JP5841475B2 - Dynamic light scattering measurement method and dynamic light scattering measurement device using low coherence light source - Google Patents

Description

  The present invention relates to a dynamic light scattering measurement method and a dynamic light scattering measurement apparatus using a low coherence light source.

  The dynamic light scattering measurement method is now an established technique, and particle size measuring instruments for fine particles using this method are widely used. Advantages of the dynamic light scattering measurement method include a small number of necessary parameters, non-destructive measurement, and simple handling. However, in the usual dynamic light scattering measurement method, the measurement target needs to be dilute, and as a method of improving this by measuring a concentrated solution, the Mach-Zehnder type that enables particle size measurement in a concentrated solution A dynamic light scattering measurement method using an interferometer, a Michelson interferometer, and a low coherence light source is disclosed (for example, see Patent Documents 1 and 2).

  The dynamic light scattering measurement apparatus disclosed in Patent Document 1 is a dynamic light scattering measurement apparatus having a low coherence light source, in which a Mach-Zehnder interferometer is incorporated, and a microscopic optical system is further introduced. This enables accurate particle size measurement in a dispersion containing fine particles at a high concentration, which is more than measurement using a conventional Michelson interferometer (for example, see Patent Document 2). The sensitivity is improved 1000 times so that even fine particles of about 10 nm dispersed in the liquid can be detected. However, this dynamic light scattering measuring device can only measure 180 ° backscattered light.

  In addition, the light scattering measuring device disclosed in Patent Document 3 performs light scattering measurement using an optical fiber having a variable angle. However, this measuring device can be used with conventional static light scattering or dynamic light scattering, and for use with dynamic light scattering using low coherence light, carefully select the type of light source and the reference light side. Considering the optical path length of the optical fiber, it is necessary to define the optical fiber material and accurately determine the position, which is difficult to handle. In addition, the size of the scattering volume related to the limit of the measurement concentration must be determined by the numerical aperture (NA) of the optical fiber, the distance between the optical fiber ends, and the angle when the optical fibers face each other. . Furthermore, in the method of preventing multiple scattering by adjusting the distance from the scattering position to be detected by adjusting the distance between the optical fibers, it is not clear how much multiple scattered light is contained in the scattered light component, so the upper limit concentration is It is difficult to understand, specifically, it is difficult to obtain data by decomposing by the optical path length.

  The dynamic light scattering method described above is a method for estimating particle size by measuring translational diffusion of particles. In a mixture of particles of different sizes, a plurality of translational diffusions depending on the particle size are detected (see FIG. 8). However, by measuring only a certain fixed scattering angle, these translational diffusions can be accurately separated to obtain a particle size. It is mathematically difficult to seek. In addition, in the polymer solution, motion modes other than translational diffusion such as internal motion mode, rotational diffusion mode, and cooperative diffusion mode due to interaction between constituent materials are detected (see FIG. 9), so only measurement of a fixed scattering angle is possible. Then it is difficult to separate the modes. In particular, in a system with a high concentration to be measured and a complicated system in which a plurality of additives and the like are mixed, it is necessary to perform interpretation and measurement while separating the modes to be observed.

  In response to the above problems, the normal dynamic light scattering method can improve the accuracy of separation of multiple translational diffusions by measuring different scattering angles, and modes other than translational diffusion and translational diffusion. It is known that (internal motion mode, etc.) can be distinguished. Systems that can measure angular dependence are also sold as commercially available devices. Information obtained by these angular decompositions is very useful information for analyzing and analyzing actual dispersion states and motion modes.

JP 2011-13162 A JP-A-2005-121600 WO00 / 31514 specification

  The present invention can distinguish the translational diffusion mode and particle size, and can measure the average particle size and distribution of fine particles with high precision and simple operation even in a dispersion containing fine particles at a high concentration. It is an object of the present invention to provide a dynamic light scattering measurement method and a dynamic light scattering measurement apparatus using a low coherence light source.

