JP2022149718A - Interface detection sensor and interface detection method - Google Patents

Abstract

To provide an interface detection sensor that can increase a scan speed at which a light scans a detection target and can suppress a decline of a detection accuracy of an interface included in a detection target.SOLUTION: An interface detection sensor comprises: a light projecting unit for sequentially projecting a projection object light set including a first projection object light having a first wavelength and a second projection object light having a second wavelength, to a detection target having multiple layers; a light receiving unit for sequentially receiving a reception object light set including a first reception object light derived from the first projection object light through passing through the detection target, and a second reception object light derived from the second projection object light through passing through the detection target; and a control unit for synchronizing a light projecting timing of the light projecting unit and a light receiving timing of the light receiving unit, and for detecting interfaces of the multiple layers included in the detection target based on the sequentially reception object light set. The light projecting unit starts projecting the second projection object light during or at finishing the projection of the first projection object light.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to interface detection sensors and interface detection methods.

Conventionally, methods for detecting interfaces are known. For example, two light pulses having different wavelengths are alternately illuminated at time intervals to illuminate a sample tube, the intensity of the two light pulses that pass through the sample tube is measured, and the intensity of the two light pulses measured is measured. An interface detection method is known for detecting interface detection according to intensity (see Patent Document 1). The two light pulses here follow essentially the same optical axis through the sample tube. Also, for example, a beam combiner emits two radiations having different wavelengths at different times toward the sample tube, and the same detector detects the two transmitted radiations to detect information about the sample tube. A separator system is known (see Patent Document 2). The two rays here go to slightly different positions, and the two penetrating rays also go to slightly different positions.

U.S. Patent Application Publication No. 2012/0013889 Special table 2015-502841 publication

In the prior art, it is difficult to increase the scanning speed for scanning a detection target such as blood while suppressing deterioration in interface detection accuracy within the detection target.

The present disclosure has been made in view of the above circumstances, and provides an interface detection sensor and an interface detection method capable of suppressing deterioration in interface detection accuracy within a detection target while increasing the scanning speed for scanning the detection target. .

One aspect of the present disclosure sequentially projects a light projection light set including a first light having a first wavelength and a second light having a second wavelength onto a detection target having a plurality of layers. a light projecting unit, a first light receiving light that is a signal transmitted through the detection object by the first light projection, and a second light that is a signal transmitted through the detection object by the second projection light; a light-receiving unit for sequentially receiving a set of received light including received light; and timing of light projection by the light-projecting unit and timing of light-receiving by the light-receiving unit are synchronized, and included in the detection target based on the set of received light. and a controller for detecting the interfaces of the plurality of layers, wherein the light projecting unit controls the projection of the second light during or at the end of the projection of the first light. Starting with the interface detection sensor.

According to one aspect of the present disclosure, a step of projecting a first projected light having a first wavelength onto a detection target having a plurality of layers; Alternatively, at the end of light projection, by starting projection of a second light having a second wavelength, the step of projecting the second light is projected; a step of receiving a received light set including a first received light that is a signal transmitted through an object and a second received light that is a signal of the second projected light transmitted through the detection object; and detecting the interfaces of the plurality of layers included in the detection target based on the received light set.

Advantageous Effects of Invention According to the present disclosure, it is possible to suppress deterioration in interface detection accuracy within a detection target while speeding up the scanning speed for scanning the detection target.

FIG. 2 is a diagram showing a configuration example of a blood interface detection system according to an embodiment; Block diagram showing a configuration example of an interface detection sensor Graph showing the transmission characteristics of each projected light for a blood sample A diagram showing a first example of the light projection timing of the light projection light set, the light reception timing of the light reception light set, and the vertical irradiation position with respect to the blood collection tube. A diagram showing a first example of the light projection timing and the light projection amount of each light beam included in the light projection light set of FIG. FIG. 4 is a diagram showing a second example of the light projection timing and the light projection amount of each light beam included in the light projection light set of FIG. 3; A diagram showing a third example of the light projection timing and the light projection amount of each light projection light included in the light projection light set of FIG. When the first projected light and the second projected light are arranged temporally adjacent to each other, the light projection timing of the light projection light set, the light reception timing of the light reception light set, and the vertical irradiation position with respect to the blood collection tube A diagram showing a second example of FIG. 4 is a diagram showing an example of light receiving timing and light receiving amount of each light receiving light included in the light receiving light set of FIG. 3 ; FIG. 6 is a diagram showing an example of light reception timing and light reception amount of each light reception light included in the light reception light set of FIG. 5 ; FIG. 11 shows an example of scanning positions for a blood collection tube and circular beams and rectangular beams for scanning each scanning position; FIG. 10 is a diagram for explaining the progression state of the projected light on the observation surface according to the presence or absence of displacement of the blood collection tube when the projected light is a circular beam; FIG. 10 is a diagram for explaining the progression state of the projected light on the observation surface according to the presence or absence of displacement of the blood collection tube when the projected light is a circular beam; FIG. 10 is a diagram for explaining the progression state of the projected light on the observation surface according to the presence or absence of displacement of the blood collection tube when the projected light is a circular beam; FIG. 10 is a diagram for explaining the progress of projected light on an observation surface according to the presence or absence of displacement of a blood collection tube when projected light is a rectangular beam; FIG. 10 is a diagram for explaining the progress of projected light on an observation surface according to the presence or absence of displacement of a blood collection tube when projected light is a rectangular beam; FIG. 10 is a diagram for explaining the progress of projected light on an observation surface according to the presence or absence of displacement of a blood collection tube when projected light is a rectangular beam; FIG. 4 is a diagram showing an example of the amount of received light corresponding to projected light when the projected light is a circular beam; FIG. 6 is a diagram showing an example of the amount of received light corresponding to the projected light when the projected light is a rectangular beam; A diagram for explaining the effect of temporal adjacency of a plurality of received lights within a set of received lights. A diagram for explaining the effect of spatial adjacency of scan areas aligned in the z-direction of a blood sample.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary verbosity in the following description and to facilitate understanding by those skilled in the art. It should be noted that the accompanying drawings and the following description are provided to allow those skilled in the art to fully understand the present disclosure and are not intended to limit the claimed subject matter thereby.

(Background leading up to the content of the embodiment)
The conventional interface detection sensor alternately emits two types of light pulses while changing the position of the sample tube irradiated with the light pulse with respect to the light source emitting the light pulse at a constant speed along the longitudinal direction of the sample tube. Repeatedly lit. The repetition period of the lighting of the two types of light pulses ( light projection cycle) is set longer.

Here, in order to shorten the time required for interface detection, it is necessary to increase the update speed (scan speed) of the position of the sample tube with respect to the light source. On the other hand, if the scanning speed is increased without changing the light projection period (for example, if the scanning speed is doubled), the interval between the irradiation positions (also referred to as vertical irradiation positions) at which the sample tube is irradiated with the light pulse is spreads. In this case, since vertical irradiation positions cannot be finely set along the longitudinal direction of the sample tube, the interface detection accuracy is lowered.

On the other hand, if the light projection period is shortened (for example, if the light projection period is halved) in order to finely set the vertical irradiation positions along the longitudinal direction of the sample tube, the rising edge of the previous signal adjacent in time series will be reduced. The downstream waveform overlaps the next signal, and affects the received light waveform of the next signal. As a result, the interface detection accuracy also decreases.

In the following embodiments, an interface detection sensor and an interface detection method capable of suppressing a decrease in interface detection accuracy in a detection target while increasing the scanning speed for scanning the detection target will be described.

(embodiment)
<Configuration of blood interface detection system>
FIG. 1 is a diagram showing a configuration example of a blood interface detection system 5 according to an embodiment. The blood interface detection system 5 includes a blood collection tube 50 , a moving mechanism 60 and an interface detection sensor 100 .

In addition, in this embodiment, the x direction, the y direction, and the z direction are defined. The z-direction is the extending direction of the blood collection tube 50, for example, the vertical direction. The y direction is a direction perpendicular to the z direction, and is the traveling direction of light projected from a light projecting unit 110, which will be described later. The x direction is the direction perpendicular to the y and z directions. The positive side in the z-direction is also described as top, and the negative side in the z-direction is also described as bottom.

The blood collection tube 50 accommodates the blood sample C (see FIG. 3, etc.). A blood sample C is an example of an interface detection target. The blood sample C has a plurality of layers, for example, a layer of blood clot C1 and a layer of serum C3 (see FIG. 3, etc.). The blood sample C may have a layer of the separation material C2 (see FIG. 3, etc.). Separating material C2 is, for example, an organic separating gel. For example, a separation material C2 is injected into the blood collection tube 50 and centrifuged by a centrifuge to separate the blood sample C into a clot C1, a separation material C2, and serum C3. The clot C1 has a layer of buffy coat C12 and a layer of red blood cells C11. Buffy coat C12 has, for example, white blood cells and platelets.

The moving mechanism 60 has a holding arm 61 that holds the blood collection tube 50 and a driving member (for example, a motor) that supplies driving force to the holding arm 61 . The movement mechanism 60 moves the blood collection tube 50 along the longitudinal direction (z direction) of the blood collection tube 50 . The longitudinal direction of the blood collection tube 50 is parallel to the vertical direction. The moving direction (z direction) of the blood collection tube 50 is the scanning direction for interface detection.

