JP2013068461A - Refraction factor measuring apparatus, sugar concentration measuring apparatus and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refraction factor measuring apparatus in which a refraction factor of a measuring target can be measured easily and highly accurately.SOLUTION: A refraction factor measuring apparatus 1 is adopted which comprises a light guide rod 10, a line sensor 20 and a CPU 30. The light guide rod 10 reflects incident illumination light on its inner surface and guides the light to its end face. The line sensor 20 measures a light flux diameter of light from the light guide rod 10, at a predetermined position from the end face of the light guide rod 10. The CPU 30 calculates a spread angle of light from the light guide rod 10 from the light flux diameter measured by the line sensor 20, and calculates a refraction factor of a sample S in contact with a side surface of the light guide rod 10 on the basis of the spread angle.

Description

  The present invention relates to a refractive index measuring device, a sugar concentration measuring device including the same, and a method thereof.

  Conventionally, the refractive index of a measurement object is measured by optically contacting a measurement object with a known refractive index and measuring the incident angle (critical angle) of light at which the total reflection occurs at the interface. Refractive index measuring devices are known (see, for example, Patent Documents 1 to 3).

JP 2009-162561 A JP 2005-257319 A JP 2003-322616 A

  However, according to the refractive index measuring devices disclosed in Patent Documents 1 to 3, the image showing the boundary of the refractive index is found in the field of view, the lens barrel is moved to match the boundary, and the angle at that time is set. Based on this, the refractive index was calculated. For this reason, it took time and effort to measure the refractive index of the measurement object. In addition, there is a disadvantage that the measurement accuracy error is large.

  The present invention has been made in view of the above-described circumstances, and provides a refractive index measuring device that can easily and accurately measure the refractive index of a measurement object, a sugar concentration measuring device including the same, and a method thereof. The purpose is to provide.

In order to achieve the above object, the present invention provides the following means.
The first aspect of the present invention measures a light guide rod that internally reflects incident illumination light and guides it to an end surface, and measures a light beam diameter of the light from the light guide rod at a predetermined position from the end surface of the light guide rod. A divergence angle of light from the light guide rod is calculated from a measurement unit and a light beam diameter measured by the measurement unit, and a refractive index of a sample contacting the side surface of the light guide rod is calculated based on the divergence angle. A refractive index measuring device including a calculating unit.

  According to the first aspect of the present invention, the illumination light incident on the light guide rod reflects the inner side surface of the light guide rod while the sample for measuring the refractive index is in contact with the side surface of the light guide rod. To the end face. And light is inject | emitted from the end surface of a light guide rod, and the light beam diameter of the light in a predetermined position from this end surface is measured by a measurement part. Then, the calculation unit calculates the divergence angle of the light from the light guide rod from the measured light beam diameter, and calculates the refractive index of the sample contacting the side surface of the light guide rod based on the divergence angle. .

  In this case, the light emitted from the end face of the light guide rod is totally reflected a plurality of times at the interface between the light guide rod and the sample. Thereby, the angle distribution of the divergence angle of the light from the light guide rod can be made steep, and the accuracy of the refractive index of the sample calculated based on the divergence angle can be improved. Further, unlike the conventional refractive index measuring apparatus, it is not necessary to find an image showing the boundary of the refractive index with the naked eye or to move the lens barrel. That is, according to the first aspect of the present invention, the refractive index of the sample can be easily and accurately measured.

In the above aspect, when the calculation unit sets the light beam radius at the predetermined position as h, the distance between the end face of the light guide rod and the predetermined position as f1, and the light spread angle as θ, The light divergence angle may be calculated based on the above.
h = f1 × tanθ

  In this way, the light divergence angle (angle formed with the optical axis of the light) can be easily calculated, and the refractive index of the sample contacting the side surface of the light guide rod is calculated based on the divergence angle. be able to.

