Optical measuring device

Abstract

Provided is a photometric device that can easily measure scattering intensity at different scattering angles or different wavelengths. This photometric device with a low-coherence interferometer has: a detection part that has at least one of a first detection unit, which causes interference in a reference light and at least a portion of scattered light obtained by shining an incident light on a liquid dispersion including particles and detects the interference light intensity per wavelength, and a second detection unit, which causes interference in a reference light and at least a portion of scattered light obtained by shining an incident light on a liquid dispersion including particles and detects the interference light intensity per scattering angle; and a conversion part that extracts, from the interference light intensity per wavelength data that was detected by the first detection unit, a plurality of scattering intensities at a specific wavelength and a specific depth of the liquid dispersion, or extracts, from the interference light intensity per scattering angle data that was detected by the second detection unit, a plurality of scattering intensities at a specific scattering angle and a specific depth of the liquid dispersion, and converts the extracted scattering intensity data into time variation data of scattered light at the specific depth of the liquid dispersion.

Description

[Technical Field]

[0001] The present invention relates to an optical measuring device for measuring the scattering intensity of a dispersion containing particles at different scattering angles or different wavelengths. [Background technology]

[0002] Dynamic light scattering is a method for investigating the dynamic properties of a scattering material by shining light onto a medium such as a suspension and detecting the time variation of the scattered light intensity from the scattering material in the medium using an autocorrelation function or power spectrum. Dynamic light scattering is widely used for various measurements, such as particle size measurement.

[0003] For example, Patent Document 1 describes a light scattering detection device for detecting fine particles in a liquid or gaseous sample, comprising: a transparent sample cell for holding the sample; a first light source means for emitting light for static light scattering measurement having a first wavelength or a first wavelength band; a second light source means for emitting light for dynamic light scattering measurement having a second wavelength or a second wavelength band different from the first wavelength or a first wavelength band; a first detection means consisting of a plurality of detectors arranged to surround the sample cell and capable of selectively detecting the first wavelength or a first wavelength band in order to detect light scattered from the sample cell with different scattering angles in response to irradiation with light for static light scattering measurement; and a first detection means for detecting light scattered from the sample cell with different scattering angles in the middle of the sample cell. The light scattering detection device described includes a second detection means consisting of one or more detectors arranged to surround the heart and capable of selectively detecting a second wavelength or a second wavelength band in order to detect light scattered from the sample cell with different scattering angles in response to irradiation with light for dynamic light scattering measurement, and a calculation processing means that receives the detection signal from the first detection means and the detection signal from the second detection means in parallel when light for static light scattering measurement from the first light source means and light for dynamic light scattering measurement from the second light source means are simultaneously irradiated onto the sample cell, and performs calculations by the static light scattering method based on the former and calculations by the dynamic light scattering method based on the latter. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-39539 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 provides two light sources, a first light source and a second light source, with different wavelengths or wavelength bands, and simultaneously irradiates the sample cell with light emitted from these light sources, either coaxially or non-coaxially. In order to irradiate both light beams coaxially, it is necessary to further provide, for example, a light unification means that introduces the light emitted from the first light source and the light emitted from the second light source along the same optical path to the sample cell. Patent Document 1 requires multiple light sources and detectors, resulting in a large and complex apparatus configuration. From this viewpoint, it is disadvantageous for increasing the number of measurable wavelengths or improving the resolution of the scattering angle. Furthermore, in order to detect scattered light generated from the same location in the sample, the effort of adjusting the optical axis is required for each detector and light source. In addition, in suspensions with multiple scattering, measurement is not possible because the signal scattered multiple times by the particles is detected. Patent Document 1 makes it difficult to easily measure the scattering intensity of a dispersion or suspension containing particles at different scattering angles or different wavelengths.

[0006] The object of the present invention is to provide an optical measuring device that can easily measure scattering intensity at different scattering angles or different wavelengths. [Means for solving the problem]

[0007] To achieve the above objectives, one aspect of the present invention provides an optical measuring device having a low-coherence interferometer, comprising: a detection unit having at least one of: a first detection unit that interferes at least a portion of the scattered light obtained by incident light on a dispersion containing particles with a reference light and detects the interference light intensity for each wavelength; and a second detection unit that interferes at least a portion of the scattered light obtained by incident light on a dispersion containing particles with a reference light and detects the interference light intensity for each scattering angle; and a conversion unit that extracts multiple data of scattering intensity at a specific depth and specific wavelength in the dispersion from the interference light intensity data for each wavelength detected by the first detection unit, or from the interference light intensity data for each scattering angle detected by the second detection unit, and converts the extracted scattering intensity data into time fluctuation data of scattered light at a specific depth in the dispersion.

[0008] It is preferable to have a calculation unit that calculates the particle size using the time fluctuation data acquired by the conversion unit. It is preferable to have a calculation unit that obtains the particle size distribution for each particle type contained in the dispersion by fitting the time fluctuation data acquired by the conversion unit and the time-averaged data obtained by averaging the time fluctuation data acquired by the conversion unit to a theoretical formula that defines the relationship between particle size and scattering intensity. Preferably, the system has a storage unit that stores at least one of the following: scattering angle-dependent data for the scattered light intensity of known particles and wavelength-dependent data for the scattered light intensity, which are determined by the complex refractive index, particle size, and shape of known particles; and a calculation unit that obtains the particle size distribution for each particle type contained in the dispersion by fitting the scattering angle-dependent data obtained from the time fluctuation data acquired by the conversion unit, or the wavelength-dependent data of scattered light obtained from the time fluctuation data acquired by the conversion unit, to the scattering angle-dependent data for the scattered light intensity of known particles or the wavelength-dependent data for the scattered light intensity stored in the storage unit. Preferably, the device has a storage unit that stores at least one of the following: scattering angle-dependent data for the scattered light intensity of known particles and wavelength-dependent data for the scattered light intensity, which are determined by the complex refractive index, particle size, and shape of known particles; and a calculation unit that uses the scattering angle-dependent data or wavelength-dependent data for the scattered light intensity of known particles stored in the storage unit to determine at least one of the particle type of the particles in the dispersion and the state of the particles in the dispersion. The first detection unit preferably has a photodetector that wavelength-decomposes scattered light that has interfered with a reference light and detects the wavelength-decomposed scattered light for each wavelength. The second detection unit preferably has a photodetector that detects scattered light that has interfered with the reference light at each scattering angle. It is preferable that the system has a polarization control unit that controls the polarization state of the incident light, and that the first detection unit or the second detection unit measures the light intensity of the polarization component of the scattered light as the scattering intensity. It is preferable to have a spectral adjustment unit that controls the central wavelength and wavelength band of the incident light. For example, the time fluctuation data of scattered light is the power spectrum or autocorrelation function. [Effects of the Invention]

[0009] According to the present invention, an optical measuring device can be provided that can easily measure scattering intensity at different scattering angles or different wavelengths. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing a first example of an optical measuring device according to an embodiment of the present invention. [Figure 2] This graph shows an example of a power spectrum obtained by the first example of the optical measurement method according to an embodiment of the present invention. [Figure 3] This graph shows an example of an autocorrelation function obtained by the first example of the optical measurement method according to an embodiment of the present invention. [Figure 4] This graph shows an example of an interference spectrum obtained in the first example of the optical measurement method according to an embodiment of the present invention. [Figure 5] This graph shows an example of the scattering profile in the depth direction of a dispersion obtained in the first example of the optical measurement method of the embodiment of the present invention. [Figure 6] This graph shows an example of the time response of the electric field in the region of interest obtained in the first example of the optical measurement method according to an embodiment of the present invention. [Figure 7] This graph shows an example of a power spectrum obtained in the first example of the optical measurement method according to an embodiment of the present invention. [Figure 8] This graph shows an example of a time correlation function obtained in the first example of the optical measurement method according to an embodiment of the present invention. [Figure 9] This graph shows the wavelength dependence of scattering intensity. [Figure 10] This graph shows the wavelength dependence of static light scattering intensity. [Figure 11] This is a schematic diagram showing an optical apparatus for illustrating a second example of an optical measurement method according to an embodiment of the present invention. [Figure 12] This graph shows an example of the light intensity obtained in a second example of the optical measurement method according to an embodiment of the present invention. [Figure 13] This graph shows an example of a scattering intensity profile with respect to scattering angle obtained in a second example of the optical measurement method according to an embodiment of the present invention. [Figure 14] This graph shows an example of the time response of the electric field in a region of interest obtained by a second example of the optical measurement method according to an embodiment of the present invention. [Figure 15] This graph shows an example of a power spectrum obtained in a second example of the optical measurement method according to an embodiment of the present invention. [Figure 16] This graph shows an example of an autocorrelation function obtained in a second example of the optical measurement method according to an embodiment of the present invention. [Figure 17] This graph shows the results of the particle size obtained by fitting and the autocorrelation function at a scattering angle of 175°. [Figure 18] This graph shows the results of the particle size obtained by fitting and the autocorrelation function at a scattering angle of 173°. [Figure 19]This graph shows the results of the autocorrelation function and particle size obtained by fitting at a scattering angle of 172.5°. [Figure 20] This flowchart shows an optical measurement method according to an embodiment of the present invention. [Figure 21] This is the histogram of particle A. [Figure 22] This is the histogram of particle B. [Figure 23] This graph shows the relationship between interference light intensity and scattering angle. [Figure 24] This is a histogram of a single particle. [Figure 25] This is a histogram of aggregates formed by the aggregation of particles. [Figure 26] This graph shows the relationship between scattering intensity and scattering angle for each particle shape. [Figure 27] This is a schematic perspective view showing spherical particles. [Figure 28] This is a schematic perspective view showing disc-shaped particles. [Figure 29] This is a schematic diagram showing a second example of an optical measuring device according to an embodiment of the present invention. [Figure 30] This is a schematic diagram showing a first example of a mask for a second example of an optical measuring device according to an embodiment of the present invention. [Figure 31] This is a schematic diagram showing a second example of a mask for a second example of an optical measuring device according to an embodiment of the present invention. [Figure 32] This is a schematic diagram showing a third example of a mask for a second example of an optical measuring device according to an embodiment of the present invention. [Figure 33] This is a schematic diagram showing a third example of an optical measuring device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] The optical measuring device of the present invention will be described in detail below based on preferred embodiments shown in the attached drawings. The figures described below are illustrative examples for illustrating the present invention, and the present invention is not limited to the figures shown below. In the following, the "~" indicating a numerical range includes the numbers written on both sides. For example, ε is the numerical value ε α ~Value ε β The range of ε is the numerical value ε α and the numerical value ε β This range includes ε α ≦ε≦ε β That is the case. Unless otherwise specified, angles expressed as specific numerical values, and angles such as "parallel," include the generally acceptable margin of error in the relevant technical field.

[0012] (First example of an optical measuring device) Figure 1 is a schematic diagram showing a first example of an optical measuring device according to an embodiment of the present invention. The optical measurement device 10 shown in Figure 1 comprises a low-coherence interferometer 12, a detection unit 14 having a first detection unit 14a and a second detection unit 14b, a conversion unit 15, a calculation unit 16, and a storage unit 17. The optical measurement device 10 also has a sample cell 18. The low-coherence interferometer 12 is an optical interferometer that uses a light source that emits low-coherence light. The low-coherence interferometer 12 includes, for example, a light source 20 and four beam splitters 21a, 21b, 21c, and 21d. Each of the four beam splitters 21a, 21b, 21c, and 21d has a transmission-reflecting surface 21e that either splits the incident light into two or combines two incident lights. The transmission-reflecting surface 21e is an inclined surface with an angle of 45°. Furthermore, the four beam splitters 21a, 21b, 21c, and 21d are all cube-shaped beam splitters. However, the shape of the beam splitters is not limited to cubes; they may also be flat, plate-shaped. Furthermore, the low-coherence interferometer 12 is not limited to the configuration shown in Figure 1.