The above problem has been solved by the following means.
(1) A dynamic light scattering measurement method for measuring the dynamic characteristics of fine particles dispersed in a dispersion using a Mach-Zehnder interferometer that uses low-coherence light. The Mach-Zehnder interferometer uses a low-coherence light source. The low-coherence light guided from the first optical fiber to the first optical coupler is branched by the first optical coupler, and one of the branched low-coherence lights is passed as a reference light to the second optical coupler through the phase modulator by the second and third optical fibers. led, the other low coherence light branched by the first optical coupler guided by the fourth optical fiber was irradiated from the light irradiation unit during partial dispersion liquid, and the light scattered by fine particles in minute dispersion liquid for each of a plurality of different scattering angles, and scattered light by the fifth optical fiber and received by a light receiving portion disposed at an angle variable with respect to the light irradiation unit guided to the second optical coupler, the reference light in the second optical coupler And scattering Preparative one which binds, dynamic light scattering measuring method and obtaining by selecting the translational diffusion mode from the time correlation function of the scattered light of the scattering angle.
(2) The dynamic light scattering measurement method according to (1), wherein the optical path length decomposition method of the Mach- Zehnder interferometer is a time domain type.
(3) The scattered light intensity of each scattering angle was measured, from the angle dependence Based on double several spreading mode determined for each scattering angle is attributed to parallel proceeds diffusion mode, the particle size distribution measurement and the diffusion movement The dynamic light scattering measurement method according to (1) or (2), wherein measurement is possible.
(4) low and coherence light source, a Mach-Zehnder type and a light receiving portion for receiving the light scattered by the fine particles to the fine particles in the dispersion and the light irradiation unit for irradiating a low-coherence light in the dispersion in the dispersion an interferometer, an angle variable unit for moving the light receiving portion to receive the scattered light at a plurality of different scattering angles, translational diffusion mode dynamic characteristics of the fine particles from the time correlation function of the scattered light for each scattering angle The Mach-Zehnder interferometer includes a first optical coupler that branches low-coherence light guided by a first optical fiber from a low-coherence light source, and a second optical-coupler-to-second optical coupler. A phase modulator that modulates the phase of one of the branched light beams guided by the optical fiber as reference light, a second optical coupler that guides the reference light from the phase modulator by a third optical fiber, and a first light Coupler A fourth optical fiber for guiding the other light branched in step 4 into the dispersion, a light irradiation unit for irradiating the light guided by the fourth optical fiber into the dispersion, and an angle variable unit for the light irradiation unit. A light receiving unit that is installed at a variable angle and receives light scattered by fine particles in the dispersion liquid at a plurality of different scattering angles, and a fifth optical fiber that guides the scattered light received by the light receiving unit to the second optical coupler. preparative has a dynamic light scattering measuring apparatus characterized that you combine the reference light and the scattered light at the second optical coupler.
( 5 ) The dynamic light scattering measurement apparatus according to ( 4 ), wherein the optical path length decomposition method of the Mach- Zehnder interferometer is a time domain type.
( 6 ) Both the light irradiating part and the light receiving part are made of optical fibers, and the angle variable part is a measurement in which the irradiation surface of the first optical fiber of the light irradiating part and the light receiving surface of the second optical fiber of the light receiving part are in dispersion The dynamic light scattering measurement device according to ( 4 ) or ( 5 ), wherein the light irradiating unit and the light receiving unit are relatively rotatable around a point.
( 7 ) The irradiation surface side end portion of the first optical fiber and the light receiving surface side end portion of the second optical fiber have shapes cut off obliquely except for the core of each optical fiber. ( 6 ) The dynamic light scattering measurement device according to ( 6 ).

According to the dynamic light scattering measurement method of the present invention, the scattered light from the dispersion liquid can be obtained by angularly resolving, so that the translational diffusion mode can be separated. Distribution can be measured with high accuracy and simple operation. Furthermore, by combining a Mach-Zehnder interferometer using a low coherence light source, it is possible to measure a dispersion containing fine particles at a high concentration.
According to the dynamic light scattering measurement apparatus of the present invention, since the light irradiating unit and the light receiving unit can be relatively rotated by the angle variable unit, the scattered light from the dispersion liquid can be obtained by angular decomposition. it can. As a result, the translational diffusion mode can be separated, and the average particle size and distribution of the fine particles can be measured with high accuracy and simple operation. Furthermore, by combining a Mach-Zehnder interferometer using a low coherence light source, it is possible to measure a dispersion containing fine particles at a high concentration.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which showed preferable one Embodiment of the dynamic light-scattering measuring apparatus of this invention, (a) is an apparatus block diagram which showed the apparatus schematically, (b) is modeled around the light irradiation part and the light-receiving part. The principal part expanded sectional view shown in figure, (c) is sectional drawing which showed the optical fiber front-end | tip, (d) is the enlarged block diagram which showed the relationship between the end surface of a light irradiation part, the end surface of a light-receiving part, and a scattering position. . It is drawing which showed the angle variable part, (a) is a side view, (b) is a top view. It is the expansion block diagram which showed typically the modification of the light irradiation part and the light-receiving part. It is the graph (image figure) which showed an example of the time correlation function from which the angle of a scattering angle differs. It is a graph (image diagram) plotted with the horizontal axis as the square of the scattering vector q and the vertical axis as the rate constant Γ for multimode analysis. 3 is a graph showing the relationship (mode analysis) between the rate constant Γ of the suspension A measured in Example 1 and the square of the scattering vector q. 6 is a graph showing the relationship (mode analysis) between the rate constant Γ of the suspension B measured in Example 2 and the square of the scattering vector q. It is explanatory drawing which modeled and showed the translational diffusion mode by the difference in a particle size. It is explanatory drawing which modeled and showed the difference of diffusion motions other than translational diffusion motion.

