JP2016144502A - Biological optical measurement apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological optical measurement apparatus which can appropriately set an amplification factor of a measurement signal for passing light received by a light receiving probe.SOLUTION: A biological optical measurement apparatus 100 disclosed by this invention comprises: a light receiving unit 120 which receives passing light that has passed through the inside of a living body 190 with a light receiving probe 151b when measurement light is emitted separately from a plurality of irradiation probes 151a, converts the received passing light to an electric signal, and outputs a measurement signal V amplified at a preset amplification factor; and a data processing unit 400 which generates biological optical measurement data by digitally converting the measurement signal V output from the light receiving unit 120. The data processing unit obtains a standard deviation of the intensity of the measurement signal and sets the amplification factor based on the obtained standard deviation and a coefficient α determined in accordance with the number N of superimposed frequencies of the measurement signal.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a biological light measurement device that measures a metabolite or the like inside a living body using measurement light of visible light or near infrared light. Specifically, preliminary measurement is performed prior to the main measurement, and the main measurement is performed. The present invention relates to a technique for appropriately setting an amplification factor of a measurement signal at the time.

  The biological light measurement device is used, for example, to measure a change in blood flow in the brain accompanying a human brain function activity. In this case, light is emitted from the scalp surface into the brain, the passing light passing through the brain is received by the scalp surface, and converted into a measurement signal of an electrical signal having an intensity corresponding to the passing light by the photoelectric conversion element. To do. And the change in the blood flow in the brain is measured by measuring the change in the concentration of the measurement target substance in the living body based on the change in the intensity of the measurement signal. In such a biological light measurement device, in order to increase measurement accuracy, it is necessary to accurately measure the intensity of light passing through the living body.

  Usually, the measurement signal is finally converted into a digital signal by an analog-digital (A / D) converter, and recorded and necessary arithmetic processing is performed by a computer or the like to measure a biological function such as a brain function. In order to increase the measurement accuracy in the measurement of such biological functions, high conversion accuracy is required in A / D conversion. On the other hand, since the photoelectric conversion element that converts the light passing through the living body into the measurement signal of the electric signal has a wide dynamic range, if the measurement signal when the amount of received light is small is A / D converted as it is, the quantization noise is larger than the measurement signal. It gets bigger.

  Therefore, in general, the preliminary measurement is performed and the amplification factor is set according to the intensity of the measurement signal corresponding to the received light amount, and then the main measurement is performed. For example, the maximum value of the amount of light passing through the living body (measurement signal) measured within a certain measurement time is obtained, and the amplification factor is calculated and set so that the maximum value becomes a target level. However, according to this, in order to obtain a certain degree of accuracy, it is necessary to perform preliminary measurement for several seconds, and there is a problem that it takes time for preliminary measurement. Further, if the measurement signal includes pulse-like noise, the noise is mistaken as the maximum value, and there is a problem that a large error occurs in the setting of the amplification factor.

  On the other hand, Patent Document 1 proposes obtaining a standard deviation of intensity (amplitude) of a measurement signal measured within a certain time and setting an amplification factor based on the standard deviation. According to this, the time for preliminary measurement for setting the amplification factor can be shortened, and noise resistance can be improved.

JP-A-11-164826

  By the way, normally, in living body light measurement, a plurality of light receiving probes which are irradiated with measurement light from a plurality of irradiation probes held in contact with the living body surface and passed through the inside of the living body are held in contact with the living body surface. An optical measurement probe that receives light is used. For example, the plurality of irradiation probes and the light receiving probes are arranged in a lattice shape or a mesh shape so that the intervals between the respective irradiation probes and the light receiving probes are equal. A certain area on or including the line connecting the irradiation probe and the light receiving probe is a measurement point or measurement site inside the living body in the optical measurement.

