JP4412667B2 - Component concentration measuring device - Google Patents

Description

  The present invention relates to a noninvasive component concentration measurement apparatus for a human or animal subject.

  With the aging of society, dealing with adult diseases is becoming a major issue. In blood glucose level and other tests, blood collection is necessary, which places a heavy burden on the patient. Therefore, a non-invasive component concentration measurement apparatus that does not collect blood has attracted attention. As a non-invasive component concentration measuring device that has been developed so far, the skin is irradiated with electromagnetic waves and absorbed by blood molecules to be measured, for example, glucose molecules in the case of blood glucose levels, and heated locally. A photoacoustic method that observes a sound wave generated from a living body due to thermal expansion has attracted attention.

  However, the interaction between glucose and electromagnetic waves is small, and there is a limit to the intensity of electromagnetic waves that can be safely irradiated to a living body, so that a sufficient effect has not been achieved in measuring blood glucose levels in the living body.

  FIG. 8 and FIG. 9 are diagrams showing a configuration example of a conventional blood component concentration measuring apparatus using a photoacoustic method as a conventional example. FIG. 8 shows a first conventional example in which a light pulse is used as an electromagnetic wave (see, for example, Non-Patent Document 1). In this example, blood glucose, that is, glucose is the measurement target as the blood component. In FIG. 8, a drive circuit 604 supplies a pulsed excitation current to a pulse light source 616, the pulse light source 616 generates a light pulse having a sub-microsecond duration, and the generated light pulse is applied to a subject 610. The The light pulse generates a sound wave called a pulsed photoacoustic signal inside the subject 610, and the generated sound wave is detected by the ultrasonic detector 613 and further converted into an electric signal proportional to the sound pressure.

  The waveform of the converted electric signal is observed by the waveform observer 620. This waveform observer 620 is triggered by a signal synchronized with the excitation current, the converted electrical signal is displayed at a fixed position on the tube surface of the waveform observer 620, and the converted electrical signal is measured by integrating and averaging. can do. The amplitude of the electrical signal thus obtained is analyzed, and the blood glucose level inside the subject 610, that is, the amount of glucose is measured. In the case of the example shown in FIG. 8, optical pulses having a sub-microsecond pulse width are repeatedly generated at a maximum of 1 kHz, and 1024 optical pulses are averaged to measure the electrical signal. However, sufficient accuracy is obtained. It is not done.

  Therefore, a second conventional example using a light source that is continuously intensity-modulated has been disclosed for the purpose of improving accuracy. FIG. 9 shows a configuration of a second conventional apparatus (see, for example, Patent Document 1). In this example as well, blood sugar is the main measurement target, and high accuracy is attempted using a plurality of light sources having different wavelengths. In order to avoid complicated explanation, the operation when the number of light sources is 2 will be described with reference to FIG. In FIG. 9, light sources having different wavelengths, that is, a first light source 601 and a second light source 605 are driven by a drive circuit 604 and a drive circuit 608, respectively, and output continuous light.

  Light output from the first light source 601 and the second light source 605 is intermittently driven by a chopper plate 617 that is driven by a motor 618 and rotates at a constant rotational speed. Here, the chopper plate 617 is formed of an opaque material, and a relatively small number of openings are formed on the circumference around which the light of the first light source 601 and the second light source 605 passes with the axis of the motor 618 as the center. Is formed.

With the above-described configuration, the light output from each of the first light source 601 and the second light source 605 is intensity-modulated at a relatively simple modulation frequency f ₁ and modulation frequency f ₂ and then multiplexed by the multiplexer 609. Then, the subject 610 is irradiated as one light beam.

The inside of the subject 610 photoacoustic signal having the frequency f ₁ is generated by the light of the first light source 601, the photoacoustic signal having the frequency f ₂ is generated by the light of the second light source 605, these photoacoustic signal Is detected by the acoustic sensor 619 and converted into an electric signal proportional to the sound pressure, and its frequency spectrum is observed by the frequency analyzer 621. In this example, the wavelengths of the plurality of light sources are all set to the absorption wavelength of glucose, and the intensity of the photoacoustic signal corresponding to each wavelength is measured as an electrical signal corresponding to the amount of glucose contained in the blood. The

Here, the relationship between the intensity of the measured value of the photoacoustic signal and the value obtained by measuring the glucose content with blood collected separately is stored in advance, and the amount of glucose is measured from the measured value of the photoacoustic signal. ing.
JP-A-10-189 University of Oulu (University of Oulu, Finland) thesis “Pulse photoacoustic technique and glucodesis in human blood and tissue” (IBS 951-42-6690-0, ul./200.

  However, the above-described conventional example has the following problems. That is, in order to efficiently detect a sound wave, which is a photoacoustic signal generated in a human body, with a sound wave detector, it is necessary to change the wave front of the sound wave to a plane wave instead of a spherical wave. For this reason, the detection distance must be increased as the light irradiation area increases, and the distance and irradiation area between the sound wave detector and the sound wave generation source are limited. For example, when a biological fingertip is used as a subject, the detection distance is short, and thus the irradiation area needs to be reduced.

On the other hand, since the limit value of the laser output that can be irradiated on the skin of a living body is defined by the JIS standard, the size of the photoacoustic signal that can be generated at the irradiation point is also limited. Here, according to JISC6802, when invisible infrared light (wavelength of 0.8 μm or more) is continuously irradiated to the skin, 1 mW per 1 mm ² is the maximum allowable amount.

  Therefore, in the above-described conventional example, the generated photoacoustic signal is inevitably weak depending on the portion of the living body irradiated with light, and there is a problem that it is easily affected by noise.

  In order to solve the above problems, the present invention disperses the sound wave generation source by combining light of two different wavelengths set based on the absorbance characteristics of the component to be measured, and further splitting and emitting the light. This is a component concentration measuring device that reduces the burden on the subject and increases the total amount of sound waves to reduce the influence of noise and accurately measure the component concentration. Here, the subject is a human or animal to be measured.

  First, the basic principle of the component concentration measuring apparatus of the present invention will be described as an example in the case of measuring the component concentration of a subject.

  In the present invention, the wavelength of the first light among the two different wavelengths of light is set to a wavelength that is significantly different from the absorbance due to water, for example, where the absorbance due to the measurement target component of the subject occupies most of the subject. The wavelength of the second light is set to a wavelength that exhibits an absorbance equal to that of water at the wavelength of the first light. The above-described wavelength setting method will be described with reference to FIG. 1, taking as an example the case of measuring the concentration of glucose in blood.

FIG. 1 shows the absorbance characteristics of water and an aqueous glucose solution at room temperature. In FIG. 1, the vertical axis indicates the absorbance, and the horizontal axis indicates the wavelength of light. In FIG. 1, the solid line indicates the absorbance characteristic of water, and the broken line indicates the absorbance characteristic of the glucose aqueous solution. The wavelength λ ₁ shown in FIG. 1 is a wavelength at which the absorbance due to glucose is significantly different from the absorbance due to water, and the wavelength λ ₂ is a wavelength at which water has the same absorbance as that at λ ₁ . Thus, for example, the wavelength of the first light can be set to λ ₁ and the wavelength of the second light can be set to λ ₂ .

In the following description, as an example, the wavelength of the first light is set to a wavelength λ ₁ where the absorbance of the component to be measured is significantly different from the absorbance of water, and the wavelength of the second light is set to the first light. The case where the wavelength λ ₂ is set to be equal to that at the wavelength λ ₁ will be described.

  Each of the two different wavelengths of light set as described above is intensity-modulated with a signal of the opposite phase at the same frequency and emitted as pulsed light, and the emitted two different wavelengths of light are absorbed by the component of the subject. Then, the generated sound wave is detected, and the concentration of the component to be measured of the subject is measured from the magnitude of the detected sound wave. When light of two different wavelengths whose intensity is modulated as described above is emitted, the first sound wave generated from the subject by the absorption of the first light by both the component to be measured and water, and the second light The second sound wave generated from the subject by absorbing water occupying most of the subject has the same frequency and an opposite phase. Therefore, the first sound wave and the second sound wave are superimposed in the subject, and only the magnitude of the sound wave generated from the subject due to absorption of the component to be measured in the first sound wave is obtained as the difference between the sound waves. Remains. Therefore, only the sound wave generated from the subject by the first light component being absorbed by the component to be measured can be measured by the remaining sound wave. In the above measurement, the measurement target component absorbs rather than the difference between the sound wave generated by the absorption of both the measurement target component and water and the sound wave generated by the water absorption. Thus, the sound wave generated from the subject can be accurately measured.