The interface detection sensor 100 includes a light projecting section 110 , a light receiving section 120 and a control section 130 . The housing of the interface detection sensor 100 has an arbitrary shape, for example, a U-shape as shown in FIG. In the U-shape, there is a space between the light projecting section 110 and the light receiving section 120, and the light projecting section 110 and the light receiving section 120 are arranged at a distance d1. A blood collection tube 50 is arranged in the space between the light projecting section 110 and the light receiving section 120 so as to be movable in the z direction. A distance d1 is the distance from the light projecting port of the light projecting unit 110 to the light receiving port of the light receiving unit 120, and is also referred to as the distance between light projecting and receiving. Alternatively, the position of the blood collection tube 50 may be fixed, and the interface detection sensor 100 may be arranged so as to be movable in the z-direction by the moving mechanism 60 . Even in this case, the relative positional relationship along the z-direction between the interface detection sensor 100 and the blood collection tube 50 can be changed.

When the interface detection sensor 100 has the above-described U-shape, the light projecting portion 110 and the light receiving portion 120 are integrally fixed. Alignment becomes easier. Note that the interface detection sensor 100 does not have to be formed in a U-shape.

The light projection unit 110 sequentially projects (irradiates) a light projection light set S10 including a plurality of light projection lights S11, S12, . . . having different wavelengths λ (λ1, λ2, . The projected light may be, for example, laser light or pulsed light. The light receiving section 120 sequentially receives a received light set S20 including a plurality of received lights S21, S22, . . . having different wavelengths λ. The received light may be, for example, laser light or pulsed light. The received light is a signal obtained by transmitting the light projected by the light projecting unit 110 through the blood collection tube 50 . Based on the received light set S20 received by the light receiving unit 120, the control unit 130 detects the boundaries (interfaces) of the layers of the blood sample C in the blood collection tube 50 in a non-contact manner.

Specifically, when the separation material C2 is present in the blood sample C in the blood collection tube 50, the controller 130 controls the interface between the layer of the clot C1 and the layer of the separation material C2, the layer of the separation material C2 and the serum C3. at least one of the interface with the layer of serum C3 and the interface between the layer of serum C3 and the air layer. Further, when the separation material C2 is not present in the blood sample C in the blood collection tube 50, the control unit 130 controls the interface between the clot C1 layer and the serum C3 layer and the interface between the serum C3 layer and the air layer. detect at least one of

FIG. 2A is a block diagram showing a configuration example of the interface detection sensor 100. As shown in FIG. The interface detection sensor 100 includes the light projecting section 110, the light receiving section 120, and the control section 130 as described above.

The light projecting unit 110 includes one or more (for example, two) drivers 111, one or more (for example, two) light projecting elements 112, one or more (for example, two) lenses 113, and a multiplexer. 114 and. A plurality of systems of the driver 111, the light projecting element 112, and the lens 113 are provided corresponding to the number of light beams projected by the light projecting unit 110 and having different wavelengths.

Each driver 111 acquires control information from the control unit 130, drives each light projecting element 112 connected to each driver 111 based on the control information, and supplies a light projection signal. For example, the driver 111A drives the light projecting element 112A and supplies a light projection signal. The driver 111B drives the light projecting element 112B and supplies a light projection signal.

Each light projecting element 112 converts the light projection signal from the driver 111 from an electrical signal to an optical signal, and projects light having different wavelengths λ (λ1, λ2, . . . ). For example, the light projecting element 112A projects light S11 having a wavelength λ1 (for example, 1550 nm or 1300 nm). The light projecting element 112A projects light S12 having a wavelength λ2 (980 nm, for example).

The wavelength λ1 of the projected light S11 and the wavelength λ2 of the projected light S12 may be determined by the control unit 130 according to the detection target. The wavelength λ1 and the wavelength λ2 are determined so that the projected light S11 and the projected light S12 change between layers to be detected. Each layer means between the layer of clot C1 and the layer of separation material 62, between the layer of separation material 62 and the layer of serum C3, between the layer of serum C3 and the layer of air, or between the layer of separation material C2. at least one between the layer of clot C1 and the layer of serum C3 in the absence of C.

The projected light S11 is light having a wavelength in the infrared region. Further, the projected light S12 is light having a wavelength in a wavelength region shorter than the wavelength of the projected light S11. The projected lights S11 and S12 are preferably lights with wavelengths in the near-infrared region. The wavelength λ1 is, for example, any wavelength between 1300 nm and 2000 nm. The wavelength λ2 is, for example, any wavelength between 800 nm and 1100 nm. The wavelength λ1 is, for example, 1550 nm. The wavelength λ2 is, for example, 980 nm.

Each lens 113 causes each light projected from each light projecting element 112 to travel to the combiner 114 . For example, the lens 113A advances the projected light S11 to the combiner 114, and the lens 113B advances the projected light S12 to the combiner 114. FIG.

The multiplexer 114 merges the projection lights (for example, the projection lights S11 and S12) obtained through the lenses 113 on the same optical path. This same optical path is an optical path from the multiplexer 114 to the light receiving section 120 through the blood collection tube 50 . Combiner 114 may comprise, for example, a reflective mirror and a dichroic mirror. The combined projection lights S11 and S12 form a projection light set S10, are emitted from the light projection port to the outside of the light projection section 110, pass through the blood collection tube 50, and proceed to the light receiving section 120. FIG.

The light receiving section 120 includes a lens 121 , a light receiving element 122 and an amplifier 123 . Note that the light receiving unit 120 does not have to include the lens 121 .

The lens 121 acquires a received light set S20 including the received lights S21 and S22 transmitted by the projected lights S11 and S12 through the light receiving opening. The lens 121 converges the received light beams S21 and S22 onto the light receiving element 122 . The light receiving element 122 converts an optical signal as received light into an electrical signal and outputs a received light signal having a signal level corresponding to the amount of received light to the amplifier 123 . The amplifier 123 amplifies each light receiving signal output from the light receiving element 21 and outputs it to the control section 130 .

The control section 130 includes an amplifier 131 , an AD converter 132 , a CPU 133 , an output section 144 and an output section 145 . Note that the control unit 130 does not have to include the amplifier 131 .

The amplifier 131 amplifies each received light signal acquired from the light receiving section 120 . The AD converter 132 converts the analog values of these received light signals into digital values and sends them to the CPU 133 . This digital value indicates the amount of received light S21 and S22 included in the received light set S20 received by the light receiving unit 120 .

The CPU 133 is an example of a processor and controls the light projecting section 110 and the light receiving section 120 . The CPU 133 synchronizes the timing of light projection by the light projecting unit 110 and the timing of light reception by the light receiving unit 120, for example. The CPU 133 detects the interface of each layer of the test object (for example, the blood sample C in the blood collection tube 50) based on the amount of received light S21 and S22 (the signal level of the received signal) obtained from the AD converter 132. .

For example, the CPU 133 collects data indicating temporal changes in the amount of received light S21 and data indicating temporal changes in the amount of received light S22, and based on the collected data, determines the interface of each layer of the blood sample C. may be detected. For example, the CPU 133 may detect the interface of each layer of the blood sample C based on the difference between the amount of received light S21 and the amount of received light S22. For example, the CPU 133 may compare a threshold value stored in a memory (not shown) included in the control unit 130 with the amount of received light, and detect the interface based on the result of this comparison. A threshold is set according to a detection target. For example, in the blood sample C to be detected, the interface between the clot C1 and the separation material C2, the interface between the layer of the separation material C2 and the layer of serum C3, and the interface between the layer of serum C3 and the air layer are detected. In this case, a threshold for detecting each interface may be set. The CPU 133 outputs a detection signal including information on the detected interface to the outside via the output unit 134 .

The CPU 133 may store characteristic information indicating the relationship between each wavelength of light and transmittance, that is, information on the transmission spectrum of each wavelength in advance in the memory. FIG. 2B is a graph showing transmission characteristics (an example of characteristic information) of each projected light with respect to the blood sample C. FIG. This transmission characteristic indicates the relationship between the wavelength of each projected light and the transmittance. This transmittance is the amount of light received when the projected light is directly received as received light by an arbitrary light receiving element, and the amount of light received when the same light receiving element receives the light that has passed through a sample with a thickness of 16 mm. Show a percentage. A solid characteristic line A1 indicates the transmittance of serum C3. A dashed characteristic line A2 indicates the transmittance of the separation material C2. A dashed characteristic line A3 indicates the transmittance of the clot C1. The CPU 133 may determine the wavelength λ1 of the projection light S11 and the wavelength λ2 of the projection light S12 projected by the light projecting section 110 based on the characteristic information. The CPU 133 may include information on the wavelength λ1 of the projected light S11 and the wavelength λ2 of the projected light S12 in the control information and send the control information to the light projecting section 110 via the output section 135 .

The CPU 133 controls light projection by the light projecting section 110 so that the amount of light received by the light receiving light set S20 increases in time series in an upward staircase pattern. For example, the CPU 133 may determine light projection information regarding each light projection based on the characteristic information held in the memory. The projection information of the projected light may include, for example, at least one of the projected amount of each projected light (the signal level of the projected light signal), the wavelength of each projected light, and the order of projection of each projected light. . In this case, the CPU 133 acquires, as the characteristic information, information on the transmittance of each layer to be detected when light of each wavelength is projected, and based on this transmittance, the projected light of each wavelength is the detection target. You may calculate the amount of attenuation when it permeate|transmits each layer of. Then, the CPU 133 may determine the amount of projected light so that the amount of received light obtained by subtracting the attenuation amount from the amount of projected light ascends in time series. Further, when the amount of projected light is determined in advance, the CPU 133 calculates the amount of attenuation at which the desired amount of received light is obtained, calculates the transmittance corresponding to the amount of attenuation, and wavelength may be derived from the characteristic information. The CPU 133 may include the determined light projection information in the control information and send it to the light projection section 110 via the output section 135 .