  Therefore, depending on the arrangement of the irradiation probe and the light receiving probe, the light receiving probe to which the passing light irradiated from the two irradiation probes is incident, the light receiving probe to which the passing light irradiated from the three irradiation probes is incident, and four A light receiving probe or the like into which the passing light irradiated from the irradiation probe enters is mixed. In addition, since a plurality of irradiation probes are arranged around the light receiving probe, it is identified from which irradiation probe the passing light received by one light receiving probe is irradiated and measured in correspondence with the measurement site. The signal needs to be discriminated.

  Therefore, the measurement light emitted from each irradiation probe is modulated at a different unique frequency. In other words, a unique modulation frequency is superimposed on the measurement light. Thereby, the modulation frequency included in the measurement signal of the light receiving probe is discriminated, a plurality of irradiation probes included in the passing light received by one light receiving probe is identified, and the measurement site can be specified corresponding to the irradiation probe. Further, measurement light having a plurality of (for example, two) wavelengths (1 / frequency) may be superimposed and used in accordance with the characteristics (for example, light absorption characteristics) of the substance to be measured. For these reasons, in the above-described example, depending on the light receiving probe, a measurement signal in which waveforms of four frequencies are superimposed (superimposed wave number = 4), a measurement signal in which six frequencies are superimposed (superimposed wave number = 6), 8 A measurement signal (superimposed wave number = 8) on which two frequencies are superimposed is a measurement signal.

  As described above, when the number of superimposed waves of the measurement signal is different, the waveform of the measurement signal to be synthesized is different, so that the standard deviation value is also different. Therefore, when the amplification factor is uniformly set based on the standard deviation of each measurement signal, there is a disadvantage that, for example, a signal of a frequency component to be viewed is compressed.

  However, in the conventional technique, when the amplification factor is set based on the standard deviation of the measurement signal, there is a problem that the amplification factor is not set appropriately because the superimposed wave number of the measurement signal is not taken into consideration. In addition, for example, when the number of irradiation probes that irradiate measurement light is changed, the number of measurement signals included in the passing light received by one reception probe changes, so the value of the standard deviation of the measurement signal is also Since it changes, it is necessary to reset the amplification factor.

  The problem to be solved by the present invention is to provide a living body light measurement device capable of appropriately setting the amplification factor of the measurement signal of the passing light received by the light receiving probe.

  In order to solve the above-described problems, the biological light measurement device of the present invention is configured such that the measurement light is irradiated from each of the plurality of irradiation probes, and the passing light that has passed through the inside of the living body is received by the light receiving probe. A light receiving unit that converts the signal into an electrical signal and outputs a measurement signal amplified at a preset amplification factor, and a data processing unit that digitally converts the measurement signal output from the light receiving unit to generate biological light measurement data The data processing unit obtains a standard deviation of the intensity of the measurement signal, and calculates the amplification factor based on the obtained standard deviation and a coefficient determined according to the superimposed wave number of the measurement signal. It is characterized by being set.

  According to the present invention configured as described above, instead of setting the amplification factor uniformly based on the value of the standard deviation of the intensity of the measurement signal, signals of different frequencies are included in the measurement signal of the light receiving probe. Since the amplification factor is set based on the value of the standard deviation of the measurement signal and the coefficient determined according to the number of superimposed frequencies (number of superimposed waves), the light received by the light receiving probe The amplification factor of the optical measurement signal can be set appropriately.

  Here, the superposed wave number included in the measurement signal can be set in advance in the storage unit provided in the data processing unit based on the number of the light receiving probe and the irradiation probe related to the passing light received by the light receiving probe. it can. However, as will be described later, the frequency of the measurement signal may be discriminated and the number of superimposed waves may be automatically obtained. According to this, even when the number of irradiation probes that irradiate measurement light is changed, measurement is performed according to the change. The amplification factor of the signal can be set appropriately.