In the above aspect, a focal position is disposed on an end surface of the light guide rod, and an optical system that emits light from the light guide rod as parallel light and emits the light to the predetermined position is provided, and the calculation unit includes light at the predetermined position. Where the light beam radius is h, the focal length of the optical system is f2, and the light spread angle is θ, the light spread angle may be calculated based on the following equation.
h = f2 × tanθ

  In this way, the light divergence angle (angle formed with the optical axis of the light) can be easily calculated, and the refractive index of the sample contacting the side surface of the light guide rod is calculated based on the divergence angle. be able to. In addition, since the light from the light guide rod can be converted into parallel light by the optical system, the position (predetermined position) at which the light beam diameter is measured can be set to an arbitrary position in the optical axis direction, and the light beam diameter is unnecessary. It is possible to limit the measurement range by the measurement unit.

In the above aspect, the calculation unit calculates an incident angle to the sample that causes total reflection in the light guide rod from a spread angle of light from the light guide rod, and refraction of the sample based on the following formula: The rate may be calculated.
θc = arcsin (n2 / n1)
here,
θc: Angle of incidence on the sample causing total reflection in the light guide rod n1: Refractive index of the light guide rod n2: Refractive index of the sample

  By doing in this way, the incident angle to the sample which causes total reflection in the light guide rod can be calculated from the divergence angle of the light from the light guide rod, and the refractive index of the sample can be easily calculated.

  In the above aspect, the light guide rod includes a first end surface on which illumination light is incident, and a second end surface that is disposed on the other end side of the first end surface and reflects the light guided by internal reflection. It is good also as having.

  With this configuration, the illumination light incident from the first end surface is repeatedly reflected by the inner surface of the light guide rod and guided to the second end surface, and is reflected by the second end surface and guided again to the first end surface. Can do. By doing in this way, the frequency | count of total reflection in the interface of a light guide rod and a sample can be increased. Thereby, the angle distribution of the divergence angle of the light from the light guide rod can be made steep, and the accuracy of the refractive index of the sample calculated based on the divergence angle can be improved. Moreover, the structure of the light guide rod can be simplified.

The said aspect WHEREIN: It is good also as providing the wavelength adjustment part which adjusts the wavelength of the illumination light entered into the said light guide rod.
By configuring in this way, the refractive index of the sample for each wavelength can be calculated while adjusting the wavelength of the illumination light incident on the light guide rod by the wavelength adjusting unit, and the accuracy of the refractive index of the sample is improved. be able to.

  According to a second aspect of the present invention, the refractive index measurement device, a spectrum measurement unit that measures a wavelength spectrum of light from the light guide rod, a wavelength spectrum measured by the spectrum measurement unit, and the calculation unit are used. It is a sugar concentration measuring apparatus provided with the calculating part which calculates the sugar content concentration of the said sample by multivariate analysis from the calculated refractive index of the said sample.

  According to the second aspect of the present invention, the refractive index of the sample can be calculated by the refractive index measuring device, and the wavelength spectrum of the light from the light guide rod can be measured by the spectrum measuring unit. Then, the sugar concentration of the sample can be calculated by multivariate analysis from the wavelength spectrum thus calculated and the refractive index of the sample. By calculating the sugar concentration of the sample in this way, the measurement accuracy can be improved compared to the case where the sugar concentration is simply calculated from the refractive index of the sample.

  According to a third aspect of the present invention, there is provided a light guide step for guiding incident illumination light to the end surface of the light guide rod by internally reflecting the light, and a light beam from the light guide rod at a predetermined position from the end surface of the light guide rod. A measurement step for measuring the diameter, and a light divergence angle from the light guide rod is calculated from the light beam diameter measured in the measurement step, and the refraction of the sample contacting the side surface of the light guide rod based on the divergence angle A refractive index measurement method including a calculation step of calculating a refractive index.

  According to a fourth aspect of the present invention, there is provided the refractive index measurement method, a spectrum measurement step of measuring a wavelength spectrum of light from the light guide rod, a wavelength spectrum measured by the spectrum measurement step, and the calculation step. And a calculation step of calculating a sugar concentration of the sample by multivariate analysis from the calculated refractive index of the sample.

  According to the present invention, it is possible to easily and accurately measure the refractive index of a measurement object.