[0013] The four beam splitters 21a, 21b, 21c, and 21d are positioned at each vertex of the quadrilateral. The transmissive reflective surfaces 21e of beam splitters 21a and 21d, which are positioned diagonally, are parallel. Also, the transmissive reflective surfaces 21e of beam splitters 21b and 21c, which are positioned diagonally, are parallel. The transmissive reflective surfaces 21e of the four beam splitters 21a, 21b, 21c, and 21d are oriented differently from the transmissive reflective surfaces 21e of adjacent beam splitters 21a, 21b, 21c, and 21d; they are non-parallel, specifically anti-parallel. A beam splitter 21a and a beam splitter 21c are arranged side by side, and a reflector 22 is positioned on the opposite side of the beam splitter 21c from the beam splitter 21a. Between the beam splitter 21c and the reflector 22, a dispersion compensation adjustment unit 23a and an objective lens 23b are positioned from the beam splitter 21c side.

[0014] The reflector 22 reflects incident light, and its reflective surface 22a is the reference surface. The reflector 22 is not particularly limited as long as it can reflect incident light; for example, a mirror or a glass plate can be used. The dispersion compensation adjustment unit 23a compensates for the group velocity dispersion caused by the sample cell 18. If the sample cell 18 is made of optical glass as described later, the dispersion compensation adjustment unit 23a compensates for the group velocity dispersion due to the thickness of the optical glass constituting the sample cell 18. A glass plate with a thickness similar to that of the optical glass constituting the sample cell 18 is placed between the beam splitter 21c and the objective lens 23b to compensate for the group velocity dispersion of the passing light. That is, the dispersion compensation adjustment unit 23a adjusts the difference in optical path length due to the difference in wavelength of the reference light Lr, and matches the optical path length of the reference light Lr and the scattered light Ld for each wavelength. The objective lens 23b focuses the light incident on the reflector 22 onto the reflective surface 22a of the reflector 22.

[0015] Beam splitters 21a and 21b are arranged side by side, with an ND (Neutral Density) filter 24a positioned between beam splitters 21a and 21b. An ND filter 24b is positioned between beam splitter 21a and beam splitter 21c. The ND filters 24a and 24b adjust the amount of light to balance the light intensity between the reference light Lr reflected by the reflective surface 22a of the reflector 22 and the scattered light Ld from the sample cell 18. Any known ND filters can be used as appropriate for ND filters 24a and 24b.

[0016] The sample cell 18 is positioned on the opposite side of the beam splitter 21a from the beam splitter 21b. An objective lens 25 is positioned between the beam splitter 21b and the sample cell 18 to focus the incident light Ls onto the sample cell 18.

[0017] The beam splitter 21c and beam splitter 21d are arranged side by side, and the first detection unit 14a is positioned on the opposite side of beam splitter 21d from beam splitter 21c. A polarization adjustment unit 26 is positioned between beam splitter 21d and the first detection unit 14a. The polarization adjustment unit 26 controls the polarization state of the scattered light emitted from the beam splitter 21d and incident on the first detection unit 14a. The polarization adjustment unit 26 is composed of, for example, a polarizing element, and a polarizing element is used as appropriate to adjust the polarization state of the scattered light Ld scattered from the dispersion Lq of the sample cell 18, such as circular polarization, linear polarization, or elliptical polarization. More specifically, for example, the polarization adjustment unit 26 is composed of a polarizer. Measurements may be performed by changing the orientation of the transmission axis of the polarizer multiple times.

[0018] The beam splitter 21b and beam splitter 21d are arranged side by side, and the second detection unit 14b is positioned on the opposite side of beam splitter 21b from beam splitter 21d.

[0019] The first detection unit 14a includes a mirror 30 and a diffraction grating 32 into which the reflected light reflected from the mirror 30 is incident. The diffraction grating 32 is an optical element that wavelength-decomposes the incident light, including scattered light, into light of each wavelength. The diffraction grating 32 makes it possible to obtain scattered light of each wavelength. Furthermore, the system includes a photodetector 33 into which diffracted light, obtained by diffraction of scattered light according to its wavelength by a diffraction grating 32, is incident. The photodetector 33 detects the wavelength-resolved scattered light for each wavelength. For example, a line camera with photoelectric conversion elements arranged in a straight line can be used as the photodetector 33. Alternatively, the photodetector 33 may be a system in which photomultiplier tubes are arranged in a straight line. The photodetector 33 of the first detection unit 14a receives diffracted light, including scattered light, that has been diffracted by the diffraction grating 32. However, the diffraction angle differs for each wavelength, determining the position where the line camera, which is the photodetector 34, receives the light. Therefore, in the first detection unit 14a, the wavelength is determined by the position where the line camera, which is the photodetector 33, receives the light. In this way, the first detection unit 14a wavelength-decomposes the scattered light and detects the wavelength-decomposed scattered light for each wavelength. This makes it possible to easily measure the scattering intensity of scattered light at different wavelengths. Although a diffraction grating 32 was used to obtain light for each wavelength, the method is not limited to a diffraction grating 32, as long as it is possible to obtain light for each wavelength. For example, multiple bandpass filters with different cutoff wavelength bands can be prepared and the scattered light for each wavelength can be obtained by swapping the bandpass filters. Alternatively, a prism can be used instead of a diffraction grating 32.

[0020] The second detection unit 14b has a photodetector 34. The photodetector 34 detects scattered light at each scattering angle. For example, a line camera in which photoelectric conversion elements are arranged in a straight line is used as the photodetector 34. In the second detection unit 14b, the scattering angle is determined by the position where the line camera, which is the photodetector 34, receives light. This makes it possible to easily measure the scattering intensity of scattered light at different scattering angles. The photodetector 34 also detects the interference light intensity at each scattering angle for interference light that occurs when scattered light interferes with a reference light. Note that the photodetector 34 may be replaced with a high-speed camera instead of a line camera. Furthermore, the photoelectric conversion elements used in the photodetectors 33 and 34 are, for example, photodiodes.

[0021] The sample cell 18 is, for example, a rectangular or cylindrical container made of optical glass or optical plastic. A dispersion Lq containing particles to be measured is placed in the sample cell 18. Incident light Ls is irradiated onto the dispersion Lq. The sample cell 18 may be placed in an immersion bath, although this is not shown in the diagram. The immersion bath is used to eliminate the refractive index difference between the sample cell 18 and the surrounding environment, and any known immersion bath can be used as appropriate. Alternatively, the sample cell 18 can be brought into contact with the metal that the Peltier element is in contact with to regulate its temperature.

[0022] The light source unit 20 is positioned on the opposite side of the beam splitter 21b from the beam splitter 21a. The light source unit 20 irradiates the sample cell 18 with incident light Ls, and directs the light emitted from the beam splitter 21a into the light source unit 20. The light source unit 20 emits low-coherence light as the incident light Ls. Unlike monochromatic laser light, low-coherence light is bandwidth light. The light source unit 20 can be, for example, a xenon lamp, a superluminescent diode (SLD), an LED (light-emitting diode), or a supercontinium (SC) light source.

[0023] Between the light source unit 20 and the beam splitter 21a, a spectral adjustment unit 27 and a polarization control unit 28 are provided, on the light source unit 20 side. The spectral adjustment unit 27 cuts out unwanted wavelength ranges according to the spectrum of the incident light Ls from the light source unit 20. For example, if the near-infrared light range in a supercontinium light source cannot be detected by the photodetector 33 of the first detection unit 14a and the photodetector 34 of the second detection unit 14b, the spectral adjustment unit 27 uses a filter that cuts out the near-infrared light range. Furthermore, when measuring the scattering intensity for each scattering angle in the second detection unit 14b, a bandpass filter may be used in the spectral adjustment unit 27, for example, in order to limit the wavelength band. Furthermore, when measuring the scattered light of a dispersion Lq using light of multiple wavelengths, it is conceivable to prepare multiple light sources with different emission wavelengths as the light source unit 20. However, by using a bandpass filter as the spectral adjustment unit 27, wavelength ranges can be cut off, thus simplifying the configuration of the light source unit 20 and thus simplifying the overall apparatus configuration.

[0024] The polarization control unit 28 controls the polarization state of the incident light and adjusts its polarization. The polarization control unit 28 is composed of, for example, polarizing elements, and a polarizing element is used as appropriate according to the polarization of the light irradiated onto the sample cell 18, such as circularly polarized, linearly polarized, or elliptically polarized light. Polarization is used for the incident light when determining the shape of the particles. More specifically, the polarization control unit 28 is composed of a combination of a polarizer and a λ / 4 plate. This makes it possible to convert unpolarized incident light Ls into circularly polarized light. Furthermore, in the optical measuring device 10, if the polarization of the light emitted from the light source unit 20 is used as is, the polarization adjustment unit 26 and the polarization control unit 28 are not necessarily required.

[0025] In the optical measuring device 10 having a first detection unit 14a and a second detection unit 14b, scattering intensity can be easily measured at different scattering angles or different wavelengths. Furthermore, in the optical measuring device 10, if only one of the scattering angle and wavelength is used, the detection unit 14 only needs to have either the first detection unit 14a or the second detection unit 14b.

[0026] Light emitted from the light source unit 20 is split by the transmission-reflecting surface 21e of the beam splitter 21a, passes through the transmission-reflecting surface 21e and enters the beam splitter 21b, and passes through the transmission-reflecting surface 21e of the beam splitter 21b and irradiates the sample cell 18 as incident light Ls. The scattered light Ld generated when the incident light Ls is scattered by the dispersion Lq of the sample cell 18 is reflected by the transmission-reflecting surface 21e of the beam splitter 21b to the beam splitter 21d. Of the light emitted from the light source unit 20, the scattered light Ld reflected by the transmission / reflection surface 21e of the beam splitter 21d is incident on the first detection unit 14a.

[0027] Light that is split by the transmission-reflecting surface 21e of the beam splitter 21a and incident on the beam splitter 21c passes through the transmission-reflecting surface 21e and is incident on the reflector 22, where it is reflected by the reflecting surface 22a of the reflector 22. This reflected light is the reference light Lr. The reference light Lr is reflected by the transmission-reflecting surface 21e of the beam splitter 21c and incident on the beam splitter 21d. The reference light Lr that has passed through the transmission-reflecting surface 21e of the beam splitter 21d is incident on the first detection unit 14a. In this way, scattered light Ld and reference light Lr are incident on the first detection unit 14a and interfere with each other. It is sufficient that at least a portion of the scattered light Ld interferes with the reference light Lr, and it is preferable to adjust the optical path length so that only the scattered light Ld generated at a specific depth in the dispersion Lq interferes with the reference light Lr. The first detection unit 14a has a diffraction grating 32 that determines the light-receiving position of the photodetector 33 for each wavelength, allowing it to detect interference light for each wavelength and obtain interference light intensity data for each wavelength. As a result, the conversion unit 15 can obtain scattering intensity data for a specific depth and wavelength in the dispersion Lq from the interference spectrum of the scattered light. Depth can be considered to refer to the optical path length through which the scattered light passes in the dispersion Lq.

[0028] Furthermore, scattered light Ld passes through the transmission / reflection surface 21e of the beam splitter 21d and is incident on the second detection unit 14b. Of the reference light Lr, the portion reflected by the transmission / reflection surface 21e of the beam splitter 21d is incident on the second detection unit 14b. In this way, scattered light Ld and reference light Lr are incident on the second detection unit 14b and interfere with each other. It is sufficient for at least a portion of the scattered light Ld to interfere with the reference light Lr, and it is preferable to adjust the optical path length so that only the scattered light generated at a specific depth in the dispersion Lq interferes with the reference light Lr. Depending on the scattering angle θb of the dispersion Lq, the reflection position of the scattered light Ld on the transmission / reflection surface 21e of the beam splitter 21b differs, and the receiving position of the photodetector 34 also differs. Therefore, the second detection unit 14b has a fixed receiving position for the photodetector 34 for each scattering angle, and can detect the interference light between the reference light and the scattered light for each scattering angle, thereby obtaining interference light intensity data for each scattering angle. As a result, the conversion unit 15 can obtain scattering intensity data for a specific scattering angle from the interference light intensity data for each scattering angle for the scattered light of the dispersion Lq at a specific depth corresponding to the same optical path length as the reference light. Note that the scattering angle θb(°) in Figure 1 is an angle based on the backscattered light at a scattering angle of 180°. The relationship with the general notation of the scattering angle θ(°), where the angle of forward scattering is 0°, is θ(°) = 180° - θb(°).

