JPWO2018110468A1 - Particle property measuring device - Google Patents

Abstract

Measurement accuracy is ensured while using a measurement cell with a simple structure. A light irradiating unit 20 that irradiates light to the measurement sample X in which a particle group is dispersed in a dispersion medium and a light detecting unit 30 that detects scattered light generated by the irradiation of the light are provided, and based on the temporal change of the scattered light. A particle physical property measuring apparatus 100 for measuring physical properties of particles, a flat measurement cell 10 on which a measurement sample X is placed, a cell holder 20 holding the measurement cell, and a temperature sensor provided in the measurement cell 10 or the cell holder 20 5 and so on.

Description

  The present invention relates to a particle property measuring apparatus for measuring particle properties such as particle size distribution.

  As this kind of particle physical property measuring apparatus, as shown in Patent Document 1, a measurement sample in which a particle group is dispersed in a dispersion medium is accommodated in a cell, and scattered light generated by irradiating the cell with light is detected. Some measure the particle size distribution.

In order to improve the measurement accuracy, this measuring device is provided with a temperature sensor in the cell holder that holds the cell, and calculates the particle size distribution using the viscosity of the dispersion medium with respect to the detected temperature as a calculation parameter.
Note that the viscosity of the dispersion medium with respect to the detected temperature is important in measuring particle physical properties that are related to the movement of particles in the dispersion medium, such as zeta potential and anisotropy. It becomes.

  By the way, in the measuring apparatus of patent document 1, the square thing called a cuvette is used for the cell which accommodates a measuring object, and light is irradiated from the side of this cuvette. In such a configuration, a cuvette with a thin space for accommodating the measurement object is required to allow the light irradiated from the side to strike the measurement object even if the measurement object is a small amount.

  However, such a cuvette has a problem that it is expensive and difficult to clean. In this regard, Patent Document 1 does not consider at all.

Special table 2001-83074 gazette

  Therefore, the present invention has been made in view of such problems, and its main purpose is to make the measurement cell inexpensive and easy to clean while improving the measurement accuracy using the temperature sensor. is there.

  That is, the particle property measuring apparatus according to the present invention includes a light irradiation unit that irradiates light to a measurement sample in which a particle group is dispersed in a dispersion medium, and a light detection unit that detects scattered light generated by the light irradiation. A particle physical property measuring apparatus for measuring the physical properties of particles based on the time change of the scattered light, a flat measurement cell on which the measurement sample is placed, a cell holder holding the measurement cell, and the measurement cell or And a temperature sensor provided in the cell holder.

In the particle physical property measuring apparatus configured as described above, since the temperature sensor is provided in the measurement cell or the cell holder, the viscosity of the dispersion medium can be calculated based on the detected temperature. By calculating the physical properties of the particles, measurement errors due to the difference between the temperature of the dispersion medium and the temperature detected by the temperature sensor can be suppressed, and the measurement accuracy can be improved.
In addition, since the measurement cell has a flat plate shape with a simple structure, the measurement cell can be made cheaper and easier to clean than, for example, a square cell called a cuvette.

  As a specific embodiment for measuring using a temperature sensor, the viscosity of the dispersion medium is calculated using the temperature detected by the temperature sensor, and the physical property value indicating the physical properties of the particles is calculated using the viscosity. An example of the configuration further includes an arithmetic device.

By the way, there are particles whose physical properties change depending on the temperature, and particles whose aggregation state changes when the temperature changes.
Therefore, it is preferable to further include a temperature control mechanism that is provided in the measurement cell or the cell holder and heats or cools the measurement cell.
With such a configuration, it is possible to measure the physical properties of the particles at an arbitrary temperature, and it is possible to observe changes in physical properties due to temperature and changes in aggregation state due to temperature.

The temperature sensor is provided in the measurement cell, a connection terminal to which the temperature sensor is connected is provided in the cell holder, and the cell holder holds the measurement cell, whereby the temperature sensor is It is preferable to be connected to a connection terminal.
If it is such a structure, a measurement cell will be positioned with respect to a cell holder by connecting a temperature sensor to a connection terminal. As a result, if the light from the light irradiator is irradiated to a predetermined position of the measurement cell and the measurement object is placed at that position, the relative positional relationship between the measurement object and the temperature sensor, the measurement object and the light are The relative positional relationship with the irradiated position does not change, and measurement errors (systematic errors) can be suppressed.

