Measuring device

Abstract

To provide a technique that can accurately measure the flow rate of blood according to the concentration of red blood cells included in the blood of a measurement object.SOLUTION: A processing apparatus may specify a Doppler shift frequency before correction on the basis of a light receiving signal output by a light receiving device, specify the concentration of red blood cells included in the blood of a measurement object on the basis of the frequency spectrum of the light receiving signal output by the light receiving device and first relevant information, correct the Doppler shift frequency before correction according to the specified concentration of the red blood cells to specify the Doppler shift frequency after correction, and specify the flow rate of the blood on the basis of the Doppler shift frequency after correction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to a measuring device.

Background Art

[0002] Patent Document 1 discloses a device for identifying the blood flow velocity based on the Doppler shift frequency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When measuring the blood flow velocity with a measuring device, variations may occur in the measurement results due to differences in the concentration of red blood cells contained in the blood to be measured. This is presumably because when the concentration of red blood cells contained in the blood is different, the blood flow velocity distribution in the tube (e.g., blood vessel) through which the blood flows is different due to the formation of red blood cell rouleaux.

[0005] This specification provides a technology capable of accurately measuring the blood flow velocity according to the concentration of red blood cells contained in the blood to be measured.

Means for Solving the Problems

[0006] In a first aspect of the present technology, a measuring device includes an irradiation device that irradiates blood with a first laser beam and a second laser beam that intersects the first laser beam, a light receiving device that receives scattered light generated when the first laser beam and the second laser beam irradiated by the irradiation device hit the blood and outputs a light reception signal corresponding to the received scattered light, and a processing device that stores in advance first relationship information indicating the relationship between the frequency spectrum of the light reception signal output by the light receiving device and the concentration of red blood cells contained in the blood. The processing device specifies the Doppler shift frequency before correction based on the light reception signal output by the light receiving device, specifies the concentration of red blood cells contained in the blood to be measured based on the frequency spectrum of the light reception signal output by the light receiving device and the first relationship information, and specifies the Doppler shift frequency after correction by correcting the Doppler shift frequency before correction according to the specified concentration of red blood cells, and may specify the blood flow velocity based on the Doppler shift frequency after correction.

[0007] According to this configuration, the relationship between the frequency spectrum of the light reception signal output by the light receiving device in response to the scattered light and the concentration of red blood cells is grasped in advance, and when actually measuring the blood flow velocity, the frequency spectrum of the light reception signal varies depending on the concentration of red blood cells contained in the blood to be measured. By utilizing this fact and correcting the Doppler shift frequency according to the concentration of red blood cells contained in the blood, the blood flow velocity can be measured accurately.

[0008] In a second aspect, in the first aspect described above, the processing device stores in advance second relationship information indicating the relationship between the concentration of red blood cells contained in the blood and the correction value corresponding thereto, and may specify the Doppler shift frequency after correction by correcting the Doppler shift frequency before correction based on the concentration of red blood cells specified based on the first relationship information and the second relationship information.

[0009] According to this configuration, the blood flow velocity can be measured accurately according to the concentration of red blood cells contained in the blood to be measured.

[0010] In a third aspect, in the first or second aspect described above, the processing device may specify the Doppler shift frequency before correction based on the difference between the frequency spectrum of the received light signal corresponding to the scattered light generated when both the first laser light and the second laser light hit the blood, and the frequency spectrum of the received light signal corresponding to the scattered light generated when only one of the first laser light and the second laser light hits the blood.

[0011] According to this configuration, the blood flow velocity can be accurately measured by using the first laser light and the second laser light.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0013] The measuring device of the embodiment will be described with reference to the drawings. As shown in FIG. 1, the measuring device 1 of the embodiment includes an irradiation device 2, a light receiving device 3, and a processing device 9. The measuring device 1 is a device for measuring the blood flow velocity of the blood flowing inside the tube 100. The tube 100 is, for example, a human blood vessel. In a modified example, the tube 100 may be a blood vessel of an animal other than a human. In another modified example, the tube 100 may not be a blood vessel but an artificial resin tube or the like. In the measuring device 1 of the embodiment, the irradiation device 2, the light receiving device 3, and the processing device 9 are arranged inside the housing 8. Also, the tube 100 passes through the inside of the housing 8. In a modified example, the tube 100 and the light receiving device 3 may be arranged outside the housing 8.