[0029] The conversion unit 15 is connected to the arithmetic unit 16, and the storage unit 17 is connected to both the conversion unit 15 and the arithmetic unit 16. The conversion unit 15 extracts multiple values ​​from the interference light intensity data detected by the first detection unit 14a, which are proportional to the scattering intensity or electric field of scattered light at a specific wavelength, or from the interference light intensity data detected by the second detection unit 14b, which are proportional to the scattering intensity or electric field of light at a specific scattering angle. The conversion unit 15 then converts the extracted scattering intensity data into time fluctuation data of scattered light at a specific depth in the dispersion Lq. The conversion unit 15 is connected to the photodetector 33 of the first detection unit 14a and the photodetector 34 of the second detection unit 14b. The conversion unit 15 acquires light intensity data at a specific wavelength detected by the photodetector 33 of the first detection unit 14a and extracts multiple data points of scattering intensity at that specific wavelength. The extracted scattering intensity data is then converted into time fluctuation data of scattered light at a specific depth in the dispersion Lq. Furthermore, the conversion unit 15 interferes only with scattered light generated at a specific depth in the dispersion Lq by controlling the position of the reflector 22 detected by the photodetector 34 of the second detection unit 14b, and acquires data on the intensity of the interfered light at a specific scattering angle, thereby extracting multiple scattering intensities at a specific scattering angle. This converts the extracted scattering intensity data into time fluctuation data of scattered light at a specific depth in the dispersion Lq. Note that time fluctuation data refers to the power spectrum or autocorrelation function.

[0030] The scattered light from the aforementioned dispersion (Lq) contains components of light scattered at various depths within the dispersion, resulting in different scattering rates and intensities. For accurate measurement of particle size and other properties, it is necessary to analyze the scattered light at a specific depth within the dispersion. By setting a specific depth within the dispersion, it is possible to obtain, for example, single-scattered light where the light is scattered only once. The analysis performed in the conversion unit 15, which converts the extracted scattering intensity data into time fluctuation data of scattered light at a specific depth in the dispersion Lq, will be explained later. The conversion unit 15 executes a program (computer software) stored in ROM (Read Only Memory) or the like, extracts multiple scattering intensities as described above, and converts the extracted scattering intensity data into time fluctuation data of scattered light at a specific depth Lq of the dispersion. The conversion unit 15 may be composed of a computer in which each part functions when the program is executed as described above, or it may be a dedicated device in which each part is composed of a dedicated circuit, or it may be composed of a server that runs on the cloud.

[0031] The calculation unit 16 calculates the particle size using the time fluctuation data acquired by the conversion unit 15. Furthermore, the calculation unit 16 obtains the particle size distribution for each particle type contained in the dispersion by fitting the time fluctuation data acquired by the conversion unit 15 and the time-averaged data obtained by averaging the time fluctuation data acquired by the conversion unit 15 to a theoretical formula that defines the relationship between particle size and scattering intensity. Various calculation methods used in dynamic light scattering can be appropriately used to calculate the particle size in the calculation unit 16. The method for obtaining the particle size distribution for each particle type contained in the dispersion will be explained later.

[0032] The memory unit 17 stores at least one of the following: scattering angle-dependent data for the scattered light intensity of a known particle and wavelength-dependent data for the scattered light intensity, which are determined by the complex refractive index, particle size, and shape of the known particle. By storing at least one of the data on the scattering angle dependence of scattered light intensity and the data on the wavelength dependence of scattered light intensity for known particles in the memory unit 17, it can be referenced when determining the particle size distribution or during fitting. For this reason, it is preferable to store at least one of the data on the scattering angle dependence of scattered light intensity and the data on the wavelength dependence of scattered light intensity for known particles for various types of particles and to build a model library. Furthermore, the memory unit 17 also stores various types of data obtained by the conversion unit 15. The storage unit 17 is not particularly limited as long as it can store the scattering angle-dependent data and wavelength-dependent data of the scattered light intensity for the known particles mentioned above, as well as the various data obtained by the conversion unit 15. For example, various storage media such as hard disks or SSDs (Solid State Drives) can be used.

[0033] Furthermore, the calculation unit 16 uses at least one of the data stored in the storage unit 17, which is the scattering angle-dependent data and the scattering angle-dependent data for known particles, to perform fitting in order to obtain the particle size distribution for each particle type. The calculation unit 16 can also read various data obtained by the conversion unit 15 stored in the storage unit 17 and perform fitting. Furthermore, the aggregation state or particle type of the particles can be determined by comparing the particle size distribution values ​​obtained from measured fluctuation data, and the wavelength dependence or intensity dependence of the measured scattered light, with the scattering characteristics of the particles stored in the model library. The scattering characteristics of a particle are, for example, data on the scattering angle dependence of the scattered light intensity and data on the wavelength dependence of the scattered light intensity for known particles. The scattering characteristics of these particles may be determined by experimental values ​​obtained using known particles such as standard particles, or by calculated values ​​obtained by theoretical formulas that define the relationship between particle size and scattering intensity, such as the Mie scattering theory formula. Alternatively, the scattering characteristics of a particle may be calculated values ​​obtained by simulation. Calculated values ​​obtained by simulation can be obtained, for example, using the FDTD method (Finite-difference time-domain method) or the DDA (Discrete dipole approximation) method. The above-mentioned scattering characteristics of particles are stored in the storage unit 17 as a model library, for example.

[0034] The calculation unit 16 performs the calculation of particle size and the particle size distribution for each particle type contained in the dispersion by executing a program (computer software) stored in ROM or the like. The calculation unit 16 may be composed of a computer in which each part functions when the program is executed as described above, or it may be a dedicated device in which each part is composed of a dedicated circuit, or it may be composed of a server that runs on the cloud.

[0035] In the optical measuring device 10, the reference light Lr may be blocked to prevent interference with scattered light. In this case, normal dynamic light scattering measurements can be performed by blocking the reference light Lr. One method of blocking the reference light Lr is to provide a movable light-shielding plate between the beam splitter 21a and the beam splitter 21c to prevent the light split from the beam splitter 21a from reaching the reflector 22. Alternatively, a movable light-shielding plate may be provided between the beam splitter 21c and the beam splitter 21d to block the reference light Lr reaching the beam splitter 21d, thereby blocking the reference light Lr. Furthermore, as long as light can be blocked, the solution is not limited to a retractable light-blocking plate; for example, a light shutter using a liquid crystal shutter can be used. With the above configuration, the optical measurement device 10 can also be used as a dynamic light scattering device for conventional homodyne detection.

[0036] Figure 2 is a graph showing an example of a power spectrum obtained by the first example of the optical measurement method according to the embodiment of the present invention, and Figure 3 is a graph showing an example of an autocorrelation function obtained by the first example of the optical measurement method according to the embodiment of the present invention. For example, the interference light intensity for each wavelength is detected in a dispersion containing polystyrene particles with a diameter of 1 μm and a concentration of 1% by mass, using the optical measuring device 10 shown in Figure 1 above. From the interference light spectrum obtained by the first detection unit 14a, the interference intensity spectra at three wavelengths, with central wavelengths of 620 nm, 640 nm, and 660 nm, are extracted as representatives. The wavelength widths for the central wavelengths of 620 nm, 640 nm, and 660 nm are ±9 nm, respectively. Next, the conversion unit 15 obtains data of signal components proportional to the electric field of scattered light of each wavelength at a specific depth from the interference light intensity detected by the first detection unit 14a. The data of the scattering intensity of each wavelength is converted into a power spectrum as the time fluctuation data of the scattered light at a specific depth of the dispersion liquid Lq. Thereby, the power spectrum shown in FIG. 2 is obtained. Further, the conversion unit 15 performs inverse Fourier transform on the power spectrum shown in FIG. 2 to obtain an autocorrelation function for each wavelength as shown in FIG. 3. The numerical values on the vertical axis of FIG. 3 are common logarithms.

[0037] Next, in the calculation unit 16, for example, for the common logarithm (log 10 ) of the autocorrelation function of each wavelength shown in FIG. 3, the slope Γg is obtained respectively. Using the slope Γg, the diffusion coefficient D at each wavelength is obtained. The diffusion coefficient D is represented by D = Γg / q 2 . Here, q is the scattering vector. Here, the diffusion coefficient D and the particle size d are represented by the Stokes-Einstein equation as d = k B T / (3πηD). Here, k B is the Boltzmann constant, T is the absolute temperature, and η is the viscosity of the solvent of the dispersion liquid. The method of calculating the particle distribution from the slope of the autocorrelation function is not limited to this method, and the CONTIN method, the histogram method, the cumulant expansion, etc. are known, and these methods can be used.

[0038] Next, in the calculation unit 16, using the diffusion coefficient D of each wavelength, the hydrodynamic particle size of the polystyrene particles at each wavelength is obtained. This hydrodynamic particle size is the above-mentioned particle size d. As a result, 0.9 μm is obtained at the central wavelength of 620 nm, 1.1 μm is obtained at the central wavelength of 640 nm, and 1.2 μm is obtained at the central wavelength of 660 nm. The average value of the obtained particle sizes is 1.06 μm. Thus, when a plurality of wavelengths are used, the particle size can be measured for polystyrene particles with a particle size of 1 μm and a concentration of 1 mass%.

[0039] <First Example of Optical Measurement Method> The first example of the optical measurement method is that the optical measurement device 10 uses a plurality of wavelengths. For example, a dispersion containing particles is measured using a supercontinuum light source. During the measurement, light of each wavelength is detected by the photodetector 33 of the first detection unit 14a. The light of each wavelength incident on the photodetector 33 includes interference light between scattered light and reference light, which is represented, for example, by the interference spectrum shown in Figure 4. In Figure 4, the vertical axis represents light intensity and the horizontal axis represents wavenumber. The intensity I of the interference spectrum shown in Figure 4 k It is expressed by the following formula. In the following formula, E S E is the electric field of scattered light, S * is E S It is the complex conjugate of E R E is the electric field of the reference light, R * is E R It is the complex conjugate of . I k =|E R +E S | 2 =|E R | 2 +|E S | 2 +E R E S * +E S E R *

[0040] Next, regarding the interference spectrum shown in Figure 4, for example, we extract the wavelength region 35a with a central wavelength of 620 nm. The width of the wavelength region 35a is ±9 nm from the central wavelength of 620 nm. This allows us to extract the scattering intensity of a specific wavelength region from the scattering intensity data for each wavelength. After extracting the scattering intensity of a specific wavelength region, we apply the intensity I of the interference spectrum to the wavelength region. k For this, the inverse Fourier transform F ‐1 This is performed to obtain, for example, the scattering profile F in the depth direction of the dispersion Lq with a central wavelength of 620 nm. ‐1 (I K ) is obtained. An example of the scattering profile in the depth direction of the dispersion Lq is shown in Figure 5. Note that in Figure 5, the vertical axis is F ‐1 (I KThe horizontal axis represents the distance from the reference optical path length position. This reference optical path length position is equal to the optical path length of the reference light. For example, if the optical path length of the reflected light generated at the interface between the sample cell and the dispersion is equal to the optical path length at the reference optical path length position, the horizontal axis represents the depth from the interface.