1 is an overall configuration diagram of a refractive index measuring apparatus according to a first embodiment of the present invention. It is a figure explaining the measurement principle of a refractive index. It is the elements on larger scale of the refractive index measuring apparatus of FIG. It is a graph which shows the simulation result about the angle characteristic of the light inject | emitted from a light guide rod. It is a figure explaining the total reflection angle in a light guide rod. It is a whole block diagram of the sugar concentration measuring apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the process performed by CPU of FIG. It is a whole block diagram of the sugar concentration measuring apparatus which concerns on the 1st modification of this invention. It is a whole block diagram of the sugar concentration measuring apparatus which concerns on the 3rd Embodiment of this invention. It is a whole block diagram of the sugar concentration measuring apparatus which concerns on the 2nd modification of this invention.

[First Embodiment]
Hereinafter, a refractive index measuring apparatus 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, the refractive index measurement device 1 according to the present embodiment includes a light source 25, a wavelength adjustment device (wavelength adjustment unit) 35, a lens L 1, a half mirror 15, a light guide rod 10, A lens L2, a line sensor (measurement unit) 20, a CPU (calculation unit) 30, a monitor 31, and a control device 38 are provided.

  The light source 25 emits illumination light having a broadband wavelength component toward the half mirror 15. On the emission optical axis of the light source 25, a wavelength adjusting device 35, which will be described later, and a lens L1 that collects the illumination light from the wavelength adjusting device 35 are arranged.

  The wavelength adjusting device 35 includes a filter wheel 36 disposed on the emission optical axis of the light source 25, and a rotation unit 37 that rotates the filter wheel 36 about a rotation axis along the emission optical axis of the light source 25. The filter wheel 36 is equipped with a plurality of band pass filters that transmit light in different wavelength bands.

  By having such a configuration, the wavelength adjusting device 35 rotates the filter hole 36 by the rotating unit 37 based on a command from the control device 38 to be described later, so that a predetermined wavelength of the illumination light from the light source 25 is obtained. The band light is emitted toward the half mirror 15.

  The half mirror 15 reflects a part of the illumination light from the light source 25 (wavelength adjusting device 35) toward the incident end surface (first end surface) 11 of the light guide rod 10, and one part of the light from the light guide rod 10. The part is transmitted toward the line sensor 20.

  The light guide rod 10 is a rod-shaped rod made of, for example, glass or the like, and the illumination light incident from the incident end surface 11 is reflected on the inner surface by the inner surface, and is a reflection disposed on the other end side from the incident end surface 11. It leads to the end face (second end face) 12. The reflection end face 12 reflects light guided through the light guide rod 10.

  By having such a structure, the light guide rod 10 repeatedly reflects the illumination light incident from the incident end surface 11 by the inner side surface of the light guide rod 10 to the reflection end surface 12 and reflects it by the reflection end surface 12. Then, the light is guided again to the incident end face 11.

  Further, the light guide rod 10 is arranged such that the outer surface thereof is in contact with the sample S that is the object of measurement of the refractive index. Specifically, for example, when a biological sample is adopted as the sample S, the entire light guide rod 10 is inserted into the living body with the incident end face 11 exposed outside the living body.

The line sensor 20 is disposed at a predetermined interval from the incident end surface 11 of the light guide rod 10 and measures the light beam diameter of the light from the light guide rod 10 at a predetermined position from the incident end surface 11 of the light guide rod 10. It is like that.
A lens L <b> 2 that collects light from the light guide rod 10 is provided between the half mirror 15 and the line sensor 20.

  The CPU 30 calculates the divergence angle of the light from the light guide rod 10 from the beam diameter measured by the line sensor 20, and calculates the refractive index of the sample S that contacts the outer surface of the light guide rod 10 based on the divergence angle. It is supposed to be.

The monitor 31 displays information such as the refractive index of the sample S calculated by the CPU 30 and the wavelength of illumination light that is selectively transmitted by the wavelength adjusting device 35.
The control device 38 operates the rotating unit 37 based on a command from the CPU 30 to control the wavelength of illumination light emitted from the wavelength adjusting device 35.