[0014] The irradiation device 2 is a device that irradiates the blood flowing inside the tube 100 with the first laser light L1 and the second laser light L2. The irradiation device 2 includes a light emitting element 21, a collimator lens 22, a condenser lens 23, a spectroscope 24, a first mirror 41, a second mirror 42, and a light shielding device 5.

[0015] The light emitting element 21 is, for example, a laser diode (LD). The light emitting element 21 is arranged to face the collimator lens 22 and emits laser light L toward the collimator lens 22. The laser light L emitted by the light emitting element 21 enters the collimator lens 22. The laser light L emitted by the light emitting element 21 is, for example, near-infrared light with a wavelength of about 850 nm - 1300 nm.

[0016] The collimator lens 22 is arranged between the light emitting element 21 and the condenser lens 23. The collimator lens 22 emits the laser light L emitted by the light emitting element 21 as parallel light. The laser light L (parallel light) emitted from the collimator lens 22 enters the condenser lens 23.

[0017] The condenser lens 23 is arranged between the collimator lens 22 and the spectroscope 24. The condenser lens 23 condenses and emits the laser light L (parallel light) emitted from the collimator lens 22. The laser light L emitted from the condenser lens 23 enters the spectroscope 24.

[0018] The spectroscope 24 is a device that splits the laser light L incident on the spectroscope 24 into the first laser light L1 and the second laser light L2. The first laser light L1 and the second laser light L2 generated by the spectroscope 24 travel in different directions from each other. In the example shown in FIG. 1, the first laser light L1 travels obliquely upward to the right, and the second laser light L2 travels obliquely upward to the left. The first laser light L1 travels toward the first mirror 41, and the second laser light L2 travels toward the second mirror 42. The wavelength of the first laser light L1 and the wavelength of the second laser light L2 are the same wavelength. Also, the frequency of the first laser light L1 and the frequency of the second laser light L2 are the same frequency.

[0019] The first mirror 41 and the second mirror 42 are disposed between the spectroscope 24 and the light shielding device 5. The first mirror 41 and the second mirror 42 face each other. The first laser beam L1 generated by the spectroscope 24 is incident on the first mirror 41 and reflected therefrom. Also, the second laser beam L2 generated by the spectroscope 24 is incident on the second mirror 42 and reflected therefrom.

[0020] The first laser beam L1 reflected by the first mirror 41 travels in the first direction D1. The second laser beam L2 reflected by the second mirror 42 travels in the second direction D2. The first laser beam L1 and the second laser beam L2 travel in directions (the first direction D1 and the second direction D2) that intersect each other. The first laser beam L1 and the second laser beam L2 are each incident inside the tube 100 through which blood flows. Thereby, the first laser beam L1 and the second laser beam L2 irradiate the blood flowing inside the tube 100. The first laser beam L1 traveling in the first direction D1 and the second laser beam L2 traveling in the second direction D2 intersect at the intersection point 10 inside the tube 100. The first laser beam L1 and the second laser beam L2 overlap and interfere with each other inside the tube 100.

[0021] The light shielding device 5 is disposed between the mirrors (the first mirror 41 and the second mirror 42) and the tube 100. The light shielding device 5 can shield the first laser beam L1 and the second laser beam L2 traveling toward the tube 100. The light shielding device 5 is configured to be switchable between a light shielding state in which one of the first laser beam L1 or the second laser beam L2 is shielded and a non-light shielding state in which neither the first laser beam L1 nor the second laser beam L2 is shielded. The light shielding state of the light shielding device 5 includes a first light shielding state in which the first laser beam L1 is shielded while the second laser beam L2 is not shielded, and a second light shielding state in which the second laser beam L2 is shielded while the first laser beam L1 is not shielded. The configuration of the light shielding device 5 is not particularly limited as long as it can switch between the light shielding state and the non-light shielding state.

[0022] The light-shielding device 5 includes, for example, a rotating body 52 disposed on the optical paths of the first laser beam L1 and the second laser beam L2. The rotating body 52 is disposed so as to cross the first laser beam L1 and the second laser beam L2. The rotating body 52 rotates at a predetermined rotational speed clockwise or counterclockwise by driving of a motor 54.

[0023] The rotating body 52 includes a light-shielding portion that shields the laser beam and a non-light-shielding portion that does not shield the laser beam (both are not shown). The non-light-shielding portion of the rotating body 52 is constituted by, for example, an opening provided in the rotating body 52, and is configured such that the laser beam (the first laser beam L1 and the second laser beam L2) can pass through. On the other hand, the light-shielding portion is constituted by, for example, a portion of the rotating body 52 that is not the opening (non-light-shielding portion), and is configured such that the laser beam (the first laser beam L1 and the second laser beam L2) cannot pass through. In the light-shielding device 5, the positions of the light-shielding portion and the non-light-shielding portion are switched as the rotating body 52 rotates.

