JP2006349386A - Optical measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized optical measuring instrument, capable of simultaneously measuring pieces of information as to particles in a plurality of fluid samples. <P>SOLUTION: This optical measuring instrument is provided with a light source 16, an electric power source 15, cells 10a, 10b, electrodes 11a, 11b serving as diffraction gratings, formed in positions near to the fluid samples in the cells and for generating a plurality of basic diffraction light patterns, arrayed along the directions different each other, when irradiated with light from the light source, and a two-dimensional photodetector 25 for detecting the basic diffraction light patterns, generated by respective diffraction gratings. The two-dimensional photodetector 25 detects the basic diffraction light patterns, generated with simultaneous emission of the light onto the electrodes serving as the diffraction gratings, and detects derived diffraction light patterns generated derivedly, by irradiating with light, density diffraction gratings M generated by impressing voltages to change density distributions periodically of the particles existing in the vicinity of the respective electrodes serving as the diffraction gratings. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical measuring device that optically measures information related to particles in a fluid such as a liquid or a gel body, and more specifically, from a density change due to diffusion and movement of particles, into the fluid. The present invention relates to an optical measuring device that optically measures information about contained particles. The present invention can be applied to, for example, confirmation of the presence or absence of particles present in a fluid, and measurement of diffusion coefficient, particle concentration, particle size, and the like.

An electrode pair is formed at a position in contact with a fluid containing particles, and an AC voltage is applied to the electrode pair to cause a dielectrophoresis phenomenon (in the case of a non-electrolyte liquid), or a DC voltage is applied to cause an electrophoretic phenomenon. (In the case of an electrolyte solution), by moving the particles in the fluid, the density of the particle density can be formed, and the refractive index distribution can be formed.
It is disclosed that particles in a solution are concentrated using a dielectrophoresis phenomenon, and a change in the refractive index of the concentrated region is measured (see Patent Document 1). According to this patent document, a metal electrode for causing surface plasmon resonance is previously formed in a region where particles are concentrated by dielectrophoresis, and the surface plasmon resonance is measured by irradiating the metal electrode with excitation light. Then, the refractive index near the surface of the metal electrode is measured.
JP 2003-65947 A

  The refractive index measurement method using surface plasmon resonance disclosed in Patent Document 1 described above has detection sensitivity in the vicinity of the metal surface where surface plasmon resonance occurs. Of these regions, the region is limited to a very narrow localized region near the metal surface.

  On the other hand, in the prior patent application, the applicant formed a diffraction grating, made the diffraction grating also function as an electrode for causing dielectrophoresis, and applied a voltage to the diffraction grating and electrode to perform dielectrophoresis. Proposed to detect the change of the diffracted light pattern before and after the particle movement by a photodetector (Japanese Patent Application No. 2004-241907). According to this, it is possible to detect an average refractive index change from a wider range than the surface plasmon resonance.

FIG. 11 is a diagram for explaining the operating principle of optical measurement for measuring the refractive index change due to particle movement using the dielectrophoresis phenomenon and diffraction phenomenon proposed by the applicant in the above-mentioned prior patent application.
A pair of two parallel linear electrode pieces 13a and 13b and a pair of two parallel linear electrode pieces 14a and 14b on the glass substrate 12 constituting the wall of the cell 10 holding the fluid sample. Are alternately arranged to form the diffraction grating electrode 11. An AC voltage is applied from the AC power supply 15 to the diffraction grating electrode 11. By applying an alternating voltage to the electrodes 13a and 13b so that the electrodes 14a and 14b are opposite to each other, by the dielectrophoresis, between the lines 13a and 14b where the lines of electric force are concentrated and between the lines 14a and 13b. Particles aggregate. The regions P in which the particles are aggregated are formed at regular intervals with a period (2d) twice that of the grating interval (d) of the diffraction grating electrode 11. The region P in which the particles are aggregated has a higher particle density and a different refractive index than the other regions, so that a diffraction grating having a grating interval 2d (hereinafter referred to as a density diffraction grating) is formed.