When the amount of light received by the received light set S20 decreases in time series in a descending staircase pattern, the CPU 133 changes the order of projection of the plurality of projected lights included in the projected light set S10. The CPU 133 may include the information on the order of light projection that has been changed in the control information and send the control information to the light projection section 110 via the output section 135 .

FIG. 3 is a diagram showing a first example of the light projection timing of the light projection light set S10, the light reception timing of the light reception light set S20, and the vertical irradiation position with respect to the blood collection tube 50. As shown in FIG. The vertical irradiation position is a position (z-direction position) along the moving direction of the blood collection tube 50, and is a position through which the light projected from the light projection unit 110 along the y-direction is transmitted. In FIG. 3, as the received light set S20, the projected light set S10 is projected such that the light receiving timing of the received light S21 and the light receiving timing of the received light S22 do not overlap in time series and are adjacent to each other.

That is, according to the control by the control unit 130, the light projecting unit 110 first starts projecting the light projecting light S11 when projecting the light projecting light set S10. Then, the light projecting section 110 starts projecting the projected light S12 when the projection of the projected light S11 ends, and then ends the projection of the projected light S12. In this case, since the control unit 130 synchronizes the light projection timing and the light reception timing, the light reception unit 120 synchronizes the light projection timing of the light projection light S11 and the light projection timing of the light projection light S12. A received light set S20 including S21 and received light S22 is received. As a result, the light-receiving unit 120 first starts receiving the received light S21 when receiving the light-receiving light set S20, starts receiving the light-receiving light S22 when the light-receiving light set S21 is finished, and then starts receiving the light-receiving light S22. finish.

In FIG. 3, the light projection period T1 of the light projection light set S10 includes a first light projection period T11 in which the light S11 is projected, a second light projection period T12 in which the light S12 is projected, including. In the light projection period T1, the first light projection period T11 is the first half period in time series, and the second light projection period T12 is the second half period in time series. The first light projection period T11 and the second light projection period T12 are adjacent and continuous in time series. After projecting one projection light set S10, the light projection unit 110 projects the next projection light set S10 after a predetermined time interval TI1. Such projection of the projection light set S10 is repeated. Therefore, a period obtained by combining the light projection period T1 and the predetermined time interval TI1 is the light projection period TP, and the projection of the light projection light set S10 is repeated at the light projection period TP. Both the projected light S11 and the projected light S12 are projected once in one period of the light projection period TP.

The light receiving period T2 of the light receiving light set S20 includes a first light receiving period T21 during which the light receiving light S21 is received and a second light receiving period T22 during which the light receiving light S22 is received. In the light receiving period T2, the first light receiving period T21 is the first half period in time series, and the second light receiving period T22 is the second half period in time series. The first light receiving period T21 and the second light receiving period T22 are adjacent and continuous in time series. After receiving one received light set S20, the light receiving section 120 receives the next received light set S20 after a predetermined time interval TI2. Such light reception of the light reception light set S20 is repeated. Therefore, a period obtained by combining the light receiving period T2 and the predetermined time interval TI2 is the light receiving period TR, and light reception by the light receiving light set S20 is repeated in the light receiving period TR. Both the received light S21 and the received light S21 are received once in one cycle of the light receiving cycle TR.

Further, the moving mechanism 60 is capable of moving the blood collection tube 50 in the z direction during the interface detection operation (during the light projection operation and the light reception operation) for detecting the interface of each layer contained in the blood sample C by the interface detection sensor 100. be. That is, while the blood collection tube 50 moves in the z-direction according to movement control by the moving mechanism 60, the light projecting unit 110 projects the light projecting light set S10 and the light receiving unit 120 receives the light receiving light set S20.

For example, in FIG. 3, the blood collection tube 50 is moving from the negative side to the positive side (upward) in the z direction during the interface detection operation. The blood collection tube 50 may move at a constant speed in the z-direction. When the moving speed of the blood collection tube 50 is constant, the light-projecting light set S10 is projected at a constant light-projecting period TP, and the light-receiving light set S20 is received at a constant light-receiving period TR.

In this case, for example, when the first set of projected light beams S10 is projected, the light projection unit 110 irradiates the first spatial region R1 of the blood collection tube 50 with the projected light beams S11 during the first light projection period T11, and receives the light beams. The unit 120 receives the received light S21 that has passed through the first spatial region R1 during the first light receiving period T21. The first spatial region R1 is located near the lower end of the layer of clot C1 located at the bottom in the blood collection tube 50 . Subsequently, the light projecting unit 110 irradiates the second spatial region R2 of the blood collection tube 50 with the light projecting light S12 during the second light projecting period T12, and the light receiving unit 120 irradiates the second space region R2 during the second light receiving period T22. The received light S22 transmitted through is received. The second spatial region R2 is included at the location of the layer of the clot C1 within the blood collection tube 50 and is positioned above and spatially continuous with the first spatial region R1. The control unit 130 determines whether or not the interface of the blood sample C exists within the combined area of the first spatial area R1 and the second spatial area R2. Each spatial region is an example of a scanning region (scanning region) for testing the blood sample C. FIG. Further, it can be said that each spatial region is a region in which the vertical irradiation positions where the blood collection tube 50 is irradiated with the projection light are continuous.

In the period from the projection of the projected light S12 of the first projected light set S10 during projection to the projection of the projected light S11 of the next second projected light set S10, the projected light is There is a time interval TI1 during which no light is emitted. Therefore, there is a time interval TI2 during which no received light is received during the period from the reception of the received light S22 of the currently received light set S20 to the projection of the received light S21 of the next received light set S20. The time intervals TI1 and TI2 may be determined taking into account the falling period S22a of the received light S22 in the second light receiving period T22. The fall period S22a is a period from immediately after the end of the reception of the received light S22 until the amount of received light S22 becomes equal to or less than a predetermined amount. The predetermined amount may have a value of 0, or even if it does not have a value of 0, the remaining signal superimposed on the received light in the first light receiving period T21 of the received light set S20 to be received next is minute. , the influence on the interface detection based on the light reception of the light reception light set S20 to be received next can be ignored. For example, the period from the end of light reception of the first set of received light S20 to the start of light reception of the second set of received light S20 subsequent to the first set of received light S20 is longer than the fall period S22a, or It may have the same length as the fall period S22a.

The light projecting unit 110 repeatedly projects the light projecting light set S10 at a constant light projecting period TP. Therefore, the projection of the light beams S11 and S12 is also repeated at a fixed light projection period TP. Therefore, the light receiving section 120 repeatedly receives the received light set S20 at a constant light receiving period TR. Therefore, the light reception of the light reception lights S21 and S22 is also repeated at a constant light reception cycle TR.

For example, the light projecting unit 110 projects the first set of projected lights S10 and then the second set of projected lights S10 subsequent to the first set of projected lights S10. In FIG. 3, the first spatial region R1 where the projected light S11 of the second projected light set S10 is projected is near the layer of the separation material C2 located near the middle in the z direction inside the blood collection tube 50. To position. The light receiving section 120 receives the received light S21 transmitted through the first spatial region R1. Further, the second spatial region R2 onto which the projected light beams S12 of the second set of projected light beams S10 are projected is located above the first spatial region R1 and spatially continuous with the first spatial region R1, Located near the lower end of the layer of serum C3 located above the layer of separation material C2. The light receiving section 120 receives the received light S22 transmitted through the second spatial region R2.

Similarly, the light projecting unit 110 projects the second set of projected lights S10 and then the third set of projected lights S10 subsequent to the second set of projected lights S10. In FIG. 3, the first spatial region R1 where the projected light S11 of the third projected light set S10 is projected is located in the air layer above the blood collection tube 50 in the z direction. The light receiving section 120 receives the received light S21 transmitted through the first spatial region R1. Further, the second spatial region R2 onto which the projection light S12 of the third projection light set S10 is projected is located above the first spatial region R1 and spatially continuous with the first spatial region R1, Located in the layer of air. The light receiving section 120 receives the received light S22 transmitted through the second spatial region R2.

The higher the moving speed of the blood sampling tube 50 in the z direction by the moving mechanism 60, the wider the spatial interval between the vertical irradiation positions that are repeatedly projected. In other words, the higher the moving speed of the blood sampling tube 50 in the z direction by the moving mechanism 60, the more the projection light S11 of the adjacent light projection light set S10 is projected in order to obtain as many detection results as possible for the detection target. It is preferable that the distance d2 along the z-direction of the vertical irradiation position where the light is applied is short. On the other hand, in order to shorten the distance d2, it is necessary to shorten the light projection period TP. In this case, if the projected light S11 and the projected light S12 are projected with a time interval, the received light S21 and the received light S22 are likely to coexist.

On the other hand, the interface detection sensor 100 can continuously receive the received light beams S21 and S22 in time series by continuously transmitting the projected light beams S11 and S12 in chronological order. can be easily shortened. Therefore, the interface detection sensor 100 can project as many light beams S11 and S12 as possible in a short period of time and receive as many light beams S21 and S22 as possible in a short period of time. Therefore, the distance d2 can be made as short as possible.