  In general, since a plurality of light receiving probes are provided, the data processing unit sets an amplification factor for each light receiving probe. Also, the coefficient determined according to the superposed wave number is set in advance in the memory of the data processing unit in correspondence with the superposed wave number. As the coefficient set in the memory, an appropriate coefficient is set by executing and analyzing in advance for each different number of superimposed waves.

  As one of the methods for setting the amplification factor based on the coefficient determined according to the superposed wave number and the standard deviation value, a value obtained by dividing the standard deviation value by the coefficient is set as the amplification factor. However, the present invention is not limited to this, and in order to obtain an appropriate amplification factor, measurement is performed in advance corresponding to each different number of superimposed waves, and the relationship between the standard deviation, the coefficient, and the amplification factor is analyzed, and the amplification factor is calculated. You may make it set.

  In addition, as described above, after automatically setting the amplification factor, the user can easily change the coefficient or amplification factor determined according to the number of superimposed waves while viewing the waveform of the measurement signal in the preliminary measurement, An interface provided with an input unit may be provided to enable setting of an amplification factor with a high degree of freedom. According to this, since the user can freely set the amplification factor, the convenience for the user can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the biological light measuring device which can set appropriately the amplification factor of the measurement signal of the passage light received by the light reception probe can be provided.

It is a block diagram which shows the whole structure of one Embodiment of the biological light measuring device of this invention. It is a figure which shows the example of arrangement | positioning of the irradiation probe and light reception probe of a biological light measurement probe. It is a flowchart which shows the process sequence of the preliminary measurement which sets the amplification factor of the measurement signal of Example 1 of this invention. 6 is a flowchart for performing the main measurement using the amplification factor set according to the first embodiment. It is a flowchart which shows the process sequence of the preliminary measurement which sets the amplification factor of the measurement signal of Example 2 of this invention. It is a figure explaining the setting screen of the gain of Example 3 of this invention. It is a figure explaining that the waveform of a measurement signal changes with superposition wave numbers. It is a figure explaining the significance which changes a coefficient by superposition wave number.

  Hereinafter, the present invention will be described based on embodiments. Note that in the drawings for describing the embodiments of the present invention, those having the same function are denoted by the same reference numerals unless otherwise specified, and repetitive description thereof is omitted.

  The living body light measurement device of this embodiment irradiates near-infrared light in the living body, detects light reflected from the vicinity of the living body surface or passed through the living body (hereinafter simply referred to as passing light), and the intensity of the light. It is assumed that an electrical signal corresponding to is generated. As shown in FIG. 1, the biological light measurement apparatus 100 according to the present embodiment performs a A / D conversion after a light source unit 110 that irradiates near-infrared light and the passing light in the living body is converted into an electric signal and amplified. And a control unit 140 that controls driving of the light source unit 110 and the light receiving unit 120 and processes optical measurement data output from the light receiving unit.

  The light source unit 110 irradiates light to a predetermined irradiation point on the body surface of the subject 190 that is a living body. The light source unit 110 includes a semiconductor laser 111 that generates light of a predetermined wavelength, and a plurality of optical modules 112 that include modulators that modulate light generated by the semiconductor laser 111 at a plurality of different frequencies. For example, as many optical modules 112 as the number of irradiation points are provided. Output light (measurement light) from each optical module 112 is irradiated onto a predetermined measurement site of the subject 190 via an optical fiber 130 (irradiation light optical fiber 131) that is an optical waveguide.

  Irradiation of measurement light is performed via each irradiation light optical fiber 131 of the probe holder 150 attached to the body surface of the subject 190, and light is emitted from a plurality of predetermined irradiation points to a predetermined part of the subject 190. Irradiate. The irradiation light optical fiber 131 is fixed to a predetermined position of the probe holder 150. The probe holder 150 is fixed to, for example, the head of the subject 190. The wavelength of the measurement light output from the light source unit 110 is determined according to the spectral characteristics (or absorption characteristics, etc.) of the target substance in the living body to be measured.

