JP2018189608A - Photometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a cell flow type absorption photometer that can conduct a sample analysis with high accuracy even when using an LED element low in light emitting intensity as a light source part.SOLUTION: A photometer comprises: a flow path pipe 11 that includes a conduction part 12 for conducting a fluid body 3 serving as a measurement object; a first light guide part 13 that is formed with a partial area of a lateral surface of the flow path pipe projected outward; a first optical path formation body 17 that is formed so as to cover the first light guide part, and includes a hollow part; a light source part 5 that is fit into the hollow part of the first optical path formation body, and includes the LED element; a second optical path formation body 27 that is the partial area of the lateral surface of the flow path pipe, is arranged at a position facing the first optical path formation body via the conduction part, and includes a hollow part; and a light reception unit 7 that is embedded and arranged in the hollow part of the second optical path formation body. The first guide part is composed of the same material as that of the flow path pipe of a part contacting with the first light guide part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an optical measuring instrument, and more particularly to an optical measuring instrument used for an absorbance measuring instrument or the like.

  2. Description of the Related Art Conventionally, a cell flow type photometer has been developed as an apparatus used for applications such as measuring the concentration of a substance contained in a fluid (for example, see Patent Document 1 below).

  Patent Document 1 discloses an optical measuring device having a body including a hole for allowing fluid to flow therethrough. The optical measuring device includes a light source unit that emits measurement light from the side of the hole, and a light receiving unit that receives light emitted from the light source unit and transmitted through the fluid (sample) flowing through the hole. , Are arranged at positions facing each other. An optical member for collimating the light emitted from the light source unit is disposed on the light source unit side, and an optical member for condensing light transmitted through the fluid is disposed on the light receiving unit side. ing. An optical fiber is attached to the light source unit and the light receiving unit.

JP, 2006-099311, A

  In recent years, in view of the progress of the development of LED elements, the use of LED elements as light sources for optical measuring devices has been studied. However, although the technology has advanced, the light emission intensity of the LED element is still weak compared to a laser element or the like, and the amount of light received is low simply by replacing the light source part with the LED element in the configuration of Patent Document 1, It is difficult to analyze a sample with high accuracy.

  An object of the present invention is to realize a cell flow type absorbance measuring instrument capable of performing sample analysis with high accuracy even when an LED element having low emission intensity is used as a light source in view of the above-described problems. And

The optical measuring device according to the present invention is
A flow path pipe including a flow passage for flowing a fluid to be measured;
A first light guide part formed such that a partial region of the side surface of the flow channel tube protrudes outward;
A first optical path forming body including a hollow portion formed so as to cover the first light guide portion;
A light source part including an LED element, fitted in the hollow part of the first optical path forming body;
A second optical path forming body including a hollow portion, which is a partial region of a side surface of the flow channel pipe and is disposed at a position facing the first optical path forming body via the flow-through portion;
A light receiving portion fitted in the hollow portion of the second optical path forming body,
Said 1st light guide part is comprised from the material same as the material of the said flow-path pipe of the location which is contacting the said 1st light guide part, It is characterized by the above-mentioned.

  According to said structure, the light inject | emitted from the light source part containing an LED element is irradiated to a flow part via a 1st light guide part. At this time, since the light source part is fitted in the hollow part of the first optical path forming body, the light emitted from the light source part is guided to the first light guide part through the inside of the first optical path forming body. Most of the light incident on the first light guide portion is substantially parallel to the side surface of the first optical path forming body.

  Since the first light guide section is made of the same material as the flow path pipe, it goes straight without being refracted when being guided from the first light guide section to the flow path pipe, and is directed to the flow path section. And injected. After this light is irradiated to the fluid flowing through the flow passage, the light transmitted through the fluid is incident on the light receiving section through the inside of the second optical path forming body provided at a position facing the first optical path forming body. .

  That is, according to said structure, the light which advances substantially toward a light-receiving part among the lights inject | emitted from the light source part can be irradiated to a fluid. Thereby, even when an LED element is used for the light source unit, it is possible to cause the light receiving unit to receive a light amount necessary for analyzing the sample.

  In particular, the first optical path forming body is preferably made of a material that absorbs light emitted from the light source unit. Thereby, among the light emitted from the light source unit, the light traveling with a divergence angle equal to or larger than a predetermined angle is absorbed by the side surface of the first optical path forming body, and therefore substantially toward the light receiving unit. It is possible to irradiate the fluid with light traveling straight.

