comprising: a light irradiation unit that irradiates the light in the first wavelength range and the second wavelength range on the sample.
The imaging unit is for imaging the sample flowing in the flow path,
The particle analysis device according to claim 1, wherein a focusing surface of the imaging unit is disposed to be inclined with respect to the flow path.
10. The particle analysis device according to claim 9, wherein the imaging unit has a tilt lens, and a focusing surface of the imaging unit is tilted by the tilt lens.
The focal plane of the imaging unit is substantially rectangular.
11. The particle analysis device according to claim 10, wherein the focusing surface is inclined at a predetermined angle around an axis substantially parallel to the short side of the focusing surface.
The focal plane of the imaging unit is inclined with respect to the flow channel direction of the flow channel,
The particle analysis device according to claim 9, wherein the imaging interval T of the imaging unit is shorter than the following equation.
T ≦ (d / sin θ) / v
Here, d is the depth of field of the imaging lens, θ is the inclination angle of the focusing surface, and v is the flow velocity of the sample.
The particle analysis device according to claim 10, wherein the tilt angle of the focusing surface is adjustable in accordance with the depth of field of the imaging lens.