  For example, when measuring oxygen saturation and blood volume from the concentrations of hemoglobin (Hb) and oxygenated hemoglobin (HbO2), one or more wavelengths are selected from light in the wavelength range of 600 nm to 1400 nm. In addition, for example, when the measurement target is two types of oxygenated hemoglobin (HbO2: oxyHb) and deoxygenated hemoglobin (deoxyHb), the light source unit 110 has two types to detect these two types of measurement targets. It is configured to generate light having the above wavelengths, for example, 695 nm and 830 nm. The light of these plural types of wavelengths is synthesized at the irradiation point and irradiated from one light irradiation position of the irradiation light optical fiber 131.

  The light receiving unit 120 receives the passing light guided from the plurality of measurement points in the measurement region via the light receiving optical fiber 132 and converts the light into measurement signals of electrical signals corresponding to the respective light amounts. And the like, a variable gain amplifier 122 that amplifies the measurement signal output from the photoelectric conversion element 121, and an A / D converter 123 that converts the output signal of the variable gain amplifier 122 into a digital signal. The variable gain amplifier 122 can variably set the amplification factor in order to amplify the measurement signal having the optimum amplitude for the A / D converter 123. The digitally converted measurement signal output from the A / D converter 123 is input to the data processing unit 400 in the control unit 140, and the data processing unit 400 can obtain target optical measurement data. Yes.

  Note that the measurement light emitted from the light source unit 110 has a waveform in which different modulation frequencies are superimposed, separately from the wavelengths of 695 nm and 830 nm. The measurement signal having these superposed wave numbers can be re-separated by a lock-in amplifier 402 having a frequency discrimination function described later after the light receiving unit 120 captures data.

  The present embodiment is characterized in that a function for optimizing the amplification factor of the measurement signal and setting the variable gain amplifier 122 is added to the data processing unit 400. First, an arrangement example of the optical measurement probe 151 connected to the light source unit 110 and the light receiving unit 120 will be described with reference to FIG. Each of the optical measurement probes 151 includes a plurality of irradiation probes 151a and light receiving probes 151b. In the optical measurement probe 151, the irradiation point of each irradiation probe 151a and the light reception point of the light reception probe 151b are arranged so that the received light propagates to the gray matter. Specifically, as shown in FIG. 2, the optical measurement probes 151 are arranged in a lattice shape. In the figure, ▲ means an irradiation point of the irradiation probe 151 a connected to the irradiation light optical fiber 131 connected to the light source unit 110. In the figure, ● represents a light receiving point of the light receiving probe 151b connected to the light receiving optical fiber 132 connected to the light receiving unit 120. In order to simplify the description, the irradiation point 151a and the light receiving point 151b will be described below.

  An area on or including the line 152 connecting the irradiation point 151a and the light receiving point 151b is referred to as a measurement point or a measurement site. As shown in FIG. 2, the light receiving point 151b is surrounded by two, three, and four irradiation points 151a depending on the location, and the measurement light from two directions, three directions, and four directions, respectively. Is received. At each irradiation point 151a, for example, in the case where measurement light having two types of wavelengths is emitted from one irradiation light optical fiber 131 as described above, the light reception point 151b receives light when considering that the modulation frequency is superimposed. The superposed wavenumbers N of light to be 4, 6, and 8 respectively. That is, the passing light received at one light receiving point 151b has a maximum superposed wavenumber N of 8. The data processing unit 400 includes an amplification factor setting unit 401 and a lock-in amplifier 402 in order to give an optimum amplification factor to the variable gain amplifier 122.

  From the modulation signal detected by the data processing unit 400, for example, the concentration of oxyhemoglobin and deoxyhemoglobin in the living tissue or the amount corresponding to the concentration can be measured. The display data included in the biological light measurement data created from the modulation signal in the data processing unit 400 includes, for example, oxygenated hemoglobin (oxyHb) concentration change, deoxygenated hemoglobin (deoxyHb) concentration change, and total hemoglobin (TotalHb). ) A graph showing density changes for each measurement point, or an image obtained by plotting these data on a two-dimensional image of the subject 190.