  Hereinafter, preferred embodiments of a light scattering intensity measurement method and a dynamic light scattering measurement apparatus of the present invention will be described in detail with reference to the drawings. As such an embodiment, a dynamic light scattering measurement apparatus using a Mach-Zehnder interferometer will be described. Note that this description is not construed as being limited by the description of this embodiment.

[Embodiment]
As shown in FIG. 1, the dynamic light scattering measurement apparatus 1 according to the present embodiment includes a low coherence light source 2, a Mach-Zehnder interferometer 3, a photodetector 4, a data processing analysis unit 5, and optical fibers F _{1 to} F _6. The signal transmission line 6 is provided.

As the low coherence light source 2, it is preferable to use a super luminescent diode (Super Luminescent Diode). Hereinafter, the super luminescent diode is referred to as SLD. The SLD does not particularly limit the oscillation wavelength, but for example, the oscillation wavelength is preferably 0.125 to 2 μm, and more preferably 0.250 to 1.5 μm. As the coherence length, for example, 0.1 to 100 μm is preferable, and 1 to 50 μm is more preferable.
The low coherence light source 2 Mach-Zehnder interferometer 3 through the optical fiber F ₁ is connected. Therefore, the light emitted from the low coherence light source 2 is transmitted through the optical fiber F ₁ and transmitted to the Mach-Zehnder interferometer 3.

The Mach-Zehnder interferometer 3 irradiates the dispersion liquid (measurement sample) S with low coherence light, obtains scattered light from the dispersion liquid S, and obtains interference light with reference light. The optical system constituting the optical system includes a first optical coupler 31 that branches light, optical fibers F ₂ , F ₃ , F ₄ , and F ₅ as optical transmission paths, and a collimator as a junction of optical paths between optical fibers and space. Meter lenses 32 and 33, a phase modulator 34 for modulating the phase of light, and a second optical coupler 35 for coupling light.
The dispersion (sample) S is obtained by dispersing fine particles S ₂ on the medium S _1.

The first optical coupler 31 branches the light transmitted is emitted from the low coherence light source 2 to the optical fiber F ₁ in two directions. One beam branched by the first optical coupler 31 is transmitted through the optical fiber F _2, F _3, and the other light is transmitted optical fiber F _4, the optical fiber F ₅ Medium. End _{F 4a} is next light irradiation unit 36 of the light irradiation side of the optical fiber _{F 4,} the end portion _{F 5a} of the light-receiving side of the optical fiber _{F 5} becomes a light receiving portion 37.

A collimator lens 32, a phase modulator 34, and a collimator lens 33 are sequentially arranged between the optical fibers F ₂ and F _{3 in the} optical transmission direction, and the phase is modulated by the phase modulator 34 to become reference light.

The optical fiber F ₄ light irradiation side is inserted into the dispersion S, and the optical fiber F ₅ is the light receiving side is inserted into the dispersion S (see Figure 1 (b)). For example, both the optical fiber F ₄ and the optical fiber F ₅ have a core Fc diameter of 5 μm and a cladding Fcl diameter of 125 μm, and a ferrule 9 having a diameter of 2500 μm is formed around each cladding Fcl. One side surface 9a of the tip portion of the ferrule 9 is formed obliquely so as to become thinner toward the end surface direction (see FIG. 1C).