Here, the measurement principle of the refractive index by the refractive index measuring apparatus 1 according to the present embodiment will be described below.
As shown in FIG. 2, reflection occurs at the interface where materials having different refractive indexes are in contact. When the refractive indexes of the substance A and the substance B are n1 and n2, respectively, it is known that total reflection occurs at an incident angle θc greater than a certain angle when n1> n2. This total reflection angle is given by the following equation.
θc = arcsin (n2 / n1)

  If the refractive index n1 of the substance A is known based on the above formula, the refractive index n2 of the substance B can be measured by measuring the total reflection angle θc. This is the basic principle of the Abbe refractometer.

In the refractive index measuring apparatus 1 according to the present embodiment, as shown in FIG. 3, when light is propagated to the light guide rod 10, total reflection is used. The angle of the light beam that can be propagated is determined by the refractive index n1 of the light guide rod 10 and the refractive index n2 of the outer medium disposed outside the light guide rod 10.
That is, if the refractive index n1 of the light guide rod 10 is known, the refractive index n2 of the outer medium can be measured by measuring the angle of the light beam that can propagate through the light guide rod 10. This is the principle of the refractive index measuring method by the refractive index measuring apparatus 1 according to this embodiment.

  According to the refractive index measuring apparatus 1 according to the present embodiment having the above-described configuration, the light beam reflects the inner surface of the light guide rod 10 many times, and thereby the angular distribution of the light beam intensity becomes steeper. The measurement accuracy of the total reflection angle can be improved.

The above effect will be described below using simulation results.
FIG. 4 shows the angle characteristics of the reflectance when the refractive index n2 = 1.33 of the outer medium and the refractive index n1 = 1.38 of the light guide rod 10 are set. The horizontal axis represents the angle expressed in radians (rad), and the vertical axis represents the reflectance. The angle at which the reflectance is 1 is the total reflection angle (critical angle).

  In FIG. 4, line G1 is a one-time reflection, and line G2 is a ten-time reflection. In the line G2 indicating 10-time reflection, the inclination near the critical angle is steep, so that the critical angle can be easily determined, and the measurement accuracy of the refractive index is improved.

  From the above, as shown in FIG. 5, the light guide rod 10 is guided so that a light beam having an incident angle equal to or smaller than the total reflection angle θc determined by the refractive index n1 of the light guide rod 10 and the refractive index n2 of the outer medium (sample S) is included. The maximum angle of the light beam incident on the optical rod 10 is determined. When the maximum angle of the incident light beam is determined in this way, the interface between the light guide rod 10 and the outer medium includes light having a total reflection angle or less and light having a total reflection angle or more. Among these, light incident on the interface at an angle greater than the total reflection angle is reflected, and only this reflected light can propagate through the light guide rod 10.

  Here, if the reflection end face 12 is provided on the end face opposite to the incident end face 11 of the light guide rod 10, the light propagated in the light guide rod 10 returns to the incident end face 11 again. This return light is only the component incident at an angle greater than the total reflection angle at the interface between the light guide rod 10 and the outer medium. Therefore, if the angular distribution of the return light is measured, the refractive index of the outer medium can be measured.

The operation of the refractive index measuring apparatus 1 according to this embodiment having the above configuration will be described below.
Illumination light emitted from the light source 25 is dispersed by the wavelength adjusting device 35, condensed on the half mirror 15 by the lens L 1, and introduced into the light guide rod 10 from the incident end face 11. Since the other end face of the light guide rod 10 is a reflection end face 12, the light beam propagating through the light guide rod 10 is returned to the incident end face 11.

  As shown in FIG. 3, the front focal point of the lens L <b> 2 is located on the incident end surface 11 of the light guide rod 10, and the line sensor 20 is disposed at the rear focal point. By arranging the lens L2 in such an arrangement, the light from the light guide rod 10 can be collimated and emitted to the surface 21 on which the line sensor 20 is arranged. Thereby, the angle information of the light from the light guide rod 10 appears on the surface 21 on which the line sensor 20 is arranged.