Further, the control unit 130 causes the light projecting unit 110 to project light so that the amount of received light in the time series included in the received light set S20 increases in an upward staircase pattern. That is, in each light receiving period T2, the light projecting section 110 is arranged such that the amount of light received during the second light receiving period T22 is larger than the amount of light received during the first light receiving period T21. The characteristics of the projected light beams S11 and S12 (for example, the amount of light projected or the wavelength) and the light projection order of the projected light beams S11 and S12 are adjusted. That is, on the light-receiving side, the amount of received light (light energy) of the light-receiving lights S21 and S22 is adjusted so as to increase in ascending steps in time series.

Within the same received light set S20, the falling component of the received light S21 received earlier in time series can be superimposed on the received light S22 received later in time series. Even in this case, the falling component of the received light beam S21 is sufficiently smaller than the received light quantity of the received light beam S22 because the received light amount in the time series of the received light set S20 is in an upward staircase pattern. Therefore, the interface detection sensor 100 detects that the received light S21 received during the first light receiving period T21 interferes with the received light S22 received during the second light receiving period T22, and the same received light set including both the received lights S21 and S22 is detected. It is possible to suppress deterioration in accuracy of interface detection based on S20.

Further, in different received light sets S20, the received light S22 of the received light set S20 that is received first is likely to be mixed with the received light S21 of the received light set S20 that is received later. On the other hand, by ensuring the time interval TI2 taking into account the falling edge, the interface detection sensor 100 detects the received light S22 of the previous received light set 20 in chronological order and the received light S21 of the later received light set S20. , thereby suppressing deterioration in accuracy of interface detection based on the subsequent received light set S20.

According to the first operation example shown in FIG. 3, the interface detection sensor 100 detects two adjacent received light beams S21 in time series after the two adjacent light beams S11 and S12 in time series pass through the blood collection tube 50. , S22 can be obtained. The interface detection sensor 100 can be adjusted so that the amount of received light S21 and S22 increases in time series in an upward staircase manner. Therefore, the interface detection sensor 100 can suppress the deterioration of the interface detection accuracy due to the slow fall of the light receiving light set S20. In addition, since the interface detection sensor 100 can maximize the repetition period of the light pulse irradiation, it is possible to obtain the received light set S20 corresponding to a large number of vertical irradiation positions along the z direction, and the resolution of the interface detection in the z direction. can be improved.

4A to 4C are diagrams showing an example of the light projection timing and the light projection amount of each of the light projection lights S11 and S12 included in the light projection light set S10 of the first example shown in FIG.

In FIG. 4A, the amount of projected light S11 and S12 included in each projected light set S10 in time series increases in an upward staircase manner. That is, the amount of projected light S12 is larger than that of projected light S11 in the same set S10 of projected light. In this case, the amount of light received in the time series of the light receiving light set S20 transmitted through the blood sample C in the blood collection tube 50 by the light projecting light set S10 also tends to increase in an upward staircase manner. For example, when the transmittance of the projected light beams S11 and S12 is substantially equal in the transmittance characteristics of the blood sample C in consideration of the wavelengths λ1 and λ2 of the projected light beams S11 and S12 as described above, the received light set is set on the light receiving side as well. The amount of received light in the time series of S20 increases in an upward stair-like manner.

In FIG. 4B, the amount of projected light S11 and S12 included in each set of projected light S10 decreases in a time-series manner. That is, the amount of projected light S12 is smaller than that of projected light S11 in the same set S10 of projected light. Even in this case, the amount of light received by the light receiving unit 120 in the time series of the light receiving light set S20 received by the light receiving unit 120 is determined according to the transmission characteristics of the blood sample C in consideration of the wavelengths λ1 and λ2 of the light emitting lights S11 and S12 as described above. should increase in the shape of an upward staircase.

In FIG. 4C, the shape indicated by the amount of light projected in time series of the light projected lights S11 and S12 included in each light projected light set S10 is rectangular. That is, the light projection amounts of the light projection light S11 and the light projection light S12 in the same light projection light set S10 are equal. Even in this case, the amount of light received by the light receiving unit 120 in the time series of the light receiving light set S20 received by the light receiving unit 120 is determined according to the transmission characteristics of the blood sample C in consideration of the wavelengths λ1 and λ2 of the light emitting lights S11 and S12 as described above. should increase in the shape of an upward staircase.

FIG. 5 is a diagram showing a second example of the light projection timing of the light projection light set S10, the light reception timing of the light reception light set S20, and the vertical irradiation position with respect to the blood collection tube 50. As shown in FIG. In FIG. 5, as the received light set S20, the projected light set S10 is projected so that the light receiving timing of the received light S21 and the light receiving timing of the received light S22 overlap in time series.

That is, according to the control by the control unit 130, the light projecting unit 110 first starts projecting the light projecting light S11 when projecting the light projecting light set S10. The light projecting unit 110 starts projecting the light S12 during the projection of the light S11, that is, before the light S11 is completely projected. exit. In this case, since the control unit 130 synchronizes the light projection timing and the light reception timing, the light reception unit 120 synchronizes the light projection timing of the light projection light S11 and the light projection timing of the light projection light S12. A received light set S20 including S21 and received light S22 is received. As a result, the light receiving section 120 first starts receiving the received light S21 when receiving the received light set S20, and starts receiving the received light S22 during the reception of the received light S21, that is, before the reception of the received light S21 ends. After that, the projection of the received light S22 is terminated.

That is, compared with the first example shown in FIG. 3, in the second example shown in FIG. The light period and the projection period of the projection light S12 at least partially overlap. Therefore, as compared with the first example shown in FIG. 3, in the second example shown in FIG. It at least partially overlaps with the light receiving period of S22.

In FIG. 5, the light projection period T1 of the light projection light set S10 consists of a first light projection period T11 during which the light projection light S11 is projected and a second light projection period T11 during which the light projection light S11 and the light projection light S12 are projected. and a light period T12. In the light projection period T1, the first light projection period T11 is the first half period in time series, and the second light projection period T12 is the second half period in time series. The first light projection period T11 and the second light projection period T12 are adjacent and continuous in time series. After projecting one projection light set S10, the light projection unit 110 projects the next projection light set S10 after a predetermined time interval TI1. Such projection of the projection light set S10 is repeated. Therefore, a period obtained by combining the light projection period T1 and the predetermined time interval TI1 is the light projection period TP, and the projection of the light projection light set S10 is repeated at the light projection period TP. Both the projected light S11 and the projected light S12 are projected once in one period of the light projection period TP.

The light receiving period T2 of the received light set S20 includes a first light receiving period T21 during which the received light S21 is received and a second light receiving period T22 during which the received light S21 and the received light S22 are received. In the light receiving period T2, the first light receiving period T21 is the first half period in time series, and the second light receiving period T22 is the second half period in time series. The first light receiving period T21 and the second light receiving period T22 are adjacent and continuous in time series. After receiving one received light set S20, the light receiving section 120 receives the next received light set S20 after a predetermined time interval TI2. Such light reception of the light reception light set S20 is repeated. Therefore, a period obtained by combining the light receiving period T2 and the predetermined time interval TI2 is the light receiving period TR, and light reception by the light receiving light set S20 is repeated in the light receiving period TR. Both the received light S21 and the received light S21 are received once in one cycle of the light receiving cycle TR.

Further, the moving mechanism 60 is capable of moving the blood collection tube 50 in the z direction during the interface detection operation (during the light projection operation and the light reception operation) for detecting the interface of each layer contained in the blood sample C by the interface detection sensor 100. be. That is, while the blood collection tube 50 moves in the z-direction according to movement control by the moving mechanism 60, the light projecting unit 110 projects the light projecting light set S10 and the light receiving unit 120 receives the light receiving light set S20.

For example, in FIG. 5, the blood collection tube 50 is moving from the negative side to the positive side (upward) in the z direction during the interface detection operation. The blood collection tube 50 may move at a constant speed in the z-direction. When the moving speed of the blood collection tube 50 is constant, the light-projecting light set S10 is projected at a constant light-projecting period TP, and the light-receiving light set S20 is received at a constant light-receiving period TR.

In this case, for example, the light projecting unit 110 irradiates the first spatial region R1 of the blood collection tube 50 with the light S11 during the first light projection period T11 when the first light projection light set S10 is used. The light receiving section 120 receives the received light S21 transmitted through the first spatial region R1 during the first light receiving period T21. The first spatial region R1 is located near the lower end of the layer of clot C1 located at the bottom in the blood collection tube 50 . Subsequently, the light projecting section 110 irradiates the second spatial region R2 of the blood collection tube 50 with the light projecting light S11 and the light projecting light S12 during the second light projecting period T12. The light receiving section 120 receives the received light S21 and the received light S22 that have passed through the second spatial region R2 during the second light receiving period T22. The second spatial region R2 is included at the location of the layer of the clot C1 within the blood collection tube 50 and is positioned above and spatially continuous with the first spatial region R1. The control unit 130 determines whether or not the interface of the blood sample C exists within the combined area of the first spatial area R1 and the second spatial area R2.

In the period from the projection of the projected light S12 of the first projected light set S10 during projection to the projection of the projected light S11 of the next second projected light set S10, the projected light is There is a time interval TI1 during which no light is emitted. Therefore, there is a time interval TI2 during which no received light is received during the period from the reception of the received light S22 of the currently received light set S20 to the projection of the received light S21 of the next received light set S20. The time intervals TI1 and TI2 may be determined in consideration of the falling period S22a of the received light S21 and the received light S22 in the second light receiving period T22. The fall period S22a is a period from immediately after the end of the reception of the received light S21 and the received light S22 until the sum of the received light amounts of the received light S21 and the received light S22 becomes equal to or less than a predetermined amount. The predetermined amount may have a value of 0, or even if it does not have a value of 0, the remaining signal superimposed on the received light in the first light receiving period T21 of the received light set S20 to be received next is minute. , the influence on the interface detection based on the light reception of the light reception light set S20 to be received next can be ignored. For example, the period from the end of light reception of the first set of received light S20 to the start of light reception of the second set of received light S20 subsequent to the first set of received light S20 is longer than the fall period S22a, or It may have the same length as the fall period S22a.