Furthermore, a method for measuring with high accuracy, excluding the cause of errors in the sound wave measurement system such as the contact state between the subject and the sound wave detection element, will be described below. For each of the light of wavelength λ _{1 and} the light of wavelength λ ₂ , the absorption coefficient of water occupying most of the subject is α ₁ ^(w) and α ₂ ^(w) , and the molar absorption of the component to be measured of the subject If the coefficients are α ₁ ^(g) and α ₂ ^(g) , the simultaneous equations including the magnitudes s ₁ and s ₂ of sound waves generated from the subject by the light of wavelength λ _{1 and} the light of wavelength λ ₂ are It is expressed by Equation (1).

By solving the above equation (1), the component concentration M of the subject to be measured can be obtained. Here, C is a coefficient that is difficult to control or predict, that is, the coupling state between the subject and the sound wave detection element, the sensitivity of the sound wave detection element, and the distance between the position where the sound wave is generated by light in the subject and the sound wave detection element. , specific heat and thermal expansion coefficient of the object, the speed of the internal wave of the subject, the wavelength lambda ₁ of light and the wavelength lambda ₂ of the light modulation frequencies, the molar absorption coefficient of the component of the absorption coefficient and the subject of water, etc. It depends on the unknown constant. Further, when C is eliminated by Expression (1), the following Expression (2) is obtained.

Here, the absorption coefficients α ₁ ^(w) and α ₂ ^{(w) of} water occupying most of the subject for each of the light of wavelength λ _{1 and} the light of wavelength λ ₂ are selected to be equal. , Α ₁ ^(w) = α ₂ ^(w) is satisfied, and the fact that s ₁ ≈s ₂ is used, the component concentration M is expressed by Equation (3).

Substituting α ₁ ^(w) , α ₁ ^(g), and α ₂ ^(g) as known coefficients into the above equation (3), and further by the light of wavelength λ _{1 and} the light of wavelength λ ₂ , respectively. The component concentration M of the subject can be calculated by measuring and substituting the magnitudes s ₁ and s ₂ of the sound waves generated from the subject. In the above mathematical formula (3), rather than measuring the _two sound wave sizes s ₁ and s ₂ individually, the difference s ₁ -s ₂ is measured and the sound wave size s ₂ measured separately is measured. The component concentration of the subject can be measured with high accuracy.

Therefore, in the component concentration measurement apparatus of the present invention, first, the light of wavelength λ _{1 and} the light of wavelength λ ₂ are intensity-modulated by modulation signals having opposite phases to each other, and are combined into one light beam and emitted. Thus, the difference (s ₁ −s ₂ ) between the sound waves generated by superimposing the sound wave magnitude s ₁ and the sound wave magnitude s ₂ generated from the subject is measured. Next, light of wavelength λ ₂ is emitted, and the magnitude s _{2 of the} sound wave generated from the subject is measured. By calculating (s ₁ −s ₂ ) ÷ s ₂ from (s ₁ −s ₂ ) and s ₂ measured as described above, the component concentration of the measurement target of the subject is increased by Equation (3). It can be measured with high accuracy.

  The above is the basic principle of the component concentration measuring apparatus of the present invention.

  Next, specific means for solving the problems according to the present invention will be described. According to the present invention, light generating means for generating and outputting light of two different wavelengths, and each of the two wavelengths of light from the light generating means are electrically intensity-modulated with a signal of the same phase and opposite phase and output. A light modulating means; a light combining means for combining and outputting two wavelengths of light from the light modulating means; and a light emitting means for branching and emitting the light combined and output by the light combining means. And a sound wave detecting means for detecting sound waves generated by a plurality of lights branched and emitted by the light emitting means at positions substantially equidistant from the respective irradiated portions irradiated with the plurality of lights. This is a component concentration measuring apparatus.

  In the present invention, the light modulation means electrically modulates and outputs the first light and the second light having different wavelengths generated by the light generation means with signals having the same frequency and opposite phase. The optical multiplexing unit combines the two wavelengths of light from the optical modulation unit and outputs the combined light. Further, the light emitting means divides the light combined by the light combining means into a plurality of light and outputs the light. The sound wave detecting means detects the sound wave generated in the subject by the first light and the second light emitted from the light emitting means as described above at a position approximately equidistant from the light irradiated portion. Here, the sound wave detected by the sound wave detecting means is a difference sound wave between the first sound wave generated by the first light and the second sound wave generated by the second light.

  In this way, light of two wavelengths is combined, branched, and emitted, so that the light intensity is dispersed into a plurality of portions, so that the light is not concentrated and irradiated at one place, so the total amount of light to be irradiated Can be increased. Furthermore, by detecting the sound wave at a position approximately equidistant from the irradiated site, it is possible to detect the sound wave at a position where the phases of the sound waves are aligned, so the magnitude of the detected sound wave is the sum of the sound waves from multiple irradiated sites. Can be detected. Therefore, the error of the sound wave from each irradiated part can be averaged. Therefore, the component concentration measuring apparatus of the present invention can accurately measure the component concentration of the measurement target with less burden on the subject and less influence of noise on sound waves generated in the subject.

The sound wave detecting means measures the sound wave generated in the subject as (s ₁ -s ₂ ) described in the above measurement principle.

  According to another aspect of the present invention, there is provided light generating means for generating and outputting a plurality of sets of two wavelengths of light having the same wavelength as each of the two different wavelengths of light, with a set of two different wavelengths of light, and from the light generating means Light modulating means for electrically modulating the intensity of each of the plurality of sets of two wavelengths in the same phase for the plurality of sets by a signal having the same frequency and opposite phase for each set, and the light modulation; Light emitting means for combining and emitting the two-wavelength light of each of the plurality of sets from the means, and combining the two-wavelength light of each of the plurality of sets by the light emitting means And a sound wave detecting means for detecting sound waves generated by the plurality of emitted light at substantially equidistant positions from respective irradiated portions irradiated with the plurality of lights. Device.

  In the present invention, the light generating means generates a plurality of sets of first light and second light having different wavelengths. Here, the first light of each set has the same wavelength, and the second light of each set has the same wavelength. The light modulation means electrically modulates the intensity of each of the first light and the second light generated by the light generation means with signals having the same frequency and opposite phase, and outputs the result. The light emitting means multiplexes and emits each set of two-wavelength light output from the light modulating means. The sound wave detecting means detects the sound wave generated in the subject by the first light and the second light emitted from the light emitting means as described above at a position approximately equidistant from the light irradiated portion. Here, the sound wave detected by the sound wave detecting means is a difference sound wave between the first sound wave generated by the first light and the second sound wave generated by the second light.

  In this way, by combining and emitting each set of two wavelengths of light, the light intensity can be dispersed into a plurality of light, so that the light does not concentrate and irradiate in one place. The total amount of light to be generated can be increased. Furthermore, by detecting the sound wave at a position approximately equidistant from the irradiated site, it is possible to detect the sound wave at a position where the phases of the sound waves are aligned, so the magnitude of the detected sound wave is the sum of the sound waves from multiple irradiated sites. Can be detected. Therefore, the error of the sound wave from each irradiated part can be averaged. Therefore, the component concentration measuring apparatus of the present invention can accurately measure the component concentration of the measurement target with less burden on the subject and less influence of noise on sound waves generated in the subject.

The sound wave detecting means measures the sound wave generated in the subject as (s ₁ -s ₂ ) described in the above measurement principle.

  In the component concentration measuring apparatus of the present invention, the light modulation means can modulate the intensity of the light of the two wavelengths by delaying each of the signals having the opposite phase at the same frequency for each of the plurality of sets. Is desirable.

  Since the light modulation means can delay the modulated signals of the first and second lights in advance before the light intensity is modulated, the physical delay amount due to the electrical wiring is adjusted and the sound wave in the sound wave detection means is adjusted. Can be aligned. Therefore, the accuracy of reaching the sound wave detecting means of the sound wave generated in the subject in phase is improved, and the signal can be increased by the sum of the sound waves.

  In the component concentration measuring apparatus of the present invention, the light emitting means may be configured to set the sound wave detection position of the sound wave detecting means with respect to a plane in which the plurality of light beams are arranged perpendicular to the light emitting direction. It is desirable that the plurality of lights be emitted so as to be distributed on a center circle.

  By distributing the array of multiple light beams on the circumference centered on the detection position of the sound wave, if the sound wave detection means is arranged on one of the straight lines passing through the center of the circle, the sound wave from each irradiated site The detection distance can be made equal. Therefore, it is possible to accurately measure the component concentration to be measured while allowing the deviation of the detection position of the sound wave by the sound wave detection means in the linear direction passing through the center of the circle. In addition, by distributing an array of a plurality of light beams on the circumference centered on the detection position of the sound wave, it is possible to distribute the light irradiated site on the circumference accordingly, so that the light irradiation is performed. It is possible to average the influence of the surface undulation and the difference in acoustic transmission between the irradiated site and the sound wave detecting means. Therefore, the state of the sound wave detection by the sound wave detection means can be kept substantially constant, the measurement error of the component concentration can be reduced, and the component concentration of the measurement object can be accurately measured.