The light receiving surface _{F 5b} of the light irradiation surface _{F 4b} and the optical fiber _{F 5} of the optical fiber _{F 4,} the dispersion liquid measurement points in S (scattering position) optical fiber _{F 4} around the P and the optical fiber _{F 5} and the angle The variable portion 7 (see FIG. 2) is installed so as to be relatively rotatable. For example, the light irradiation unit 36 is fixed, and the light receiving unit 37 is installed with a variable angle. Details of the angle variable unit 7 will be described later.
For example, in the optical fiber F ₄ and the optical fiber F ₅ , the intersection of the normals from the center position of the core end surface of each of the light irradiation surface F _4b and the light receiving surface F _5b is defined as a measurement point (scattering position) P. The distances from P to the light irradiation surface F _4b and the light receiving surface F _5b are always constant (for example, equidistant) (see FIG. 1D). It is assumed that the end face of the exit end of the optical fiber F ₄ and the end face of the entrance end of the optical fiber F ₅ are formed as flat surfaces that are smooth in the direction perpendicular to the length direction of each optical fiber.

Accordingly, the light emitted from the optical fiber F ₄ is irradiated onto the dispersion S as the measurement sample, and the optical fiber F ₅ is arranged so as to receive the scattered light from the dispersion S at predetermined angles. Become. The predetermined angle (hereinafter referred to as scattering angle θ) is the light L ₂ scattered and received by the optical fiber F ₅ with respect to the emission direction of the light L ₁ emitted from the optical fiber F _4. The angle formed. Accordingly, the scattering angle of forward scattering is 0 °, and the scattering angle of back scattering is 180 °. The scattering angle θ may be in a range in which the attribution of diffusion is possible. For example, the scattering angle θ is most preferably 0 ° to 180 °, but 60 ° or more and 140 ° due to restrictions such as the shape of the optical fiber and the core diameter. The following is sufficient. For example, the difference between the upper limit value and the lower limit value of the range of the scattering angle θ may be 80 ° or more, preferably 100 ° or more, more preferably 120 ° or more.

End F _4a of the optical fiber F _4, the end portion F _5a of the optical fiber F _5, the cell 11 so as not taken adsorption effect of the bottom and wall surfaces, and specific convection and walls (see FIG. 2), It is necessary to insert the cell 11 at a necessary distance from the bottom and the wall surface. The end portion _{F 4a} of the optical fiber _{F 4} to the bottom and walls of the cell 11, the end portion _{F 5a} of the optical fiber _{F 5,} to 50μm or more spaced manner, preferably not Hedatara than 200 [mu] m, more preferably , Separated by 1000 μm or more.

The second optical coupler 35 is coupled reference light emitted from the optical fiber F _3, the emitted from the optical fiber F ₅ scattered light.

The said second optical coupler 35 photodetector 4 through the optical fiber F ₆ is connected. The photodetector 4 has a photoelectric conversion function such as a photodiode or a photomultiplier tube, for example, and converts the intensity of light emitted from the second optical coupler 35 and transmitted by the optical fiber F ₆ into an electrical signal. To convert. Therefore, the scattered light intensity due to the interference of the scattered light obtained by the Mach-Zehnder interferometer 3 is detected.
An electrical signal reading unit (not shown) for converting an electrical signal, which is an analog signal, into a digital signal is connected to the photodetector 4 via a signal transmission line 6, and further data processing and analysis are performed by data processing analysis. Part 5 is connected. As the data processing analysis unit 5, for example, a personal computer, a spectrum analyzer, or the like can be used. Data processing and analyzing unit 5 processes the data of the fluctuation of the scattered light obtained by the photodetector 4, and analyzed to separate the translational diffusion mode, to analyze the particle size distribution of the fine particles S ₂ in the dispersion S etc. .

Incidentally, the optical fiber _F 1 _~F 3, _{F 6} may be constituted by space propagation.
Moreover, it is preferable that the said 1st optical coupler 31 can change a branching ratio according to a measuring object. In the middle of the optical path through which one of the divided lights is guided, a phase modulation unit including the collimator lenses 32 and 33 and the phase modulator 34 is configured as described above. As shown in the figure, the phase modulator may emit light into space to perform modulation, or may modulate in an optical fiber. Alternatively, such a phase modulation unit includes a circulator (not shown) and an optical fiber (not shown) provided in the middle of the optical path, and includes a mirror that can vibrate in the light emitting direction at the end of the optical fiber. Thus, it is possible to modulate the light so as to give an arbitrary phase. Furthermore, it is possible to adjust the amount of light by interposing an attenuator between the optical fiber F ₂ and the optical fiber F ₃ if necessary. For each of the above components, the second optical coupler 35, and the photodetector 4, it is possible to adopt commercially available products having necessary specifications. Further, intensity modulation may be used instead of phase modulation.