  The first optical path forming body is more preferably composed of an elastic body. Thereby, it becomes easy to mount | wear with a 1st optical path formation body so that a 1st light guide part may be covered.

  The first light guide portion may be integrally formed by projecting a part of the flow channel pipe to the outside. Thereby, manufacture of the said optical measuring device is facilitated. In this case, the channel tube and the first light guide unit can be made of a resin such as cycloolefin polymer or acrylic, for example.

The flow channel tube has a first flat portion in a region of a side surface including a place where the first light guide portion is in contact with the flow tube,
The end portion of the first optical path forming body may be pressed against the first flat portion.

  According to the above configuration, since the first optical path forming body can be formed in close contact with the flow path tube, the light emitted from the light source unit can be efficiently irradiated onto the fluid.

The optical measuring device includes a second light guide part formed so that a partial region of the side surface of the flow channel tube protrudes outward at a position facing the first light guide part via the flow passage part. Prepared,
The second optical path forming body is formed so as to cover the second light guide part,
The second light guide part may be made of the same material as the material of the flow channel tube in contact with the second light guide part.

  According to the above configuration, the second light guide unit is also provided on the light receiving unit side in the same manner as the first light guide unit provided on the light source unit side. Can be guided to the light receiving portion with high efficiency. Thereby, even when light is scattered by the movement of the fluid, the influence of the movement of the fluid can be suppressed, and the amount of light depending on the concentration of the sample contained in the fluid can be guided to the light receiving unit. As a result, the concentration of the substance contained in the fluid can be measured with high accuracy.

  The second optical path forming body is preferably made of a material that absorbs light emitted from the light source unit. As a result, of the light transmitted through the fluid and incident on the inside of the second optical path forming body, the light traveling with a predetermined divergence angle is absorbed by the side surface of the second optical path forming body. Therefore, light traveling substantially straight can be incident on the light receiving unit. Thereby, it can suppress that the amount of received light changes with the motion of a fluid.

  The second optical path forming body is more preferably composed of an elastic body. Thereby, it becomes easy to mount | wear with a 2nd optical path formation body so that a 2nd light guide part may be covered.

  The second light guide portion may be formed by being integrally formed by projecting a part of the flow path tube to the outside.

The flow channel tube has a second flat portion in a region of a side surface including a place where the second light guide portion is in contact,
The end portion of the second optical path forming body may be pressed against the second flat portion.

  According to the optical measuring instrument of the present invention, it is possible to realize a cell flow type absorbance measuring instrument capable of performing sample analysis with high accuracy even when an LED element having low emission intensity is used as the light source unit.

It is a perspective view which shows typically the structure of one Embodiment of the optical measuring device of this invention. It is a perspective view of the optical measuring device which abbreviate | omitted illustration of the main body accommodating part from FIG. It is a top view when the optical measuring device shown in FIG. 2 is seen from the front. It is a top view when the optical measuring device shown in FIG. 2 is seen along the flow direction of fluid. It is sectional drawing when the optical measuring device shown in FIG. 2 is cut | disconnected by the AA line shown in FIG. FIG. 3 is a perspective view in which some elements are further omitted from the optical measuring device shown in FIG. 2. It is sectional drawing when the optical measuring device shown in FIG. 6 is cut | disconnected by the AA line shown in FIG. It is the perspective view which abbreviate | omitted some elements from the optical measuring device shown in FIG. It is sectional drawing when the optical measuring device shown in FIG. 8 is cut | disconnected by the AA line shown in FIG. It is sectional drawing when the optical measuring device of another embodiment is cut | disconnected by the AA line shown in FIG. It is sectional drawing when the optical measuring device of another embodiment is cut | disconnected by the AA line shown in FIG.

  An embodiment of an optical measuring device according to the present invention will be described with reference to the drawings. In the following drawings, the actual dimensional ratio does not necessarily match the dimensional ratio on the drawing.

  FIG. 1 is a perspective view schematically showing a configuration of an embodiment of an optical measuring device according to the present invention. The optical measuring instrument 1 is connected to the pipe 41 and the pipe 42 and is used for measuring the concentration of the measurement target substance contained in the fluid 3 flowing from the pipe 41 as the absorbance. In the present embodiment, the fluid 3 is a liquid.