  In the component concentration measuring apparatus according to the present invention, the light emitting unit may be configured to set the detection position of the sound wave of the sound wave detecting unit with respect to a plane in which the plurality of irradiated portions are arranged perpendicular to the light emitting direction. It is desirable that the plurality of lights be emitted so as to be distributed on a center circle.

  By distributing the light irradiated parts on the circumference, if the sound wave detecting means is arranged on any one of the straight lines passing through the center of the circle, the detection distance of the sound wave from each irradiated part can be made equal. it can. Therefore, it is possible to accurately measure the component concentration to be measured while allowing the deviation of the detection position of the sound wave by the sound wave detection means in the linear direction passing through the center of the circle. Further, by distributing the light irradiated portion on the circumference, it is possible to average the influence of the undulation of the light irradiated surface and the difference in acoustic transmission between the irradiated portion and the sound wave detecting means. Therefore, the state of the sound wave detection by the sound wave detection means can be kept substantially constant, the measurement error of the component concentration can be reduced, and the component concentration of the measurement object can be accurately measured.

  In the component concentration measuring apparatus according to the present invention, the light generating means may use the two-wavelength light having a wavelength difference between the two wavelengths that is greater than a difference in absorption exhibited by water. It is desirable to set the wavelength to.

  Measuring the concentration of components by reducing the influence of water absorption by setting the wavelength of two wavelengths of light to be two wavelengths, where the difference in absorption exhibited by the component to be measured is greater than the difference in absorption exhibited by water Measurement accuracy can be improved.

  In the component concentration measuring apparatus according to the present invention, the light generating means sets the wavelength of one of the two wavelengths to a wavelength at which the component to be measured exhibits characteristic absorption, and the other light. Is preferably set to a wavelength at which water exhibits absorption equal to that of the one light.

  Among the two wavelengths of light, a predetermined one wavelength is set to a wavelength at which the component to be measured exhibits characteristic absorption, and the other one wavelength of light is set to the wavelength of the predetermined one wave. By setting the wavelength to the same absorption as the wavelength, the influence of water absorption can be reduced and the measurement accuracy of the component concentration measurement can be improved.

  In the component concentration measuring apparatus of the present invention, it is desirable that the light generating means sets the wavelength of one of the two wavelengths of light so that a component other than the component to be measured does not exhibit absorption. .

  The effect of the absorption of the other components is obtained by setting the wavelength of the two wavelengths to the wavelength of the two wavelengths of light that is larger than the difference in the absorption of the other components. And the measurement accuracy of the component concentration can be improved.

  In the component concentration measuring apparatus of the present invention, it is desirable that the component to be measured is glucose or cholesterol.

  When measuring the concentration of glucose or cholesterol, it can be measured with high accuracy by irradiating with a wavelength exhibiting the characteristic absorption of glucose or cholesterol.

  In the component concentration measuring apparatus of the present invention, the light generating means may combine the two wavelengths of light from the light modulating means into one light beam and irradiate the water with zero pressure of the sound wave generated. It is desirable to adjust the relative intensity of each of the two wavelengths of light.

  The pressure of the sound wave generated by irradiating the subject with light of two different wavelengths corresponds to the total absorption in the state where the component to be measured and the water of one wavelength generated in the subject are mixed with water as described above. Since it is detected as a difference between the pressure of the sound wave and the pressure of the sound wave generated only by the water in which the other light occupies most of the subject, light of two wavelengths different so that the value of this difference becomes zero It is possible to improve the measurement accuracy of the component concentration by calibrating the relative intensity of the.

  In the component concentration measuring apparatus of the present invention, it is desirable that the light modulating means modulates at the same frequency as a resonance frequency related to detection of sound waves generated by the two wavelengths of light.

  In the present invention, the measurement value of the sound wave is obtained by modulating the modulation frequency for electrically intensity-modulating each of the two different wavelengths of light at the same frequency as the resonance frequency related to the detection of the sound wave generated in the subject. Measures sound waves for light of two different wavelengths selected in consideration of the non-linearity related to the absorption coefficient, and eliminates the influence of many parameters that are difficult to keep constant from these measured values. Sound waves generated inside can be detected.

  In the component concentration measuring apparatus of the present invention, it is preferable that the light generating means and the light modulating means directly modulate each of the two semiconductor laser light sources with rectangular wave signals having the same frequency and opposite phases.

  In the present invention, by directly modulating each of the two semiconductor laser light sources with rectangular wave signals having the same frequency and opposite phases, light of two different wavelengths can be generated and simultaneously modulated. It can be simplified.

  In the component concentration measuring apparatus of the present invention, it is preferable that the sound wave detecting means detects sound waves by synchronous detection synchronized with the modulation frequency.

  By detecting the sound wave by synchronous detection synchronized with the modulation frequency, the sound wave can be detected with high accuracy.

  In the component concentration measuring apparatus of the present invention, it is desirable to further include a component concentration calculating means for calculating the component concentration from the pressure of the sound wave detected by the sound wave detecting means.

  In the present invention, the component concentration measuring device further includes a component concentration calculating means, thereby storing a theoretical value or an experimental value indicating a relationship between a sound wave generated in a sample prepared in advance and a component concentration to be measured, The component concentration of the measurement object is calculated from the value of the sound wave generated in the subject.

  Further, in the component concentration measuring apparatus of the present invention, the component concentration calculating means sets the pressure of the sound wave generated by the two wavelengths of light from the light modulating means to zero the one wavelength of the two wavelengths of light. It is desirable to divide by the pressure of the sound wave that is generated.

In the present invention, the magnitude (s ₁ -s ₂ ) of the sound wave generated from the subject by the two-wavelength light emitted from the light emitting means and the sound wave generated from the subject by the one-wavelength light emitted from the light emitting means. From the result of measuring the magnitude s ₂ by the sound wave intensity measuring means, the component concentration of the measurement target can be calculated by executing the calculation of (s ₁ −s ₂ ) ÷ s ₂ in accordance with the measurement principle described above. Therefore, the component concentration measuring apparatus of the present invention can accurately measure the component concentration of the subject to be measured with a simple configuration.

  The component concentration measuring apparatus of the present invention can accurately measure the component concentration of the measurement target with less burden on the subject and less influence of noise on sound waves generated in the subject.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  The following embodiment is an example of the configuration of the present invention, and is an embodiment in the case where a component concentration is measured by a finger of a human body as a subject, but the present invention is limited to the following embodiment is not. In the following, an embodiment in which the concentration of a component of a measurement object is measured can be obtained by replacing the object with the measurement object. Also, in FIGS. 2 to 4 showing the configuration of the component concentration measuring apparatus according to each embodiment, portions that can be realized by a normal technique such as a power source or a control unit that controls the overall operation are not shown.

(First embodiment)
A component concentration measuring apparatus according to this embodiment will be described. The component concentration measuring apparatus according to the present embodiment electrically generates light of two different wavelengths and outputs the light, and the two wavelengths of light from the light generating means are electrically output by signals of the same frequency and opposite phase. A light modulating means for intensity-modulating and outputting light, a light combining means for combining and outputting light of two wavelengths from the light modulating means, and a light output by being combined by the light combining means and splitting into a plurality of lights And a sound wave for detecting a sound wave generated by a plurality of lights branched and emitted by the light emitting means at a position approximately equidistant from each irradiated portion irradiated with the plurality of lights. Detecting means. Furthermore, it is preferable that the component concentration measuring apparatus of the present embodiment includes a component concentration calculating unit of the subject.

  FIG. 2 shows a schematic configuration diagram of a component concentration measuring apparatus according to the present embodiment.

  The component concentration measuring apparatus 10 according to the present embodiment includes an oscillator 101, a drive circuit 102, a 180 ° phase shift circuit 104, a drive circuit 105, a first light source 103, and a second light source as part of a light generation unit and a light modulation unit. Light source 106, multiplexing unit 107 as optical multiplexing unit, optical branching unit 108 as light emitting unit, acoustic wave detection unit 111, filter 112 and phase detection amplification unit 113 as part of acoustic wave detection unit, component concentration calculation unit As a component concentration calculation unit 114. In the present embodiment, the acoustic matching material 110 is provided between the subject 2 and the sound wave detection unit 111 in order to increase the transmission efficiency of sound waves generated in the subject 2.