The cell holder holds the measurement cell so that light is irradiated from below, the measurement cell has translucency, and the light irradiation unit is provided below the cell holder. It is preferable that the lower surface of the measurement cell is irradiated with light.
In such a configuration, since the light irradiation unit is provided below the cell holder, the work for placing the measurement cell on the cell holder or dropping the measurement sample on the placed cell holder is provided above the cell holder. Space can be secured and workability is good.

  In order to secure a larger working space as described above, the light detection unit is provided below the cell holder, and out of scattered light scattered by the measurement sample, scattered light passing through the lower surface of the measurement cell. It is preferable to detect.

Depending on the arrangement of the light irradiation unit and the light detection unit, the reflected light reflected by the measurement cell in the light emitted from the light irradiation unit may be detected by the light detection unit, and an error may occur in the scattered light intensity to be detected. .
Therefore, in order to ensure measurement accuracy, it is preferable that the light detection unit is provided at a position where the reflected light reflected by the measurement cell among the light emitted from the light irradiation unit is not detected.

  According to the present invention configured as described above, it is possible to make the measurement cell inexpensive and easy to clean while improving the measurement accuracy using the temperature sensor.

The schematic diagram which shows the particle | grain physical property measuring apparatus in one Embodiment of this invention. The schematic diagram which shows the measurement cell in the embodiment. The schematic diagram which shows the particle | grain physical property measuring apparatus in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment. The schematic diagram which shows the measurement cell in other embodiment.

DESCRIPTION OF SYMBOLS 100 ... Particle physical property measuring apparatus X ... Measurement sample 10 ... Measurement cell 20 ... Cell holder 30 ... Light irradiation part 40 ... Photodetection part 5 ... Temperature sensor 51 ... Thermoelectric Pair 6 ... Temperature control mechanism

  An embodiment of a particle property measuring apparatus according to the present invention will be described below with reference to the drawings.

  The particle physical property measuring apparatus 100 according to the present embodiment is a particle diameter distribution measuring apparatus that measures the particle diameter distribution based on, for example, fluctuations in scattered light generated due to the Brownian motion of particles, as shown in FIG. A measurement cell 10 on which a measurement sample X in which a particle group is dispersed in a dispersion medium such as water is placed, a cell holder 20 in which the measurement cell 10 is installed, and a light irradiation unit 30 that irradiates the dropped measurement sample X with light. And a light detection unit 40 that detects scattered light generated thereby, and an arithmetic device C that calculates a particle size distribution based on a temporal change of the scattered light detected by the light detection unit 40.

As shown in FIG. 1, the measurement cell 10 has a flat plate shape, and one to several drops of the measurement sample X are dropped on one face plate portion 11 (hereinafter referred to as the upper surface 11). The flat plate here is not only a complete flat plate but also a concept including a flat plate provided with a concave portion or a convex portion or a curved surface.
Although the location where the measurement sample X is dropped on the upper surface 11 of the measurement cell 10 is not limited, here, as shown in FIG. 2, the central portion of the upper surface 11 is set as a dropping region R where the measurement sample X is dropped as a guide. It is. The dropping region R here is set to a region where the measurement sample X is in contact with the upper surface 11 or slightly larger than that when a predetermined number of drops or a predetermined amount of the measurement sample X is dropped onto the upper surface 11. It is an area. The dropped measurement sample X is held on the upper surface 11 in a state of rising due to surface tension.

  The measurement cell 10 of the present embodiment has translucency, and is irradiated with light on the other face plate portion 12 (hereinafter referred to as the lower surface 12), and transmits the light to the upper surface 11. Specifically, Is a transparent substrate having a rectangular shape in plan view, such as a glass plate. A marker 13 (color, mark, etc.) for identifying the type of measurement sample X to be dropped or identifying the upper surface 11 or the lower surface 12 of the measurement cell 10 is provided at the end of the measurement cell 10 or the like. ing. Here, the end portion of the measurement cell 10 is a grip portion gripped by the user, and the marker 13 is provided on the upper surface 11 side of the grip portion.