  The optical measuring instrument 1 shown in FIG. 1 includes a ball valve 31 and is configured to be able to control whether or not the fluid 3 is guided into the optical measuring instrument 1 by operating the ball valve 31. . The optical measuring instrument 1 includes a main body housing portion 30, and a light source unit 5 and a light receiving unit 7 described later are built in the main body housing unit 30.

  FIG. 2 corresponds to the drawing in which the main body accommodating portion 30 is removed from the optical measuring device 1 illustrated in FIG. FIG. 3 corresponds to a plan view when the optical measuring device 1 shown in FIG. 2 is viewed from the front. 4 is different from FIG. 3 in viewing angle, and corresponds to a plan view when the optical measuring device 1 shown in FIG. 2 is viewed along the flowing direction of the fluid 3. FIG. 5 corresponds to a cross-sectional view of the optical measuring device 1 shown in FIG. 2 taken along line AA shown in FIG.

  6 is a perspective view in which some elements are further omitted from the optical measuring device 1 shown in FIG. FIG. 7 corresponds to a cross-sectional view of the optical measuring device 1 shown in FIG. 6 taken along the line AA shown in FIG. FIG. 8 is a perspective view in which some elements are further omitted from the optical measuring device 1 shown in FIG. FIG. 9 corresponds to a cross-sectional view of the optical measuring device 1 shown in FIG. 8 taken along line AA shown in FIG.

  The optical measuring instrument 1 includes a flow channel tube 11. The flow path pipe 11 is configured in a hollow shape (cylindrical shape), and this hollow portion constitutes a flow-through portion 12 through which the fluid 3 flows. The channel tube 11 is made of a resin such as cycloolefin polymer or acrylic. The channel tube 11 is made of a translucent material for light emitted from at least the light source unit 5.

  The channel tube 11 is attached to the cap 34 and the case 33. The cap 34 and the flow channel tube 11 are connected by an O-ring 35, and the case 33 and the flow channel tube 11 are connected by an O-ring 36. More specifically, flanges (not shown) are formed on the upstream and downstream end faces of the flow channel tube 11, and the cap 34 is fitted by fitting the O-rings (35, 36) into the grooves of the flanges. The flow path pipe 11, the case 33, and the flow path pipe 11 are connected to each other. The case 33 and the cap 34 are made of metal such as stainless steel (SUS).

  The channel tube 11 has a first light guide portion 13 and a second light guide portion 23 formed in a partial region of the side surface. The first light guide portion 13 and the second light guide portion 23 are formed by projecting a partial region of the side surface of the flow channel tube 11 to the outside, and both are made of the same material as the flow channel tube 11. Yes. In the optical measuring instrument 1 of the present embodiment, the first light guide portion 13 and the second light guide portion 23 are formed by being integrally formed by projecting a part of the side surface outward when the flow channel tube 11 is formed. Has been. In the present embodiment, the first light guide portion 13 and the second light guide portion 23 are formed at positions facing each other via the flow passage portion 12.

  In the present embodiment, the channel tube 11 has a flat surface (first flat portion) 15 on a part of the side surface including the region where the first light guide portion 13 is formed, and the second light guide portion 23 is A flat surface (second flat portion) 25 is provided on a part of the side surface including the formed region.

  The optical measuring device 1 includes a cylindrical first optical path forming body 17 and a second optical path forming body 27. The first optical path forming body 17 is disposed so that the end face is pressed against the first flat portion 15 of the flow path tube 11. The first light guide portion 13 is located in the hollow portion 18 of the first optical path forming body 17. The second optical path forming body 27 is arranged so that the end face is pressed against the second flat portion 25 of the flow path tube 11. The second light guide portion 23 is located in the hollow portion 28 of the second optical path forming body 27.

  In the present embodiment, the first optical path forming body 17 and the second optical path forming body 27 are preferably made of a light-absorbing material, and in particular, are made of a light-absorbing elastic body. Is more preferable. As the elastic body having a light absorption property, a silicone resin such as polydimethylsiloxane (PDMS) in which a light absorption material is dispersed can be used. Silicone resins can be used more suitably because of the low autofluorescence that they emit. Moreover, as a light absorptive substance, black powder can be used, for example, and carbon black, a carbon nanotube, etc. are mentioned as black powder. The refractive index of the elastic body in which the light-absorbing substance is dispersed is preferably 1.3 or more and 1.8 or less.