  The oscillator 101 outputs a modulation signal for intensity-modulating light of two wavelengths output from the first light source 103 and the second light source 106. The 180 ° phase shift circuit 104 inverts one of the modulation signals from the oscillator 101 and outputs it.

  The drive circuit 102 drives the first light source 103 based on the modulation signal from the oscillator 101. The drive circuit 105 drives the second light source 106 based on the modulation signal inverted by the 180 ° phase shift circuit 104. The first light source 103 modulates the intensity of one of the two different wavelengths of light with a signal from the drive circuit 102 and outputs the intensity of the other light by the signal from the drive circuit 105. Modulate and output. As a result, each of two different wavelengths of light can be outputted after being electrically intensity-modulated with a signal having the same frequency and opposite phase.

  Here, for example, a semiconductor laser can be applied to the first light source 103 and the second light source 106, and the difference in absorption exhibited by the components whose measurement targets are two wavelengths of light is the difference in absorption exhibited by water. It is assumed that the wavelength of the two wavelengths is larger than that. In addition, the wavelength of each of the first light source 103 and the second light source 106 is set such that the wavelength of one light exhibits a characteristic absorption by the component to be measured, and the wavelength of the other light is set by water. It can also be set to a wavelength that exhibits absorption equal to that of one of the wavelengths of light. Furthermore, the wavelength of the two wavelengths of light can be set to the wavelength of the two wavelengths of light, where the difference in absorption exhibited by the component to be measured is greater than the difference in absorption exhibited by the other components. As a result, it is possible to improve the measurement accuracy of the component concentration measurement by reducing the influence of absorption by components other than water and components to be measured. Here, when the component to be measured is glucose or cholesterol, the concentration of glucose or cholesterol can be measured with high accuracy by irradiating with a wavelength indicating characteristic absorption of glucose or cholesterol. The semiconductor lasers as the first light source 103 and the second light source 106 can change the wavelength of light generated by heating or cooling with a heater or a Peltier element.

  In addition, the drive circuits 102 and 105 combine the two-wavelength light from the first light source 103 and the second light source 106 into one light beam and irradiate the water with water so that the pressure of the sound wave generated becomes zero. It is desirable to adjust the relative intensity of each of the two wavelengths of light. The pressure of the sound wave generated by irradiating the subject with light of two different wavelengths corresponds to the total absorption in the state where the component of the measurement target generated in the subject and water are mixed as described above. Since the difference between the pressure of the sound wave to be detected and the pressure of the sound wave generated by only the water in which the other one wave of light occupies most of the subject is detected, the difference value is different to be zero. The relative intensity of the two wavelengths of light can be calibrated to improve the measurement accuracy of the component concentration.

  In addition, it is desirable that the drive circuits 102 and 105 perform modulation at the same frequency as the resonance frequency related to detection of sound waves generated by light of two wavelengths from the first light source 103 and the second light source 106.

  By modulating the modulation frequency for electrically modulating the intensity of each of the two different wavelengths of light at the same frequency as the resonance frequency for detecting the sound wave generated in the subject, it is related to the absorption coefficient in the measurement value of the sound wave. Measure sound waves for light of two different wavelengths selected in consideration of nonlinearity, eliminate the influence of many parameters that are difficult to keep constant from these measured values, and generate sound waves in the subject with high accuracy Can be detected.

  In the present embodiment, a rectangular wave signal is output from the oscillator 101, and the first light source 103 and the second light source 106, which are the two semiconductor laser light sources, are connected to each other at the same frequency and in opposite phases. To modulate directly. In this way, by directly modulating each of the two semiconductor laser light sources with rectangular wave signals having the same frequency and opposite phases, it is possible to generate light of two different wavelengths and simultaneously modulate them, thereby simplifying the device configuration. Can be

  The multiplexing unit 107 combines the light from the first light source 103 and the light from the second light source 106 by, for example, a half mirror and emits the light toward the light branching unit 108.

  The optical branching unit 108 splits the light from the multiplexing unit 107 into a plurality of beams and emits the modulated light 120. As the optical branching unit 108, for example, a fiber coupler, a metal plate with holes, or a PLC (planar light wave circuit) can be applied. Here, the arrangement of the optical fibers of the fiber coupler is arranged on the circumference with respect to a plane perpendicular to the core center line direction of the optical fiber, or the holes of the metal plate are arranged on the circumference with respect to the metal plate surface. By arranging or arranging the optical waveguide of the PLC on the circumference with respect to the plane perpendicular to the emission direction of the modulated light 120, the optical branching unit 108 can transmit the modulated light 120 as a plurality of light beams. Light can be emitted so as to be distributed and arranged on a circle centered on the detection position of the sound wave of the sound wave detection unit 111 with respect to a surface whose arrangement is perpendicular to the light emission direction. When a metal plate with holes is applied as the light branching portion 108, parallel light with an expanded beam diameter is expanded to a size including the holes and irradiated onto the metal plate. The irradiated site formed on the surface of the subject 2 by the light emitted from the light branching unit 108 will be described later.

  The sound wave detection unit 111 is disposed at a substantially equidistant position from the light irradiation site, detects the sound wave generated in the subject 2 by the light emitted from the light branching unit 108 via the acoustic matching material 110, and An electrical signal proportional to the amplitude of is output. The filter 112 removes high frequency noise from the electrical signal from the sound wave detection unit 111 and outputs the result. The phase detection amplification unit 113 synchronously detects the electrical signal from the filter using the modulation signal from the oscillator 101, and outputs an electrical signal proportional to the sound pressure. Thus, by detecting the sound wave by synchronous detection synchronized with the modulation frequency, the sound wave can be detected with high accuracy.

The component concentration calculation unit 114 stores the magnitudes of sound waves generated by two-wavelength light and one-wavelength light emitted at different times, respectively, and calculates the component concentration from the previously prepared equation (3). Thus, by having the component concentration calculation unit 114, it is possible to calculate the component concentration of the measurement target by executing the calculation of (s ₁ −s ₂ ) ÷ s ₂ in accordance with the measurement principle described above. Therefore, the component concentration measuring apparatus of the present embodiment can accurately measure the component concentration of the subject to be measured with a simple configuration.

  Here, the arrangement of the irradiated region of the living body by the light emitted from the light branching unit 108 and the positional relationship between the irradiated region and the sound wave detection unit will be described.

  FIG. 5 is a schematic view showing the arrangement of irradiated portions formed by light emitted from the light branching section and the arrangement of the sound wave detecting sections. In FIG. 5, (1) shows a top view of the subject, and (2) shows a cross-sectional view taken along the AA ′ plane of (1). (1) and (2) show only a part including the irradiated part of the subject. In FIG. 5, the portion irradiated with the modulated light 120i (i = a to h) is interpreted as the portion to be irradiated 121i.

  As described above, the detection position of the sound wave of the sound wave detection unit 111 is set to the center 5 with respect to a plane in which the arrangement of the modulated light 120 as a plurality of light beams from the light branching unit 108 shown in FIG. When light is emitted so as to be distributed on the circumference, a plurality of irradiated parts 121a to 121h are arranged on the circumference around the sound wave detection unit 111 as shown in FIG. Can be made. In the present embodiment, since light is branched into eight by the light branching unit 108, eight irradiated portions 121 a to 121 h are formed on the subject 2. Further, since the sound wave detection unit 111 is set to the center 5 of the circle where the irradiated parts 121a to 121h are arranged, the propagation distance of the sound waves 130a to 130h from the irradiated parts 121a to 121h shown in FIG. Can be the same.

  In this way, by splitting the combined two-wavelength light at the light branching unit 108 and emitting it, the light intensity can be dispersed by making the irradiated parts plural, so that the light is concentrated in one place. Since it is not irradiated, the total amount of light to be irradiated can be increased. Furthermore, since the sound waves are detected by the sound wave detection unit 111 arranged at approximately the same distance from the irradiated portions 121a to 121h, the sound waves 130a to 130h can be detected at the positions where the phases of the sound waves 130a to 130h are aligned. The magnitude can be detected as the sum of the sound waves 130a to 130h from the plurality of irradiated portions 121a to 121h. Therefore, the errors of the sound waves 130a to 130h from the irradiated portions 121a to 121h can be averaged. Therefore, the component concentration measuring apparatus 10 of the present embodiment shown in FIG. 2 has a small burden on the subject 2 and reduces the influence of noise from the sound waves 130a to 130h generated in the subject 2 to reduce the component to be measured. The concentration can be measured accurately.