As shown in FIG. 2, the angle variable unit 7 includes a surface plate 70, a first stage 71 installed on the surface plate 70, a second stage 72, a rotation mechanism 73, and a placement unit 74. On the mounting part 74, the mounting base 75 on which the cell 11 into which the dispersion liquid S is put is placed. A light irradiation unit 36 inserted into the dispersion S in the cell 11 is fixed to the first stage 71. The second stage 72 has a rotation mechanism 73 that is inserted into the dispersion S in the cell 11 and allows the light receiving surface of the light receiving unit 37 to rotate with a predetermined distance from the measurement point (scattering position) P. It is configured. Therefore, the first stage 71 (71x, 71y) is a stage that can be finely and coarsely moved in the xy axis direction. For example, the first stage 71x is movable in the x direction, and the first stage 71y is y. It can move in the direction. The second stage 72 is a stage that can be finely and coarsely moved in the z-axis direction. Of course, both the first and second stages 71 and 72 may be capable of coarse movement and fine movement in the three-dimensional direction (xyz axis direction). In addition, the above-described placement unit 74 may be configured to be able to move up and down.
The light irradiation unit 36 may be rotatable and the light receiving unit 37 may be fixed, or both may be configured to be rotatable. That is, in the dispersion liquid S, the angle variable unit 7 includes the end surface (light irradiation surface) F _4b of the optical fiber F ₄ of the light irradiation unit 36 and the end surface (light reception surface) F _5b of the optical fiber F ₅ of the light receiving unit 37. What is necessary is just to make the light irradiation unit 36 and the light receiving unit 37 relatively rotatable around the measurement point P (see FIG. 1).

Further, as shown in FIG. 3, the light L ₁ irradiated from the light irradiation unit 36 and the light L ₂ of scattered light at each scattering angle received by the light receiving unit 37 are included in the same surface in the dispersion S. The end F _4a of the light irradiation unit 36 and the end F _5a of the light receiving unit 37 may be arranged.

Next, the optical paths of reference light and scattered light (measurement light) in this embodiment will be described.
<Reference light>
The light emitted from the low-coherence light source 2 propagates through the optical fiber F ₁ , enters the first optical coupler 31, and is split into two lights by the first optical coupler 31. One light split by the first optical coupler 31 passes through the optical fiber F ₂ , is collimated by the collimator lens 32, passes through the phase modulator 34, and is incident on the optical fiber F ₃ by the collimator lens 33. The second optical coupler 35 is reached. This light is the reference light in this embodiment. From the first optical coupler 31 to the second optical coupler 35, the reference light has an optical path length d _ref that is fixed to a predetermined value.

<Scattered light>
On the other hand, the other light split by the first optical coupler 31 passes through the optical fiber F ₄ and enters the dispersion liquid S from the end face F _{4 b} as incident light L ₁ . Scattered light generated as a result is incident on the end face F _5b of the optical fiber F ₅ like the illustrated scattered light L ₂ and reaches the second optical coupler 35 through the optical fiber F ₅ . This light is the scattered light in this embodiment. The optical path length d ₁ from the first optical coupler 31 to the location where scattering occurs in the dispersion S and the optical path length d ₂ from the location where scattering occurs in the dispersion S to the second optical coupler 35 From the first optical coupler 31 to the second optical coupler 35, the scattered light has an optical path length d _sca = d ₁ + d ₂ . Accordingly, the optical path length d _sca includes the distances from the end face F _4b to the scattering position P and from the scattering position P to the end face F _5b . Moreover, the behavior of the fine particles S ₂ to freely Brownian motion, the intensity of the scattered light has a temporal fluctuation fluctuations.

Thus, the scattered light from the phase modulator 34 phase modulation is adjusted by also taking into account, particulate S ₂ at a position having a certain optical path length d _sca corresponding to the optical path length d _ref of the reference light, the optical detector 4 It can be measured as the light intensity. Since the measured light intensity has fluctuations with time as described above, the translational diffusion coefficient indicating the Brownian velocity and the particle size distribution of the fine particles can be obtained by obtaining the autocorrelation function. Therefore, once the distance between the collimator lenses 32 and 33 is moved to adjust the optical path length d _ref of the reference light, even if the cell 11 containing the dispersion S to be measured is replaced, the optical fiber F ₄ Since the end face F _4b and the end face F _5b of the optical fiber F ₅ are in contact with the dispersion liquid S, it is possible to similarly measure the fine particles S _{2 at} the same position having the same optical path length d _sca with high accuracy.