[0041] The inverse Fourier transform mentioned above is expressed by the following equation. F ‐1 (I K )=|r r | 2 E0 2 δ(z)+r r E0 2 ρ(s / 2)+E0 2 Γ ρ (s / 2) Furthermore, r r Γ is the reflectance of the reflector 22 to the electric field, E0 is the electric field of the light irradiated onto the sample, δ(z) is the delta function, ρ is the diffuse reflectance of the scattered electric field from a depth s / 2 from the interface of the dispersion, and Γ ρ This is the autocorrelation function for the depth dependence of the diffuse reflectance of the scattered electric field. In the depth profile of the dispersion shown in Figure 5, for example, the single-scatter region is extracted as the depth of interest region 35b. The single-scatter region, that is, the region where light is scattered only once, is determined by the optical path length in the optical measurement device 10, and it is preferable to pre-determine the optical path length of the single-scatter region in the optical measurement device 10. The depth of interest region 35b described above corresponds to a specific depth of the dispersion Lq.

[0042] The first detection unit 14a obtains the time response of the electric field in the region of interest 35b. All time-series data of the signal obtained by the line detector are processed in the same manner to obtain the time dependence of the signal amount proportional to the scattered electric field E0ρ(s / 2) in the region of interest 35b. This is shown in Figure 6. In Figure 6, the vertical axis is the electric field and the horizontal axis is time. The time dependence of the scattered electric field shown in Figure 6 is subjected to a Fourier transform and then squared. This yields the frequency response of the scattered light intensity, i.e., the power spectrum shown in Figure 7. In Figure 7, the vertical axis represents intensity and the horizontal axis represents frequency. Power spectrum I shown in Figure 7 ES It is expressed by the following formula. Note that the Γ in the following formula ES This is the time correlation function (= autocorrelation function) of the electric field.

[0043]

number

[0044] Next, the power spectrum I shown in Figure 7 ES An inverse Fourier transform is performed on this. This yields the autocorrelation function of the scattered electric field. This is shown in Figure 8. In Figure 8, the vertical axis is the autocorrelation function and the horizontal axis is the delay time. The inverse Fourier transform described above is expressed by the following equation. F ‐1 (I ES )=Γ ES (τ) = G ES (1) (τ) As described above, a power spectrum or autocorrelation function is obtained from the extracted interference light intensity data as time fluctuation data of scattered light at a specific depth in the dispersion Lq. The conversion of the scattering intensity data for each wavelength detected by the first detection unit 14a to a power spectrum or autocorrelation function at a specific depth in the dispersion Lq is performed by the conversion unit 15. Next, the calculation unit 16 calculates the particle size using the power spectrum or autocorrelation function, which are time fluctuation data acquired by the conversion unit 15. The method for calculating the particle size using the autocorrelation function is shown in Figure 3 above.

[0045] The wavelength dependence of the time-averaged scattered electric field can be obtained by first extracting the signal for the wavelength region 35a shown in Figure 4, then calculating the time-averaged signal for the region of interest 35b shown in Figure 5, and dividing this by the intensity signal for the same wavelength region as the aforementioned wavelength region 35a in the spectrum of the reference light. Squaring this further yields the scattered light intensity normalized by the light source spectrum. In this way, for example, information on static light scattering of single-scattered light in the wavelength region with a central wavelength of 620 nm can be obtained. For example, for both the wavelength region with a central wavelength of 640 nm and the wavelength region with a central wavelength of 660 nm, information on single-scattered static light scattering at each wavelength can be obtained by extracting the wavelength region with a central wavelength of 640 nm and the wavelength region with a central wavelength of 660 nm from the interference spectrum shown in Figure 4. The width of the wavelength region is, for example, ±9 nm from the central wavelengths of 640 nm and 660 nm.

[0046] Here, Figure 9 is a graph showing the wavelength dependence of scattering intensity, and Figure 10 is a graph showing the wavelength dependence of static light scattering intensity. Figure 9 was obtained by theoretical calculation, and Figure 10 was obtained by experimental measurement. Profile 36, shown in Figure 9, represents the scattering intensity of a cross-linked aggregate with a hydrodynamic diameter of 1000 nm, composed of polystyrene particles with a diameter of 50 nm. The average inter-particle distance of the cross-linked aggregate is greater than or equal to the particle size of the polystyrene. Profile 37 represents the scattering intensity of a single polystyrene particle with a diameter of 1000 nm. In Figure 9, the vertical axis represents scattering intensity and the horizontal axis represents wavelength. For example, the data for the single particle and cross-linked aggregate in Figure 9 are stored as a model library in the storage unit 17 (see Figure 1). Crosslinked aggregates are composed, for example, of particles of a predetermined size and polymers present between the particles. The polymers are often those that have functional groups (e.g., polar groups) that cause the particles to aggregate.

[0047] As shown in Figure 9, in the crosslinked aggregate represented by profile 36, the scattering intensity decreases with increasing wavelength. On the other hand, in the single particle with a diameter of 1000 nm represented by profile 37, the scattering intensity increases with increasing wavelength. Figure 10 shows the static light scattering intensity obtained by measuring a single polystyrene particle with a diameter of 1000 nm and a concentration of 1 mass%. As shown in the wavelength dependence of the static light scattering intensity in Figure 10, the scattering intensity of a single polystyrene particle increases with increasing wavelength.

[0048] In dynamic light scattering (DLS), as shown in the example of analyzing the time fluctuation data of scattered light described above, all that can be determined is that the hydrodynamic size of the particle is 1000 nm. Therefore, even if the particle size is known to be 1000 nm, it is not possible to determine whether it is a cross-linked aggregate or a single particle. As shown in profile 37 in Figure 9, the scattering intensity of a single particle increases with increasing wavelength, so the signal obtained in the experiment in Figure 10 can be determined to be a single polystyrene particle with a diameter of 1000 nm. The determination of whether it is a single particle is performed by the calculation unit 16. As described above, by combining the wavelength dependence of dynamic and static light scattering and comparing it with data from a model library using the procedure described later (see Figure 20), it is possible to determine not only the hydrodynamic particle size but also the state of the particles in the dispersion and the type of particles in the dispersion. The state of the particles in the dispersion is, for example, an aggregated state. The type of particles in the dispersion and the state of the particles in the dispersion are determined by the calculation unit 16. Note that the calculation unit 16 only needs to be able to determine at least one of the type of particles in the dispersion and the state of the particles in the dispersion.

[0049] <Second example of optical measurement method> A second example of an optical measurement method utilizes multiple scattering angles. For example, a supercontinuum light source is used to measure a dispersion containing particles. Figure 11 is a schematic diagram showing an optical apparatus for illustrating a second example of an optical measurement method according to an embodiment of the present invention. The optical apparatus 38 shown in Figure 11 is a simplified version of the optical measurement apparatus 10 shown in Figure 1, in order to illustrate measurement using multiple scattering angles. In Figure 11, components identical to those in the optical measurement apparatus 10 shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0050] The optical device 38 shown in Figure 11, for example, has a cubic beam splitter 39 flanked by a photodetector 34 and a reflector 22. An objective lens 23b is positioned between the beam splitter 39 and the reflector 22. The surface 39a of the beam splitter 39 is perpendicular to the direction in which the reflector 22 and the photodetector 34 are arranged. A sample cell 18 containing a dispersion liquid Lq is provided opposite the surface 39a of the beam splitter 39. An objective lens 25 is positioned between the surface 39a of the beam splitter 39 and the dispersion liquid Lq. The beam splitter 39 has a transmission and reflection surface 39e that splits the incident light into two or combines two incident lights. In addition, although the beam splitter 39 is a cubic beam splitter, the form of the beam splitter is not limited to a cube shape, and may also be a flat plate shape.

[0051] The photodetector 34 is a line camera in which photoelectric conversion elements are arranged in a straight line, as described above. In the photodetector 34, when the position coordinate of the line camera is x, the coordinate xc is the coordinate when the scattering angle θb is 0° relative to the angle of the backscattered light or the specularly reflected light from the sample cell, that is, the coordinate when the scattering angle θ is 180°. The position coordinate x of the line camera is expressed as x = f·sinθb + xc, where f is the focal length of the objective lens 25. Therefore, Figures 12 and 13, described later, contain information on scattered light from each depth. By adjusting the position of the reflector 22, the position at which the reference light and the scattered light in the depth direction of the dispersion Lq interfere can be changed. By doing so, the optical path length of the reference light can be adjusted to match the optical path length of the single scattered light from the dispersion, thereby creating a signal in which the single scattered light is interfered with.

[0052] Incident light Ls is incident on the surface 39b of the beam splitter 39, which is opposite the surface 39a. The incident light Ls passes through the transmission / reflection surface 39e, passes through the objective lens 25, and irradiates the dispersion liquid Lq, generating scattered light Ld with a scattering angle θ. The scattered light Ld is incident on the transmission / reflection surface 39e of the beam splitter 39, reflected by the transmission / reflection surface 39e, and the scattered light Ld is incident on the photodetector 34. Meanwhile, the incident light Ls is split by the transmission reflection surface 39e of the beam splitter 39 and incident on the reflector 22. The reference light Lr reflected by the reflection surface 22a of the reflector 22 passes through the transmission reflection surface 39e and is incident on the photodetector 34. In this way, the scattered light Ld and the reference light Lr are incident on the photodetector 34, causing interference. This results in the intensity of the interference light shown in Figure 12. In Figure 12, the vertical axis is the light intensity and the horizontal axis is the position coordinates of the line camera. The intensity of the interference light shown in Figure 12 is expressed by the following formula.

[0053] I 干渉 (x,t)=I R +I S +2Re{E R E S * (x,z 干渉 )}(t) Here, I 干渉 In the equation (x,t), x is the position coordinate of the line camera, t is time, I R The intensity of the reference light is I. s The intensity of scattered light, Re{E R E S *} is a function that takes its real part, E R E is the electric field of the reference light. s is the electric field of scattered light, and z represents the interference position in the optical axis direction in the dispersion, i.e., the interference position in the depth direction of the dispersion.

[0054] Furthermore, the light intensity during non-coherence is I 非干渉 (x,t)=I R +I SThis is represented by [formula]. A non-coherent spectrum can be obtained, for example, by changing the optical path length by placing a thick glass plate at the position of the dispersion-safety adjustment unit 23a shown in Figure 1 to increase the optical path length of the reference light. 非干渉 (x,t) can be more simply approximated as I 干渉 Time average of (x,t) 干渉 This can also be obtained by taking (x,t)>t.

[0055] Using the above-mentioned x = f·sinθb + xc, the light intensity shown in Figure 12 is converted to light intensity with respect to the scattering angle θ, as shown in Figure 13. Figure 13 shows the scattering intensity profile with respect to the scattering angle. In Figure 13, the vertical axis represents light intensity, indicating the scattering intensity, and the horizontal axis represents the scattering angle. The light intensity in Figure 13 is I 干渉 (θ,t)=I R +I S +2Re{E R E S * It is expressed as}. Also, the light intensity in non-coherent conditions is I 非干渉 (θ,t)=I R +I S It is represented as follows.

[0056] Next, in Figure 13, for example, an angle of interest region 40 and an angle of interest region 42 are set. This allows the interference light intensity I, which contains information about the scattered light electric field at a specific scattering angle, to be determined. 干渉 Multiple values ​​of (θ,t) are selected. The second detection unit 14b obtains the time response of the electric field in the angle-of-interest regions 40 and 42. This yields a profile 41 showing the time dependence of the scattered electric field in the angle-of-interest region 40, as shown in Figure 14. Similarly, a profile 43 showing the time dependence of the scattered electric field in the angle-of-interest region 42 is obtained, as shown in Figure 14. Figure 14 shows the time-series changes of the scattering angle component in the region of interest, illustrating the time-domain fluctuations of the scattering angle θ component. The vertical axis in Figure 14 represents the electric field, and the horizontal axis represents time.