  Also, by distributing an array of modulated light 120a to 120h as a plurality of light beams on a circumference with the sound wave detection position as the center 5, the sound wave detection unit 111 is any one of straight lines that penetrate the center 5 of the circle. If it arrange | positions to, the detection distance of the sound waves 130a to 130h from the irradiated parts 121a to 121h to the sound wave detection part 111 can be made into equal distance. Therefore, it is possible to accurately measure the component concentration of the measurement target while allowing the detection position shift of the sound waves 130a to 130h by the sound wave detection unit 111 in the linear direction passing through the center 5 of the circle. Further, by distributing the array of modulated lights 120a to 120h as a plurality of light beams on the circumference with the sound wave detection position as the center 5, the irradiated portions 121a to 121h are arranged on the circumference accordingly. Can be distributed. For this reason, it is possible to average the influence of the undulation of the irradiated surface of light and the difference in acoustic transmission between the irradiated portions 121a to 121h to the sound wave detecting unit 111. Therefore, the state of the sound wave detection in the sound wave detection unit 111 can be kept substantially constant, the measurement error of the component concentration can be reduced, and the component concentration of the measurement target can be accurately measured.

  Further, in accordance with the shape of the surface of the subject 2, the arrangement of the optical fiber of the fiber coupler as the optical branching unit 108 and the arrangement of the holes on the metal plate of the metal plate with the holes formed are adjusted, as shown in FIG. As shown in (1), the circumference where the arrangement of the plurality of irradiated parts 121a to 121h is perpendicular to the emission direction of the plurality of modulated lights 120a to 120h, with the sound wave detection position of the sound wave detection unit 111 as the center 5. It is desirable to emit a plurality of modulated lights 120a to 120h so as to be distributed and arranged above. By distributing the light irradiated portions 121a to 121h on the circumference, if the sound wave detection unit 111 is arranged on any one of the straight lines passing through the center 5 of the circle, the light irradiation portions 121a to 121h to the sound wave detection unit 111 are arranged. The detection distances of the sound waves 130a to 130h can be made equal. Therefore, it is possible to accurately measure the component concentration of the measurement target while allowing the detection position shift of the sound waves 130a to 130h by the sound wave detection unit 111 in the linear direction passing through the center 5 of the circle. Further, by distributing the light irradiated portions 121a to 121h on the circumference, the influence of the undulation of the light irradiated surface and the difference in acoustic transmission between the irradiated portions 121a to 121h and the sound wave detection unit 111 can be affected. Can be averaged. Therefore, the state of the sound wave detection in the sound wave detection unit 111 can be kept substantially constant, the measurement error of the component concentration can be reduced, and the component concentration of the measurement target can be accurately measured.

  Further, by increasing the number of modulated lights 120 as a plurality of light beams, the number of irradiated parts can be increased. Here, FIG. 6 shows a schematic diagram of the shape of the irradiated site when the number of irradiated sites is increased as much as possible.

  When the number of modulated light 120 is increased and the number of irradiated portions 121a to 121h shown in FIG. 5 is increased from eight, the shape of the entire irradiated portion approaches an annular shape. When the number of irradiated parts is increased as much as possible, the overall shape of the irradiated parts becomes an annular shape as shown in the irradiated part 120k in FIG. When an annular shape is used like the irradiated portion 120k, the area of the entire irradiated portion is maximized under the same conditions of the circles where the irradiated portions 121a to 121h shown in FIG. The total amount of sound waves can be maximized. Here, to form an annular shape like the irradiated portion 120k, for example, in the above-described metal plate having a plurality of holes, the annular holes can be formed instead of the plurality of holes. .

  Next, the component concentration measurement operation of the component concentration measuring apparatus 10 according to the present embodiment will be described with reference to FIGS.

  The component concentration measuring apparatus 10 performs the following operation as the mixed light emission procedure.

First, the drive circuit 102 outputs a signal for driving the first light source 103 in synchronization with the modulation signal from the oscillator 101. Further, the drive circuit 105 outputs a signal for driving the second light source 106 in synchronization with the modulation signal via the 180 ° phase shift circuit 104. Here, the signal output from the drive circuit 102 and the signal output from the drive circuit 105 are inverted from each other. The first light source 103 sets the wavelength of the generated light to, for example, the wavelength λ ₁ at which the component to be measured exhibits characteristic absorption, and electrically transmits the light having the set wavelength by a signal from the drive circuit 102. Output intensity modulated. The second light source 106 is set to a wavelength λ ₂ that exhibits the same absorption as that of water at one wavelength of light, and the intensity of the light having the set wavelength is electrically modulated by a signal from the drive circuit 105. Output. Here, since the signal output from the drive circuit 102 and the signal output from the drive circuit 105 are inverted from each other, the first light emitted from the first light source 103 and the second light source 106 are emitted. The second light is emitted alternately.

  The multiplexing unit 107 multiplexes and emits the first light received from the first light source 103 and the second light received from the second light source 106. Then, the light branching unit 108 branches the light from the multiplexing unit 107 into a plurality of beams and emits the modulated light 120 toward the subject 2.

  Next, the component concentration measuring apparatus 10 performs the following operation as a sound intensity detection procedure.

The sound wave detection unit 111 generates a first sound wave from the subject 2 by the first light emitted from the light branching unit 108, and generates and superimposes the second sound wave from the subject 2 by the second light. As a sound wave of the difference between the first sound wave and the second sound wave, a sound wave (s ₁ -s ₂ ) is obtained as the sum of the sound waves 130a to 130h from the irradiated portions 121a to 121h of the subject 2 shown in FIG. The component concentration calculation unit 114 detected through the acoustic matching material 110 and shown in FIG. 2 stores the magnitude of the sound wave (s ₁ -s ₂ ) detected by the sound wave detection unit 111.

Next, the component concentration measuring apparatus 10 performs the following operation as a single sound intensity measurement procedure. The first light source 103 stops the generation of the first light, the second light source 106 generates the second light having the wavelength λ ₂ , and the electric intensity is modulated by the signal from the driving circuit 105 and output. Then, the modulated light 120 is emitted from the light branching unit 108. Acoustic wave detection unit 111 detects the sound waves _{s 2} as the sum of 130h from the sound wave 130a from 121h from the target irradiation section 121a of the subject 2, component concentration calculation unit 114 stores the size of the waves _{s 2.}

Next, the component concentration measuring apparatus 10 performs the following operation as a component concentration calculation procedure. The component concentration calculation unit 114 calculates the component concentration from (s ₁ -s ₂ ) and s ₂ acquired from the sound wave detection unit 111 according to Equation (3) according to the measurement principle described above.

  Since the component concentration measuring apparatus 10 according to the present embodiment branches the light combined by the light branching unit 108 and emits a plurality of lights, the component concentration is measured by the above procedure, and the burden on the subject 2 is measured. And the influence of noise on sound waves generated in the subject 2 can be reduced, and the concentration of the component to be measured can be accurately measured.

(Second Embodiment)
A component concentration measuring apparatus according to the second embodiment will be described.

  FIG. 3 shows a schematic configuration diagram of the component concentration measuring apparatus according to the present embodiment. In FIG. 3, the same component numbers are used for the same components as in the first embodiment.

  The component concentration measuring apparatus 11 according to the present embodiment has a configuration in which a calibration sample 811 is introduced as means for adjusting the powers of light output from the first semiconductor laser light source 801 and the second semiconductor laser light source 805 to be equal. . Further, the component concentration measuring apparatus 11 of the present embodiment is a light generating means of the first light source 103, the second light source 106, and the light branching unit 108 in the component concentration measuring apparatus 10 according to the first embodiment described with reference to FIG. The light modulating means and the light emitting means have different points.

  Since the other parts of the component concentration measuring apparatus 11 of the present embodiment are the same as those of the component concentration measuring apparatus 10 according to the first embodiment shown in FIG. 2, here the component concentration measuring apparatus 11 according to the present embodiment is described. A different part from the component concentration measuring apparatus 10 of 1st Embodiment is demonstrated. In addition, since the measurement principle of the component concentration measuring apparatus 11 according to the present embodiment is the same as that of the component concentration measuring apparatus 10 according to the first embodiment, FIG. 5 is appropriately described for explaining the component concentration measuring apparatus 11 according to the present embodiment. refer.

  The component concentration measurement apparatus 11 according to this embodiment includes a first semiconductor laser light source 801, a second semiconductor laser light source 805, a lens 802, a lens 806, and an optical multiplexing unit as part of the light generation unit and the light modulation unit. A combining unit 107 as a part, a lens 815, a fiber coupler 812 as a light emitting unit, a fiber collimator 813, and a glass plate 814 are provided.