The reference light and scattered light incident on the second optical coupler 35 pass through the optical fiber F ₆ and enter the light detection unit 4, and this electrical conversion signal passes through the signal transmission line 6 and passes through the electrical signal reading unit ( A power spectrum of the interference intensity of light is output on the data processing analysis unit 5 via (not shown). This spectrum is called “heterodyne spectrum”. On the other hand, a power spectrum obtained by blocking the optical path of the reference light and detecting the intensity of only the scattered light is called “homodyne spectrum”. JP, 2005-121600, A can be referred to for details, such as a coherence function of a low-coherence light source concerning these series of measurements and calculations, a power spectrum of interference light intensity, and a scattered light spectrum.

<Data processing and analysis methods>
The fine particles S ₂ in the dispersion S is irradiated with light emitted from the low coherence light source, the scattered light by changing the θ scattering angle of the scattered light with respect to the irradiation direction detecting photons of the scattered light. At this time, the scattered light interferes, and the particles are moved by Brownian motion, so that the intensity due to the interference of the scattered light also fluctuates. This fluctuation is measured to obtain an autocorrelation function.
Specifically, first, a temporal change in the interference light intensity is detected (interference light intensity-time relationship).
Subsequently, corresponding to each scattering angle θ, the temporal change of the detected interference light intensity is Fourier transformed to obtain a power spectrum (relationship between power and frequency).
Further, only the vicinity of the modulation frequency is extracted with the peak value of the power spectrum as the origin, and is subjected to Fourier transform to obtain a time correlation function (see FIG. 4). An exponential function is superimposed on the obtained time correlation function to obtain a matching exponential function G = Aexp (−Γτ). Here, Γ is a rate constant, and τ is time.
Furthermore, the diffusion coefficient (translational diffusion coefficient) for each scattering angle θ is obtained from the relationship between the rate constant Γ and the scattering vector q for each scattering angle θ: Γ = q ² D (D is a diffusion coefficient). Here, q is q = (4πn / λ) sin (θ / 2), θ is the scattering angle, n is the refractive index of the solvent, and λ is the wavelength of the irradiation light. At this time, when fine particles having different particle diameters are present in the dispersion S, different translational diffusion coefficients D corresponding to the fine particle diameters are obtained.
Further, the diameter d of the fine particles is obtained from the Stokes-Einstein equation: D = k _B T / 3πηd. Here, k _B is the Boltzmann constant, T is the absolute temperature of the dispersion, η is the viscosity of the solvent, and d is the particle size.

  As described above, the translational diffusion coefficient D is the coefficient of the linear function when the square value of the rate constant and the scattering vector is approximated by a linear function (see FIG. 5). When the relationship between the rate constant and the square value of the scattering vector is a curve (see FIG. 5), a diffusion mode other than translational diffusion (for example, rotational diffusion mode, internal motion mode, joint diffusion mode, etc.) is set.

  The optical path length resolution method in the Mach-Zehnder interferometer 3 is a time domain type. The optical path length decomposition of the light scattered light is a function of detecting light scattered by a specific optical path length from the scattered light generated by the sample. More specifically, single scattered light is a function for distinguishing between a region having a short main optical path length and multiple scattered light being a region having a long main optical path length. In addition, it is a function capable of distinguishing between the scattered light generated in the vicinity of the interface between the cell and the dispersion liquid, or the fiber end face and the dispersion liquid, and the scattered light generated in the deep part away from the interface. By adopting the time domain type in the optical path length decomposition method as described above, a spectroscope and an imaging element are not required, and the time resolution is excellent. On the other hand, the Fourier domain type is expensive because a spectroscope and an imaging element (including a line type detector) are required, and the time resolution is not excellent.

  Embodiments of the dynamic light scattering measurement apparatus 1 and the dynamic light scattering measurement method of the present invention are not limited to the above embodiments. For example, in addition to the interferometer using an optical fiber, a space propagation type interferometer can be used. Various other changes can be made.