As shown in FIG. 2, the cell holder 20 holds the measurement cell 10, and here has a placement surface 21 on which the measurement cell 10 is placed from above. The measurement cell 10 placed on the placement surface 21 is held in a horizontal state.
Specifically, the cell holder 20 is formed with a step portion on which the measurement cell 10 is set. Here, the mounting surface 21 described above and the side surface of the measurement cell 10 mounted on the mounting surface 21 are provided. The step portion is formed by the contacted surface 22 that comes into contact.

  The mounting surface 21 has the same shape as the lower surface 12 of the measurement cell 10 (in this case, a rectangular shape in plan view), and a light passage hole 21h through which light passes is formed at the center. As a result, the entire mounting surface 21 and the entire lower surface 12 of the measurement cell 10 are overlapped, so that the light passage hole 21 h is positioned below the center of the measurement cell 10, that is, below the dropping region R.

  As shown in FIG. 1, the light irradiation unit 30 is disposed below the cell holder 20, and emits light toward the light passage hole 21 h described above, thereby transmitting the light through the measurement cell 10 and measuring the light. The sample X is irradiated. Specifically, the light irradiation unit 30 includes a laser device 31 as a light source and a reflection mirror 32 that reflects the laser light L emitted from the laser device 31 toward the light passage hole 21h. In order to prevent the laser beam L reflected by the lower surface 12 of the laser beam 10 from returning to the laser device 31, the laser beam L is disposed so as to be obliquely applied to the lower surface 12 of the measurement cell 10.

As shown in FIG. 1, the light detection unit 40 is disposed below the cell holder 20 and detects scattered light that has passed through the light passage hole 21 h among scattered light scattered by the measurement sample X. Specifically, the light detection unit 40 includes a lens 41 as a light receiving unit, an optical fiber 42 that transmits scattered light collimated by the lens 41, and a photodetector 43 that detects the scattered light transmitted by the optical fiber 42. With.
The light detection unit 40 of the present embodiment is provided at a position where the laser light L emitted from the light irradiation unit 30 and reflected by the lower surface 12 of the measurement cell 10 is not detected. Specifically, the lens 41 serving as the light receiving unit is provided at a position displaced from the optical path of the reflected light. The lens 41 here is disposed so as to face the lower surface 12 of the measurement cell 10 from obliquely below.

  Here, the photodetector 43 calculates an autocorrelation function based on the temporal change of the detected scattered light, and transmits autocorrelation data indicating the autocorrelation function to the arithmetic unit C described later.

  The arithmetic device C is physically a general purpose or dedicated computer having a CPU, a memory, an input / output interface, etc., and the CPU and peripheral devices cooperate in accordance with a program stored in a predetermined area of the memory. Thus, the autocorrelation data calculated by the photodetector 43 described above is acquired, and the particle size distribution is calculated by performing a predetermined calculation process on the autocorrelation function indicated by the autocorrelation data.

  However, the particle physical property measuring apparatus 100 of the present embodiment includes the temperature sensor 5 provided in the measurement cell 10 as shown in FIGS. 1 and 2.

Examples of the temperature sensor 5 include those using a thermistor or a platinum resistance thermometer, but here, a thermocouple 51 is used, and a temperature measuring contact of the thermocouple 51 is provided in the dropping region R described above. It is provided in the vicinity so that the temperature of the dropping region R can be detected.
Here, the thermocouple 51 is a linear one provided on the upper surface 11 of the measurement cell 10. More specifically, a pair of connection terminals (hereinafter referred to as cell side terminals a1) are provided at the edge of the upper surface 11 of the measurement cell 10, and the thermocouple 51 is directed from each of these cell side terminals a1 toward the dropping region R. Is extended.

In the present embodiment, a pair of connection terminals (hereinafter referred to as holder side terminals b1) to which the thermocouple 51 is connected to the cell holder 20 described above are provided as reference contacts. Specifically, these holder-side terminals b1 are provided on the contacted surface 22 of the cell holder 20 described above, and the cell-side terminal a1 is electrically connected by placing the entire lower surface 12 of the measurement cell 10 on the mounting surface 21. Are arranged to be connected to each other.
Thereby, by mounting the measurement cell 10 on the mounting surface 21 and connecting the cell side terminal a1 and the holder side terminal b1, the dropping region R or the vicinity thereof is based on the potential difference generated between the holder side terminals b1. The temperature can be detected.