[0057] ​Next, the square of the Fourier transform is performed on the profiles 41 and 43 showing the time dependence of the electric field shown in FIG. 14. Thereby, the frequency response of the intensity, that is, the power spectrum shown in FIG. 15 is obtained. In FIG. 15, only one of the regions of interest angle 40 is shown in the power spectrum, but for the region of interest angle 42 as well, a power spectrum can be obtained in the same manner as for the region of interest angle 40. Note that in FIG. 15, the vertical axis is the intensity and the horizontal axis is the frequency. The value represented by the vertical axis in FIG. 15 is the following P 干渉 (θ,t) minus the following P 非干渉 (θ,t). In the following formula, F * indicates the complex conjugate. P 干渉 (θ,t)=F{I 干渉}F * {I 干渉} P 非干渉 (θ,t)=F{I 非干渉}F * {I 非干渉}

[0058] Next, an inverse Fourier transform is performed on the power spectrum shown in FIG. 15. Thereby, as shown in FIG. 16, the autocorrelation function of the scattered electric field Es at the scattering angle θ is obtained. Note that in FIG. 16, the vertical axis is the autocorrelation function and the horizontal axis is the delay time. The power spectrum shown in FIG. 15, or the autocorrelation function shown in FIG. 16, is the above-mentioned time fluctuation data. By performing fitting based on the principle of the dynamic light scattering method using the power spectrum shown in FIG. 15, or the autocorrelation function shown in FIG. 16, the hydrodynamic size of the particles can be obtained.

[0059] Here, the spatial intensity distribution I R (x) is represented by I R (x)=|E R | <00001​​​​​​​​​​​​​This is the spatial intensity distribution of the reference light I R (x) is conveniently rewritten as a function of θ corresponding to the coordinates of the line detector. R By using (θ), normalizing, and taking a time average, the scattering angle dependence of the static light scattering electric field, Is(θ), can be obtained. Is(θ)=<|Re{E R E S *}(θ)| 2 > time average / 2I R

[0060] The results of measurements taken using the above-described optical measurement device 10, with incident light having a central wavelength of 650 nm, for a dispersion containing polystyrene particles with a particle size of 1000 nm and a concentration of 1% by mass, are described below. The solvent of the dispersion was water. The measurement depth was set to 50 μm from the surface of the dispersion, i.e., from the gas-liquid interface. The depth of the dispersion was set to 50 μm. The incident light was set to have a central wavelength of 650 nm and a wavelength width of ±33 nm relative to the central wavelength by using, for example, a bandpass filter. Of the multiple scattering angles obtained, the particle size was measured using the scattered light components at scattering angles of 175°, 173°, and 172.5°. Note that the scattering intensity mentioned above represents the central angle, and the total width of the scattering angle is 0.5°. A total width of 0.5° means the angle center value ±0.25°. For example, if the scattering angle is 175°, then the total width is 175° ± 0.25°.

[0061] In the optical measuring device 10, the scattered light generated by irradiating the dispersion liquid Lq with the aforementioned central wavelength of 650 nm is detected by the second detection unit 14b using the photodetector 34 at each scattering angle, and interference light intensity data is obtained. In the conversion unit 15, scattering intensity data for specific scattering angles, 175°, 173°, and 172.5° as described above, is obtained from the scattering intensity data. Next, the extracted scattering intensity data is converted into an autocorrelation function as time fluctuation data of scattered light at a dispersion depth of 50 μm, as described above. As a result, the autocorrelation functions shown in the plots in Figures 17 to 19 are obtained. Figure 17 shows the autocorrelation function for a scattering angle of 175°, Figure 18 shows the autocorrelation function for a scattering angle of 173°, and Figure 19 shows the autocorrelation function for a scattering angle of 172.5°.

[0062] The calculation unit 16 calculated the particle size by fitting, and the results shown in Figures 17 to 19 were obtained. To calculate the particle size, as shown in Figure 3 above, the slope Γg of the autocorrelation function is determined, and the diffusion coefficient D at the scattering angle is determined using the slope Γg. The particle size d is calculated from the diffusion coefficient D using the Stokes-Einstein equation, which expresses the relationship between the diffusion coefficient D and the particle size d. As shown in Figure 17, when the scattering angle is 175°, the median particle size is 1.03 μm. As shown in Figure 18, when the scattering angle is 173°, the median particle size is 1.04 μm. As shown in Figure 19, when the scattering angle is 172.5°, the median particle size is 1.01 μm. The average of the obtained particle sizes is 1.027 μm. Thus, even when using multiple scattering angles, the particle size of 1 μm polystyrene particles can be measured with sufficient accuracy.

[0063] Next, we will explain how the calculation unit 16 fits the time fluctuation data obtained by the conversion unit 15 and the time-averaged data obtained by averaging the time fluctuation data obtained by the conversion unit 15 to a theoretical formula that defines the relationship between particle size and scattering intensity. Through the above fitting, the particle size distribution for each particle type contained in the dispersion can be obtained. The above example was for the case where there is one type of particle in the dispersion, but the following calculation formula can be similarly applied to quantitative analysis or determination of particle types when there are two or more types of particles contained in the dispersion. The method is shown below. In addition to the theoretical formula that defines the relationship between particle size and scattering intensity, the scattering characteristics of known particles can also be used for fitting.

[0064] Here, Figure 20 is a flowchart showing an optical measurement method according to an embodiment of the present invention. As shown in Figure 20, the optical measurement method includes, for example, a measurement step (step S10), a step of obtaining experimental data (step S12), a step of obtaining pre-calculated values ​​(step S14), and an optimization step (step S16). The optimization step (step S16) yields analysis results, i.e., particle size distributions for each of several types of particles (step S18). The measurement step (step S10) measures, for example, the time fluctuation of the interference light intensity, and the scattering angle dependence or wavelength dependence of the time-averaged interference light intensity. The step of obtaining experimental data (step S12) involves obtaining, for example, the time correlation of the interference light intensity with respect to time fluctuations, based on the measurements taken in the measurement step (step S10). It also involves obtaining the scattering angle dependence of the time-averaged interference light intensity, or the wavelength dependence of the time-averaged interference light intensity.

[0065] In the step of obtaining pre-calculated values ​​(step S14), the scattering characteristics of the particles are obtained by using data for single particles and cross-linked aggregation, such as the data shown in Figure 9 above, which are stored in the storage unit 17 as a model library. The scattering characteristics of known particles may be measured values ​​using standard particles, as described above. Alternatively, calculated values ​​obtained through theoretical formulas or simulations may be used as the scattering characteristics of the particles. As mentioned above, the scattering characteristics of a particle include, for example, data on the scattering angle dependence of the scattered light intensity and data on the wavelength dependence of the scattered light intensity for known particles. The scattering characteristics of the particles obtained in step S14 are used, for example, to identify the particles in the dispersion or the type of particles in the dispersion. For example, by comparing the measured values ​​obtained in step S10, such as the particle size distribution values ​​obtained from the measured fluctuation data and the wavelength-dependent data or intensity-dependent data of the measured scattered light, with the scattering characteristics of the particles in step S14, the type of particles in the dispersion and the state of the particles in the dispersion are determined. The wavelength-dependent data and intensity-dependent data of the measured scattered light are obtained from the time fluctuation data of the scattered light acquired by the conversion unit 15. In the optimization step (step S16), for example, the first-order autocorrelation function and the theoretical formula for scattering intensity are fitted to the time correlation of the time fluctuations of the interference light intensity and the time-averaged value of the interference light intensity obtained in step S12. In step S16, initial values ​​are set for the number of particles for all particle sizes, and then the evaluation values ​​are updated to minimize them to obtain the final number of particles. The fitting process will be explained in more detail below.

[0066] (First example of fitting) This section describes the case where a dispersion contains two types of particles, particle A and particle B. It is assumed that particle A, particle B, particle types, and the wavelength dependence of the complex refractive index of each particle at each particle size are known. In this case, there is data on the wavelength dependence of scattered light intensity, which can be determined from the complex refractive index, particle size, and shape of the known particles, and this data is stored as a model library in the storage unit 17 (see Figure 1). First-order autocorrelation function g (1) (τ) is g (1) (τ) = exp(-Dq) 2 It is represented as τ). When there are two types of particles, particle A and particle B, in a dispersion, the first-order autocorrelation function is given by equation (1) below. The scattering intensity is given by equation (2) below. Equations (1) and (2) below are theoretical formulas, and the I of equations (1) and (2) total These are all calculated values. Also, I d A and I d B This is a theoretical value, and the pre-calculated value obtained in step S14 described above can be used. In addition, in the following equations (1) and (2), g (1) This shows the first-order autocorrelation function. total'x' represents the total scattering intensity. 'd' represents the particle size. The subscripts 0 to M for 'd' indicate the ordinal numbers of the histogram bins shown in Figures 21 and 22. 'N' represents the number of particles. The subscripts 0 to M for 'N' indicate the ordinal numbers of the histogram bins shown in Figures 21 and 22. Note that a histogram bin refers to a data interval in a histogram, and is represented by a bar in the histogram. Furthermore, D represents the diffusion coefficient. The subscript d of the diffusion coefficient D indicates that it depends on the particle size d. q represents the scattering vector. τ represents the time lag of the first-order autocorrelation function. θ represents the scattering angle. I represents the scattering intensity. The subscript d of the scattering intensity I indicates that it depends on the particle size d. In equations (1) and (2) below, the superscripts A and B indicate that the scattering intensity wavelength dependence corresponds to particle A and particle B, respectively.

[0067]

number

[0068] In equation (1) above, the following term corresponds to particle A, and corresponds to the histogram of particle A shown in Figure 21. In the following term, exp(-Dq 2 τ) is the first-order autocorrelation function, and other N d A I d A / I total The part represents the ratio of the scattering intensity of all particles A belonging to the bottle of particle size d to the total reflected intensity. In other words, it is the weighting of particle A. Note that I in equation (1) total This is a theoretical value determined by the particle size. The Mie scattering theory formula can be used as the theoretical value.

[0069]

number

[0070] In equation (1) above, the following term corresponds to particle B, and corresponds to the histogram of particle B shown in Figure 22. In the following term, exp(-Dq 2τ) is the first-order autocorrelation function, and other N d B I d B / I total The part indicates the ratio of the scattering intensity of all particles B belonging to the bottle with particle size d to the total reflected intensity. In other words, it is the weighting of particle B.

[0071]

number

[0072]

number

[0073] In equation (2) above, N d A I d A This corresponds to the scattering intensity of particle A, and N d B I d B This corresponds to the scattering intensity of particle B.

[0074] The following describes the fitting process for determining the particle size distribution for multiple types of particles. In the fitting process, the number of particles is used as a variable, and the number of particles for each particle size is ultimately determined. First-order autocorrelation function g (1) (τ) has been measured for each wavelength, and there are multiple such measurements. Examples of these measured values ​​include the autocorrelation functions for multiple wavelengths shown in Figure 3 above. In the fitting process, for the first-order autocorrelation function for each wavelength, the initial number of particles is set using equation (1) as the variable. The calculated value of the first-order autocorrelation function in equation (1) is obtained based on the set initial number of particles. The first-order autocorrelation function for each wavelength corresponds to the time fluctuation data derived from the scattering characteristics using the theoretical formula. For each wavelength, the difference between the measured value of the first-order autocorrelation function and the calculated value of the first-order autocorrelation function from equation (1) is determined. This difference between the measured value of the first-order autocorrelation function and the calculated value of the first-order autocorrelation function from equation (1) is called the difference in the first-order autocorrelation function. The difference in the first-order autocorrelation function is obtained for each wavelength.