Further, according to a preferred embodiment of the present invention, the following becomes possible.
Dynamic light scattering measurement apparatus 1 described above is preferably applied to the measurement of high concentration and dispersion S containing fine particles S ₂ of nanometer order. According to the dynamic light scattering measurement apparatus 1, fine particles having a particle size of less than 100 nm are contained (actually, 10 nm or more), and the particle size can be easily measured with extremely high accuracy in a dispersion having a high concentration of fine particles. In a polydispersed dispersion containing fine particles having a particle size of less than 100 nm and particles having a particle size of 100 nm or more, and measurement and calculation of a wide particle size, or their scattering coefficient, and Translational diffusion coefficient can be calculated. Note The polydispersity state, typically, microparticles S ₂ with different particle sizes are present in the dispersion S together refers to a state indicating the two or more peaks in its particle size distribution. However, a broad particle size distribution may exist in a wide particle size range, and this may be included in polydispersion.

  Further, when such adjustment is not performed by adjusting the branching ratio of the first optical coupler 31 in the Mach-Zehnder interferometer 3 in order to adjust the reference light intensity and the scattered light intensity to an appropriate intensity ratio. On the other hand, the sensitivity improvement of about 10 to 100 times or more can be achieved.

  Furthermore, in a dispersion containing a pigment such as a color filter or an ink jet ink, under conditions containing fine particles at a high concentration (the concentration is not particularly limited, for example, 0.0001 to 50% by mass, preferably 0.001 to 50% by mass, more preferably 0.01 to 30% by mass), and the state of aggregation can be quantified, and further, quality control and process control using it can be performed. In addition, inorganic particles and organic particles are not subject to measurement. Magnetic particles used in recording media and various particles used in medical / biological (biotechnology) fields, etc. It can be applied to light scattering analysis that can be developed for behavioral evaluation under conditions of concentration. Furthermore, the present invention is not limited to fine particles, and can be applied to analysis of gel structures and polymer structures in solutions that cause multiple scattering and differences between places.

The dynamic light scattering measurement method of the present invention for measuring the dynamic characteristics of the fine particles S ₂ dispersed in the dispersion S using the dynamic light scattering measurement apparatus 1 as described above is the same as that in the dispersion S. a light irradiation unit 36 for irradiating light to S _2, the scattered light of the scattering angle and characterized by measuring at a condensing section 37 for condensing light, more conveniently, and make a measurement with high accuracy Is possible. Note that the dynamic characteristics of the fine particles S _2, a characteristic that is specified by the Brownian motion in the dispersion S of particulate S _2, including the particle size and its distribution, and the like.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited thereto.

[Production of optical system]
An optical system was fabricated based on the apparatus configuration diagram shown in FIG. Then, the dispersion S as a sample was put in the cell 11 and measured.

[Preparation of polystyrene suspension (dispersion)]
A commercially available polystyrene suspension was purchased and the particle size was evaluated with a transmission electron microscope. The polystyrene particles contained in the suspension A had an average particle size of 99 nm, and the suspension B was prepared by mixing samples having an average particle size of 99 nm and 755 nm at a mass ratio of 25: 1. The concentration of polystyrene particles was 10% by mass.

(Example)
Using the dynamic light scattering measuring apparatus (apparatus having the configuration of FIG. 1), the polystyrene suspension A (Example 1) and the polystyrene suspension B (Example 2) are respectively subjected to the following measurement procedures. Thus, the particle size of the particles was measured. The distance between the fiber end face F _4b and the measurement point P + the distance between the fiber end face F _5b and the measurement point P is set to about 100 μm, and the optical path length of the scattered light or the reference light so that d = d _sca The power spectrum was measured. Thereafter, the time correlation function was determined by the method described above, the translational diffusion coefficient was determined, and the particle size distribution was analyzed.

The measurement result of the polystyrene suspension A of Example 1 is shown in FIG. 6, and the measurement result of the polystyrene suspension B is shown in FIG. As a result, as shown in FIG. 6, from the relationship between the rate constant Γ and the scattering vector q depending on each scattering angle θ: Γ = q ² D, it is analyzed that it is translational diffusion, and from the translational diffusion coefficient D, Stokes Einstein The particle diameter was determined to be 100 nm by the formula of In the case of 180 °, the backscattered light was measured using a dynamic light scattering measurement apparatus equipped with a Mach-Zehnder interferometer disclosed in Japanese Patent Application Laid-Open No. 2012-032308. Further, as shown in FIG. 7 of Example 2, two approximate lines passing through the origin were obtained from the relationship between the rate constant Γ and the scattering vector q depending on each scattering angle θ: Γ = q ² D. Two types of translational diffusion with a particle size of 99 nm and a particle size of 755 nm were analyzed. Thus, it was found that the particle size can be obtained from the translational diffusion coefficient. In addition, the reliability was improved compared to the measurement using only backscattering.