[0024] In the measuring device 1 shown in FIG. 1, in the first light-shielded state (a state in which the first laser beam L1 is shielded while the second laser beam L2 is not shielded), the second laser beam L2 enters the inside of the tube 100. Further, in the second light-shielded state (a state in which the second laser beam L2 is shielded while the first laser beam L1 is not shielded), the first laser beam L1 enters the inside of the tube 100. Further, in the non-light-shielded state (a state in which neither the first laser beam L1 nor the second laser beam L2 is shielded), both the first laser beam L1 and the second laser beam L2 enter the inside of the tube 100.

[0025] The first laser beam L1 and / or the second laser beam L2 that has entered the inside of the tube 100 scatters when hitting the blood flowing inside the tube 100. More specifically, the first laser beam L1 and / or the second laser beam L2 scatters when hitting the red blood cells contained in the blood. Thereby, scattered light is generated. The first laser beam L1 and the second laser beam L2 hit the blood from different directions. The first laser beam L1 travels in the first direction D1 and hits the blood. The second laser beam L2 travels in the second direction D2 and hits the blood.

[0026] In the measuring device 1, when the first laser beam L1 and / or the second laser beam L2 hits the blood and scatters, the frequencies of the respective laser beams L1 and L2 change due to the Doppler shift. The frequencies of the scattered light generated by the scattering of the respective laser beams L1 and L2 are different from the respective frequencies of the laser beams L1 and L2. The scattered light generated by the scattering of the respective laser beams L1 and L2 travels in various directions. Among the scattered light generated by the scattering of the respective laser beams L1 and L2, the receiving device 3 receives the scattered light P traveling toward the receiving device 3.

[0027] The receiving device 3 is arranged to face the tube 100 through which the blood flows. The receiving device 3 includes a light receiving element 31 that receives the scattered light P. The light receiving element 31 is, for example, a photodiode (PD). Among the scattered light generated by the scattering of the respective laser beams L1 and L2, the scattered light P traveling toward the receiving device 3 enters the light receiving element 31. When the light receiving element 31 receives the scattered light P, it outputs a light receiving signal corresponding to the intensity of the scattered light P. Thereby, a light receiving signal corresponding to the intensity of the scattered light P is transmitted from the receiving device 3 to the processing device 9. The receiving device 3 outputs the light receiving signal by a voltage signal. In a modified example, the receiving device 3 may output the light receiving signal by a current signal.

[0028] As shown in FIG. 2, the processing device 9 of the measuring device 1 is electrically connected to the irradiation device 2 and the receiving device 3. The processing device 9 includes, for example, a processing unit 92 and a storage unit 94. The processing unit 92 includes, for example, a CPU and executes various controls and processes related to the measuring device 1 based on a predetermined program. For example, the processing unit 92 calculates the flow velocity of the blood flowing inside the tube 100. The processing unit 92 calculates the flow velocity of the blood by an arithmetic method based on the Doppler shift.

[0029] The storage unit 94 includes, for example, a ROM and a RAM and stores various information related to the measuring device 1. For example, the storage unit 94 stores the first relationship information and the second relationship information in advance.

[0030] The first relationship information is information indicating the relationship between the frequency spectrum of the light reception signal output by the light reception device 3 and the concentration of red blood cells contained in the blood. The frequency spectrum of the light reception signal output by the light reception device 3 differs depending on the concentration of red blood cells contained in the blood to be measured. Specifically, as shown in FIG. 3, when the concentration of red blood cells contained in the blood is low, the maximum value in the frequency spectrum of the light reception signal becomes large, and when the concentration of red blood cells is high, the maximum value in the frequency spectrum becomes small. The processing device 9 stores these relationships in advance in the storage unit 94 as the first relationship information. In the present embodiment, the first relationship information is information indicating the relationship between the frequency spectrum of the third light reception signal output in response to the scattered light P received by the light reception device 3 when the light shielding device 5 is in the non-light shielding state and the concentration of red blood cells contained in the blood. In a modified example, the first relationship information may be information indicating the relationship between the frequency spectrum of the first light reception signal or the second light reception signal output in response to the scattered light P received by the light reception device 3 when the light shielding device 5 is in the light shielding state and the concentration of red blood cells contained in the blood. The first relationship information is obtained in advance, for example, by performing regression analysis on the experimental results obtained by prior experiments. The first relationship information is represented, for example, by the following formula (1). In the following formula (1), x1 is the maximum value in the frequency spectrum of the light reception signal (the third light reception signal in the present embodiment), and y1 is the concentration of red blood cells contained in the blood. In a modified example, x1 may be a value other than the maximum value in the frequency spectrum (for example, a value in the vicinity of the maximum value). Note that the expression form of the first relationship information is not particularly limited.