The light projecting unit 110 repeatedly projects the light projecting light set S10 at a constant light projecting period TP. Therefore, the projection of the light beams S11 and S12 is also repeated at a fixed light projection period TP. Therefore, the light receiving section 120 repeatedly receives the received light set S20 at a constant light receiving period TR. Therefore, the light reception of the light reception lights S21 and S22 is also repeated at a constant light reception cycle TR.

For example, the light projecting unit 110 projects the first set of projected lights S10 and then the second set of projected lights S10 subsequent to the first set of projected lights S10. In FIG. 5, the first spatial region R1 where the projected light S11 of the second projected light set S10 is projected is near the layer of the separation material C2 located near the middle in the z direction inside the blood collection tube 50. To position. The light receiving section 120 receives the received light S21 transmitted through the first spatial region R1. A second spatial region R2, in which the projected light beams S11 and S12 of the second projected light set S10 are projected, is spatially continuous with the first spatial region R1 above the first spatial region R1. and near the lower end of the layer of serum C3 located above the layer of separation material C2. The light receiving section 120 receives the received light S21 and the received light S22 transmitted through the second spatial region R2.

Similarly, the light projecting unit 110 projects the second set of projected lights S10 and then the third set of projected lights S10 subsequent to the second set of projected lights S10. In FIG. 5, the first spatial region R1 projected by the projection light S11 of the third projection light set S10 is located in the air layer located above in the z-direction inside the blood collection tube 50 . The light receiving section 120 receives the received light S21 transmitted through the first spatial region R1. Further, the second spatial region R2 onto which the projection light S12 of the third projection light set S10 is projected is located above the first spatial region R1 and spatially continuous with the first spatial region R1, Located in the layer of air. The light receiving section 120 receives the received light S21 and the received light S22 transmitted through the second spatial region R2.

The higher the moving speed of the blood sampling tube 50 in the z direction by the moving mechanism 60, the wider the spatial interval between the vertical irradiation positions that are repeatedly projected. In other words, the higher the moving speed of the blood sampling tube 50 in the z direction by the moving mechanism 60, the more the projection light S11 of the adjacent light projection light set S10 is projected in order to obtain as many detection results as possible for the detection target. It is preferable that the distance d2 along the z-direction of the vertical irradiation position where the light is applied is short. On the other hand, in order to shorten the distance d2, it is necessary to shorten the light projection cycle TP. In this case, if the projected light S11 and the projected light S12 are projected with a time interval, the received light S21 and the received light S22 are likely to coexist.

On the other hand, the interface detection sensor 100 can overlap and receive the received lights S21 and S22 in time series by emitting the projected lights S11 and S12 in a time series overlapping manner. The period TR can be easily shortened. Therefore, the interface detection sensor 100 can project as many light beams S11 and S12 as possible in a short period of time and receive as many light beams S21 and S22 as possible in a short period of time. Therefore, the distance d2 can be made as short as possible.

Further, the control unit 130 causes the light projecting unit 110 to project light so that the amount of light received in the time series of the light receiving light set S20 increases in an upward staircase pattern. That is, in each light receiving period T2, the light projecting section 110 is arranged such that the amount of light received during the second light receiving period T22 is larger than the amount of light received during the first light receiving period T21. to adjust the characteristics of the projected light beams S11 and S12 (for example, the amount of projected light or the wavelength). That is, on the light receiving side, the sum (optical energy) of the received light amount (optical energy) of the received light S21 in the first light receiving period T21 and the received amount of the received light S21 and the received light S22 in the second light receiving period T22 is time-series. It is adjusted so that it becomes larger in the shape of an upward staircase.

In the same received light set S20, the received light S21 and the received light S22 are superimposed and received in the second light receiving period T22 that is received later in time series. Here, since the received light S21 is continuously received from the first light receiving period T21, the characteristics of the received light S21 are known during the second light receiving period T22. Therefore, the control unit 130 can calculate the characteristics of the received light S22 by subtracting the known characteristics of the received light S21 from the total characteristics of the received light S21 and the received light S22. Therefore, the interface detection sensor 100 can suppress deterioration in accuracy of interface detection based on the same received light set S20 including both the received lights S21 and S22.

Further, in different received light sets S20, the received light S22 of the received light set S20 that is received first is likely to be mixed with the received light S21 of the received light set S20 that is received later. On the other hand, by ensuring the time interval TI2 taking into account the falling edge, the interface detection sensor 100 detects the received light S22 of the previous received light set 20 in chronological order and the received light S21 of the later received light set S20. , thereby suppressing deterioration in accuracy of interface detection based on the subsequent received light set S20.

Furthermore, in the second light-receiving period T22, the light-receiving lights S21 and S22 are superimposed. can be adjusted to a large extent. Therefore, the interface detection sensor 100 can simplify the projection amount control of the projected light by the control section 130 and reduce the processing load of the control section 130 .

According to the second operation example shown in FIG. 5, the interface detection sensor 100 acquires the received light beams S21 and S22 that are superimposed in time series after the projected light beams S11 and S12 that are superimposed in time series pass through the blood collection tube 50. can. The interface detection sensor 100 can be adjusted so that the amount of received light S21 and S22 increases in time series in an upward staircase manner. In addition, it is possible to suppress the deterioration of the interface detection accuracy due to the blunted fall of the received light set S20. In addition, since the interface detection sensor 100 can maximize the repetition period of the light pulse irradiation, it is possible to obtain the received light set S20 corresponding to a large number of vertical irradiation positions along the z direction, and the resolution of the interface detection in the z direction. can be improved.

FIG. 6 is a diagram showing an example of light reception timings and light reception amounts of the light reception lights S21 and S22 included in the light reception light set S20 of the first example shown in FIG.

Although FIG. 3 illustrates that the amount of received light S21 and S22 included in each set of received light S20 is constant, the amount of received light S21 and S22 may vary in practice. Based on the received light amounts of the received light beams S21 and S22 in the received light set S20, the control unit 130 controls the time series so that the received light amount of the received light set S20 increases in an upward staircase manner, that is, the first The order of projection lights S11 and S12 may be adjusted so that the amount of light received during the second light receiving period T22 is greater than the amount of light received during the light receiving period T21. For example, when the amount of received light received during the second light receiving period T22 is greater than the amount of received light received during the first light receiving period T21, the order of projection lights S11 and S12 need not be changed. . This is because, in the current state, it is in the shape of an upward staircase. For example, when the amount of received light received during the second light receiving period T22 is smaller than the amount of received light received during the first light receiving period T21, the order of projection lights S11 and S12 may be changed. As a result, the interface detection sensor 100 has a high possibility that the amount of received light in the time series of the received light set S20 increases in a stepwise manner after the order of light projection is changed, and an improvement in interface detection accuracy is expected. can. Further, for example, when the amount of received light received during the first light receiving period T21 and the amount of received light received during the second light receiving period T22 are equal, the order of the projected lights S11 and S12 may be changed. No need to replace.

The control unit 130 receives the light in the first light receiving period T21 so that the amount of light received in the time series of the light receiving light set S20 increases in an upward staircase every time the light receiving unit 120 receives the light receiving light set S20. The order of the projected lights S11 and S12 may be adjusted so that the amount of received light received during the second light receiving period T22 is greater than the amount of received light. In this case, the control unit 130 may constantly monitor the light receiving state of the light receiving unit 120 in order to feed back the light receiving state of the light receiving unit 120 to the light projecting unit 110 each time. Then, the control unit 130 may control the state of light projection by the light projecting unit 110 (for example, the amount of light to be projected) according to the light receiving state of the light receiving unit 120 when necessary.

In FIG. 6, in the first received light set S20 in time series, the amount of received light received during the second light receiving period T22 is greater than the amount of received light received during the first light receiving period T21. 130 does not change the light projection order (the order of the light projection lights S11 and S12). As a result, in the second received light set S20 in time series, the received lights S21 and S22 are received in this order. In addition, in the received light set S20 that is second in time series, the amount of received light received in the first light receiving period T21 and the amount of received light received in the second light receiving period T22 are equal, and the control unit 130 The light order (the order of the projected light beams S11 and S12) is not changed. As a result, the received light beams S21 and S22 are received in this order in the received light set S20, which is the third in time series. In addition, in the received light set S20 that is third in time series, the amount of received light received during the second light receiving period T22 is smaller than the amount of received light received during the first light receiving period T21. , the light projection order is changed, and the order of the light projection lights is S12 and S11. As a result, the received light beams S22 and S21 are received in this order in the received light set S20, which is fourth in time series. In addition, in the received light set S20 that is fourth in time series, the amount of received light received during the second light receiving period T22 is greater than the amount of received light received during the first light receiving period T21. The light projection order (the order of the light projection lights S12 and S11) is not changed. As a result, the received light beams S22 and S21 are received in this order in the received light set S20, which is fifth in time series.

FIG. 7 is a diagram showing an example of light reception timings and light reception amounts of the light reception lights S21 and S22 included in the light reception light set S20 of the second example shown in FIG.