DESCRIPTION OF SYMBOLS 1 Dynamic light-scattering measuring apparatus 2 Low coherence light source 3 Mach-Zehnder interferometer 4 Photo detector 5 Data processing analysis part 6 Signal transmission line 7 Angle variable part 70 Surface plate 71 First stage 72 Second stage 73 Rotation mechanism 74 portion 75 mounting table 31 first optical coupler 32, 33 the collimator lens 34 phase modulator 35 second optical coupler 36 the light irradiation portion 37 light receiving portion _F 1 to F ₆ optical fibers _{F 4a} light irradiating unit end (optical fiber end Part)
F _4b light irradiation surface (end face of optical fiber)
F _5a light receiving end (optical fiber end)
F _5b light receiving surface (end face of optical fiber)
L ₁ light (irradiation light)
L ₂ light (scattered light)
P Scattering position (measurement point)
S dispersion (sample)
S ₁ medium S ₂ fine particles

Claims (7)

A dynamic light scattering measurement method for measuring dynamic characteristics of fine particles dispersed in a dispersion using a Mach-Zehnder interferometer that uses low-coherence light. The low-coherence light guided by one optical fiber is branched by a first optical coupler, and one of the branched low-coherence lights is guided to a second optical coupler as reference light through a phase modulator by the second and third optical fibers. The other low-coherence light branched by the first optical coupler is guided by a fourth optical fiber to irradiate the dispersion from the light irradiator , and the light scattered by the fine particles in the dispersion for each of a plurality of different scattering angles, and scattered light by the fifth optical fiber is received by the installed light receiving unit in a variable angle led to the second optical coupler to said light irradiating section, before Second in the optical coupler is intended to couple the scattered light and the reference light, a dynamic light scattering measuring method and obtaining by selecting the translational diffusion mode from the time correlation function of the scattered light of each scattering angle .   2. The dynamic light scattering measurement method according to claim 1, wherein the optical path length resolution method of the Mach-Zehnder interferometer is a time domain type.   The scattered light intensity at each scattering angle is measured, and the translational diffusion mode is assigned from the plurality of types of diffusion modes determined based on the angle dependency of each scattering angle, thereby measuring the particle size distribution and measuring the diffusion motion. The dynamic light scattering measurement method according to claim 1, wherein: Mach-Zehnder type interference having a low coherence light source, a light irradiation unit for irradiating fine particles in the dispersion with low coherence light in the dispersion, and a light receiving unit for receiving light scattered by the fine particles in the dispersion An angle variable unit that moves the light receiving unit so as to receive the scattered light at a plurality of different scattering angles, and the dynamic characteristics of the fine particles are translated from the time correlation function of the scattered light for each scattering angle. a data processing and analyzing unit for determining to select a spreading mode,
The Mach-Zehnder interferometer includes a first optical coupler that branches the low-coherence light guided from the low-coherence light source by a first optical fiber, and a branched light that is guided from the first optical coupler by a second optical fiber. A phase modulation unit that modulates the phase of one of the lights to obtain reference light, a second optical coupler that guides the reference light from the phase modulator through a third optical fiber, and the other branched by the first optical coupler A fourth optical fiber for guiding the light into the dispersion, the light irradiating part for irradiating the light guided by the fourth optical fiber into the dispersion, and the angle variable with respect to the light irradiating part. A light receiving portion that is installed at a variable angle by the light receiving portion and receives light scattered by the fine particles in the dispersion liquid at a plurality of different scattering angles; and the second optical coupler that receives the scattered light received by the light receiving portion. 5th leading to And a fiber, a dynamic light scattering measuring apparatus characterized that you couple the scattered light and the reference light in the second optical coupler. 5. The dynamic light scattering measurement apparatus according to claim 4, wherein the optical path length decomposition method of the Mach-Zehnder interferometer is a time domain type. The light irradiating unit and the light receiving unit are both made of an optical fiber, and the angle variable unit includes a dispersion liquid in which an irradiation surface of the first optical fiber of the light irradiation unit and a light receiving surface of the second optical fiber of the light receiving unit are included in the dispersion liquid. 6. The dynamic light scattering measurement apparatus according to claim 4 , wherein the light irradiation unit and the light receiving unit are relatively rotatable around a measurement point inside. The irradiation surface side end portion of the first optical fiber and the light receiving surface side end portion of the second optical fiber have a shape cut off obliquely except for the core of each optical fiber. Item 7. The dynamic light scattering measurement device according to Item 6 .

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