[0075] For example, as shown in Figures 9 and 10, the total scattering intensity I total These measurements have been taken for each wavelength. Furthermore, from the explanations of Figures 9 and 10 above, it can be determined that the particles are individual particles and not aggregates. In equation (2), the number of particles is set as a variable. The total scattering intensity I in equation (2) is based on the set initial number of particles. total Find the value of this. As shown in Figures 9 and 10, the measured total scattering intensity I for each wavelength total The value of and the total scattering intensity I in equation (2) total The difference between this value and the calculated value is calculated. Note that the measured total scattering intensity I at any wavelength is calculated. total The value of and the total scattering intensity I in equation (2) total The difference from the calculated value is the total scattering intensity I at wavelength. total This is called the difference in total scattering intensity I total Regarding the total scattering intensity at wavelength I total The difference is obtained. Total scattering intensity I in equation (2) total The calculated value corresponds to the time-averaged data obtained by averaging the derived time fluctuation data over time.

[0076] In the fitting process, the difference between the first-order autocorrelation functions obtained for each wavelength and the difference in total scattering intensity at each wavelength are used to determine the final particle number. For example, an evaluation value is obtained by summing the square of the difference between the first-order autocorrelation functions obtained for each wavelength and the square of the difference in total scattering intensity at each wavelength for all wavelengths. The particle number that minimizes this evaluation value is taken as the final particle number. Therefore, in the fitting process, the number of particles is repeatedly updated in equations (1) and (2) to minimize the evaluation value, and the final number of particles is obtained. This corresponds to step S16 described above. After setting initial values ​​for the number of particles for all particle sizes, the evaluation value is updated to minimize it. By performing the above process to obtain the final number of particles for each particle size, for example, the histogram of particle A shown in Figure 21 and the histogram of particle B shown in Figure 22 can be obtained. That is, N d A , N d B For all d=d0~d M By determining this, the particle size distribution can be obtained. This corresponds to step S18 described above. The particle size distribution is the distribution of the number of particles against the particle size, and for example, the unit is expressed in percent. The above steps describe the process for determining the particle size distribution for each of several types of particle species. Note that the evaluation values ​​used for fitting are not limited to those described above.

[0077] Furthermore, the type of particles in the dispersion can be determined by utilizing the difference in scattering intensity with respect to wavelength, as shown in Figures 9 and 10. Therefore, by pre-determining the relationship between the type of particle and the scattering intensity with respect to wavelength, it is possible to determine the type of particle and the particle size distribution. It is preferable to store the relationship between the type of particle and the interference light intensity with respect to wavelength in the storage unit 17. The calculation unit 16 can also read the relationship between the type of particle and the interference light intensity with respect to wavelength from the storage unit 17 and determine the type of particle and the particle size distribution.

[0078] As described above, the two theoretical equations, equations (1) and (2), are used in relation to the experimentally measured first-order autocorrelation function and the experimentally measured total scattering intensity I total The final number of particles is determined by fitting the model to the model. However, the optimization method for the fitting is not limited to the one described above; for example, Bayesian optimization can be used for fitting. As mentioned above, a first-order autocorrelation function was used to determine the number of particles, but this is not the only option; a power spectrum can also be used instead. Furthermore, as described above, by fitting the autocorrelation function or power spectrum of scattering intensity and the scattering intensity for each wavelength to a theoretical formula, the number of particles and the particle size distribution for each particle type, such as particle A and particle B, can be obtained. In addition, if the dispersion contains impurity components, the impurity components and the particle size distribution for each particle type can be obtained, thus separating the effect of the impurity components. Note that, in addition to theoretical formulas, time fluctuation data derived from the scattering characteristics of known particles and time-averaged data obtained by time averaging the derived time fluctuation data can also be used for fitting. Although I have explained wavelengths using two examples, wavelengths are not limited to two; if there are multiple wavelengths, there could be three, four, or any other number.

[0079] (Second example of fitting) This section describes the case where a dispersion contains two types of particles: single particles and aggregates. It is assumed that the types of single particles and aggregates, and the dependence of the complex refractive index of particles on scattering intensity at each particle size are known. In this case, data on the scattering angle dependence of scattered light intensity, which can be determined from the complex refractive index, particle size, and shape of known particles, is stored in the storage unit 17 as a model library. The scattering angle dependence of interference light intensity is calculated in advance for single particles and aggregates. This calculation corresponds to step S14 described above. Furthermore, for example, with respect to the dispersion, as shown in Figure 23, the relationship between scattering intensity and scattering angle is obtained by obtaining the measured value of the scattering angle dependence of the time-averaged interference light intensity (see step S10). Obtaining this relationship between scattering intensity and scattering angle corresponds to step S12 described above. This data showing the relationship between scattering intensity and scattering angle corresponds to the scattering angle dependence data obtained from the time fluctuation data acquired by the conversion unit. It is also possible to obtain data showing the relationship between scattering intensity and wavelength, which corresponds to the wavelength dependence data obtained from the time fluctuation data acquired by the conversion unit.

[0080] When there are two types of particle species in a dispersion, the first-order autocorrelation function is given by equation (3) below. The scattering intensity is given by equation (4) below. Equations (3) and (4) below are theoretical formulas, and the I of equations (3) and (4) total These are all calculated values. Also, I d single and I d floc This is a theoretical value, and the pre-calculated value obtained in step S14 described above can be used. Equation (3) below is basically the same as equation (1), and equation (4) below is basically the same as equation (2). In equations (3) and (4) below, the superscript single of scattering intensity I represents the scattering intensity of a single particle, and the superscript floc represents a bridged aggregate.

[0081]

number

[0082] In equation (3) above, the following term corresponds to a single particle and corresponds to the histogram of a single particle shown in Figure 24. In the following term, exp(-Dq 2 τ) is the first-order autocorrelation function, and other N d single I d single / I total The part in parentheses represents the ratio of the scattering intensity by all single particles belonging to the bottle of particle size d to the total scattering intensity. It shows the proportion of single particles among all particles. In other words, it is the weighting of single particles. Note that in equation (3), I total This is a theoretical value determined by the particle size.

[0083]

number

[0084] In equation (3) above, the following term corresponds to aggregates formed by cross-linking of particles, and corresponds to the histogram of aggregates shown in Figure 25. In the following term, exp(-Dq2 τ) is the first-order autocorrelation function, and other N d floc I d floc / I total The part indicated by the symbol represents the ratio of the scattering intensity due to all aggregates belonging to the bottle with particle size d to the total scattering intensity. In other words, it is the weighting of the aggregates.

[0085]

number

[0086]

number

[0087] In equation (4) above, N d single I d single This corresponds to the scattering intensity of a single particle belonging to the bottle with particle size d, N d floc I d floc This corresponds to the scattering intensity of aggregates formed by cross-linking aggregates of particles belonging to the bottle with particle size d.

[0088] The following describes the fitting process for determining the particle size distribution for multiple types of particles. In the fitting process, the number of particles for each particle size is used as a variable, and the final number of particles for each particle size is determined. First-order autocorrelation function g (1) (τ) has been measured for each scattering angle, and there are multiple values ​​for it. In the fitting process, for each scattering angle, the number of particles is used as a variable in equation (3) to set the initial number of particles. The calculated value of the first-order autocorrelation function in equation (3) is then determined based on the set initial number of particles. The first-order autocorrelation function for each scattering angle corresponds to the time fluctuation data derived from the scattering characteristics using the theoretical formula. For each scattering angle, the difference between the measured value of the first-order autocorrelation function and the calculated value of the first-order autocorrelation function from equation (3) is determined. This difference between the measured value of the first-order autocorrelation function and the calculated value of the first-order autocorrelation function from equation (3) is called the difference in the first-order autocorrelation function. The difference in the first-order autocorrelation function is obtained for each scattering angle.

[0089] Total scattering intensity I total This has been measured for each scattering angle, as shown in Figure 23. In equation (4), the total scattering intensity I of equation (4) is based on the set initial number of particles. total Find the value of this. The total scattering intensity I measured for each scattering angle, as shown in Figure 23. total The value of and the total scattering intensity I in equation (4) total The difference between this value and the calculated value is calculated. Note that the measured total scattering intensity I at any scattering angle is calculated. total The value of and the total scattering intensity I in equation (4) total The difference from the calculated value is the total scattering intensity I at the scattering angle. total This is called the difference in total scattering intensity I total Regarding the total scattering intensity I at the scattering angle, total The difference is obtained. Total scattering intensity I in equation (4) total The calculated value corresponds to the time-averaged data obtained by averaging the derived time fluctuation data over time.

[0090] In the fitting process, the difference between the first-order autocorrelation functions obtained for each scattering angle and the difference in total scattering intensity at each scattering angle are used to determine the final particle number. For example, an evaluation value is obtained by summing the square of the difference between the first-order autocorrelation functions obtained for each scattering angle and the square of the difference in total scattering intensity at each scattering angle for all scattering angles. The particle number that minimizes this evaluation value is taken as the final particle number. Therefore, in the fitting process, the number of particles is repeatedly updated in equations (3) and (4) to minimize the evaluation value, and the final number of particles is obtained. This corresponds to step S16 described above. After setting initial values ​​for the number of particles for all particle sizes, the evaluation value is updated to minimize it. For example, a histogram of a single particle shown in Figure 24 and a histogram of aggregated particles shown in Figure 25 can be obtained. That is, N d single , N d floc For all d=d0~d M By determining this, the particle size distribution can be obtained. This corresponds to step S18 described above. The above steps describe the process for determining the particle size distribution for each of several types of particle species. Note that the evaluation values ​​used for fitting are not limited to those described above.

[0091] As described above, the two theoretical equations, equations (3) and (4), are used in relation to the experimentally measured first-order autocorrelation function and the experimentally measured total scattering intensity I total The final number of particles is determined by fitting the model to the model. However, the optimization method for the fitting is not limited to the one described above; for example, Bayesian optimization can be used for fitting. As mentioned above, a first-order autocorrelation function was used to determine the number of particles, but this is not the only option; a power spectrum can also be used instead. Furthermore, as described above, by fitting the autocorrelation function or power spectrum of scattering intensity and the scattering intensity for each scattering angle to a theoretical formula, the number of particles and particle size distribution for single particles and aggregates can be obtained. In addition, if the dispersion contains impurity components, the impurity components and the particle size distribution for each particle type can be obtained, thus separating the effect of the impurity components. Note that, in addition to theoretical formulas, time fluctuation data derived from the scattering characteristics of known particles and time-averaged data obtained by time averaging the derived time fluctuation data can also be used for fitting.

[0092] <Third example of an optical measurement method> A third example of the optical measurement method utilizes polarization. In the optical measurement device 10, the light intensity of the polarization component of the scattered light of the dispersion obtained by irradiating the dispersion with incident light of a specific polarization may be measured as the scattering intensity. For example, circularly polarized laser light is irradiated onto the dispersion Lq of sample cell 18 as incident light, and the polarization component of the scattered light of the dispersion Lq is measured. For example, the light intensity of the polarization component of the scattered light is measured as the difference between the light intensity of vertically linearly polarized light and the light intensity of horizontally linearly polarized light. In this case, as in the first example of the dynamic light scattering measurement method described above, by changing the scattering angle during measurement, a graph showing the relationship between scattering intensity and scattering angle, as shown in Figure 26, can be obtained. Furthermore, perpendicular linear polarization refers to the direction of linear polarization being perpendicular when the scattering surface is considered horizontal. Horizontal linear polarization refers to the direction of linear polarization being horizontal when the scattering surface is considered horizontal.

[0093] Figure 26 is a graph showing the relationship between scattering intensity and scattering angle for each particle shape. Figure 26 shows the relationship between scattering intensity and scattering angle for spherical particles shown in Figure 27 and disc-shaped particles shown in Figure 28. As shown in Figure 26, the scattering intensity profile 52 for spherical particles and the scattering intensity profile 53 for disc-shaped particles are different. Thus, the change in scattering intensity with respect to the scattering angle differs depending on the particle shape. In other words, for each of several types of particles, the scattering intensity profile obtained by changing the scattering angle will be different. By measuring the polarization component of the scattered light using a laser beam polarized as the incident light, the differences in particle shapes can be determined from the differences in scattering intensity profiles.