  Here, the temperature sensor 5 transmits the detected temperature to the arithmetic device C described above, the arithmetic device C calculates the viscosity of the dispersion medium using the detected temperature, and uses this viscosity and the autocorrelation function described above. A physical property value (in this case, particle size distribution) indicating the physical properties of the particles is calculated.

  The particle physical property measuring apparatus 100 of the present embodiment further includes a temperature control mechanism 6 that heats the measurement cell 10. The temperature adjustment mechanism 6 includes a heating wire heater 61 that is a heating resistor, and a temperature control device 62 that applies a voltage to the heating wire heater 61.

The heating wire heater 61 is a linear thing provided in the upper surface 11 of the measurement cell 10 here. More specifically, a pair of connection terminals (hereinafter referred to as second cell side terminals a2) is provided at the edge of the upper surface 11 of the measurement cell 10, and the dropping region R is surrounded by each of the second cell side terminals a2. Thus, a heating wire heater 61 is provided.
In addition, like the holder side terminal b1 described above, by placing the measurement cell 10 on the placement surface 21 of the cell holder 20, a pair of connection terminals (hereinafter, referred to as the second cell side terminal a2) are electrically connected. The second holder side terminal b <b> 2) is provided on the contacted surface 22.

Physically speaking, the temperature control device 62 is provided with at least an electronic board. In addition, the temperature control device 62 includes a CPU, a memory, and the like, and the CPU and peripheral devices cooperate in accordance with a program stored in a predetermined area of the memory. By operating, the detected temperature detected by the temperature sensor 5 is acquired, and the voltage applied to the heating wire heater 61 is controlled so that the detected temperature becomes a preset target temperature.
Here, the temperature control device 62 is provided in the cell holder 20, but the temperature control device 62 may be provided separately from the cell holder 20, and the function as the temperature control device 62 is provided in the arithmetic device (not shown) described above. May be.

According to the particle physical property measuring apparatus 100 according to the present embodiment configured as described above, since the temperature sensor 5 is provided in the measurement cell 10, the viscosity of the dispersion medium can be calculated based on the detected temperature. By calculating the particle size distribution using this viscosity, the measurement accuracy can be improved.
In addition, since a flat plate having a simple structure is used as the measurement cell 10, the measurement cell 10 is cheaper and easier to clean than a square cell called a cuvette, for example. In particular, the cuvette used when the measurement sample X is a small amount is expensive and very difficult to clean, so the above-described effects are more remarkable as the measurement sample X is a small amount.

  In addition, since the heating cell heater 61 is provided in the measurement cell 10 and the voltage applied to the heating wire heater is controlled by the temperature control device 62, the measurement cell 10 can be adjusted to an arbitrary temperature, depending on the temperature. It is possible to observe changes in physical properties and changes in the aggregation state due to temperature.

Furthermore, the cell-side terminal a1 of the thermocouple 51 is connected to the holder-side terminal b1 by superimposing the lower surface 12 of the measurement cell 10 on the mounting surface 21 of the cell holder 20, and the second cell side of the heating wire heater 61 is connected. Since the terminal a2 is connected to the second holder side terminal b2, the temperature detection and temperature adjustment of the measurement cell 10 can be easily performed.
Further, the measurement cell 10 is positioned with respect to the cell holder 20 by connecting the cell side terminal a1 and the second cell side terminal a2 to the holder side terminal b1 and the second holder side terminal b2. As a result, it is possible to prevent positional deviation between the dropping region R set in the measurement cell 10 and the region irradiated with the laser light L from the light irradiation unit 30, and suppress measurement errors (systematic errors) due to such positional deviation. can do.

  In addition, since the light irradiation unit 30 and the light detection unit 40 are provided below the cell holder 20, the measurement cell 10 is placed on the cell holder 20 above the cell holder 20, or the measurement sample X is placed on the placed cell holder 20. The working space for dripping can be secured, and the workability is good.

  In addition, since the lens 41 serving as the light receiving unit is displaced from the optical path of the reflected light reflected from the lower surface 12 of the measurement cell 10 out of the light emitted from the light irradiation unit 30, the reflected light is detected by the light detection unit 40. Measurement error due to reflected light can be suppressed.

  In addition, since the heating wire heater 61 is provided so as to surround the dropping region R, the entire dropping region R can be heated uniformly.

  In addition, for example, when protein is a measurement target, changes in protein structure such as the aggregation state of the protein can be observed by changing the temperature of the protein by the temperature control mechanism 6.