Specifically, as shown in FIG. 3, the distance from the optical axis center of light on the surface 21 is h, the focal length of the lens L2 is f2, and the angle (light spread angle) between the optical axis of the light is θ. Then, the relationship expressed by the following equation is established.
h = f2 × tanθ

  By measuring the distance h from the center of the optical axis by the line sensor 20 and substituting it into the above formula, the light spread angle θ can be calculated. Thus, by measuring the maximum angle of the return light by the line sensor 10, the total reflection angle in the light guide rod 10 can be known, and the refractive index of the outer medium (sample S) can be measured.

  As described above, according to the refractive index measuring apparatus 1 according to the present embodiment, the sample S for measuring the refractive index is incident on the incident end surface 11 of the light guide rod 10 while being in contact with the side surface of the light guide rod 10. The illuminated illumination light is reflected by the inner side surface of the light guide rod 10 and the reflection end surface 12 and guided again to the incident end surface 11. Then, light is emitted from the incident end face 11 of the light guide rod 10, and the light beam diameter at a predetermined position from the incident end face 11 is measured by the line sensor 20. Then, the CPU 30 calculates the divergence angle of the light from the light guide rod 10 from the light beam diameter measured in this way, and the refractive index of the sample S contacting the side surface of the light guide rod 10 based on the divergence angle. Calculated.

  In this case, the light emitted from the end face of the light guide rod 10 is totally reflected a plurality of times at the interface between the light guide rod 10 and the sample S. Thereby, the angle distribution of the divergence angle of the light from the light guide rod 10 can be made steep, and the accuracy of the refractive index of the sample S calculated based on the divergence angle can be improved. Further, unlike the conventional refractive index measuring apparatus, it is not necessary to find an image showing the boundary of the refractive index with the naked eye or to move the lens barrel. That is, according to the refractive index measuring apparatus 1 according to the present embodiment, the refractive index of the sample S can be measured easily and with high accuracy.

  In addition, since the light from the light guide rod 10 can be converted into parallel light by the lens L2, the position (predetermined position) at which the beam diameter is measured can be set to an arbitrary position in the optical axis direction. Further, it is possible to limit the measurement range of the line sensor 20 by preventing the light beam diameter from being unnecessarily widened.

  Further, since the light guide rod 10 has the reflection end face 12 on the other end side of the incident end face 11, the illumination light incident from the incident end face 11 is repeatedly reflected by the inner side face of the light guide rod 10 to the reflection end face 12. At the same time, it can be reflected by the reflection end face 12 and led to the incident end face 11 again. By doing in this way, the frequency | count of total reflection in the interface of the light guide rod 10 and the sample S can be increased. Thereby, the angle distribution of the divergence angle of the light from the light guide rod 10 can be made steep, and the accuracy of the refractive index of the sample S calculated based on the divergence angle can be improved. Moreover, the structure of the light guide rod 10 can be simplified.

  Moreover, by providing the wavelength adjusting device 35 that adjusts the wavelength of the illumination light incident on the light guide rod 10, the refractive index of the sample S for each wavelength is adjusted while adjusting the wavelength of the illumination light incident on the light guide rod 10. And the accuracy of the refractive index of the sample S can be improved.

In the refractive index measuring apparatus 1 according to the present embodiment, the light divergence angle (angle formed with the optical axis of light) may be calculated based on the following formula without providing the lens L2.
h = f1 × tanθ
Here, h is a light beam radius at a predetermined position (surface 21 in FIG. 3), f1 is a distance between the incident end surface 11 of the light guide rod 10 and the predetermined position (surface 21 in FIG. 3), and θ is a light spread angle. It is.

  In this way, the light divergence angle can be easily calculated without providing the lens L2, and the refractive index of the sample S contacting the side surface of the light guide rod 10 is calculated based on the divergence angle. be able to.