[0094] Furthermore, a third example of the optical measurement method uses polarized laser light as the incident light, measures the polarization component of the scattered light, and calculates the particle size in the same manner as the first example of the optical measurement method described above. In addition, the particle size distribution for each of the multiple types of particles can be determined in a dispersion containing multiple types of particles. Furthermore, if the types of particles in the dispersion can be determined, the particle size distribution of each particle in the dispersion can be calculated. As described above, by incidenting polarized light as incident light into a dispersion, detecting the light intensity of the polarization component of the scattered light as the scattering intensity, and combining this with at least one of the scattering angle and wavelength described above, it is possible to determine the particle size distribution for multiple types of particles, even for particles with different shapes. Furthermore, if the dispersion contains impurity components, the effect of the impurity components can be separated, and the particle size distribution for multiple types of particles can be determined. For fitting, in addition to theoretical formulas, time fluctuation data derived from the scattering characteristics of known particles and time-averaged data obtained by time averaging the derived time fluctuation data can also be used. Furthermore, by using polarization and utilizing the difference in scattering intensity with respect to the scattering angle as shown in Figure 26, the calculation unit 16 can determine the type of particles in the dispersion, for example, their shape. The particle size distribution of the determined particles can also be calculated. For this reason, it is preferable to acquire data representing the relationship between polarization and particle shape in advance as information regarding the particle shape and store it in the storage unit 17.

[0095] As described above, when polarization is used, for example, when multiple wavelengths are used, equations (1) and (2) above can be used. Furthermore, when polarization is used as described above, for example, when multiple scattering angles are used, equations (3) and (4) above can be used. Furthermore, the first example of the optical measurement method described above and the second example of the optical measurement method may be combined. That is, the particle size distribution for multiple types of particles can be determined using the multiple wavelengths and multiple scattering angles described above. In this case as well, if the dispersion contains impurity components, the impurity components and the particle size distribution for each particle type can be obtained, thus separating the effect of the impurity components.

[0096] Furthermore, in the context of multiple types of particles, "multiple types" refers to the aggregate structure, particle material, and particle shape, etc. These multiple types of particles include the single particles, aggregates formed by the aggregation of particles, spherical particles, disc-shaped particles, etc.

[0097] (Second example of an optical measuring device) Figure 29 is a schematic diagram showing a second example of an optical measuring device according to an embodiment of the present invention. Figures 30 to 32 are schematic diagrams showing first to third examples of masks for the second example of an optical measuring device according to an embodiment of the present invention. In Figures 29 to 32, components identical to those in the optical measuring device 10 shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted. The optical measuring device 10a shown in Figure 29 differs from the optical measuring device 10 shown in Figure 1 in the arrangement of optical elements such as beam splitters. Furthermore, the optical measuring device 10a has a different configuration from the detection unit 14 of the optical measuring device 10 shown in Figure 1, and includes a detection unit 14c that detects the scattering intensity of backscattered light for each scattering angle, and a detection unit 14d that detects the scattering intensity of forward-scattered light for each scattering angle.

[0098] The optical measuring device 10a includes a beam splitter 60, a beam splitter 62, and a beam splitter 63. Beam splitters 60, 62, and 63 are all cube-shaped beam splitters and have transmissive reflective surfaces 60e, 62e, and 63e that split the incident light into two or combine two incident lights. The angle of the transmissive reflective surfaces 60e, 62e, and 63e is 45°. Beam splitter 63 is larger than beam splitter 60 and beam splitter 62.

[0099] Beam splitters 60, 62, and 63 are arranged side by side. The surface 60b of beam splitter 60 and the surface 62a of beam splitter 62 are facing each other, and the surface 62b of beam splitter 62 and the surface 63a of beam splitter 63 are facing each other. The transmissive reflective surface 60e of beam splitter 60 and the transmissive reflective surface 60e of beam splitter 62 are oriented in different directions and are antiparallel. The transmissive reflective surface 63e of beam splitter 63 is oriented in a different direction from the transmissive reflective surface 60e of beam splitter 60 and is nonparallel, specifically antiparallel.

[0100] A light source unit 20 is positioned opposite the beam splitter 62 of the beam splitter 60, facing the surface 60a of the beam splitter 60. A spectral adjustment unit 27 is positioned between the beam splitter 60 and the light source unit 20. A sample cell 18 is positioned on the opposite side of the beam splitter 63 from the beam splitter 62, facing the surface 63b of the beam splitter 63. An objective lens 65a is positioned between the beam splitter 63 and the sample cell 18. A beam splitter 64 is positioned on the opposite side of the beam splitter 63 of the sample cell 18. The orientation of the transmission / reflection surface 64e of the beam splitter 64 is the same as and parallel to the orientation of the transmission / reflection surface 63e of the beam splitter 63. An objective lens 65b is positioned between the sample cell 18 and the beam splitter 64.

[0101] A mirror 61 is positioned on the optical axis C1 of the light split by the beam splitter 60. A beam expander 66 is positioned on the optical axis C2 of the light reflected by the mirror 61. The beam expander 66 emits the incident light as collimated light with a larger diameter than when it was incident. A beam splitter 67 is positioned adjacent to the beam expander 66, with its surface 67a facing the beam expander 66. The beam splitter 67 has a transmissive reflective surface 67e that combines two incident beams of light. The orientation of the transmission / reflection surface 67e of the beam splitter 67 is the same as the orientation of the transmission / reflection surface 60e of the beam splitter 60, and they are parallel. A mask 68 is provided adjacent to the emission surface 67b of the beam splitter 67. On the opposite side of the beam splitter 67 of the mask 68, the objective lens 69 is positioned with the mask 68 in between. A first photodetector 71 is positioned, which has an optical fiber 70 into which light focused by an objective lens 69 is incident. The first photodetector 71 detects the backscattered light from the scattered light of the sample cell 18 and detects the intensity of the interference light between the backscattered light and the reference light for each scattering angle.

[0102] A mirror 72 is positioned on the optical axis C3 of the light split by the beam splitter 62. A beam expander 73 is positioned on the optical axis C4 of the light reflected by the mirror 72. The beam expander 73 emits the incident light as collimated light with a larger diameter than when it was incident. A beam splitter 74 is positioned adjacent to the beam expander 73, with its surface 74a facing the beam expander 73. The beam splitter 74 has a transmissive reflective surface 74e that combines two incident beams of light. The orientation of the transmission / reflection surface 74e of the beam splitter 74 is the same as the orientation of the transmission / reflection surface 60e of the beam splitter 60, and is parallel to it. Here, beam splitters 64, 67, and 74 are all cube-shaped beam splitters and have transmissive reflective surfaces 64e, 67e, and 74e that split the incident light into two or combine two incident light beams. The angle of the transmissive reflective surfaces 64e, 67e, and 74e is 45°.

[0103] A mask 68 is provided adjacent to the emission surface 74b of the beam splitter 74. On the opposite side of the beam splitter 74 of the mask 68, the objective lens 69 is positioned with the mask 68 in between. A second photodetector 76 is positioned, which has an optical fiber 75 into which light focused by an objective lens 69 is incident. The second photodetector 76 detects the forward scattered light from the scattered light of the sample cell 18 and detects the intensity of the interference light between the forward scattered light and the reference light for each scattering angle.

[0104] The mask 68 transmits light emitted from specific positions among the light emitted from the emission surfaces 67b and 74b of the beam splitters 67 and 74. This means that it transmits light with a specific scattering angle. The mask 68 has openings corresponding to the scattering angle. For example, the mask 68 shown in Figures 30 and 31 has ring-shaped openings 68a and 68b. The mask 68 shown in Figure 32 has a circular opening 68c in the central part. The mask 68 shown in Figure 32 transmits light with a scattering angle of 0° or 180°. Furthermore, the mask 68 is switchable, and any of the masks 68 shown in Figures 30 to 32 can be used. With the mask 68, only a specific scattering angle component of the scattered light passes through and is detected by the first photodetector 71, and a spectral distribution is obtained for each scattering angle. As a result, the signal of the interfered scattered light is detected for each scattering angle. Alternatively, a mask switching unit (not shown) equipped with multiple masks 68 may be provided, and the masks 68 positioned between the beam splitters 67, 74 and the objective lens 69 may be switched by the mask switching unit to a mask 68 corresponding to the scattering angle. The beam expanders 66 and 73 are not particularly limited in their configuration, and known ones can be used as appropriate, as long as they can emit collimated light with a larger diameter than when incident. Furthermore, the position in which the beam expanders 66 and 73 are installed is not particularly limited to the position shown in the figure, and they may be placed immediately after the light source 20.

[0105] In the optical measuring device 10a, light emitted from the light source unit 20 toward the sample cell 18 is split into two by the transmission and reflection surface 60e of the beam splitter 60. One of the split beams passes through beam splitter 62 and beam splitter 63, is focused by the objective lens 65a, and enters the sample cell 18 as incident light Ls. In the sample cell 18, scattered light is generated, consisting of forward scattered light and back scattered light. The backscattered light passes through the objective lens 65a, through the surface 63b of the beam splitter 63, is reflected by the transmission reflective surface 63e, and enters the beam splitter 67. Further reflection occurs at the transmission reflective surface 67e of the beam splitter 67, and light at a specific scattering angle passes through the mask 68, is focused by the objective lens 69, and enters the optical fiber 70. Depending on the scattering angle of the dispersion, the reflection positions of the backscattered light differ on the transmission and reflection surface 63e of the beam splitter 63 and the transmission and reflection surface 67e of the beam splitter 67.

[0106] Meanwhile, the other beam of light, which is split into two by the transmissive reflective surface 60e of the beam splitter 60, is the reference beam. It is reflected by the mirror 61, and then collimated into a larger diameter beam by the beam expander 66 before being emitted to the beam splitter 67, where it passes through the transmissive reflective surface 67e of the beam splitter 67. The other beam of light, which is split by the beam splitter 60, passes through the aperture 68a of the mask 68 (see Figure 30), is focused by the objective lens 69, and is incident on the optical fiber 70. In this way, the backscattered light and the reference light, which is the other light split into two by the transmission / reflection surface 60e of the beam splitter 60, are incident on the beam splitter 67, interfere with each other, and are detected by the first photodetector 71 via the optical fiber 70. This provides data on the scattering intensity of the interference light at a specific scattering angle of the backscattered light. By changing the mask 68, data on the intensity of the interference light at various scattering angles of the backscattered light can be obtained, and multiple data on the intensity of the interference light at a specific scattering angle can be extracted for the backscattered light. In this way, the scattering intensity of the backscattered light can be easily measured at different scattering angles. The detection unit 14c is composed of a mask 68, an objective lens 69, an optical fiber 70, and a first photodetector 71.

[0107] Furthermore, the forward scattered light passes through the objective lens 65b, through the surface 64a of the beam splitter 64, is reflected by the transmission reflective surface 64e, and enters the beam splitter 74. After being reflected again by the transmission reflective surface 74e of the beam splitter 74, light of a specific scattering intensity passes through the mask 68, is focused by the objective lens 69, and enters the optical fiber 75. Depending on the scattering angle of the dispersion, the reflection positions of the forward scattered light differ on the transmission and reflection surface 64e of the beam splitter 64 and the transmission and reflection surface 74e of the beam splitter 74.

[0108] Meanwhile, the light split by the transmission-reflecting surface 62e of the beam splitter 62 is the reference light, which is reflected by the mirror 72, converted into a collimated light with a larger diameter by the beam expander 73, and emitted to the beam splitter 74, passing through the transmission-reflecting surface 74e of the beam splitter 74. The light split by the beam splitter 62 passes through the aperture 68a of the mask 68 (see Figure 30), is focused by the objective lens 69, and is incident on the optical fiber 75. In this way, the forward scattered light and the reference light, which is the light split by the transmission / reflection surface 60e of the beam splitter 62, are incident on the beam splitter 74, interfere with each other, and are detected by the second photodetector 76 via the optical fiber 75. This provides data on the intensity of the interference light at a specific scattering angle of the forward scattered light. By changing the mask 68, data on the intensity of the interference light at various scattering angles of the forward scattered light can be obtained, and multiple data points for the intensity of the interference light at a specific scattering angle can be extracted for the forward scattered light. In this way, the scattering intensity of the forward scattered light can be easily measured at different scattering angles. The detection unit 14d is composed of a mask 68, an objective lens 69, an optical fiber 75, and a second photodetector 76.