When light is irradiated toward the diffraction grating electrode 11 using the light source 16 and the lens optical system 17 that focuses the light source light, an original diffracted light pattern generated by the diffraction grating electrode 11 is generated and the density diffraction grating is used. Since the derived diffracted light pattern is generated in a superimposed manner, a change in the derived diffracted light intensity can be achieved by aligning the photodetector 18 with a position where the primary light, the secondary light,. From this, it is possible to detect a change in refractive index. In order to clearly distinguish the original diffracted light pattern from the derived diffracted light pattern, in the following description, the diffracted light pattern formed by the diffraction grating and electrode is also referred to as a basic diffracted light pattern.
Further, when the voltage application is stopped after the voltage application, the particles diffuse from the region P, and the derived diffracted light disappears with time. Therefore, the change in the refractive index and the change in the concentration can be obtained by measuring the change. Further, the diffusion coefficient can be obtained from the concentration change based on the diffusion equation.

  FIG. 12 is a schematic block diagram showing the configuration of an optical measuring device that measures the refractive index based on the operating principle of FIG. The light source 16 and the lens optical system 17 irradiate the diffraction grating electrode 11 of the cell 10 with measurement light. In the embodiment shown in this figure, the light is incident perpendicularly to the diffraction grating electrode 11 of the cell 10, but may be incident obliquely as shown in FIG.

  The light transmitted through the diffraction grating electrode 11 includes a basic diffracted light pattern A (indicated by a thick line in the figure) in which a plurality of diffracted light spots appear at intervals, and a derived diffracted light pattern B (transmitted through the density diffraction grating) The position of the photodetector 18 is adjusted by an angle adjusting mechanism (not shown) according to the angle at which any one of the derived diffracted light patterns B is generated alone. It is. The photodetector 18 is a photomultiplier tube or a photodiode.

  Further, as a control system of the above-described optical measuring apparatus, a control unit 20 that controls the entire apparatus, a signal analysis unit 21 that is controlled by the control unit 20, a voltage application unit 22, and a liquid transport / recovery unit 23 are provided. . These control systems are constituted by a computer system including a CPU, a ROM, and a RAM. The signal analysis unit 21 takes in the detection signal of the derived diffracted light detected by the photodetector 18 and performs arithmetic processing such as the amount of change before and after the applied voltage is stopped. The power application unit 22 controls the frequency, voltage value, on / off timing, and the like of the voltage when the output voltage from the AC power supply 15 is applied to the electrodes. The liquid transport / recovery unit 23 controls the fluid supply valve and the discharge valve (not shown) attached to the cell 10 to inject and discharge the fluid into the cell 10.

  According to this optical measuring apparatus, a change in the density diffraction grating accompanying the particle movement can be detected as a change in the derived diffraction light, and information on the density diffraction grating detected as the change in the derived diffraction light can be used to detect the change in the fluid. The presence / absence of particles, refractive index, diffusion coefficient, and the like can be measured.

  By the way, when measuring the presence / absence of particles in the fluid, the particle concentration, the refractive index, and the like, there are cases where it is desired to measure many fluid samples efficiently and in a short time. In addition, there is a case where it is desired to efficiently perform measurement under different conditions for one sample in a short time. In addition, when the refractive index or the like of a plurality of fluid samples changes with time due to a chemical change or the like, it may be desired to measure a plurality of fluid samples at the same time and compare changes over time.

  In such a case, conventionally, for example, as shown in FIGS. 13 and 14, a plurality of cells 10 and an incident optical system and a detection optical system for each cell 10 are separately prepared and measured simultaneously. It was broken. More specifically, the incident light to the cell 10 uses a plurality of light sources 16 (FIG. 14), or the light emitted from one light source 16 is divided by the half mirror 16a (FIG. 13). I was trying to lead to. Further, the detection of the diffracted light (detection light) transmitted through each cell 10 is guided to the photodetector 18 provided independently (FIG. 13), or a large number of light detection elements are arranged in an array. A CCD 18 or the like in which each light detection element independently detects light is used as the detector 18, and diffracted light (detection light) from each cell 10 is guided to a different light detection element by a lens 18 a or the like so as to be detected almost simultaneously. I was doing. Or the optical system of the combination which replaced the incident light optical system shown in FIG. 13 and FIG. 14 with the detection light optical system was used.

  However, since the conventional measurement method as described above uses a large number of light sources, detectors, and optical components, the incident optical system of adjacent cells, the incident light between the detection optical systems, and the diffracted light (detection light) Since a light shielding means (for example, a light shielding wall) for separating the two is necessary, the apparatus becomes large.