  In the present embodiment, the first semiconductor laser light source 801 and the second semiconductor laser light source 805 set the wavelengths of light to wavelengths of 1608 nm and 1381 nm, respectively, and reverse the light having the light intensity CW light of 12 mW at the frequency of 450 kHz of the oscillator 101. The light is emitted as phase intensity modulated light.

  The combining unit 107 has two wavelengths of light emitted from the first semiconductor laser light source 801 and condensed via the lens 802 and light emitted from the second semiconductor laser light source 805 and condensed via the lens 806. Are combined and output.

  The fiber coupler 812 divides the light coupled to the optical fiber by the lens 815 into four equal powers and outputs them. A fiber collimator 813 is connected to the tip of each branched fiber, and the fiber collimator 813 converts the light from the fiber coupler 812 into a 1 mm diameter parallel light beam and emits it through the glass plate 814. The method is not limited to the method of dividing the light into equal power and beam diameter. As described in the first embodiment, for example, a metal plate in which parallel beams with large diameters are formed with holes at equal intervals. It is possible to divide in the same way even if it is transmitted through. In addition, the optimum value of the number of light branches is adjusted based on the obtained acoustic frequency characteristics, and is not limited to four. Here, in this embodiment, the sound receiving surface of the sound wave detection unit 111 installed on the opposite side to the light irradiated surface of the subject 2 has a diameter of 16 mm, and a radius of 4 mm from the center 5 of the sound receiving surface. The position of the fiber collimator 813 immediately above the subject 2 was adjusted so that the irradiated portions shown in FIG.

  Here, in this embodiment, the light from the fiber collimator 813 is emitted toward the belly of the finger so that no bone is interposed between the sound source at the light irradiation position and the sound wave detection unit 111. Furthermore, the glass plate 814 is pressed against the irradiated surface of the subject 2 in order to prevent the distance between the sound source and the sound receiving surface, which are the irradiated portions, from being changed due to the unevenness of the finger surface. For pressing the glass plate 814, in order to avoid blood ischemia in the finger epidermis of the pressing surface, a hole is prepared at a position to be an irradiated site so that the irradiated site does not directly contact the glass, The contact portion was limited to the periphery of the irradiated site. In addition, gel is applied to the surface of the sound wave detection unit 111 so that air bubbles are not scattered between the fingers.

  In addition, the position of the finger is adjusted so that the distance between the sound source that is the irradiated part and the sound receiving surface is a long-distance sound field so that the sound wave from each irradiated part becomes a plane wave on the sound receiving surface of the sound wave detection unit 111 To do. In the case of the present embodiment, since the thickness of the finger as the subject 2 is about 15 mm, the distance for the far field is about 15 mm. Note that this value depends on the sound source size that is the sound wave detection unit 111 and the irradiated portion, and is not necessarily limited to this value.

  The component concentration measuring apparatus 11 is configured as described above, and only light having a wavelength of 1381 nm is emitted from the second semiconductor laser light source 805, and various parameters such as light irradiation position and irradiation power are adjusted. The distance between the center 5 (FIG. 5) of the sound wave detection unit 111 and the light emission position and the modulation frequency of the oscillator 101 are manipulated to adjust the sound wave to the maximum value. In addition, since the acoustic transmission path / characteristics to the sound wave detection unit 111 are randomly different depending on the position of the sound source that is each irradiation site, each resonance peak is blunted as a result of adding these signals on the sound wave detection unit 111. To do.

  Here, the blunting of the resonance peak will be described. FIG. 7 is a diagram showing a change in sound intensity with respect to the modulation frequency of the oscillator. In FIG. 7, the solid line indicates the sound wave intensity when the light is not branched (the number of branches is 1), and the dotted line indicates the sound wave intensity when the light branch number in the above-described fiber coupler is 4.

  As shown in FIG. 7, it can be seen that when the number of branches of light is 4, the resonance peak becomes duller than when the number of branches is 1. Moreover, the ripple of the frequency characteristic can be partially flattened to 3 dB or less. It was also found that the intensity of the resonance peak is weakened and the flatness is increased more in the palm where the distance between the sound source that is the irradiation site and the sound wave detection unit 111 is longer than the finger as the subject 2.

  After the above adjustment procedure, the finger as the subject 2 in FIG. 3 is fixed. The signal from the sound wave detection unit 111 was amplified by a preamplifier that is a part of the phase detection amplification unit 113 and then phase-detected by a lock-in amplifier, and the indicated value was 1.65 mV. Many of the signal changes that accompany changes in the acoustic transfer characteristics of the finger (acoustic impedance, shift due to weak body movement) are caused by the shift of the frequency domain, and are therefore suppressed by the flattening of the frequency characteristics. The signal change rate was 1% or less.

  Next, in place of the subject 2, a calibration specimen 811, which is a silicon rubber cell filled with water, is disposed, and light having a wavelength of 1.60 μm is additionally emitted from the first semiconductor laser light source 801. Then, the optical power was adjusted, and the signal value of the lock-in amplifier was set to about 0.5 μV. Again, the finger as the subject 2 was placed in place of the calibration sample 811 and the signal was observed. As a result, the indicated value of the lock-in amplifier was about 4 μV. In addition, the indication value with only light having an optical wavelength of 1.38 μm, which absorbs only water, is 1.72 mV. The signal value is divided, and the glucose component is multiplied by the target component glucose / water absorbance ratio. The concentration was calculated and found to be 145 mg / dl.

(Third embodiment)
A component concentration measuring apparatus according to the third embodiment will be described. The component concentration measuring apparatus according to the present embodiment includes a light generating means for generating and outputting a plurality of sets of two wavelengths of light having the same wavelength as each of the two wavelengths of different wavelengths, with a set of lights having different two wavelengths as a set, Optical modulation means for outputting each of the two-wavelength light of each of the plurality of sets from the light generating means by electrically modulating the intensity of the plurality of sets in phase with the same frequency and opposite phase signals for each set. And a light emitting means for combining and emitting light of two sets of each of the plurality of sets from the light modulation means, and two wavelengths of each of the plurality of sets by the light emitting means. Sound wave detecting means for detecting sound waves generated by a plurality of light beams that are combined and emitted at a position approximately equidistant from each irradiated site irradiated with the plurality of light beams. Furthermore, it is preferable that the component concentration measuring apparatus of the present embodiment includes a component concentration calculating unit of the subject.

  FIG. 4 shows a schematic configuration diagram of a component concentration measuring apparatus according to the present embodiment. In FIG. 4, the same constituent elements as those in the first embodiment are given the same constituent element numbers, and when there are two or more identical constituent elements, the English numerals are assigned to the constituent element numbers.

  The component concentration measuring apparatus 12 according to the present embodiment has a plurality of light sources instead of branching light by the light branching unit 108 as in the component concentration measuring apparatus 10 of the first embodiment shown in FIG. It is.

  Since the other parts of the component concentration measuring apparatus 12 of the present embodiment are the same as those of the component concentration measuring apparatus 10 according to the first embodiment shown in FIG. 2, here the component concentration measuring apparatus 12 according to the present embodiment is described. A different part from the component concentration measuring apparatus 10 of 1st Embodiment is demonstrated. In addition, since the measurement principle of the component concentration measuring apparatus 12 according to the present embodiment is the same as that of the component concentration measuring apparatus 10 according to the first embodiment, FIG. 5 is appropriately used to describe the component concentration measuring apparatus 12 according to the present embodiment. refer.

  The component concentration measuring apparatus 12 according to the present embodiment includes an oscillator 101, a 180 ° phase shift circuit 104, multi-channel drive circuits 115a and 115b, first light sources 103a and 103b, and a light generation unit and a light modulation unit. Second light sources 106a and 106b, combining units 107a and 107b as optical combining units, optical fibers 118a and 118b and light irradiators 117 as light emitting units, and a sound wave detecting unit 111 as a sound wave detecting unit. Furthermore, the component concentration measuring apparatus 12 according to the present embodiment, as a part of the light modulation unit, outputs signals of opposite phases at the same frequency for intensity-modulating the light from the first light source 103b and the second light source 106b. Delay generators 116a and 116b for delaying are provided.

  In this embodiment, the first light source 103a and the second light source 106a make one set, and the first light source 103b and the second light source 106b make one set. Lights of two different wavelengths output from the first light source 103a and the second light source 106a are combined by the combining unit 107a and output toward the optical fiber 118a. On the other hand, light of two different wavelengths output from the first light source 103b and the second light source 106b are combined by the combining unit 107b and output toward the optical fiber 118b. Here, the light wavelengths of the first light sources 103a and 103b are the same, and the light wavelengths of the second light sources 106a and 106b are the same.