[0031]

Number

[0032] The second relationship information is information indicating the relationship between the concentration of red blood cells contained in the blood and the correction value for correcting the Doppler shift frequency. The second relationship information is obtained in advance, for example, by performing regression analysis on the experimental results obtained by prior experiments. The second relationship information is represented by, for example, the following formula (2). In the following formula (2), x2 is the concentration of red blood cells contained in the blood, and y2 is the correction value for correcting the Doppler shift frequency. The x2 in formula (2) is substituted with the y1 in the above formula (1). The correction value (y2) in formula (2) is a value corresponding to the error between the actual blood flow rate and the measured blood flow rate. The actual blood flow rate is not the flow rate calculated from the blood flow velocity measured by the measuring device 1, but the blood flow rate actually measured by other means. On the other hand, the measured blood flow rate is the flow rate calculated from the blood flow velocity measured by the measuring device 1.

[0033]

Number

[0034] (Measurement process; Figure 4) Next, the measurement process of the embodiment will be described with reference to FIG. 4. The measurement process starts, for example, when the light emitting element 21 of the irradiation device 2 emits the laser beam L. The start trigger of the measurement process is not particularly limited. As shown in FIG. 4, in S2 of the measurement process, the processing device 9 acquires a light reception signal from the light receiving device 3. The processing device 9 acquires a first light reception signal when the light shielding device 5 is in the first light shielding state, a second light reception signal when the light shielding device 5 is in the second light shielding state, and a third light reception signal when the light shielding device 5 is in the non-light shielding state.

[0035] When the light shielding device 5 is in the first light shielding state, only the second laser beam L2 is irradiated onto the blood from the irradiation device 2. Therefore, the first light reception signal when the light shielding device 5 is in the first light shielding state is a light reception signal due to scattered light generated when the second laser beam L2 hits the blood. Also, when the light shielding device 5 is in the second light shielding state, only the first laser beam L1 is irradiated onto the blood from the irradiation device 2. Therefore, the second light reception signal when the light shielding device 5 is in the second light shielding state is a light reception signal due to scattered light generated when the first laser beam L1 hits the blood.

[0036] On the other hand, when the light shielding device 5 is in the non-light shielding state, both the first laser beam L1 and the second laser beam L2 are irradiated onto the blood from the irradiation device 2. Therefore, the third light reception signal when the light shielding device 5 is in the non-light shielding state is a light reception signal due to scattered light generated when both the first laser beam L1 and the second laser beam L2 hit the blood.

[0037] In subsequent S4, the processing device 9 specifies the Doppler shift frequency fd1 before correction based on the light reception signal acquired from the light reception device 3. The processing device 9 specifies, for example, the Doppler shift frequency fd1 before correction based on the difference between the frequency spectrum of the third light reception signal when the light shielding device 5 is in the non-light shielding state and the frequency spectra of the light reception signals (the first light reception signal and the second light reception signal) when the light shielding device 5 is in the light shielding state (the first light shielding state and the second light shielding state).

[0038] More specifically, when the processing device 9 acquires the first light reception signal, the second light reception signal, and the third light reception signal from the light reception device 3, it samples them at intervals of, for example, 0.06 seconds. Subsequently, the processing device 9 performs Fourier transform on each of the sampled first light reception signal, second light reception signal, and third light reception signal. The processing device 9 can perform Fourier transform by, for example, an FFT (Fast Fourier Transform) analyzer. Fourier transform is a technique that can convert a function of time into a function of frequency. Since Fourier transform is well known, detailed description thereof is omitted. The processing device 9 generates a frequency spectrum by performing Fourier transform. Further, the processing device 9 performs decibel conversion on the generated frequency spectrum. The decibel-converted frequency spectrum is shown in relation to frequency and voltage level, for example, as shown in FIG. 3.