  As shown in FIG. 1, the control unit 140 of the present embodiment includes a processing result by the data processing unit 400, for example, a display unit 142 that displays the created image, and data necessary for processing by the data processing unit 400. And a storage unit 143 for storing processing results and an input unit 141 for inputting various commands necessary for the operation of the biological light measurement apparatus 100 are connected.

  Each function realized by the control unit 140 is realized by loading a program stored in advance in the storage unit 143 into a memory and executing it by a CPU included in the control unit 140. In addition, you may implement | achieve by hardware, such as PLD (Programmable Logic Device).

  Next, the preliminary measurement processing performed by the control unit 140 and the data processing unit 400 will be described in each embodiment.

  A first embodiment of the preliminary measurement process performed by the control unit 140 and the data processing unit 400 will be described with reference to the flowchart of FIG. In step S <b> 1001, the measurement light emitted from the light source unit 110 is transmitted to the irradiation probe (irradiation point) 151 a via the irradiation light optical fiber 131 and irradiated into the living body 190. The light passing through the living body 190 is received by the light receiving probe (light receiving point) 151 b and transmitted to the light receiving unit 120. At this time, when measurement light including two types of wavelengths is emitted from one optical module 112, the passing light transmitted to the light receiving unit 120 has a maximum of eight types of superimposed waveforms.

  In step S <b> 1002, the received passing light is converted into an electric signal measurement signal V by the photoelectric conversion element 121. Next, in step S1003, the measurement signal V is amplified by the amplification factor set in the variable gain amplifier 122. Here, it is assumed that the initial value of the amplification factor is set to 1, for example. The amplified measurement signal V is converted into a digital measurement signal by the A / D converter 123. Here, in order to reduce the quantization error in the A / D converter 123, it is important to use a wide input range of the A / D converter 123. Therefore, it is necessary to set the amplification factor of the variable gain amplifier 122 optimally.

Next, a procedure for optimally setting the amplification factor, which is a feature of the present embodiment, will be described. First, the standard deviation (Vstd) of the measurement signal in the preliminary measurement is calculated with the initial amplification factor (S1005). Here, when the number of measurement data in the preliminary measurement time is n (n is a natural number), the measurement signal Vi (i = 1,..., N), and the average value of the measurement signal Vi is Vave, the standard deviation (Vstd) Is obtained by Equation 1.

  Although the standard deviation of the measurement signal including the superimposed wave varies depending on the superimposed wave number N, since the probe arrangement is determined in advance, the superimposed wave number N of the passing light incident on each light receiving point 151b is known in advance. Therefore, the coefficient α can be set according to the superposed wave number N of the passing light incident on each light receiving point 151b. For example, the coefficient α is set in the data table of the storage unit 143 so as to correspond to the superimposed wave number N, and is obtained by reading the coefficient α corresponding to the superimposed wave number N at each light receiving point 151b (S1006).

  Subsequently, in step S1007, V ′ (= Vstd / α) obtained by dividing the standard deviation Vstd of the measurement signal V by the coefficient α is obtained. The obtained V 'is compared with the target voltage k (S1008). If V ′ is not the target voltage k (or k ± 10% or less), the process proceeds to step S1009, and the gain (Gain) is readjusted so that V ′ becomes the target voltage k (S1009). The gain is reset in the variable gain amplifier 122. Then, returning to step S1003, steps S1003 to S1009 are repeated until V ′ reaches the target voltage k. The above processing is performed at each light receiving point 151b, and the gain (Gain) is set so that all the light receiving points 151b have the target voltage k at V '. In this way, an appropriate amplification factor for the measurement signal V is set so as to be within the range of the target voltage k.