Although FIG. 5 illustrates that the amount of received light S21 and S22 included in each set of received light S20 is constant, the amount of received light may vary in practice. In FIG. 7, in the first light receiving period T21 included in the light receiving period T2 of each light receiving light set S20, one light receiving light S21 is received, and in the second light receiving period T22, both the light receiving light S21 and the light receiving light S22 are received. do. Therefore, even if the received light amounts of the received lights S21 and S22 change, the received light amount during the second light receiving period T22 is always larger than the received light amount during the first light receiving period T21. Therefore, the amount of light received by the light receiving light set S20 in time series always increases in an upward staircase manner. Therefore, adjustment of the light projection order as described above is unnecessary.

Next, the light beam shapes of the projected lights S11 and S12 will be described.

FIG. 8 is a diagram showing an example of the vertical irradiation position on the blood collection tube 50 and the circular beam B1 and rectangular beam B2 arranged at each scanning position.

The light beam shape of the light projected by the light projecting unit 110 may be circular, rectangular, or the like. The length l1 of the circular beam B1 and the rectangular beam B2 along the x direction perpendicular to the z direction indicates the length of the light receiving aperture of the light receiving section 120 along the x direction. A length l2 along the z-direction of the circular beam B1 and the rectangular beam B2 indicates the length along the z-direction of the light-receiving aperture of the light-receiving unit 120 . Therefore, referring to FIG. 8, it can be understood that the circular beam B1 has a larger amount of light beams not received by the light receiving aperture than the rectangular beam B2. That is, the rectangular beam B2 has a higher light energy utilization efficiency than the circular beam B1.

FIGS. 9A, 9B, and 9C are diagrams for explaining how the projected light progresses on the observation plane according to the presence or absence of displacement of the blood collection tube 50 when the projected light is a circular beam. .

In FIG. 9A, the layer of separation material C2 in the blood collection tube 50 has a vertical illumination position, includes a viewing plane, and shows that the floodlight is projected in the y-direction. 9B shows a top view of the blood collection tube 50 held by the holding arm 61 of the moving mechanism 60. FIG. In FIG. 9B, the blood collection tube 50 is arranged without any displacement in the direction parallel to the xy plane, and the circular beam B1 of the projected light passes straight through the center of the blood collection tube 50 in the x direction. showing. 9C shows a top view of the blood collection tube 50 held by the holding arm 61 of the moving mechanism 60. FIG. In FIG. 9C, the blood collection tube 50 is displaced in the direction parallel to the xy plane, and the circular beam B1 of the projected light is slightly shifted from the center of the blood collection tube 50 in the x direction. , is refracted in the blood collection tube 50 and exits the blood collection tube 50 .

FIGS. 10A, 10B, and 10C are diagrams for explaining the progress of the projected light on the observation plane according to the presence or absence of positional displacement of the blood collection tube 50 when the projected light is the rectangular beam B2. be.

FIG. 10A shows that the layer of separation material C2 in the blood collection tube 50 has a vertical illumination position, includes the viewing plane, and the floodlight is projected in the y-direction. 10B shows a top view of the blood collection tube 50 held by the holding arm 61 of the moving mechanism 60. FIG. In FIG. 10B, the blood collection tube 50 is arranged without any displacement in the direction parallel to the xy plane, and the rectangular beam B2 of the projected light passes straight through the center of the blood collection tube 50 in the x direction. showing. 10C shows a top view of the blood collection tube 50 held by the holding arm 61 of the moving mechanism 60. FIG. In FIG. 10C, the blood collection tube 50 is displaced in the direction parallel to the xy plane, and the rectangular beam B2 of the projected light is slightly shifted from the center of the blood collection tube 50 in the x direction. is incident on However, although the rectangular beam B2 is refracted inside the blood collection tube 50, it is emitted out of the blood collection tube 50 with most of the rectangular beam B2 existing on the optical axis of the light receiving section 120. FIG.

Therefore, in FIG. 10C, when compared with the circular beam B1 in FIG. 9C, most of the rectangular beam B2 remains on the optical axis OC of the light receiving unit 120 even if the blood collection tube 50 is misaligned on the xy plane. exist. Therefore, in the interface detection sensor 100, the light receiving section 120 can receive most of the received light as the rectangular beam B2, thereby suppressing deterioration in interface detection accuracy.

FIG. 11A is a diagram showing an example of the amount of received light corresponding to the projected light when the projected light is a circular beam B1.

Since the circular beam B1 has the same length in the x direction and the length in the z direction, if the length in the x direction is increased to match the width of the blood collection tube 50, the length in the z direction also increases. In this case, it is likely to be affected by the state of each layer in the blood sample C over a wide range in the z direction. For example, even if it is actually desired to detect the components of the layer of serum C3, the received light transmitted through the layer of separation material C2 and the layer of air existing above and below the serum C3 can be acquired. Therefore, the amount of light received near the interface of each layer in the blood sample C tends to change smoothly.

FIG. 11B is a diagram showing an example of the amount of received light corresponding to the projected light when the projected light is the rectangular beam B2.

The rectangular beam B2 can be shorter in the z direction than in the x direction. In FIG. 11B, the length in the x direction is made longer to match the width of the blood collection tube 50, while the length in the z direction is made shorter than the length in the x direction. In this case, interface detection sensor 100 can suppress the influence of the state of each layer in blood sample C over a wide range in the z direction. Therefore, the amount of received light that has passed through the vicinity of the interface of each layer in the blood sample C tends to sharply change. Therefore, the interface detection sensor 100 can improve the accuracy of interface detection based on the amount of received light.

It is preferable that the length in the x direction of the circular beam B1 and the rectangular beam B2 is shorter than the width of the blood collection tube 50. FIG. This is to avoid a drop in interface detection accuracy due to receiving light that does not pass through the blood collection tube 50 .

Note that both the projection light S11 with the wavelength λ1 and the projection light S12 with the wavelength λ2 have a low transmittance with respect to the blood clot C1. Further, the projection light S11 with the wavelength λ1 has a low transmittance for the serum C3, and the projection light S12 with the wavelength λ2 has a high transmittance for the serum C3. Further, the projected light S11 with the wavelength λ1 and the projected light S12 with the wavelength λ2 both have high transmittance with respect to the separation material C2. Further, the projected light S11 with the wavelength λ1 and the projected light S12 with the wavelength λ2 have a higher transmittance to air than the transmittance to the separation material C2. Therefore, the projected light S11 is projected first in time series, and the projected light S12 is projected later, so that the amount of light received by the received light set S20 in time series tends to increase like an upward staircase.

The received light set S20 received by the light receiving unit 120 includes both the received light S21 and the received light S22 that have passed through the blood sample C. FIG. Therefore, the amount of light received by the light receiving light set S20 is arranged in ascending order of clot C1, serum C3, separation material C2, and air.

Since the length of the beam shape of the projected light in the z direction is shorter than the length of the beam shape in the x direction, the interface detection sensor 100 can detect the data at each vertical irradiation position for interface detection. can improve the stability of measurement and data measurement. The interface detection sensor 100 can shorten the scanning (detection) interval in the z direction, and can improve the detection resolution. Therefore, sensitivity to changes in the z-direction can be increased. In addition, by ensuring the length of the beam shape in the x direction, it is possible to obtain a wide range of received light that has passed through the blood sample C in the blood collection tube 50. Even if the blood collection tube 50 is slightly displaced, Since light is likely to be included, measurement stability is improved. Note that when the length of the beam shape in the z direction is shorter than the length of the beam shape in the x direction, the beam shape is not limited to a rectangular shape, and may include other shapes (for example, an elliptical shape).

Next, the effects of temporal adjacency and spatial adjacency in this embodiment will be described.

FIG. 12 is a diagram for explaining the effect of the temporal adjacency of the received light beams S21 and S22 in the received light set S20.

In FIG. 12, as a comparative example, two received light beams S21X and S22X of two different wavelengths are alternately obtained separated in time series. A case where two received light beams S21 and S22 with wavelengths λ1 and λ2 are obtained is shown. It is assumed that the light-receiving period is the same between the case of being isolated in time series and the case of being adjacent in time series in FIG. 12 . Also, it is assumed that the sampling interval SI for extracting two received light beams for detecting the interface is approximately half the light receiving period. It is also assumed that the movement mechanism 60 continuously moves the blood collection tube 50 in the z direction at a constant speed.

In this case, as shown in FIG. 12, when separated in time series as in the comparative example, within one sampling interval SI, one received light having one of two different wavelengths only included. On the other hand, when adjacent in time series as in the embodiment, two received light beams S21 and S22 of two different wavelengths (received light set S20) are both included inside one sampling interval SI.

Therefore, in the comparative example, since the interface is detected based on the received light amount of one received light included in the spatial region corresponding to the spatial sampling interval in the blood sample C, the detection accuracy of the interface in this spatial region is insufficient. Become. On the other hand, the interface detection sensor 100 of the present embodiment performs interface detection based on two received light beams included in the spatial region corresponding to the spatial sampling interval in the blood sample C, thereby detecting the spatial region. The interface in can be detected with high accuracy.

The layer of clot C1 also includes a layer of buffy coat C12 containing white blood cells and platelets and a layer containing red blood cells C11. The length of the layer of the buffy coat C12 in the z-direction is much shorter than the length of the layer of the red blood cells C11 in the z-direction, forming a spatial region with an extremely thin thickness in the z-direction. The interface detection sensor 100 of the present embodiment can detect the interface of the layer of the buffy coat C12 with high accuracy even when such buffy coat C12 is included in the spatial region corresponding to the spatial sampling interval in the blood sample C. . In this manner, the interface detection sensor 100 can accurately measure the amount of transmitted light (the amount of received light) in a minute area with a short length in the z direction using the two received light beams S21 and S22 having two different wavelengths λ1 and λ2. can be implemented.