  The light source unit 5 is disposed so as to be fitted into the hollow portion 18 of the first optical path forming body 17. The light source part 5 is comprised by LED elements, such as white LED, for example. The light receiving part 7 is disposed so as to be fitted into the hollow part 28 of the second optical path forming body 27. The light receiving unit 7 is configured by a photodiode such as an RGB color sensor or a phototransistor, for example, and outputs an electrical signal corresponding to the amount of received light. For example, the concentration of the protein contained in the fluid 3 can be quantified by the BCA method from the absorbance of light near the wavelength of 560 nm detected by the light receiving unit 7 or by the Bradford method from the absorbance of light near the wavelength of 600 to 700 nm. it can.

  When the 1st optical path formation body 17 is comprised with the elastic body, the 1st light guide part 13 and the light source part 5 can be easily engage | inserted in the hollow part 18 of the 1st optical path formation body 17. FIG. Similarly, when the second optical path forming body 27 is formed of an elastic body, the second light guide section 23 and the light receiving section 7 can be easily fitted into the hollow portion 28 of the second optical path forming body 27.

  In the present embodiment, the optical measuring device 1 includes a substrate 16 and a substrate 26. The substrate 16 and the case 33 are sealed with an insulator 19, and the substrate 16 and the insulator 19 are fixed with screws 14. Similarly, the substrate 26 and the case 33 are sealed with an insulator 29, and the substrate 26 and the insulator 29 are fixed with screws 24. The insulators (19, 29) are made of, for example, a resin such as ABS, and the optical path forming bodies (17, 27) and the substrates (16, 26) are secured while ensuring insulation with the substrates (16, 26). Is held stably.

  A control unit that controls the light source unit 5 is mounted on the substrate 16. A control unit that controls the light receiving unit 7 is mounted on the substrate 26. A calculation unit (not shown) is mounted on the substrate 26, and an electrical signal corresponding to the amount of light received by the light receiving unit 7 is sent. In the calculation unit, the concentration of the predetermined substance contained in the sample is calculated based on the amount of light received by the light receiving unit 7.

  The hollow portion 18 of the first optical path forming body 17 constitutes the optical path of the measuring light 6 emitted from the light source unit 5, and the hollow portion 28 of the second optical path forming body 27 is passed through the fluid 3. Constitutes an optical path until the light is guided to the light receiving unit 7. As described above, according to the configuration of the present embodiment, since the flat surfaces (15, 25) are formed on a part of the side surface of the optical measuring instrument 1, the cylindrical optical path forming body (17, 27) is formed. The end surface can be pressed against each flat surface (15, 25). Thereby, it can suppress that the measurement light 6 leaks outside from an optical path formation body (17, 27).

  As described above, the first optical path forming body 17 is formed so as to sandwich the light source unit 5. Therefore, the measurement light 6 emitted from the light source unit 5 is guided to the first light guide unit 13 through the hollow portion 18 of the first optical path forming body 17. In the present embodiment, since the first optical path forming body 17 is made of a light-absorbing material, the light having a divergence angle of a predetermined angle or more out of the measurement light 6 emitted from the light source unit 5 is It is absorbed by the side surface of the first optical path forming body 17. As a result, the measurement light 5 emitted from the light source unit 5 as substantially straight light is incident on the first light guide unit 13.

  The first light guide unit 13 is made of a material having translucency with respect to the measurement light 6, similar to the channel tube 11. For this reason, the measurement light 6 incident on the first light guide portion 13 is directly irradiated into the flow passage portion 12 through the first light guide portion 13 and the flow channel tube 11. Since the first light guide portion 13 and the flow channel tube 11 are made of the same material, the measurement light 6 passes without being refracted at the interface between the first light guide portion 13 and the flow channel tube 11. Go straight to the stream 12. Thereby, the measurement light 6 having high intensity is irradiated to the fluid 3 flowing through the flow passage 12.

  Of the irradiated measurement light 6, the measurement light 6 that has passed through the fluid 3 travels substantially straight as it is and enters the thick portion of the channel tube 11, and is then guided to the second light guide 23. . Thereafter, the measurement light 6 that has passed through the second light guide 23 is guided to the light receiver 7 through the hollow portion 28 of the second optical path forming body 27. In the present embodiment, since the second optical path forming body 27 is made of a light-absorbing material, the second light guide has a divergence angle of a predetermined angle or more out of the measurement light 6 transmitted through the fluid 3. The light incident on the light unit 23 is absorbed by the side surface of the second optical path forming body 27. As a result, the measurement light 6 emitted from the light source unit 5 as a substantially straight light is guided to the light receiving unit 7 through the hollow portion 28.