  In the present embodiment, two sets of two-wavelength light, the first light source 103a, the second light source 106a, the first light source 103b, and the second light source 106b, are provided. In order to match the number of irradiation parts, the number of sets is not limited to two, and a large number of sets may be provided in accordance with the size of sound waves detected by the sound wave detection unit 111. In other words, since the size of the sound wave increases as the number of irradiated portions increases, the light intensity at each irradiated portion can be weakened.

  The multi-channel driving circuit 115 a outputs signals for driving the second light sources 106 a and 106 b in synchronization with the modulation signal from the oscillator 101. The multi-channel driving circuit 115b outputs signals for driving the first light sources 103a and 103b in synchronization with the modulation signal from the oscillator 101.

  The delay generator 116a delays a signal for driving the second light source 106b among signals output from the multi-channel drive circuit 115a for a predetermined time. The delay generator 116b delays a signal for driving the first light source 103b among the signals output from the multi-channel driving circuit 115b for a predetermined time.

  As described above, the delay generators 116a and 116b are provided so that the first and second light modulation signals can be respectively delayed in advance before the light intensity modulation, thereby reducing the physical delay amount due to the electrical wiring. The phase of the sound wave at the sound wave detection unit 111 can be adjusted to be adjusted. Therefore, the accuracy with which the sound wave generated in the subject 2 reaches the sound wave detection unit 111 in the same phase is improved, and the signal can be increased due to the sum of the sound waves. Here, in this embodiment, the signals to the first light source 103b and the second light source 106b are delayed, but a delay generator that delays the signals to the first light source 103a and the second light source 106a. May be further provided. Furthermore, complicated delay processing can be performed. In this embodiment, the delay generators 116a and 116b are provided to delay the modulation signals for intensity-modulating the first and second lights, respectively. However, instead of the delay generators 116a and 116b, a pulse delay is provided. It is good also as applying a regulator. The pulse delay adjuster is a device that measures the pulse time of a modulation signal that is a pulse signal at an internal clock frequency provided in the pulse delay adjuster, and re-outputs a pulse corresponding to a specified delay time.

  Here, the amount of delay in the delay generators 116a and 116b varies depending on the delay difference in the electrical system, the delay difference in the optical system, and the difference in the speed of sound waves in the subject (the speed of sound differs in bone and meat). The physical distance between the sound source that is the irradiated site and the sound wave detection unit 111 cannot be determined. Therefore, the delay generators 116a and 116b adjust the delay amount in advance. For example, only the light of the set of the first light source 103b and the second light source 106b is emitted, the delay amount of the delay generators 116a and 116b is delayed one by one, and the magnitude of the sound wave due to the light increases. Perform delay adjustment.

  The light irradiator 117 applies the above-described fiber coupler, for example, and emits light incident on the optical fibers 118 a and 118 b toward the subject 2 as modulated light 120. Here, in the light irradiator 117, as described with reference to FIG. 5 in the first embodiment, the arrangement of the modulated light 120 as a plurality of light beams emitted toward the subject 2 is light. It is desirable to emit a plurality of modulated lights 120 so as to be distributed on a circumference centered at a detection position of the sound wave detection unit 111 with respect to a plane perpendicular to the emission direction. By distributing the array of modulated light 120 as a plurality of light beams on a circle having the sound wave detection position as the center 5 shown in FIG. 5, the sound wave detection unit 111 is one of the straight lines passing through the center 5 of the circle. If it arrange | positions to, the detection distance of the sound wave from each irradiated part to the sound wave detection part 111 can be made into equal distance. Therefore, the deviation of the detection position of the sound wave by the sound wave detection unit 111 in the linear direction passing through the center 5 of the circle is allowed, and the component concentration of the measurement target can be accurately measured. Further, by distributing the array of modulated light 120 as a plurality of light beams on the circumference with the detection position of the sound wave as the center 5 shown in FIG. 5, the portion to be irradiated with light is distributed on the circumference accordingly. Can be made. For this reason, it is possible to average the influence of the undulation of the irradiated surface of light and the difference in acoustic transmission between the irradiated portion and the sound wave detection unit 111. Therefore, the state of the sound wave detection in the sound wave detection unit 111 can be kept substantially constant, the measurement error of the component concentration can be reduced, and the component concentration of the measurement target can be accurately measured.

  Further, according to the shape of the surface of the subject 2, the arrangement of the optical fiber of the fiber coupler as the light irradiator 117 and the arrangement of the holes on the metal plate of the metal plate with the holes formed are adjusted, as shown in FIG. As shown in (1), the arrangement of a plurality of irradiated portions is distributed on a circumference centering on the detection position of the sound wave of the sound wave detection unit 111 with respect to a plane perpendicular to the emission direction of the plurality of modulated lights 120. It is desirable to emit the plurality of lights so as to be arranged. If the sound wave detection unit 111 is arranged on any one of the straight lines passing through the center 5 of the circle by distributing the light irradiation site on the circumference, the detection distance of the sound wave from each irradiation site to the sound wave detection unit 111 is increased. It can be equidistant. Therefore, the deviation of the detection position of the sound wave by the sound wave detection unit 111 in the linear direction passing through the center 5 of the circle is allowed, and the component concentration of the measurement target can be accurately measured. Further, by distributing the light irradiated portion on the circumference, it is possible to average the influence of the undulation of the light irradiated surface and the difference in acoustic transmission between the irradiated portion and the sound wave detection unit 111. . Therefore, the state of the sound wave detection in the sound wave detection unit 111 can be kept substantially constant, the measurement error of the component concentration can be reduced, and the component concentration of the measurement target can be accurately measured.

  As described in the first embodiment, the sound wave detection unit 111 is disposed at a substantially equidistant position from the light irradiation site, and acoustic waves generated by the subject 2 are emitted by the light emitted from the combining unit 107. An electrical signal detected by the matching material 110 and proportional to the amplitude of the sound wave is output.

  In this way, the two wavelengths of light of each set of the first light source 103a, the second light source 106a, the first light source 103b, and the second light source 106b are combined by the combining units 107a and 107b and emitted respectively. Thus, since the light intensity can be dispersed in a plurality, light is not concentrated and irradiated at one place, so that the total amount of light to be irradiated can be increased. Furthermore, by detecting the sound wave at a position approximately equidistant from the irradiated site, it is possible to detect the sound wave at a position where the phases of the sound waves are aligned, so the magnitude of the detected sound wave is the sum of the sound waves from multiple irradiated sites. Can be detected. Therefore, the error of the sound wave from each irradiated part can be averaged. Therefore, the component concentration measurement apparatus 12 of the present embodiment can accurately measure the component concentration of the measurement target with less burden on the subject 2 and less influence of noise on sound waves generated in the subject 2. Can do.

  Next, the component concentration measurement operation of the component concentration measuring apparatus 12 according to the present embodiment will be described with reference to FIG.

  The component concentration measuring device 12 performs the following operation as the mixed light emission procedure.

First, the multi-channel driving circuit 115b outputs signals for driving the first light source 103a and the first light source 103b in synchronization with the modulation signal from the oscillator 101. The multi-channel driving circuit 115a outputs signals for driving the second light source 106a and the second light source 106b in synchronization with the modulation signal via the 180 ° phase shift circuit 104. Here, the signal output from the multi-channel drive circuit 115a and the signal output from the multi-channel drive circuit 115b are inverted from each other. The first light source 103a sets the wavelength of the generated light to, for example, the wavelength λ ₁ at which the component to be measured exhibits characteristic absorption, and the light of the set wavelength is electrically generated by a signal from the multi-channel drive circuit 115b. The intensity is modulated and output. In addition, the second light source 106a is set to a wavelength λ ₂ that exhibits absorption equivalent to that of water at one wavelength of light, and the light of the set wavelength is electrically intensified by a signal from the multi-channel drive circuit 115a. Modulate and output. Here, since the signal output from the multi-channel drive circuit 115a and the signal output from the multi-channel drive circuit 115b are inverted with each other, the first light and the second light emitted from the first light source 103a are inverted. The second light emitted from the light source 106a is emitted alternately. Meanwhile, the first light source 103b is the wavelength of the generated light is set to the first light source 103a and the same wavelength lambda _1, electrically by a signal light of a wavelength set from a multi-channel driving circuit 115b intensity Modulate and output. The second light source 106b is set to the same wavelength λ2 as that of the _second light source 106a, and the light having the set wavelength is electrically intensity-modulated by a signal from the multi-channel driving circuit 115a and output.

  The multiplexing unit 107a combines and emits the first light received from the first light source 103a and the second light received from the second light source 106a. On the other hand, the multiplexing unit 107b combines and emits the first light received from the first light source 103b and the second light received from the second light source 106b. The light irradiator 117 emits the light from the multiplexing units 107a and 107b toward the subject 2 as modulated light 120, respectively.