When the range of the refractive index of the outer medium is known, a small line sensor 20 that can measure the range can be used. Thereby, size reduction of an apparatus can be achieved.
The light guide rod 10 only needs to be in contact with the sample S, and may have a portion protruding into the atmosphere.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the refractive index measurement device 1 according to the first embodiment described above is applied to, for example, a sugar content measurement device that measures a blood sugar level or the like will be described. Hereinafter, with respect to the sugar content measuring apparatus 2 of the present embodiment, description of points that are common to the refractive index measuring apparatus 1 according to the first embodiment will be omitted, and different points will be mainly described.

  As shown in FIG. 6, the sugar content measuring apparatus 2 according to the present embodiment partially passes through the line sensor 20 in addition to the configuration of the refractive index measuring apparatus 1 according to the first embodiment (see FIG. 1). The lens L3 which condenses the light from the light guide rod 10 and the photodetector (spectrum measurement unit) 40 which detects the light collected by the lens L3 are provided.

  The light detector 40 detects the intensity of light emitted from the incident end face 11 by being internally reflected in the light guide rod 10 for each wavelength of the illumination light selectively transmitted by the wavelength adjusting device 35. ing. Thereby, the absorption spectrum of the sample S is measured.

  Here, in the phenomenon of total reflection in the light guide rod 10, the total reflected light enters the outer medium side a little and is reflected, so that if the outer medium is absorbed, the influence of this influence decreases the energy of the reflected light. To do. Therefore, the spectrum of the outer medium can be obtained by variously changing the wavelength of the illumination light or by spectroscopically analyzing the reflected light. This is a spectral measurement method called attenuated total reflection (ATR).

According to the sugar content measuring apparatus 2 according to the present embodiment having the above-described configuration, both the refractive index and the spectrum of the outer medium can be measured with the single light guide rod 10.
The line sensor 20 blocks a part of the light from the light guide rod 10, but most of the light is transmitted through a part other than the line sensor 20, so that the influence on the spectrum measurement is small.

  In the sugar content measuring apparatus 2 according to the present embodiment, the CPU (calculation unit, calculation unit) 30 has a refraction of the sample S calculated from the absorption spectrum measured by the photodetector 40 and the beam diameter measured by the line sensor 20. From the rate, the sugar concentration of the sample S is calculated by multivariate analysis.

  The flow of information processing in the above calculation is as shown in FIG. According to the sugar content measuring apparatus 2 according to the present embodiment, it is possible to measure a wide range of solute concentrations such as alcohols, sugars, fatty acids, polymers, etc. Here, blood sugar level measurement will be described as an example. The spectrum measurement value and the refractive index measurement value obtained by the attenuated total reflection method are finally subjected to arithmetic processing including a regression analysis method such as the PLS method to obtain a final value as a blood glucose level.

  As described above, according to the sugar content measuring device 2 according to the present embodiment, the refractive index of the sample S is calculated by the refractive index measuring device 1 according to the above-described embodiment, and the light detector 40 removes the refractive index from the light guide rod 10. The wavelength spectrum of light can be measured. Then, from the thus calculated wavelength spectrum and the refractive index of the sample S, the CPU 30 can calculate the sugar concentration of the sample S through multivariate analysis. By calculating the sugar concentration of the sample S in this way, the measurement accuracy can be improved compared to a case where the sugar concentration is simply calculated from the refractive index of the sample S.

Moreover, since there is no movable part in the sugar content measuring apparatus 2 according to the present embodiment, stable sugar content measurement is possible.
Also, when the refractive index and concentration fluctuation range of the solvent and solute to be measured are limited, by optimizing the refractive index of the light guide rod 10 and maximizing the change in the beam diameter on the line sensor 20, The measurement accuracy of the refractive index can be increased.

  Moreover, since the sensitivity does not decrease even if the diameter of the light guide rod 10 is reduced, it is possible to measure the substance concentration in the living body by installing the light guiding rod 10 having a small diameter in the living body. Thereby, invasion at the time of blood glucose level measurement can be reduced.