FIG. 13 is a diagram for explaining the effect of spatial adjacency of the scan regions of the blood sample C aligned in the z-direction. In FIG. 13, when the light projection period TP of the light projection unit 110 is set constant (for example, the upper limit, the shortest), and the movement speed (scan speed) of the blood collection tube 50 in the z direction is V1, V2, V3, A plurality of patterns of vertical irradiation positions (spatial regions) irradiated with two projection lights in the z direction are exemplified. Here, V3, V2 and V1 are in order of high speed (that is, V3>V2>V1).

FIG. 13 shows two spatially separated vertical irradiation positions as a comparative example. Also, as this embodiment, two spatially adjacent vertical irradiation positions are shown. For interface detection, two received lights with different wavelengths are required.

In FIG. 13, when the vertical irradiation positions are spatially separated, the length in the z-direction required to obtain two received light beams with different wavelengths becomes longer, and the interface detection target based on these two received light beams becomes longer. The spatial region that becomes becomes wide. Alternatively, if we wait until received light beams with different wavelengths are obtained at the same vertical irradiation position and try to detect the interface using a pair of received light beams obtained at the same vertical irradiation position, it takes a long time to detect the interface. become Furthermore, when the scanning speed is high like V3, it may not be possible to obtain a pair of received light beams having different wavelengths at the same vertical irradiation position.

On the other hand, when the vertical irradiation positions are spatially adjacent to each other, the length in the z-direction required to obtain two received light beams with different wavelengths becomes shorter, and the object of interface detection based on these two received light beams is becomes a narrow range. Therefore, the accuracy of interface detection is higher when the vertical irradiation positions are spatially adjacent to each other as in the present embodiment than when the vertical irradiation positions are spatially separated. Furthermore, since the interface detection sensor 100 can obtain the received light beams S21 and S22 received at two adjacent vertical irradiation positions without depending on the scanning speed, the movement speed of the blood collection tube 50 in the z direction can be increased. Even if it is reduced, it is possible to suppress the deterioration of the interface detection accuracy and improve the selectivity of the scanning speed.

As described above, the interface detection sensor 100 of the present embodiment can detect the interface such as the lower surface or the upper surface of the blood clot C1 or serum C3 in the blood sample C. FIG. Then, the interface detection sensor 100 can easily obtain the amount of serum based on, for example, the detected interface between the lower surface and the upper surface of the serum C3. In addition, the interface detection sensor 100 can improve the tact time (for example, the time required to detect the interface of the entire detection target) and improve the interface detection accuracy. Also, the interface detection sensor 100 can maintain, increase, etc., the number of vertical illumination positions per unit length in the z-direction, ie, the number of light pulses per unit length in the z-direction. Therefore, even when the scanning speed of the blood collection tube 50 containing the detection target is increased in order to improve the tact time, the interface detection accuracy can be maintained or improved. In addition, the interface can be efficiently detected by suppressing an increase in the total power (average power) of light irradiated per unit time.

Further, the interface detection sensor 100 continuously emits the two light beams S11 and S12 as the light set S10, so that even if the scanning speed of the blood collection tube 50 is increased, the emitted light pulse is can be suppressed from widening, and deterioration of the temporal and spatial coincidence of the two projection lights S11 and S12 can be suppressed. Therefore, the interface detection sensor 100 cannot acquire detection data of a minute layer (for example, a buffy coat (about 1 mm thick) or a meniscus (about 2 mm thick), or the accuracy of interface determination of a minute layer decreases. can be suppressed.

Various embodiments have been described above with reference to the drawings, but it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present invention. Understood. Moreover, each component in the above embodiments may be combined arbitrarily without departing from the spirit of the invention.

In the above embodiment, the blood collection tube 50 moves in the direction (upward) from the negative side to the positive side in the z direction during the operation of detecting the interface of the blood sample C contained in the blood collection tube 50. You may move in this reverse direction (downward).

In the above embodiments, in FIGS. 3, 4A to 4C, and 5, the light projecting unit 110 first projects the light having the wavelength λ1 in chronological order as the basic light projecting operation, and the wavelength Although the example of projecting the projection light having λ2 later in time series has been described, the present invention is not limited to this. As a basic light projecting operation, light projecting section 110 may project light having wavelength λ2 first in time series, and may project light having wavelength λ1 later in time series.

In the above embodiment, the relative positional relationship between the interface detection sensor 100 and the blood collection tube 50 along the z-direction was exemplified as changeable, but the present invention is not limited to this. For example, the interface detection sensor 100 is long enough to cover the length of the blood collection tube 50, and includes a plurality of light emitting elements in the z direction and light receiving elements corresponding to the plurality of light emitting elements. In the interface detection sensor 100, which constitutes an optical axis photoelectric sensor, the relative positional relationship between the interface detection sensor 100 (e.g., the light projecting unit 110 or the light receiving unit 120) and the blood collection tube 50 along the z direction is unchanged. good too. In this case, the control unit 130 may sequentially change the projection direction of the light projected from the light projecting unit 110 to sequentially change the irradiation position of the light projected onto the blood sampling tube 50. good.

In the above embodiments, processors such as CPUs may be physically configured in any way. Moreover, if a programmable processor is used, the content of processing can be changed by changing the program, so that the degree of freedom in designing the processor can be increased. The processor may be composed of one semiconductor chip, or physically composed of a plurality of semiconductor chips. When configured with a plurality of semiconductor chips, each control of the above embodiments may be realized by separate semiconductor chips. In this case, it can be considered that the plurality of semiconductor chips constitutes one processor. Also, the processor may be composed of a member (capacitor, etc.) having a function different from that of the semiconductor chip. Also, one semiconductor chip may be configured to implement the functions of the processor and other functions. Also, a plurality of processors may be composed of one processor.

As described above, the interface detection sensor 100 of the embodiment includes the light projecting section 110, the light receiving section 120, and the control section . Light projecting unit 110 projects light S11 (an example of first wavelength) having wavelength λ1 (an example of first wavelength) and wavelength λ2 onto blood sample C (an example of a detection target) having a plurality of layers. A light projection light set S10 including a light projection light S12 (an example of a second light projection light) having (an example of a second wavelength) is sequentially projected. The light receiving unit 120 includes a received light S21 (an example of a first received light) that is a signal of the projected light S11 transmitted through the detection target, and a received light S22 (a first received light) that is a signal of the projected light S12 transmitted through the detection target. 2) and the received light set S20 are sequentially received. The control unit 130 synchronizes the light projection timing by the light projection unit 110 and the light reception timing by the light reception unit 120, and based on the sequentially received light reception light set S20, a plurality of layers (for example, blood clot C1) included in the detection target. , separation material C2, and serum C3). The light projecting unit 110 starts projecting the light S12 during or when the light S11 is being projected.

As a result, the light receiving periods of the received light S21 and the received light S22 are temporally continuous, so that the detection area to be detected by the received light S21 and the received light S22 is a spatially continuous area. Therefore, the interface detection sensor 100 can maintain the interface detection accuracy in this detection area even if the detection area by the light receiving light set S20 is a minute area having a minute length along the scanning direction (for example, the z direction). . In addition, since the detection areas by the received light beam S21 and the received light beam S22 are spatially continuous areas, the two received light beams S21 and S22 are applied to the detection area by the received light beam set S20 without depending on the scanning speed. interface can be detected based on Therefore, the interface detection sensor 100 can achieve high scanning speed. In this way, the interface detection sensor 100 can speed up the scanning speed for scanning the detection target while suppressing deterioration in interface detection accuracy within the detection target. Further, since the projection timings of the projected light beam S11 and the projected light beam S12 do not completely match, the light receiving timings of the received light beam S21 and the received light beam S21 do not completely match. Therefore, the interface detection sensor 100 can obtain the unknown characteristics of the received light by subtracting the characteristics of the known received light from the characteristics of the received light set S20 including each received light. S22 can be identified.

Further, the light receiving section 120 may start receiving the received light S22 during or at the end of receiving the received light S21 in synchronization with the projection of the projected light set S10 by the light projecting section 110 . The control unit 130 controls the amount of light received by the light receiving unit 120 after the start of receiving the received light S22 to be higher than the amount of light received by the light receiving unit 120 before the start of receiving the light S22 among the amounts of light received by the light receiving light set S20. The light projection unit 110 may be caused to project the projection light set S10 so that the amount of light received increases.

As a result, the amount of received light in the second light receiving period T22, which is the period after the start of light reception of the light receiving light S22, is greater than the amount of light received in the first light receiving period T21, which is the period before the start of light receiving of the light receiving light S22. The amount of light received increases. That is, the amount of light received by the received light set S20 increases in ascending steps in time series. Further, since the received light S21 and the received light S22 are received continuously, the fall of the received light S21 received in the first light receiving period T21 can remain in the second light receiving period T22. Even in this case, the amount of light received increases in an upward staircase manner, so that the remaining falling component of the received light S21 is sufficiently smaller than the amount of light received during the second light receiving period T22. Therefore, the interface detection sensor 100 detects the interface based on the same received light set S20 including the received light received during the first light receiving period T21 and the received light received during the second light receiving period T22. It is possible to suppress the deterioration of the accuracy of Further, by subtracting the known characteristics of the received light S21 from the characteristics of the received light set S20, the unknown characteristics of the received light S22 may be obtained, thereby suppressing the deterioration of the interface detection accuracy.