  When an appropriate amplification factor for the measurement signal V is set, the measurement signal is separated by the lock-in amplifier 402 for each corresponding irradiation point 151a and each substance to be measured, and intensity information of each measurement signal is obtained ( S1010). Next, the digital gain β is set according to each intensity so that all pieces of intensity information separated by the lock-in amplifier 402 have the same level (S1011). By such preliminary measurement processing, it is possible to obtain target biological light measurement information.

  FIG. 4 shows a flowchart in the control unit 140 and the data processing unit 400 in the main measurement. Since the amplification factor (Gain) and the digital gain value are set by preliminary measurement, the measurement signal V is multiplied by the amplification factor (Gain) set (S2003), then A / D converted (S2004), and the lock-in amplifier 402 Thus, it is possible to perform the real measurement processing in real time until the frequency is discriminated (S2005) and the digital gain β is further set (S2005).

  As described above, according to the first embodiment, the amplification factor is not uniformly set based on the standard deviation value Vstd of the intensity of the measurement signal V, but the frequency different from that of the measurement signal V of the light receiving probe 151b. Therefore, the amplification factor is set based on the standard deviation value Vstd of the measurement signal and the coefficient α determined in accordance with the superposed wave number N of the superposed frequency. The amplification factor of the measurement signal V of the passing light received by the probe 151b can be set appropriately.

  The superposed wave number N included in the measurement signal V is related to the memory of the control unit 140 in advance or based on the number of light receiving probes 151b and the number of irradiation probes 151a related to the passing light received by the light receiving probe 151b. Is set in the storage unit 143 provided.

  In general, since a plurality of light receiving probes are provided, the data processing unit sets an amplification factor for each light receiving probe. The coefficient α determined according to the superposed wave number N is set in advance in the memory of the control unit 140, the storage unit 143, or the like in correspondence with the superposed wave number N. The coefficient α set in the memory is measured in advance for each different superposed wave number N, and an appropriate coefficient α is set by analyzing the relationship between the standard deviation, the coefficient, and the amplification factor.

  In the first embodiment, as a specific method for setting the amplification factor based on the coefficient α determined according to the superposed wave number N and the standard deviation value Vstd, the standard deviation value Vstd is divided by the coefficient α. An obtained value V ′ (= Vstd / α) is obtained, and an amplification factor is set so that this V ′ becomes the target voltage k (or k ± 10%). Thereby, even if the measurement signal V of the passing light received by the light receiving probe 121b has a different superimposed wave number N, the amplification factor of the measurement signal V can be set appropriately. However, the present invention is not limited to this, and measurement is performed in advance corresponding to each different number of superposed waves N so that an appropriate amplification factor is obtained, and the relationship between the standard deviation Vstd and the coefficient α is analyzed to obtain an appropriate coefficient α. Set.

  FIG. 5 shows a flowchart of the second embodiment of the preliminary measurement process performed by the control unit 140 and the data processing unit 400. In FIG. 5, the processes from step S3001 to S3004 are the same as steps S1002 to S1004 of the first embodiment. The difference between the present embodiment and the first embodiment is that, in the first embodiment, the superposed wave number N included in the measurement signal is equal to the number of the light receiving probe 151b and the number of irradiation probes 151a related to the passing light received by the light receiving probe 151b. Based on this, an example of setting in the storage unit 143 provided in association with the control unit 140 in advance is shown. In this embodiment, instead of this, the measurement signal V is frequency discriminated using the lock-in amplifier 402 (S3005), and then the intensity ratio of the waveform of each frequency is calculated (S3006). That is, since the superimposed wave number N can be determined from the intensity ratio of the superimposed waveform, the coefficient α is read and set from the table of the storage unit 143 as in the first embodiment (S3008).

  Thereafter, as in the first embodiment, V ′ is obtained in step S3009, and the process returns to step S3003 via steps S3010 and S3011 until V ′ is within the target voltage k or a certain range, and the above processing is performed. repeat. Thus, the present Example 2 can obtain | require the superimposition wave number N automatically, and can set the amplification factor of a measurement signal appropriately.