[First Modification]
As a modification of the sugar content measuring apparatus 2 according to the present embodiment, as shown in FIG. 8, a U-shaped light guide rod 10 is used, and a total reflection mirror 16 is used instead of the half mirror 15 in FIG. It may be adopted.
According to the sugar content measuring apparatus 3 according to this modification, it is possible to avoid the attenuation of light that occurs in the half mirror, and it is possible to improve the measurement accuracy of the refractive index and the sugar concentration of the sample S.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which a two-dimensional sensor is employed instead of the line sensor 20 and the photodetector 40 in the sugar content measuring apparatus 3 according to the above-described modification will be described. Hereinafter, with respect to the sugar content measuring device 4 of the present embodiment, description of points common to the sugar content measuring devices 2 and 3 according to the above-described embodiments will be omitted, and different points will be mainly described.

  As shown in FIG. 9, the sugar content measuring apparatus 3 according to this embodiment includes a light source 25, a lens L4, a light guide rod 10, a cylindrical lens L5, a grating 41, and a two-dimensional sensor (measurement unit, spectrum measurement). Unit) 42, a CPU (calculation unit) 30, and a monitor 31.

  The light source 25 is, for example, a mid-infrared lamp, and emits illumination light having a broadband wavelength component toward the incident end face 11 of the light guide rod 10. A lens L4 that condenses the illumination light from the light source 25 is disposed on the emission optical axis of the light source 25.

  The light guide rod 10 is a U-shaped rod formed of, for example, glass or the like, and the illumination light incident from the incident end surface 11 is internally reflected by the inner surface, and is disposed on the other end side with respect to the incident end surface 11. Further, it is guided to the outgoing end face 13.

  Further, the light guide rod 10 is arranged such that the outer surface thereof is in contact with the sample S that is the object of measurement of the refractive index. Specifically, for example, when a biological sample is adopted as the sample S, the entire light guide rod 10 is inserted into the living body with the incident end face 11 and the emitting end face 13 exposed outside the living body.

On the emission optical axis of the light guide rod 10, a cylindrical lens L5 and a grating 41 are arranged.
The cylindrical lens L5 condenses the light emitted from the emission end face 13 of the light guide rod 10 only in the one-dimensional direction out of the two-dimensional directions orthogonal to the optical axis. As a result, the light having a circular cross section emitted from the light emitting end face 13 of the light guide rod 10 is condensed on the grating 41 by the cylindrical lens L5 so that the horizontal cross section is an oval shape.

  Note that the light beam diameter of the light emitted from the emission end face 13 of the light guide rod 10 has the refractive index information of the sample S. Therefore, the refractive index information of the sample S is held for the major axis of the light condensed into an oval shape by the cylindrical lens L5.

  The grating 41 separates the light collected in an oval shape by the cylindrical lens L5 into the short diameter direction for each wavelength band and reflects it toward the two-dimensional sensor. In the grating 41, as shown in FIG. 9, light having an elliptical cross section is decomposed for each wavelength component in the minor axis direction. The light thus dispersed has refractive index information in the major axis direction and wavelength spectrum information in the minor axis direction.

  The two-dimensional sensor 42 detects the light beam diameter and intensity of the dispersed light from the grating 41. More specifically, the two-dimensional sensor 42 detects the major axis (refractive index information) and the intensity for each wavelength (wavelength spectrum information) with respect to the dispersed light from the grating 41.

  The CPU 30 calculates the refractive index of the sample S from the light beam diameter (major axis) of the light detected by the two-dimensional sensor 42, and calculates the sugar concentration of the sample S from the refractive index and the wavelength spectrum detected by the two-dimensional sensor 42. Calculations are made by multivariate analysis.

  The monitor 31 displays information such as the refractive index of the sample S calculated by the CPU 30, the wavelength spectrum detected by the two-dimensional sensor 42, and the sugar concentration of the sample S calculated from these.

  According to the sugar content measuring apparatus 4 according to this embodiment having the above-described configuration, in addition to the same effects as those of the sugar content measuring apparatuses 2 and 3 according to the above-described embodiments, the refractive index and the wavelength spectrum of the sample S can be obtained from a single sensor. Therefore, the apparatus can be downsized.