Further, the light receiving section 120 may receive the second received light set S20 following the first received light set S20. The first period from the time when the first received light set S20 ends receiving light to the time when the second received light set S20 starts receiving light is the rise required for the amount of received light to fall at the time when the first received light set S20 ends receiving light. It may be longer than the fall period S22a or the same length as the fall period S22a.

As a result, even if the fall of the received light (at least the received light S22) received during the second light receiving period T22 remains after the second light receiving period T22, the interface detection sensor 100 detects the next received light set S20. is ensured until the time interval TI2 is received, it is possible to suppress deterioration in interface detection accuracy based on the subsequent received light set S20. The fall of the received light received during the second light receiving period T22 corresponds to the fall of the received light amount at the end of light reception of the received light set S20.

Further, the light projecting unit 110 determines the amount of projected light S11 and the amount of projected light S12 based on the transmittance of the projected light S11 to the detection target and the transmittance of the projected light S12 to the detection target. and may be determined.

Thereby, the interface detection sensor 100 can adjust the light projection amount of each light projection light to various light projection amounts in consideration of the transmittance of each light projection light. For example, the higher the transmittance of the projected light to the detection target, the easier the interface detection sensor 100 transmits the detection target and the less it is attenuated. On the other hand, the smaller the transmittance of the detection target, the more difficult the interface detection sensor 100 is to transmit the detection target and the more likely it is to attenuate. Even in this case, the interface detection sensor 100 can suppress a decrease in interface detection accuracy by increasing the amount of light received by the light receiving light set S20 in a time-series manner.

In addition, the control unit 130 controls the first light receiving amount, which is the amount of light received by the light receiving unit 120 before the start of light reception of the light receiving light S22, which is included in the light receiving amount of the light receiving light set S20, and the light reception start amount of the light receiving light S22. You may compare with the 2nd light reception amount which is the light reception amount of the light reception part 120 after that. When the first received light amount is larger than the second received light amount, the control unit 130 may instruct the light projecting unit 110 to change the order of projecting the light beams S11 and S12.

As a result, the interface detection sensor 100 detects the received light amount of the received light set S20 in time series according to the actual received light amount in the first light receiving period T21 and the received light amount in the second light receiving period T22. It can be fed back to the light projecting section 110 so that it increases like an upward staircase. Therefore, the interface detection sensor 100 can arrange the light projecting order of each light projecting light by the light projecting unit 110 so that the above-mentioned ascending staircase pattern is formed on the light receiving side without grasping the characteristics of each light projecting light in advance. can be adjusted to Also, in the case where the characteristics of each projected light are grasped in advance and the light projection order of each light is adjusted, the magnitude of the received light amount of each received light may be reversed unintentionally depending on the detection environment of the detection target. can. Even in this case, the interface detection sensor 100 adjusts the light projection order of the respective light beams by the light projecting unit 110 according to the actual amount of received light so that the light receiving side becomes the above-mentioned ascending staircase pattern. can.

Further, the detection target may be accommodated in a blood collection tube 50 (an example of a container) and extend along the first direction (eg, z direction, vertical direction). The position of the detection target with respect to light projecting section 110 may be movable along the first direction. The light projecting unit 110 projects the light projecting light set S10 in a direction perpendicular to the first direction (for example, the y direction) with respect to successive positions (for example, vertical irradiation positions) of the detection target along the first direction. Light may be emitted sequentially.

As a result, the interface detection sensor 100 can detect the amount of received light S21 and S22 having different wavelengths at successive positions along the first direction of the detection target, and the interface detection sensor 100 can detectable. Therefore, the interface detection sensor 100 can detect the interface in a spatially continuous narrow area.

Further, the lengths of the projected light S11 and the projected light S12 projected by the light projecting unit 110 in the direction parallel to the first direction are perpendicular to the first direction and the lengths of the projected light S11 and the projected light S12 shorter than the length of the direction (eg, x-direction) perpendicular to the traveling direction (eg, y-direction) of the light beam S12,

When the beams of the projection lights S11 and S12 have the same length in the z direction and the length in the x direction (for example, the beam shape is circular or square), the detection interval in the z direction is narrowed to increase the interface detection accuracy. If so, the lengths of the beam of projection light in the z-direction and the x-direction are shortened. Therefore, if the detection target is displaced in the x-direction due to, for example, axial misalignment of the blood collection tube 50 containing the detection target, there is a high possibility that the received light beams S21 and S22 will not be received by the light receiving unit 120. . As a result, the stability of the received light beams S21 and S22 is degraded, and the interface detection accuracy may be degraded. On the other hand, in the interface detection sensor 100, by making the length of the beams of the projected light beams S11 and S12 in the z direction shorter than the length in the x direction, the spatial detection interval can be narrowed and the interface detection accuracy can be improved. Moreover, even if the object to be detected is shifted in the x direction, the stability of the received light can be maintained. In this way, it is possible to increase the utilization efficiency of the light energy of the projection light beam.

Also, the blood sample C may be the detection target. The multiple layers may include a layer of serum C3 and a layer of clot C1.

Serum C3 and clot C1 in blood sample C have different transmittances at wavelength λ1 and wavelength λ2. The interface detection sensor 100 can detect, for example, the interface between the serum C3 layer and the blood clot C1 layer in the blood sample C and the interface with other layers by using the difference in transmittance.

INDUSTRIAL APPLICABILITY The present disclosure is useful for an interface detection sensor, an interface detection method, and the like capable of suppressing deterioration in interface detection accuracy within a detection target while increasing the scanning speed for scanning the detection target.

5 Blood Interface Detection System 50 Blood Collection Tube 60 Moving Mechanism 61 Holding Arm 100 Interface Detection Sensor 110 Light Projecting Unit 111 Driver 112 Light Projecting Element 113 Lens 114 Multiplexer 120 Light Receiving Unit 121 Lens 122 Light Receiving Element 123 Amplifier 130 Control Unit 131 Amplifier 132 AD converter 133 CPU
134, 135 Output section B1 Circular beam B2 Rectangular beam C Blood sample C1 Blood clot C11 Red blood cell C12 Buffy coat C2 Separating material C3 Serum S10 Projected light set S11, S12 Projected light S20 Received light set S21, S22 Received light

Claims (9)

a light projecting unit that sequentially projects a light set including a first light having a first wavelength and a second light having a second wavelength onto a detection target having a plurality of layers;
The first projected light includes first received light that is a signal transmitted through the detection target, and the second projected light includes second received light that is a signal transmitted through the detection target. a light receiving unit that sequentially receives the received light set;
a control unit for synchronizing the timing of light projection by the light projecting unit and the timing of light reception by the light receiving unit, and detecting the interfaces of the plurality of layers included in the detection target based on the set of received light sequentially received; ,
with
The light projecting unit starts projecting the second light projecting during or at the end of projecting the first light projecting light,
Interface detection sensor. the light-receiving unit starts receiving the second light-receiving light during or at the end of receiving the first light-receiving light in synchronization with the projection of the set of light-projecting light by the light-projecting unit;
The control section controls the amount of light received by the light receiving section before the start of reception of the second light reception among the light reception amounts of the light reception light set. causing the light projecting unit to project the light projecting light set so that the amount of received light received by the light receiving unit increases;
The interface detection sensor according to claim 1. The light receiving unit receives a second set of received light subsequent to the first set of received light,
A first period from the end of light reception of the first set of received light to the start of light reception of the second set of received light is required for the amount of received light to fall at the end of light reception of the first set of received light. longer than or as long as the fall period;
The interface detection sensor according to claim 2. The light projecting unit
Based on the transmittance of the first projected light with respect to the detection target and the transmittance of the second projected light with respect to the detection target, the amount of the first projected light and the second 2. determine the amount of projected light;
The interface detection sensor according to claim 2 or 3. The control unit
A first received light amount that is the amount of received light received by the light receiving unit before the start of receiving the second received light, which is included in the amount of received light of the set of received light, and after the start of receiving the second received light. with a second received light amount, which is the amount of received light received by the light receiving unit, and
instructing the light projecting unit to change the order of projecting the first light and the second light when the first amount of received light is greater than the second amount of received light;
The interface detection sensor according to any one of claims 2 to 4. The detection target is accommodated in a container and extends along a first direction,
a position of the detection target is movable with respect to the light projecting unit along the first direction;
The light projecting unit sequentially projects the light projecting light set in a direction perpendicular to the first direction on successive positions of the detection target along the first direction.
The interface detection sensor according to any one of claims 1 to 5. The lengths of the first projected light and the second projected light projected by the light projection unit in a direction parallel to the first direction are perpendicular to the first direction and shorter than the length of the direction perpendicular to the traveling direction of the first projected light and the second projected light;
The interface detection sensor according to claim 6. The detection target is a blood sample,
wherein said plurality of layers comprises a layer of serum and a layer of clot;
The interface detection sensor according to any one of claims 1 to 7. projecting a first floodlight having a first wavelength onto a detection target having a plurality of layers;
By starting to project a second projected light having a second wavelength onto the detection target during or at the end of projecting the first projected light, the second projected light is emitted to the detection target. a step of projecting light;
The first projected light includes first received light that is a signal transmitted through the detection target, and the second projected light includes second received light that is a signal transmitted through the detection target. receiving a set of received light;
detecting an interface between the plurality of layers included in the detection target based on the received light set;
interface detection method.

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