[0039] Subsequently, the processing device 9 calculates a differential frequency spectrum based on the frequency spectrum of the first light reception signal, the frequency spectrum of the second light reception signal, and the frequency spectrum of the third light reception signal. For example, the processing device 9 calculates the voltage level Vx of the differential frequency spectrum by the following formula (3). The processing device 9 calculates the voltage level Vx of the differential frequency spectrum based on the voltage level V1 of the frequency spectrum of the first light reception signal, the voltage level V2 of the frequency spectrum of the second light reception signal, and the voltage level V3 of the frequency spectrum of the third light reception signal. The processing device 9 calculates the difference between the voltage levels corresponding to each frequency of the frequency spectrum by formula (3) for each frequency of the frequency spectrum. The processing device 9 stores the differential frequency spectrum Spx specified by the calculation in the storage unit 94.

[0040]

Equation

[0041] Subsequently, the processing device 9 identifies the peak frequency fp in the differential frequency spectrum Spx. The peak frequency fp is the frequency corresponding to the most prominent voltage level (maximum value) in the frequency spectrum. Also, the frequency in its vicinity may be regarded as the peak frequency fp. Then, the processing device 9 sets the peak frequency fp in the differential frequency spectrum Spx as the Doppler shift frequency fd1 before correction. The processing device 9 stores the identified Doppler shift frequency fd1 before correction in the storage unit 94. Note that the calculation method of the Doppler shift frequency fd1 before correction is not particularly limited.

[0042] In subsequent S6, the processing device 9 identifies the concentration of red blood cells contained in the blood to be measured. More specifically, the processing device 9 identifies the concentration of red blood cells contained in the blood to be measured based on the frequency spectrum of the light reception signal acquired from (output by) the light reception device 3 and the first relationship information pre-stored in the storage unit 94. The processing device 9 identifies the concentration of red blood cells contained in the blood based on the above formula (1). In this embodiment, based on the maximum value of the frequency spectrum of the third light reception signal output by the light reception device 3 when the light shielding device 5 is in the non-light shielding state and the first relationship information, the concentration of red blood cells contained in the blood to be measured is identified. In a modified example, based on the maximum value of the frequency spectrum of the first light reception signal or the second light reception signal output by the light reception device 3 when the light shielding device 5 is in the light shielding state and the first relationship information, the concentration of red blood cells contained in the blood may be identified. The processing device 9 stores the identified concentration of red blood cells in the storage unit 94.

[0043] In subsequent S8, the processing device 9 identifies a correction value for correcting the Doppler shift frequency based on the concentration of red blood cells identified in the above S6 and the second relationship information pre-stored in the storage unit 94. The processing device 9 identifies the correction value based on the above formula (2).

[0044] In the following S10, the processing device 9 specifies a corrected Doppler shift frequency fd2 based on the correction value specified in S8 above and the Doppler shift frequency fd1 before correction specified in S4 above. The processing device 9 specifies the corrected Doppler shift frequency fd2 based on, for example, the following equation (4). In the following equation (4), y2 is a correction value for correcting the Doppler shift frequency fd1 before correction, and is y2 in the above equation (2).

[0045]

number

[0046] In the next step S12, the processing device 9 determines the blood flow velocity v of the measurement target based on the corrected Doppler shift frequency fd2 determined in step S10. The processing device 9 determines the blood flow velocity v, for example, based on the following equation (5): In equation (5), λ is the wavelength of the first laser light L1 and the second laser light L2, and θ is half the intersection angle of the first laser light L1 and the second laser light L2 (see FIG. 1). The processing device 9 also determines the flow rate based on the determined blood flow velocity v. For example, the processing device 9 determines the blood flow rate by multiplying the determined blood flow velocity v by the cross-sectional area of the tube 100. The processing device 9 may also determine the blood flow velocity and flow rate using other calculation methods. The calculation method is not particularly limited.

[0047]

number

[0048] The measuring apparatus 1 of the embodiment has been described above. As is clear from the above description, the processing device 9 stores in advance first relationship information indicating the relationship between the frequency spectrum of the light reception signal output by the light reception device 3 and the concentration of red blood cells contained in the blood. The processing device 9 specifies the Doppler shift frequency fd1 before correction based on the light reception signal output by the light reception device 3. Further, the processing device 9 specifies the concentration of red blood cells contained in the blood to be measured based on the frequency spectrum of the light reception signal output by the light reception device 3 and the first relationship information, and corrects the Doppler shift frequency fd1 before correction according to the specified concentration of red blood cells, thereby specifying the Doppler shift frequency fd2 after correction. The processing device 9 specifies the blood flow velocity v based on the Doppler shift frequency fd2 after correction.