Therefore, the present invention provides an optical measuring device that simultaneously measures the diffracted light of a plurality of samples while miniaturizing the device by minimizing the number of components used for light sources, detectors, optical components, and light shielding means. The purpose is to do.
It is another object of the present invention to provide an optical measuring apparatus that can simultaneously detect diffracted light (detected light) under a plurality of different conditions for one sample.

  The optical measuring device of the present invention made to solve the above problems includes a light source, a power source, at least one cell holding a fluid sample containing particles, and a position in proximity to the fluid sample in the cell. A plurality of diffraction gratings that generate a plurality of basic diffracted light patterns arranged in different directions when irradiated with light from a light source, and at least part of each diffraction grating and voltage from a power source And a two-dimensional photodetector that detects a basic diffraction light pattern generated by each diffraction grating. The two-dimensional detector simultaneously irradiates a plurality of diffraction gratings with light from a light source. In addition to detecting a plurality of generated basic diffraction light patterns, a voltage is applied to the electrodes to periodically change the density distribution of particles existing in the vicinity of each diffraction grating. There has been to detect the derivative diffracted light pattern consequentially caused by being irradiated.

Here, the cells may be formed such that a plurality of cells are adjacent to each other, and a diffraction grating may be formed in each cell at a position close to the fluid sample in each cell.
In addition, the cell may be formed such that a plurality of diffraction gratings having different lattice intervals are close to the fluid sample in the cell with respect to one cell.

According to the present invention, a cell for holding a fluid sample containing particles to be measured is used. When a single fluid sample is measured simultaneously under different diffraction conditions, a sample in which one cell is formed is used. When it is desired to measure a plurality of fluid samples at the same time, a sample in which a plurality of cells are formed is used. In the cell, a plurality of diffraction gratings are formed at positions close to the fluid sample in a state where the fluid sample is placed in the cell. When a plurality of diffraction gratings are irradiated with light from a light source, each of the diffraction gratings independently generates a basic diffraction light pattern, but the basic diffraction light patterns are arranged in different directions. The diffraction directions of the diffraction gratings (directions in which the light shielding portions and the light transmission portions of the diffraction grating are alternately arranged) are all directed in different directions so as to form a pattern. Further, each of the plurality of diffraction gratings is at least partially connected to a power source, and serves as a diffraction grating electrode.
In a state where a particle-containing fluid sample is placed in the cell, light is irradiated from the light source toward the diffraction grating electrode. At this time, the light is diffracted by the diffraction grating and electrode to generate a plurality of basic diffracted light patterns arranged in different directions. Subsequently, a voltage is applied to the diffraction grating electrode from the power source to move the particles in the fluid sample. When particles are moved using dielectrophoresis, an AC voltage is applied to the electrodes, and when particles are moved using electrophoresis (or electrostatic electrophoresis), a DC voltage is applied to the electrodes. As the particles move, the density of particles in the fluid sample is periodically varied, and a refractive index distribution that periodically changes in the vicinity of the diffraction grating is generated. When the refractive index distribution of the fluid sample periodically changes, a derivative diffraction grating (referred to as a density diffraction grating) that is different from the diffraction grating that generates the basic diffraction light pattern is newly generated. The period (grating interval) of the density diffraction grating can be arbitrarily set by changing the voltage application pattern to the diffraction grating / electrode, but is different from the period (grating interval) of the diffraction grating / electrode. Is more preferable for detecting a change in particle density with high sensitivity. For example, when dielectrophoresis is used, a density diffraction grating can be formed with a period (grating interval) twice that of the diffraction grating electrode by taking the same voltage application pattern as in FIG. 11 shown in the conventional example.

Due to this density diffraction grating, new derivative diffracted light is generated, and as a result, a new derivative diffracted light pattern is superimposed on the basic diffracted light pattern. The derived diffracted light patterns generated are arranged in the same direction as the basic diffracted light pattern formed by the diffraction grating corresponding to the density diffraction grating.
A plurality of diffraction gratings having different diffraction directions form density diffraction gratings having different diffraction directions by applying an electrode, so that a plurality of derived diffraction light patterns having different directions are generated. In addition to the basic diffracted light pattern, the plurality of derived diffracted light patterns are also detected.
Therefore, based on the detection data of only the basic diffracted light pattern before the voltage application (or after the voltage is stopped) and the detection data on which the derived diffracted light pattern after the voltage application is superimposed, the change due to the density diffraction grating, and hence the density diffraction grating. It is possible to obtain information on particles accompanying the movement of the particles forming the.