  The light receiving section 7 is made with the same conditions for the configuration in which the light guide section (13, 23) is not provided (comparative example) and the configuration in which the light guide section (13, 23) is provided (example). As a result of comparing the amount of light received in the example, it was confirmed that the amount of light received was 2.4 times that of the comparative example.

  In the present embodiment, the first light guide portion 13 and the second light guide portion 23 are both formed with the same dimensions. Specifically, it is preferable that the light guides (13, 23) are designed to have a size satisfying L / a ≧ 1, where a is the diameter and L is the length in the optical axis direction. As an example, a = 3 mm and L = 3 mm. Thereby, the measurement light 6 emitted from the light source unit 5 and the measurement light 6 that has traveled through the fluid 3 substantially increase the amount of light that travels straight through the light guides (13, 23). Can do. However, this does not mean that the case where the dimensions of the first light guide portion 13 and the second light guide portion 23 are not the same is excluded from the scope of the present invention.

[Another embodiment]
Hereinafter, another embodiment will be described.

  <1> As shown in FIG. 10, the widths of the first light guide 13 and the second light guide 23 may not be the same. In FIG. 10, the case where the width of the second light guide 23 is longer than the width of the first light guide 13 is illustrated. Note that the width of the first light guide 13 may be longer than the width of the second light guide 23.

  Moreover, as shown in FIG. 11, the position of the 1st light guide part 13 and the 2nd light guide part 23 may be shifted | deviated a little with respect to the direction through which the fluid 3 flows. In this case, the first light guide 13 and the second light guide 23 are in a positional relationship in which the measurement light 6 emitted through the first light guide 13 can enter the second light guide 23. Good. Specifically, the amount of positional deviation between the first light guide 13 and the second light guide 23 may be within 50% of the diameter of each light guide (13, 23).

  In the above embodiment, the optical axis of the measurement light 6 incident through the first light guide unit 13 and the optical axis of the measurement light 6 guided to the light receiving unit 7 through the second light guide unit 23 are both It is shown so as to be substantially orthogonal to the direction in which the fluid 3 flows. However, the optical axis of the measurement light 6 incident through the first light guide 13 may be inclined with respect to the direction in which the fluid 3 flows, and is guided to the light receiver 7 through the second light guide 23. The optical axis of the measurement light 6 may be inclined with respect to the direction in which the fluid 3 flows.

  <2> In the above-described embodiment, the first light guide portion 13 and the second light guide portion 23 are described as both projecting outward only with respect to the flow channel tube 11. However, one or both of the first light guide portion 13 and the second light guide portion 23 may be formed so as to protrude also on the flow passage portion 12 side.

  Moreover, the 1st light guide part 13 and the 2nd light guide part 23 may each be formed in multiple places.

  <3> In the above embodiment, the first light guide portion 13 and the second light guide portion 23 have been described as being formed by being integrally formed with the flow path tube 11. However, at least one of the first light guide portion 13 and the second light guide portion 23 may be formed separately from the flow channel tube 11 and bonded to the side surface of the flow channel tube 11. I do not care.

  <4> The configuration of the optical measuring instrument 1 described above with reference to the drawings is merely an example, and various modifications can be made.

  The optical measuring instrument 1 may be configured to include the first light guide unit 13 on the light source unit 5 side but not the second light guide unit 23 on the light receiving unit 7 side.

  The flow channel tube 11 may be configured not to include the first flat surface 15 for improving the adhesion with the first optical path forming body 17. Similarly, the channel tube 11 may be configured not to include the first flat surface 25 for enhancing the adhesion with the second optical path forming body 27.

  The first optical path forming body 17 and the second optical path forming body 27 may be made of a material having low absorbability with respect to the measurement light 6. However, as described above, as described above, the first optical path forming body 17 and the second optical path forming body 17 and the second optical path forming body 17 and 27 are used from the viewpoint of suppressing the influence on the amount of light received by the light receiving unit 7 due to the reflected light on the side surfaces of the optical path forming body (17 27). The optical path forming body 27 is preferably made of a material having high absorbability with respect to the measurement light 6.