[0109] Although the beam splitters 60, 62, 63, 64, 67, and 74 mentioned above are all cube-shaped beam splitters, the form of the beam splitter is not limited to a cube shape; it may also be a flat plate shape. The first photodetector 71 and the second photodetector 76 are not particularly limited as long as they can detect light, and for example, photoelectric conversion elements or photomultiplier tubes can be used. The photoelectric conversion element is, for example, a photodiode. The first photodetector 71 and the second photodetector 76 may be single-pixel photodetectors or spectrometers. When the first photodetector 71 and the second photodetector 76 are spectrometers, an interference spectrum is obtained.

[0110] Using the scattering intensity data for each scattering angle of forward-scattered light, or the scattering intensity data for each scattering angle of back-scattered light, the particle size of the particles contained in the dispersion can be obtained as described above, and the particle size distribution for each type of particle contained in the dispersion can also be obtained.

[0111] In the optical measuring device 10a, the reference light may be blocked to prevent interference with scattered light. In this case, normal dynamic light scattering measurements can be performed by blocking the reference light. One method of blocking the reference light is to provide a movable light-shielding plate on the optical axis C1 or optical axis C2 to prevent the reference light from reaching the beam expander 66. Another method involves, for example, providing a light-shielding plate that can move forward or backward on the optical axis C3 or optical axis C4 to prevent the reference light from reaching the beam expander 73. Furthermore, as long as light can be blocked, the solution is not limited to a retractable light-blocking plate; for example, a light shutter using a liquid crystal shutter can be used. With the above configuration, the optical measurement device 10a can also be used as a dynamic light scattering device for conventional homodyne detection.

[0112] (Third example of an optical measuring device) Figure 33 is a schematic diagram showing a third example of an optical measuring device according to an embodiment of the present invention. In Figure 33, components identical to those in the optical measuring device 10 shown in Figure 1 are given the same reference numerals, and their detailed descriptions are omitted. The optical measuring device 10b shown in Figure 33 differs from the optical measuring device 10 shown in Figure 1 in that it propagates light emitted from the light source 20 through the optical fiber 80. It also has multiple photodetectors 85-88. Each of the multiple photodetectors 85-88 detects light at different scattering angles. The photodetectors 85-88 are not particularly limited as long as they can detect light; for example, photoelectric converters or photomultiplier tubes can be used. A photoelectric converter is, for example, a photodiode. Furthermore, the photodetectors 85-88 may also be spectrometers.

[0113] The optical measuring device 10b has a photocoupler 81 into which light emitted from the light source unit 20 is incident. The photocoupler 81, for example, splits the emitted light into two intensity ratios of 1:99. Of the split light, the light with the higher intensity ratio is designated as the incident light Ls, and the light with the lower intensity ratio is designated as the reference light Lr. The optical fiber 80 extending from the photocoupler 81, through which the incident light Ls, which has a high intensity ratio, propagates, is connected to the bundle fiber 82. The bundle fiber 82 is made up of multiple optical fibers (not shown) bundled together.

[0114] A sample cell 18 is positioned opposite the end face 82b of the bundle fiber 82. An objective lens 83 is positioned between the end face 82b of the bundle fiber 82 and the sample cell 18. Scattered light Ld, scattered by the dispersion Lq in the sample cell 18, is incident on the bundle fiber 82. For each scattering angle θ, the scattered light Ld is incident on and propagates through optical fibers (not shown) at different positions among the multiple optical fibers of the bundle fiber 82. Therefore, the position of the optical fibers in the bundle fiber 82 can be associated with the scattering angle. As a result, scattered light Ld with different scattering angles can be obtained for each optical fiber of the bundle fiber 82. Furthermore, each optical fiber in the bundle fiber 82 is connected to the optical fiber 80a at its end face 82a.

[0115] Photocoupler 84 is connected to optical fiber 80 through which the reference light Lr propagates, using the light with a low intensity ratio from the light branched by photocoupler 81. Photocoupler 84 branches the reference light Lr according to the number of photodetectors 85, 86, 87, and 88. Furthermore, optical fibers 80a connected to each optical fiber of bundle fiber 82 are connected to optical fibers 80b, which connects photocoupler 84 to each of the photodetectors 85, 86, 87, and 88, using photocoupler 89. The configuration of the photocouplers 81, 84, and 89 is not particularly limited, and known types can be used as appropriate, as long as they can split the incident light into specific ratios or combine the incident light.

[0116] The incident light Ls emitted from the light source 20 passes through the optical fiber 80, photocoupler 81, and bundle fiber 82, then through the objective lens 83, and irradiates the dispersion Lq in the sample cell 18. Scattered light Ld, scattered by the dispersion Lq in the sample cell 18, is incident on the bundle fiber 82. The scattered light Ld is incident on different optical fibers at different scattering angles, propagates through optical fiber 80a, passes through photocoupler 89, and then propagates to optical fiber 80b. Meanwhile, reference light Lr is propagated through optical fiber 80b. As a result, the reference light Lr and scattered light Ld are propagated and interfere with each photodetector 85, 86, 87, and 88. Data on the scattering intensity of the interference light for each scattering angle can be obtained from each photodetector 85, 86, 87, and 88, and multiple data points for the scattering intensity at a specific scattering angle can be extracted. In this way, the scattering intensity can be easily measured at different scattering angles. If a spectrometer is used with photodetectors 85, 86, 87, and 88, the spectrum of the interference light can be obtained. Using the scattering intensity data for each scattering angle of scattered light, the particle size of the particles contained in the dispersion can be obtained as described above, and the particle size distribution for each type of particle contained in the dispersion can also be obtained.

[0117] In the optical measuring device 10b, the reference light Lr may also be attenuated with an attenuator to prevent interference with the scattered light Ld. In this case, by blocking the reference light Lr, normal dynamic light scattering measurements can be performed. One method for blocking the reference light Lr is to install an attenuator in the optical fiber 80 connecting the photocoupler 81 and the photocoupler 84, thereby preventing the reference light Lr from reaching the photocoupler 84. Furthermore, the device is not limited to an attenuator, as long as it can block or sufficiently reduce the light. Alternatively, the photocoupler 81 may be made to have a variable branching ratio, and light may not be emitted into the optical fiber 80 connecting the photocoupler 81 and the photocoupler 84. With the above configuration, the optical measurement device 10b can also be used as a dynamic light scattering device for conventional homodyne detection.

[0118] The present invention is basically configured as described above. Although the optical measuring device of the present invention has been described in detail above, the present invention is not limited to the embodiments described above, and various improvements or modifications may be made without departing from the spirit of the present invention. [Explanation of symbols]

[0119] 10, 10a, 10b Optical measuring device 12. Low-coherence interferometer 14 Detection unit 14a First detection unit 14b Second detection unit 14c, 14d detection unit 15 Conversion section 16 Arithmetic section 17 Memory section 18 sample cells 20 Light source section 21a, 21b, 21c, 21d, 39 Beam Splitter 21e, 39e, 60e, 62e, 63e, 64e, 67e, 74e Transmissive reflective surface 22 Reflector 22a Reflecting surface 23a Dispersion guarantee adjustment unit 23b, 25 Objective lens 24a, 24b ND filter 26 Polarization adjustment unit 27 Spectral adjustment unit 28 Polarization control unit 33, 34 Photodetector 30, 61, 72 Mirror 32 Diffraction grating 35a Wavelength region 35b Depth of interest region 36, 37 Profile 38 Optical device 39a, 39b Surface 40, 42 Region of interest angle 41, 43 Profile 60, 62, 63, 64, 67, 74 Beam splitter 63b, 64a Surface 65a, 65b, 69, 83 Objective lens 66, 73 Beam expander 67b Exit surface 68 Mask 68a, 68b, 68c Aperture 70, 75, 80, 80a, 80b Optical fiber 71 First photodetector 74b Exit surface 76 Second photodetector 81, 84, 89 Photocoupler 82 Bundle fiber 82a, 82b End face 85, 86, 87, 88 Photodetector C1, C2, C3, C4 Optical axis Lr Reference light Ld Scattered light Lq Dispersion liquid Ls Incident light θb Scattering angle

Claims

1. An optical measuring device having a low coherence interferometer, A first detection unit that detects the interference light intensity for each wavelength by interfering at least a portion of the scattered light obtained by incident light on a dispersion containing particles with a reference light, and A detection unit having at least one of a second detection unit that interferes at least a portion of the scattered light obtained by incident light on the dispersion containing the particles with the reference light, and detects the interference light intensity for each scattering angle, A conversion unit that extracts multiple data points of scattering intensity at a specific depth and specific scattering angle of the dispersion from the interference light intensity data for each wavelength detected by the first detection unit, or from the interference light intensity data for each scattering angle detected by the second detection unit, and converts the extracted scattering intensity data into time fluctuation data of scattered light at the specific depth of the dispersion; A storage unit that stores at least one of the following: scattering angle-dependent data for the scattered light intensity of a known particle and wavelength-dependent data for the scattered light intensity, which are determined by the complex refractive index, particle size, and shape of the known particle. An optical measuring device comprising: a calculation unit that obtains a particle size distribution for each particle type contained in the dispersion by fitting scattering angle-dependent data obtained from time fluctuation data acquired by the conversion unit, or wavelength-dependent data of scattered light obtained from time fluctuation data acquired by the conversion unit, to scattering angle-dependent data or wavelength-dependent data of the scattered light intensity of known particles stored in the storage unit.

2. An optical measuring device having a low coherence interferometer, A first detection unit that detects the interference light intensity for each wavelength by interfering at least a portion of the scattered light obtained by incident light on a dispersion containing particles with a reference light, and A detection unit having at least one of a second detection unit that interferes at least a portion of the scattered light obtained by incident light on the dispersion containing the particles with the reference light, and detects the interference light intensity for each scattering angle, A conversion unit that extracts multiple data points of scattering intensity at a specific depth and specific scattering angle of the dispersion from the interference light intensity data for each wavelength detected by the first detection unit, or from the interference light intensity data for each scattering angle detected by the second detection unit, and converts the extracted scattering intensity data into time fluctuation data of scattered light at the specific depth of the dispersion; A storage unit that stores at least one of the following: scattering angle-dependent data for the scattered light intensity of a known particle and wavelength-dependent data for the scattered light intensity, which are determined by the complex refractive index, particle size, and shape of the known particle. An optical measuring device having a calculation unit that uses scattering angle-dependent data or wavelength-dependent data for the scattered light intensity of known particles stored in the memory unit to determine at least one of the particle type of the particles in the dispersion and the state of the particles in the dispersion.

3. The optical measuring device according to claim 1 or 2, wherein the first detection unit has a photodetector that wavelength-decomposes scattered light that has interfered with the reference light and detects the wavelength-decomposed scattered light for each wavelength.

4. The optical measuring device according to any one of claims 1 to 3, wherein the second detection unit has a photodetector that detects scattered light that has interfered with the reference light at each scattering angle.

5. The system includes a polarization control unit that controls the polarization state of the incident light, The optical measuring device according to any one of claims 1 to 4, wherein the first detection unit or the second detection unit measures the light intensity of the polarization component of the scattered light as the scattering intensity.

6. The optical measuring device according to any one of claims 1 to 5, further comprising a spectral adjustment unit for controlling the central wavelength and wavelength band of the incident light.

7. The optical measuring device according to any one of claims 1 to 6, wherein the time fluctuation data of the scattered light is a power spectrum or an autocorrelation function.

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