  In addition, this invention is not limited to the said embodiment.

For example, although the temperature sensor 5 is provided in the measurement cell 10 in the embodiment, the temperature sensor 5 may be provided in the cell holder 20 as shown in FIG. In this case, the temperature sensor 5 is preferably in contact with the measurement cell 10 installed in the cell holder 20, and is provided on the mounting surface 21 here.
The same applies to the heating wire heater 61 constituting the temperature adjustment mechanism 6, and it may be provided in the cell holder 20 as shown in FIG. 3. In this case as well, the heating wire heater 61 is preferably in contact with the measurement cell 10 installed in the cell holder 20, and is provided on the mounting surface 21 here.

The temperature control mechanism 6 of the above embodiment uses the linear heating wire heater 61, but may use a planar heater 63 made of, for example, a metal foil.
In this case, for example, the planar heater 63 may be provided on the side surface of the measurement cell 10 as shown in FIG. 4A, or the upper surface of the measurement cell 10 as shown in FIG. 11 may be provided on the lower surface 12 of the measurement cell 10 although not shown. When provided on the upper surface 11 of the measurement cell 10, it is preferable to make a dropping hole 63 h into which the measurement sample X is dropped in the planar heater 63.

  Furthermore, as shown in FIG. 5, the thermocouple 51 is arranged such that an insertion hole 10 h for inserting the thermocouple 51 is formed on the side surface of the measurement cell 10, and the thermocouple 51 is connected to the insertion hole 10 h. May be inserted into the measuring cell 10. The thermocouple 51 is obtained by providing a foil metal at the tip of a pair of linear metals.

  Moreover, as shown in FIG. 6, the measurement cell 10 may have a recess 14 into which the measurement sample X is dropped. In this case, the measurement cell 10 may include a covering member 15 such as a glass plate that is provided so as to close the recess 14 and prevents the measurement sample X from flowing out.

  Furthermore, as shown in FIG. 7, the measurement cell 10 may be provided on the outer periphery of the measurement cell 10 and may be provided with a flow-off prevention unit 16 that prevents the dropped measurement sample X from flowing down.

  Although the measurement cell 10 of the above embodiment has a rectangular shape in plan view, for example, the shape of the measurement cell 10 such as a circular shape in plan view as shown in FIG. It may be changed as appropriate.

Furthermore, as shown in FIG. 9, the measurement cell 10 may have a plurality of flat substrates 10a, 10b, and 10c stacked in the thickness direction. Specifically, in the measurement cell 10, the measurement sample X is dropped on the upper surface 11a of the first substrate 10a located at the uppermost stage, and the upper surface 11b of the second substrate 10b located at the lower stage of the first substrate 10a. Are provided with a thermocouple 51 and a heating wire heater 61.
With such a configuration, since the thermocouple 51 and the heating wire heater 61 provided on the upper surface 11b of the second substrate 10b are in contact with the lower surface of the first substrate 10a, temperature detection and temperature control of the first substrate 10a are performed. It is possible to prevent the measurement sample X from adhering to the thermocouple 51 and the heating wire heater 61 while performing with high accuracy.

  In addition, the cell holder 20 of the embodiment has the placement surface 21 on which the measurement cell 10 is placed. However, the cell holder 20 may be any one that can hold the measurement cell 10 in a desired position. As shown in FIG. 9, the measuring cell 10 may be provided with a pair of holding members 20a and 20b that hold the measurement cell 10 from the side.

Further, as shown in FIG. 10, the cell holder 20 may have a sandwiching member 23 that sandwiches and holds the measurement cell 10 with the mounting surface 21.
Specifically, the sandwiching member 23 is an elastic member provided so as to press the measurement cell 10 toward the placement surface 21, and here is a second holder made of metal and connected to the heating wire heater 61. Also used as the side connection terminal b2. The sandwiching member 23 may also be used as a first holder side connection terminal to which the thermocouple 51 is connected.

  Although the temperature control mechanism 6 of the said embodiment heated a measurement cell, it may be comprised, for example, provided with the Peltier device provided in the measurement cell, and cooling a measurement cell.