  Whether or not the optical measuring instrument 1 includes the ball valve 31 is arbitrary. Note that the ball valve 31 may be provided not only on the upstream side but also on the downstream side with respect to the optical path of the measurement light 6.

<5> The optical measuring instrument 1 can be used for the following applications, for example.
(1) The optical measuring instrument 1 measures the absorbance of a specific wavelength of the fluid 3 flowing through the flow channel tube 11 based on the amount of light received by the wavelength band in the light receiving unit 7, and a substance (foreign matter) different from the normal is a fluid. 3 can be used for the purpose of monitoring the inclusion.
(2) The optical measuring instrument 1 is used to measure the turbidity contained in the fluid 3 by measuring the absorbance at a specific wavelength of the fluid 3 flowing through the flow path tube 11 based on the amount of light received by the wavelength band in the light receiving unit 7. Can be used.
(3) The optical measuring instrument 1 measures the absorbance of a specific wavelength of the fluid 3 flowing through the flow channel 11 based on the amount of light received by the wavelength band at the light receiving unit 7 and monitors whether the fluid 3 is flowing. It can be used for
(4) The optical measuring instrument 1 uses an infrared light sensor as the light receiving unit 7 to measure the amount of infrared light radiated from the fluid 3 flowing through the channel tube 11 with the light receiving unit 7, and the temperature of the fluid 3 It can be used for the purpose of measuring.

  Note that the fluid 3 to be measured by the optical measuring device 1 may be a gas as well as a liquid.

DESCRIPTION OF SYMBOLS 1: Optical measuring device 3: Fluid 5: Light source part 6: Measuring light 7: Light-receiving part 11: Channel pipe 12: Flow-through part 13: 1st light guide part 14: Screw 15: 1st flat part 16: Board | substrate 17: 1st optical path formation body 18: Hollow part of 1st optical path formation body 19: Insulator 23: 2nd light guide part 24: Screw 25: 2nd flat part 26: Board | substrate 27: 2nd optical path formation body 28: 1st Hollow part 29: insulator 30: body housing part 31: ball valve 33: case 34: cap 35: O-ring 36: O-ring 41: pipe 42: pipe

Claims (8)

A flow path pipe including a flow passage for flowing a fluid to be measured;
A first light guide part formed such that a partial region of the side surface of the flow channel tube protrudes outward;
A first optical path forming body including a hollow portion formed so as to cover the first light guide portion;
A light source part including an LED element, fitted in the hollow part of the first optical path forming body;
A second optical path forming body including a hollow portion, which is a partial region of a side surface of the flow channel pipe and is disposed at a position facing the first optical path forming body via the flow-through portion;
A light receiving portion fitted in the hollow portion of the second optical path forming body,
The said 1st light guide part is comprised from the material same as the material of the said flow path pipe of the location which is contacting the said 1st light guide part, The optical measuring device characterized by the above-mentioned.   The optical measuring instrument according to claim 1, wherein the first light guide portion is formed by being integrally formed by projecting a part of the flow channel tube to the outside. The flow channel tube has a first flat portion in a region of a side surface including a place where the first light guide portion is in contact with the flow tube,
The optical measuring instrument according to claim 1, wherein an end portion of the first optical path forming body is pressed against the first flat portion.   4. The optical measuring instrument according to claim 1, wherein the first optical path forming body is made of a material that absorbs light emitted from the light source unit. 5. In a position facing the first light guide portion through the flow passage portion, a second light guide portion formed by protruding a part of the side surface of the flow channel pipe to the outside,
The second optical path forming body is formed so as to cover the second light guide part,
The said 2nd light guide part is comprised from the material same as the material of the said flow path pipe of the location which is contacting the said 2nd light guide part, The any one of Claims 1-4 characterized by the above-mentioned. The optical measuring instrument described in 1.   The optical measuring instrument according to claim 5, wherein the second light guide unit is formed by being integrally formed by projecting a part of the flow channel tube to the outside. The flow channel tube has a second flat portion in a region of a side surface including a place where the second light guide portion is in contact,
The optical measuring instrument according to claim 5 or 6, wherein an end portion of the second optical path forming body is pressed against the second flat portion.   The optical measuring instrument according to claim 5, wherein the second optical path forming body is made of a material that absorbs light emitted from the light source unit.

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