  Therefore, according to the second embodiment, the frequency of the measurement signal is discriminated and the superimposed wave number N is automatically obtained. Therefore, even when the number of the irradiation probes 151a that irradiate the measurement light is changed, the measurement signal is adjusted to the change. Can be set appropriately. That is, according to the second embodiment, even if the superimposed wave number of the measurement light incident on the light receiving point 151b is not known in advance, or specific light among the measurement light emitted from the irradiation light optical fiber 131 is not detected. Even when it does not reach the light receiving point 151b, it is possible to set an accurate amplification factor.

  FIG. 6 shows an example of a preliminary measurement screen on the display unit 142 of this embodiment. The present embodiment is different from the first and second embodiments in that the measurement signal amplification factor can be set manually. The functions of the present embodiment are realized by the cooperation of the input unit 141, the display unit 142, and the data processing unit 400. As shown in the figure, the preliminary measurement screen displays an area 160 of measurement points that the light receiving unit 120 is responsible for, and displays the set amplification factor on the display unit 161. Further, it has a function of variably setting the amplification factor displayed on the display unit 161 by a technique. This makes it possible to set an amplification factor that meets the user's needs. Further, the waveform 162 of the measurement signal related to the preliminary measurement is displayed on the preliminary measurement screen. Accordingly, even when it is difficult to automatically set the amplification factor due to a lot of noise, an appropriate amplification factor can be set.

  According to the third embodiment, after the amplification factor is automatically set according to the first and second embodiments, the coefficient α or amplification determined according to the superposed wave number N while the user looks at the waveform of the measurement signal in the preliminary measurement. By providing an interface including the display unit 142 and the input unit 141 that can easily change the rate, it is possible to set an amplification factor with a high degree of freedom. According to this, since the user can freely set the amplification factor, the convenience for the user can be improved. In addition, according to the present embodiment, since an appropriate amplification factor can be set for the variable gain amplifier 122, the S / N of the measurement signal is increased, and more accurate measurement is possible.

  That is, in the third embodiment, the data processing unit 400 displays the waveform of the measurement signal V output from the light receiving unit 120 on the display unit 142, and sets the amplification factor according to the command input from the input unit 141. It is characterized by being formed. Further, the data processing unit 400 displays the maximum value of the intensity of the measurement signal V and the standard deviation Vstd on the display unit 142 so that the amplification factor can be set according to the amplification factor setting command input from the input unit 141. It is characterized by being made.

  FIG. 7 shows an example of the simulation result of the waveform of the measurement signal and the value of the standard deviation Vstd when the superimposed wave number N of the measurement light is changed. FIG. 4A shows a waveform with a superimposed signal wave number N of “1” and “Vstd”, and FIG. 5B shows a waveform with a superimposed wave number N of a measurement signal of “2” and “Vstd”, and FIG. The waveform with the superimposed wave number N of “8” and “Vstd” are shown. In the figure, the maximum value of the amplitude of the measurement signal is normalized to 1. As can be seen from these figures, when the superposed wave number N changes, the waveform changes, and the value of the standard deviation Vstd also changes.

  FIG. 8 is a diagram illustrating a comparison between the case where the embodiment of the present invention is applied and the amplification factor setting according to the conventional method. In the figure, the left waveform is the original waveform of the measurement signal level, and the right waveform is the waveform obtained by amplifying the original waveform. FIG. 4A shows the case where the amplification factor is set based on the maximum value of the amplitude. As shown in the figure, pulse-like noise is on two places in the measurement signal at a fixed measurement time. Therefore, when the amplification factor is set based on the maximum value, the amplification factor is set by being pulled by the maximum value of noise, so that it can be seen that the amplitude of the signal to be viewed is compressed (collapsed). In this respect, when the amplification factor is set based on the standard deviation as shown in FIG. 5B, the amplification factor can be set without being affected by noise.