  In the above-described embodiment, the light irradiation unit is arranged below the cell holder. However, the arrangement of the light irradiation unit can be appropriately changed. For example, the light irradiation unit is arranged above the cell holder so that the measurement sample is irradiated with light from above. Alternatively, it may be arranged on the side of the cell holder so that the measurement sample is irradiated with light from the side. In these cases, the measurement cell may not have translucency.

  In the above-described embodiment, the light detection unit is disposed below the cell holder. However, the arrangement of the light detection unit can be changed as appropriate, and may be disposed above or on the side of the cell holder, for example.

In the above-described embodiment, the particle property measuring device is described as a particle size distribution measuring device. However, a device for measuring zeta potential, a device for measuring the number of particles, a device for measuring particle anisotropy, a gel structure (gel It is also possible to use a device for measuring a mesh distance, a device for measuring an interaction between particles, or the like.
In addition, as a particle | grain physical property measuring apparatus in the case of measuring zeta-electron, as shown in FIG. In addition, a pair of electrode 7 may be provided in any of the upper surface 11, the lower surface 12, and the inside of the measurement cell 10, and may be provided in a cell holder (not shown).

The measurement cell described above is also one aspect of the present invention.
That is, a measurement cell according to the present invention includes a light irradiation unit that irradiates light to a measurement sample in which a particle group is dispersed in a dispersion medium, and a light detection unit that detects secondary light generated by the light irradiation. , A measurement cell used in a particle physical property measuring apparatus for measuring physical properties of particles based on the temporal change of the secondary light, and having a flat plate shape on which the measurement sample is mounted and a temperature sensor is provided. It is characterized by.

Devices that measure the physical properties of particles based on temporal changes in secondary light include Raman spectroscopic devices that detect Raman light (visible light) as secondary light, fluorescent spectroscopic devices that detect fluorescence as secondary light, etc. Is mentioned.
In such an apparatus, it is preferable to use a CCD or the like as the photodetector, and to provide a spectroscope, a filter, or the like between the measurement cell and the photodetector.

Further, the particle property measuring apparatus may further include a scanning mechanism for scanning the measurement cell.
With such a configuration, two-dimensional information of the measurement sample can be obtained, and the aggregation state of the particle group can be grasped.

  In addition, the particle physical property measuring apparatus may measure the particle physical property by detecting each of scattered light, Raman light, and fluorescence.

  In addition, the present invention is not limited to the above-described embodiments, and the respective partial configurations may be combined, and it goes without saying that various modifications can be made without departing from the spirit of the invention.

  ADVANTAGE OF THE INVENTION According to this invention, the particle | grain physical property measuring apparatus which can make a measurement cell cheap and easy to wash | clean can be provided, aiming at the improvement of the measurement accuracy using a temperature sensor.

Claims (7)

A light irradiating unit that irradiates light onto a measurement sample in which a particle group is dispersed in a dispersion medium; and a light detecting unit that detects scattered light generated by the irradiation of the light. A particle physical property measuring apparatus for measuring physical properties,
A flat measurement cell on which the measurement sample is placed;
A cell holder for holding the measurement cell;
A particle physical property measuring apparatus comprising: a temperature sensor provided in the measurement cell or the cell holder.   The particle physical property measurement according to claim 1, further comprising an arithmetic unit that calculates the viscosity of the dispersion medium using the temperature detected by the temperature sensor and calculates a physical property value indicating the physical property of the particle using the viscosity. apparatus.   The particle physical property measuring apparatus according to claim 1, further comprising a temperature control mechanism that is provided in the measurement cell or the cell holder and heats or cools the measurement cell. The temperature sensor is provided in the measurement cell;
A connection terminal to which the temperature sensor is connected is provided on the cell holder,
The particle physical property measuring apparatus according to claim 1, wherein the temperature sensor is connected to the connection terminal by the cell holder holding the measurement cell. The cell holder holds the measurement cell so that light is irradiated from below;
The measurement cell has translucency,
The particle physical property measuring apparatus according to claim 1, wherein the light irradiation unit is provided below the cell holder and irradiates light to a lower surface of the measurement cell.   The particle physical property measuring apparatus according to claim 5, wherein the light detection unit is provided below the cell holder and detects scattered light passing through the lower surface of the measurement cell among scattered light scattered by the measurement sample.   The particle physical property measuring apparatus according to claim 1, wherein the light detection unit is provided at a position where the reflected light reflected by the measurement cell among the light emitted from the light irradiation unit is not detected.

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