  Next, the component concentration measuring apparatus 12 performs the following operation as a sound intensity detection procedure.

The sound wave detection unit 111 generates a first sound wave from the subject 2 by the first light emitted from the light irradiator 117, and generates and superimposes the second sound wave from the subject 2 by the second light. Then, as the sound wave of the difference between the first sound wave and the second sound wave, the sound wave (s ₁ -s ₂ ) is detected as the sum of the sound waves from each irradiated part of the subject ₂ through the acoustic matching material 110, The component concentration calculation unit 114 stores the magnitude of the sound wave (s ₁ -s ₂ ) detected by the sound wave detection unit 111.

Next, the component concentration measuring apparatus 12 performs the following operations as a single sound intensity measurement procedure. The first light source 103a, 103b is the generation of the first light stop, a second light source 106a, 106b generates a second light of the wavelength lambda _2, the multi-channel driving circuit 115a, a signal from 115b The intensity is electrically modulated and output, and the modulated light 120 is emitted from the light irradiator 117. The sound wave detection unit 111 detects the sound wave s ₂ as the sum of the sound waves from each irradiated part of the subject ₂ , and the component concentration calculation unit 114 stores the magnitude of the sound wave s ₂ .

Next, the component concentration measuring apparatus 12 performs the following operation as a component concentration calculation procedure. The component concentration calculation unit 114 calculates the component concentration from (s ₁ -s ₂ ) and s ₂ acquired from the sound wave detection unit 111 according to Equation (3) according to the measurement principle described above.

  Since the component concentration measurement apparatus 12 according to the present embodiment emits a plurality of lights from the light irradiator 117, the component concentration is measured by the above procedure, and the burden on the subject 2 is small and occurs in the subject 2. It is possible to reduce the influence of noise on the sound wave to be measured and accurately measure the concentration of the component to be measured.

  The component concentration measuring apparatus of the present invention can be used for daily health management and cosmetic check. Moreover, not only humans but also animals can be used for health management.

  In addition, the component concentration measuring apparatus of the present invention can be applied not only to humans and animals but also to the field of measuring component concentrations in liquids, for example, sugar content measurement of fruits.

It is the figure which showed the light absorbency characteristic of the water and glucose aqueous solution in normal temperature. It is a schematic block diagram of the component concentration measuring apparatus which concerns on 1 embodiment. It is a schematic block diagram of the component concentration measuring apparatus which concerns on 1 embodiment. It is a schematic block diagram of the component concentration measuring apparatus which concerns on 1 embodiment. It is the schematic which showed arrangement | positioning of the to-be-irradiated site | part formed with the light radiate | emitted from a light branching part, and arrangement | positioning of a sound wave detection part. It is the schematic which showed the shape of the irradiated part when the number of irradiated parts was increased without limit. It is the figure which showed the change of the sound wave intensity with respect to the modulation frequency of an oscillator. It is a figure which shows the structural example of the conventional blood component concentration measuring apparatus. It is a figure which shows the structural example of the conventional blood component concentration measuring apparatus.

Explanation of symbols

2: Subject 5: Center 10: Component concentration measuring device 11: Component concentration measuring device 12: Component concentration measuring device 101: Oscillator 102: Drive circuit 103: First light source 103a, b: First light source 104: 180 ° Phase shift circuit 105: drive circuit 106: second light source 106a, b: second light source 107: multiplexing unit 107a, b: multiplexing unit 108: light branching unit 110: acoustic matching substance 111: sound wave detection unit 112: Filter 113: Phase detection amplification unit 114: Component concentration calculation unit 115a, b: Multi-channel drive circuit 116a, b: Delay generator 117: Light irradiator 118a, b: Optical fiber 120: Modulated light 120a-h: Modulated light 121a -H: irradiated portion 121k: irradiated portion 130a-h: sound wave 601: first light source 604: drive circuit 605: second light source 608: drive circuit 609: multiplexer 61 : Subject 613: ultrasonic detector 616: pulse light source 617: chopper plate 618: motor 619: acoustic sensor 620: waveform observer 621: frequency analyzer 801: first semiconductor laser light source 802: lens 805: second Semiconductor laser light source 806: lens 807: 180 ° phase shift circuit 811: calibration sample 812: fiber coupler 813: fiber collimator 814: glass plate 815: lens

Claims (15)

Light generating means for generating and outputting light of two different wavelengths;
Light modulating means for electrically modulating the intensity of each of the two wavelengths of light from the light generating means with a signal of the opposite phase at the same frequency; and
Optical multiplexing means for multiplexing and outputting two-wavelength light from the optical modulation means;
A light emitting means for branching the light output by the light combining means and outputting the light;
A sound wave detecting means for detecting sound waves generated by a plurality of lights branched and emitted by the light emitting means at positions substantially equidistant from respective irradiated portions irradiated with the plurality of lights;
A component concentration measuring apparatus comprising: Light generating means for generating and outputting a plurality of sets of two wavelengths of light having the same wavelength as each of the two different wavelengths of light, with two different wavelengths of light as a set;
Optical modulation that outputs each of the two-wavelength light of each of the plurality of sets from the light generating means by electrically modulating the intensity of the plurality of sets in phase with the same frequency and opposite phase signals for each set Means,
A light emitting means for combining and emitting the two-wavelength light of each set of the plurality of sets from the light modulation means;
Sound waves generated by a plurality of light beams that are combined and emitted from the two-wavelength light of each of the plurality of sets by the light emitting means are approximately equidistant from each irradiated site irradiated with the plurality of light beams. A sound wave detection means for detecting the position;
A component concentration measuring apparatus comprising:   3. The light modulation unit according to claim 2, wherein the light modulation means can modulate the intensity of the light of the two wavelengths by delaying each signal of the opposite phase at the same frequency for each of the plurality of sets. Ingredient concentration measuring device.   The light emitting means is arranged in such a manner that an array of the plurality of light beams is distributed on a circumference centering on a detection position of the sound wave of the sound wave detecting means with respect to a plane perpendicular to the emission direction of the plurality of lights. The component concentration measuring apparatus according to claim 1, wherein the plurality of lights are emitted as described above.   The light emitting means is arranged in such a manner that a plurality of the irradiated portions are arranged on a circumference centered on a detection position of the sound wave of the sound wave detecting means with respect to a plane perpendicular to the emission direction of the plurality of lights. The component concentration measuring apparatus according to claim 1, wherein the plurality of lights are emitted as described above.   The light generation means sets the wavelength of the two wavelengths of light to a wavelength of two wavelengths of light in which the difference in absorption exhibited by the component to be measured is greater than the difference in absorption exhibited by water. Item 6. A component concentration measuring apparatus according to any one of Items 1 to 5.   The light generating means sets the wavelength of one of the two wavelengths of light to a wavelength at which the component to be measured exhibits characteristic absorption, and the wavelength of the other light is the wavelength of the one of the lights 6. The component concentration measuring apparatus according to claim 1, wherein the wavelength is set to a wavelength exhibiting an absorption equal to that of the component.   The component according to claim 6 or 7, wherein the light generation means sets one of the two wavelengths of light to a wavelength at which a component other than the component to be measured does not exhibit absorption. Concentration measuring device.   The component concentration measuring apparatus according to claim 6, wherein the component to be measured is glucose or cholesterol.   The light generating means combines the two wavelengths of light from the light modulation means so that the pressure of the sound wave generated by combining the two wavelengths of light into one light beam and irradiating it with water becomes zero. The intensity | strength of a component is measured, The component concentration measuring apparatus in any one of Claim 1 to 9 characterized by the above-mentioned.   11. The component concentration measuring apparatus according to claim 1, wherein the light modulator modulates at a frequency that is the same as a resonance frequency related to detection of a sound wave generated by the light of the two wavelengths.   12. The component according to claim 1, wherein the light generating means and the light modulating means directly modulate each of the two semiconductor laser light sources with rectangular wave signals having the same frequency and opposite phases. Concentration measuring device.   The component concentration measuring apparatus according to claim 1, wherein the sound wave detecting unit detects a sound wave by synchronous detection synchronized with the modulation frequency.   The blood concentration measuring device according to any one of claims 1 to 13, further comprising a component concentration calculating means for calculating a component concentration from the pressure of the sound wave detected by the sound wave detecting means. The component concentration calculation means divides the pressure of the sound wave generated by the light of two wavelengths from the light modulation means by the pressure of the sound wave generated when the light of one wavelength out of the two wavelengths of light is zero. The component concentration measuring apparatus according to claim 14.

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