  According to the present invention, it is possible to provide a compact optical measuring device with a reduced number of components such as a light source, a detector, an optical component, and a light shielding means, and a plurality of samples or a plurality of diffraction conditions for one sample. The basic diffracted light pattern and the derived diffracted light pattern can be measured at the same time, and an optical measuring apparatus capable of measuring a sample efficiently in a short time can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the spirit of the present invention.

FIG. 1 is a schematic block diagram showing the overall configuration of an optical measuring apparatus according to an embodiment of the present invention. In the figure, parts that are the same as those described in FIG.
The optical measuring apparatus 1 includes a composite cell 8, an AC power source 15, a light source 16, a lens optical system 17, a CCD 25 (two-dimensional photodetector), a control unit 20, a signal analysis unit 21, a voltage application unit 22, a liquid transport / The collection unit 23 is configured.

  As shown in the perspective view of FIG. 2, the composite cell 8 includes a cell 10a, a cell 10b, and a substrate 9 on which diffraction grating electrodes 11a and 11b are formed. The fluid supply channels 6a and 6b and the discharge channels 7a and 7b are provided in the cell 10a and the cell 10b, respectively, so that the fluid sample can be injected and discharged independently from each cell by the liquid transport / recovery unit 23. It is.

  The two diffraction grating electrodes 11a and 11b are integrally formed on the substrate 9 by a patterning method. As shown in the plan view of FIG. 3, the direction in which the grooves of the diffraction grating are arranged is 90 degrees different from each other. The direction in which the pattern is generated (diffraction direction) forms an angle of 90 degrees. Note that the angle of intersection between the two basic diffracted light patterns does not necessarily have to be 90 degrees as long as the patterns can be distinguished from each other. In this embodiment, the electrodes of the two diffraction grating electrodes 11a and 11b are connected to each other on the substrate 9, and the voltages applied to the diffraction grating electrodes 11a and 11b are synchronized. In addition, when performing the measurement which does not necessarily need to synchronize an applied voltage, these may be isolate | separated and you may make it apply a separate voltage.

Further, the diffraction grating electrode 11a, 11b has a region where electric lines of force concentrate (that is, a region where particles concentrate due to dielectrophoresis) at a period twice that of the diffraction grating when an AC voltage is applied from the AC power supply 15. A repeated pattern is formed (see FIG. 11). As a result, as shown in FIG. 4, a density diffraction grating M having a period twice that of the diffraction grating electrode 11a, 11b is generated. The grating produces a derived diffracted light pattern having a period different from that of the basic diffracted light pattern. Note that the electrode pattern may be repeated so that the derived diffracted light pattern has a period that is three times or more than the period of the diffraction grating electrodes 11a and 11b, and some diffraction gratings are connected to the power source. In other words, a diffraction grating and electrode pattern having a periodic structure capable of obtaining a derived diffracted light pattern that can be distinguished from the basic diffracted light pattern may be formed.

As shown in FIG. 1, the light source 16 and the lens optical system 17 simultaneously irradiate the diffraction grating / electrodes 11a and 11b of the cells 10a and 10b with measurement light. The AC power supply 15 has a variable AC frequency and voltage value, and a desired AC voltage is applied under the control of the voltage application unit 22.
A CCD 25, which is a two-dimensional photodetector, is used as a photodetector that detects transmitted diffraction light that has passed through the diffraction grating electrodes 11a and 11b. The CCD 25 simultaneously displays basic diffracted light patterns A1 and A2 (shown by thick lines in FIG. 1) by the diffraction grating electrodes 11a and 11b and derived diffracted light patterns B1 and B2 (shown by thin lines in FIG. 1) by the density diffraction grating. Can be detected.

  As a control system, a control unit 20 that controls the entire apparatus, a signal analysis unit 21 that is controlled by the control 20, a voltage application unit 22, and a liquid transport / recovery unit 23 are provided. These control systems are constituted by a computer system including a CPU, a ROM, and a RAM. The signal analysis unit 21 takes in the detection signals of the basic diffracted light pattern and the derived diffracted light pattern detected by the CCD 25 and performs arithmetic processing such as the amount of change before and after stopping the applied voltage or before and after applying voltage modulation. The power application unit 22 controls the frequency, voltage value, on / off timing, and the like of the voltage when the output voltage from the AC power supply 15 is applied to the electrodes. The liquid transport / recovery unit 23 controls the supply valve and the discharge valve attached on the flow path to the cells 10a and 10b to inject and discharge the fluid sample to and from the cells 10a and 10b.