[Second Modification]
As a modification of the sugar content measuring device 4 according to the present embodiment, as shown in FIG. 10, a rod-shaped light guide rod 10 is used instead of the U-shaped light guide rod, and the emission optical axis of the light source 25 is used. The half mirror 15 may be disposed at the intersection with the optical axis emitted from the light guide rod 10.
According to the sugar content measuring apparatus 5 according to this modification, the light guide rod 10 can be made small, and the invasion at the time of blood glucose level measurement can be reduced.

  As mentioned above, although each embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention. . For example, you may apply this invention to embodiment which combined each said embodiment and each modification suitably.

L1, L2, L3, L4 lens (optical system)
L5 Cylindrical lens S Sample 1 Refractive index measurement device 2, 3, 4, 5 Sugar content measurement device 10 Light guide rod 11 Incident end surface (first end surface)
12 Reflective end face (second end face)
13 Output end face (second end face)
15 Half mirror 20 Line sensor (measurement part)
25 Light source 35 Wavelength tuning device (wavelength tuning unit)
30 CPU (calculation unit)
31 Monitor 38 Control device 40 Photodetector (spectrum measurement unit)
41 grating 42 two-dimensional sensor (measurement unit, spectrum measurement unit)

Claims (9)

A light guide rod that internally reflects incident illumination light and leads it to the end face;
A measuring unit for measuring a light beam diameter of light from the light guide rod at a predetermined position from an end surface of the light guide rod;
Calculating a divergence angle of light from the light guide rod from the beam diameter measured by the measurement unit, and calculating a refractive index of a sample contacting the side surface of the light guide rod based on the divergence angle; Refractive index measuring device provided. When the calculation unit sets the light beam radius at the predetermined position as h, the distance between the end face of the light guide rod and the predetermined position as f1, and the light spread angle as θ, the light is calculated based on the following formula: The refractive index measuring apparatus of Claim 1 which calculates the divergence angle of.
h = f1 × tanθ A focal position is disposed on an end face of the light guide rod, and an optical system that emits light from the light guide rod as parallel light and emits the light to the predetermined position;
The calculation unit calculates a light divergence angle based on the following expression, where h is a light beam radius at the predetermined position, h2 is a focal length of the optical system, and θ is a light divergence angle. Item 2. The refractive index measurement apparatus according to Item 1.
h = f2 × tanθ The calculation unit calculates an incident angle to the sample that causes total reflection in the light guide rod from a spread angle of light from the light guide rod, and calculates a refractive index of the sample based on the following equation: The refractive index measuring device according to claim 2 or 3.
θc = arcsin (n2 / n1)
here,
θc: Angle of incidence on the sample causing total reflection in the light guide rod n1: Refractive index of the light guide rod n2: Refractive index of the sample   2. The light guide rod has a first end surface on which illumination light is incident, and a second end surface that is disposed on the other end side of the first end surface and reflects light guided by internal reflection. The refractive index measuring apparatus as described in 2.   The refractive index measuring apparatus according to claim 1, further comprising a wavelength adjusting unit that adjusts a wavelength of illumination light incident on the light guide rod. Refractive index measuring device according to claim 6,
A spectrum measuring unit for measuring a wavelength spectrum of light from the light guide rod;
A sugar concentration measuring apparatus comprising: an arithmetic unit that calculates a sugar concentration of the sample by multivariate analysis from the wavelength spectrum measured by the spectrum measuring unit and the refractive index of the sample calculated by the calculating unit. A light guide step for guiding the incident illumination light to the end surface of the light guide rod by internal reflection;
A measurement step of measuring a light beam diameter of light from the light guide rod at a predetermined position from an end surface of the light guide rod;
Calculating a divergence angle of light from the light guide rod from the light beam diameter measured in the measurement step, and calculating a refractive index of a sample contacting the side surface of the light guide rod based on the divergence angle; Including refractive index measurement method. Refractive index measurement method according to claim 8,
A spectrum measuring step for measuring a wavelength spectrum of light from the light guide rod;
A sugar concentration measuring method including a calculation step of calculating a sugar concentration of the sample by multivariate analysis from the wavelength spectrum measured by the spectrum measuring step and the refractive index of the sample calculated by the calculating step.

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