[0049] According to this configuration, the relationship between the frequency spectrum of the light reception signal output by the light reception device 3 in response to the scattered light P and the concentration of red blood cells is grasped in advance. When actually measuring the blood flow velocity v, by utilizing the fact that the frequency spectrum of the light reception signal varies depending on the concentration of red blood cells contained in the blood to be measured, the Doppler shift frequency fd is corrected according to the concentration of red blood cells contained in the blood, so that the blood flow velocity v can be measured accurately. In addition, since a device for measuring the concentration of red blood cells is not separately required, a low-cost and small-sized configuration can be achieved.

[0050] Further, the processing device 9 stores in advance second relationship information indicating the relationship between the concentration of red blood cells contained in the blood and the correction value corresponding thereto. The processing device 9 corrects the Doppler shift frequency fd1 before correction based on the concentration of red blood cells specified based on the first relationship information and the second relationship information, thereby specifying the Doppler shift frequency fd2 after correction. According to this configuration, the blood flow velocity v can be accurately measured according to the concentration of red blood cells contained in the blood to be measured.

[0051] The processing device 9 identifies the Doppler shift frequency fd1 before correction based on the difference between the frequency spectrum of the third light reception signal by the first laser beam L1 and the second laser beam L2, the frequency spectrum of the first light reception signal by the second laser beam L2, and the frequency spectrum of the second light reception signal by the first laser beam L1. According to this configuration, the blood flow velocity v can be accurately measured by using the first laser beam L1 and the second laser beam L2.

[0052] (Modification example) In the above embodiment, the light shielding device 5 is configured to be able to shield the first laser beam L1 and the second laser beam L2, but the configuration is not limited to this. In a modification example, the light shielding device 5 may be configured to shield only the first laser beam L1 and not shield the second laser beam L2. In another modification example, the light shielding device 5 may be configured to shield only the second laser beam L2 and not shield the first laser beam L1.

[0053] As described above, specific examples of the present invention have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technology illustrated in this specification or the drawings can achieve a plurality of purposes simultaneously, and achieving one of these purposes itself has technical utility.

Explanation of reference numerals

[0054] 1: Measuring device, 2: Irradiating device, 3: Light receiving device, 5: Light shielding device, 8: Housing, 9: Processing device, 10: Intersection, 21: Light emitting element, 22: Collimator lens, 23: Condensing lens, 24: Spectrometer, 31: Light receiving element, 41: First mirror, 42: Second mirror, 52: Rotating body, 54: Motor, 92: Processing unit, 94: Storage unit, 100: Tube, L1: First laser beam, L2: Second laser beam, P: Scattered light

Claims

1. An irradiation device that irradiates blood with a first laser beam and a second laser beam that intersects the first laser beam, a light receiving device that receives scattered light generated when the first laser beam and the second laser beam irradiated by the irradiation device hit the blood, and outputs a light reception signal corresponding to the received scattered light, a processing device that stores in advance first relationship information indicating the relationship between the frequency spectrum of the light reception signal output by the light receiving device and the concentration of red blood cells contained in the blood, and the processing device, identifies the Doppler shift frequency before correction based on the light reception signal output by the light receiving device, identifies the concentration of red blood cells contained in the blood to be measured based on the frequency spectrum of the light reception signal output by the light receiving device and the first relationship information, identifies the Doppler shift frequency after correction by correcting the Doppler shift frequency before correction according to the identified concentration of red blood cells, and a measuring device that identifies the blood flow velocity based on the Doppler shift frequency after correction.

2. The processing device, stores in advance second relationship information indicating the relationship between the concentration of red blood cells contained in the blood and the correction value corresponding thereto, and identifies the Doppler shift frequency after correction by correcting the Doppler shift frequency before correction based on the concentration of red blood cells identified based on the first relationship information and the second relationship information. The measuring device according to claim 1.

3. The processing device identifies the Doppler shift frequency before correction based on the difference between the frequency spectrum of the light reception signal corresponding to the scattered light generated when both the first laser beam and the second laser beam hit the blood and the frequency spectrum of the light reception signal corresponding to the scattered light generated when only one of the first laser beam and the second laser beam hits the blood. The measuring device according to claim 1 or 2.

Images