Next, the measurement operation by the optical measurement apparatus 1 will be described.
First, two types of fluids are injected into the two cells 10a and 10b by the liquid transport / recovery unit 23, and the diffracted light is detected by the CCD 25 without applying a voltage. The detection signals detected by the CCD 25 at this time are only signals U1 and U2 of two orthogonal basic diffracted light patterns by the diffraction grating and electrodes 11a and 11b as shown in FIG. In the two basic diffracted light patterns, U1 and U2 overlap at the central diffraction spot generated by the 0th-order basic diffracted light, but the other diffraction spots do not overlap.

Subsequently, voltage application is performed by the voltage application unit 22, and diffracted light is detected by the CCD 25 in a state where a density diffraction grating is generated in the fluid. As shown in FIG. 5B, the detection signals detected by the CCD 25 at this time are two detection signals U1 and U2 of the two basic diffraction light patterns by the diffraction grating electrode 11 and two further by the density diffraction grating. This is a signal in which the detection signals V1 and V2 of the derived diffracted light pattern are superimposed.
The two derived diffracted light patterns are generated on the same straight line as the corresponding basic diffracted light patterns, and a part of the diffracted spot is overlapped but a part of the diffracted spot is found in the basic diffracted light pattern. appear. Accordingly, by measuring the detection signal for the newly generated diffraction spot by the CCD 25 using the derived diffracted light pattern, it is possible to detect the information regarding the density diffraction grating, and hence the information regarding the particles in the fluid.

FIG. 6 is a schematic perspective view of a composite cell 8a used in an optical measurement apparatus according to another embodiment of the present invention. In this embodiment, since the composite cell 8 in FIG. 1 is the same except that it is replaced with the composite cell 8a, description of portions other than the composite cell 8a is omitted.
In the composite cell 8a, a cell 40a, a cell 40b, a cell 40c, a cell 40d, and a substrate 42 on which diffraction grating electrodes 41a to 41d are formed are attached to each other. The cells 40a to 40d are provided with fluid supply channels 43a to 43d and discharge channels 44a to 44d, respectively.

  In the diffraction grating electrodes 41a to 41d, the direction in which the grooves of the diffraction grating are arranged differs from each other by 45 degrees, and the direction in which the basic diffracted light pattern is generated (diffraction direction) forms an angle of 45 degrees. Note that the intersection angle of the four basic diffracted light patterns may not necessarily be 45 degrees as long as the patterns can be distinguished from each other. In this embodiment, the electrodes of the four diffraction grating electrodes 41a to 41d are connected on the substrate 42, and the voltages applied to the diffraction grating electrodes 41a to 41d seem to be synchronized.

The measurement operation is the same as in FIG. A detection signal detected by the CCD 25 at this time will be described with reference to FIG. FIG. 7A shows a basic diffracted light pattern obtained when no voltage is applied. Four basic diffracted light patterns are generated that are linearly arranged in different directions by 45 degrees. The four basic diffracted light patterns overlap at the central diffraction spot generated by the zeroth-order basic diffracted light, but the other diffraction spots do not overlap.
FIG. 7B is a diagram showing four derivative diffracted light patterns that newly appear due to the density diffraction grating generated when a voltage is applied. That is, after voltage application, the CCD 25 detects a pattern in which the pattern of FIG. 7A and the pattern of FIG. At this time, the four basic diffracted light patterns and the derived diffracted light patterns are generated on the same straight line, and a part of the diffraction spot is newly generated between the diffraction spots forming the basic diffracted light pattern. . Accordingly, by measuring the detection signal for the newly generated diffraction spot by the CCD 25 using the derived diffracted light pattern, it is possible to detect the information regarding the density diffraction grating, and hence the information regarding the particles in the fluid.

FIG. 8 is a schematic perspective view of a composite cell 8b used in an optical measurement apparatus according to another embodiment of the present invention. Also in this embodiment, since the composite cell 8 in FIG. 1 is the same except that it is replaced with the composite cell 8b, description of portions other than the composite cell 8b is omitted.
In the composite cell 8a, one cell 50 and a substrate 52 on which diffraction grating electrodes 51a and 51b are formed are bonded together. Each cell 50 is provided with a fluid supply channel 53a and a discharge channel 54a.