  Further, FIG. 10C shows the amplification factor of the measurement signal with the superposed wave number “8” based on the coefficient α determined according to the superposed wave number N and the standard deviation Vstd as in the first and second embodiments. Is set. On the other hand, FIG. 4D is a conventional example in which the amplification factor is set based on only the standard deviation of the measurement signal having the superposed wave number N of “2”. As can be seen by comparing (c) and (d) in the same figure, the characteristic of the original waveform can be emphasized by setting the amplification factor in consideration of the coefficient α determined according to the superposed wave number N. It can be seen that if the amplification factor is set based on the same coefficient α as N = 8, for example, even when the superposed wave number N = 2, the signal to be viewed is destroyed as shown in FIG.

  As mentioned above, although this invention was demonstrated based on one Embodiment and Examples 1-3, this invention is not limited to these, It implements with the form deform | transformed or changed in the range of the main point of this invention. It will be apparent to those skilled in the art that such modifications and variations are within the scope of the claims herein.

  100: biological light measurement device, 110: light source unit, 111: semiconductor laser, 112: optical module, 120: light receiving unit, 121: photoelectric conversion element, 122: variable gain amplifier, 123: A / D converter, 130: light Fiber: 131: Optical fiber for irradiation light, 132: Optical fiber for light reception, 140: Control unit, 141: Input unit, 142: Display unit, 143: Storage unit, 150: Probe holder, 151: Optical measurement probe, 151a: Irradiation probe (irradiation point), 151b: light reception probe (light reception point), 190: subject, 400: data processing unit, 401: amplification factor setting unit, 402: lock-in amplifier

Claims (9)

Measurement light irradiated from each of a plurality of irradiation probes, passing light that has passed through the inside of the living body is received by a light receiving probe, the received passing light is converted into an electrical signal, and amplified by a preset amplification factor A light receiving unit that outputs a signal, and a data processing unit that digitally converts the measurement signal output from the light receiving unit to generate biological light measurement data,
The data processing unit obtains a standard deviation of the intensity of the measurement signal, and sets the amplification factor based on the obtained standard deviation and a coefficient determined according to the superimposed wave number of the measurement signal. A living body light measuring device.   The superimposed wave number of the measurement signal is set in a storage unit provided in the data processing unit based on the number of the light receiving probe and the irradiation probe related to the passing light received by the light receiving probe. 2. The biological light measurement device according to claim 1, wherein: A plurality of the light receiving probes are provided,
The biological light measurement apparatus according to claim 1, wherein the data processing unit sets the amplification factor for each of the light receiving probes.   4. The measurement light according to claim 1, wherein measurement light having a plurality of frequencies having different wavelengths for each substance to be measured is superimposed and modulated at a modulation frequency different for each irradiation probe. The biological light measurement device according to any one of the above.   The biological light measurement apparatus according to claim 1, wherein the coefficient is set in advance according to a superimposed wave number of the measurement signal.   Further, the data processing unit separates signal components of different frequencies included in the input measurement signal, calculates an intensity ratio for each of the separated signal components of different frequencies, and based on the calculated intensity ratio The biological light measurement apparatus according to claim 1, wherein the coefficient is set.   The data processing unit sets the amplification factor so that a value obtained by dividing the obtained standard deviation by the coefficient becomes a preset target value or a target range. The biological light measurement device according to any one of the above. And a display unit and an input unit for inputting a command to the data processing unit.
The data processing unit is configured to display the waveform of the measurement signal output from the light receiving unit on the display unit, and to set the amplification factor according to a command input from the input unit. The biological light measurement device according to claim 1, wherein:   The data processing unit is configured to display the maximum value of the intensity of the measurement signal and the standard deviation on the display unit, and to set the amplification factor according to the amplification factor setting command input from the input unit. The biological light measurement device according to claim 8, wherein:

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