  The diffraction grating electrodes 51a and 51b are different from each other in the direction in which the grooves of the diffraction grating are arranged by 90 degrees, and the direction in which the basic diffracted light pattern is generated (diffraction direction) forms an angle of 90 degrees. Note that the angle of intersection between the two basic diffracted light patterns does not necessarily have to be 90 degrees as long as the patterns can be distinguished from each other. Further, as shown in FIG. 9, the grating interval between the diffraction grating electrode 51a and 51b is narrower 51a, wider than 51b, and different grating intervals.

  In this case, when a voltage is applied, a diffracted light pattern similar to that in FIG. 5 is obtained. However, since the electrode spacing between the two diffraction grating electrodes is different, the electric field gradient in the vicinity of the electrodes is different from the diffraction grating electrode 51a, It becomes different in each 51b. As a result, as shown in FIG. 10, since the particle distribution concentrated by dielectrophoresis is different, information on the dispersion of the particle diameter can be measured.

Moreover, even if it is the composite cell 8 in which the same diffraction grating electrode 11a, 11b as FIG. 1-4 demonstrated was formed, the magnitude | size and frequency of the alternating voltage applied to both differ also by particle | grains. The distribution can be different.
In the above description, the density diffraction grating is formed by using dielectrophoresis. However, in the case where the fluid is an electrolyte solution, a DC voltage is applied by a DC power source, and particles are separated by an electrophoresis phenomenon. You may make it move. In this case as well, basically the same is performed except that the migration of particles is replaced by electrophoresis instead of dielectrophoresis.

  The present invention can be used in an optical measurement apparatus that optically measures information related to particles in a fluid, for example, diffusion coefficient, particle size, particle distribution, and the like.

1 is a schematic configuration diagram showing an overall configuration of an optical measuring device according to an embodiment of the present invention. The perspective view which shows the structure of the composite cell used for the apparatus of FIG. The top view which shows the structure of the diffraction grating and electrode of the composite cell shown in FIG. The figure explaining the density diffraction grating which generate | occur | produces when a voltage is applied to the composite shield shown in FIG. The figure explaining the diffracted light pattern by the optical measuring device of FIG. The perspective view which shows the structure of the composite cell used with the optical measuring device which is other one Embodiment of this invention. The figure explaining the diffracted light pattern by the composite cell of FIG. The perspective view which shows the structure of the composite cell used with the optical measuring device which is other one Embodiment of this invention. FIG. 9 is a diagram for explaining an electrode interval between diffraction grating electrodes formed in the composite cell of FIG. 8. The figure explaining particle distribution when a voltage is applied in the composite cell of FIG. The figure explaining the relationship between the diffraction grating electrode and the density diffraction grating in the optical measuring apparatus shown in FIG. The figure which shows the whole structure of the conventional optical measuring device. The figure which shows the structure of the conventional optical measuring device. The figure which shows the structure of the conventional optical measuring device.

Explanation of symbols

1: Optical measuring device 8: Composite cell 9: Substrate 10, 10a, 10b: Cell 11, 11a, 11b: Diffraction grating electrode 15: AC power supply 16: Light source 17: Lens optical system 20: Control unit 21: Signal analysis Unit 22: Voltage application unit 23: Liquid transport / recovery unit 25: CCD (two-dimensional photodetector)
M: Density diffraction grating

Claims (3)

A light source, a power source, at least one cell holding a fluid sample containing particles, and a position close to the fluid sample in the cell are formed in different directions when irradiated with light from the light source. A plurality of diffraction gratings that generate a plurality of basic diffraction light patterns arranged in parallel, electrodes that form at least a part of each diffraction grating and to which a voltage is applied from a power source, and basic diffraction light patterns that each diffraction grating generates. And a two-dimensional photodetector for detecting
The two-dimensional photodetector detects a plurality of basic diffracted light patterns generated by simultaneously irradiating light from a light source to a plurality of diffraction gratings, and applies a voltage to the electrodes to present particles in the vicinity of each diffraction grating. An optical measurement apparatus for detecting a derivative diffracted light pattern that is derived by irradiating light onto a density diffraction grating generated by periodically changing the density distribution of the light. The optical measurement apparatus according to claim 1, wherein a plurality of cells are formed adjacent to each other, and a diffraction grating is formed in each cell at a position close to a fluid sample in each cell. The optical measurement apparatus according to claim 1, wherein a plurality of diffraction gratings having different grating intervals are formed at a position close to the fluid sample in the cell for one cell.

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