Measuring device

Abstract

This invention provides a measuring device that can improve various characteristics in absorption spectroscopy using multiple reflections. [Solution] The measuring device 1 according to the present disclosure is a measuring device 1 for measuring the state of an object S by absorption spectroscopy, comprising: an irradiation unit 10 for irradiating the object S with irradiation light L; a first prism 21 having retrospectivity and arranged on the opposite side of the irradiation unit 10; a second prism 22 having retrospectivity and arranged on the same side as the irradiation unit 10; a light receiving unit 30 for receiving the irradiation light L that has passed through the object S multiple times between the first prism 21 and the second prism 22; and a first light guiding unit 40 arranged on the same side as the first prism 21 for guiding the irradiation light L toward the light receiving unit 30, wherein the centers of the first prism 21 and the second prism 22 are eccentric to each other in the first direction, and multiple passages of the irradiation light L are arranged in two rows along the first direction on each optical surface.

Description

Technical Field

[0001] The present disclosure relates to a measuring device.

Background Art

[0002] Conventionally, a technique for measuring the state of a measurement target including the presence or absence and concentration of a measurement target such as a gas by absorption spectroscopy is known. For example, Patent Document 1 discloses an optical multiple reflection cell that is small and low-cost, does not require the installation of a cooling mechanism around a mirror, and can increase the number of reflections of laser light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional absorption spectroscopy using multiple reflections, there is room for improvement in characteristics including measurement sensitivity or ease of installation of the measuring device.

[0005] An object of the present disclosure is to provide a measuring device capable of improving various characteristics in absorption spectroscopy using multiple reflections.

Means for Solving the Problems

[0006] Some embodiments of the measuring apparatus are measuring apparatus for measuring the state of an object to be measured by absorption spectroscopy, comprising: an illumination unit that irradiates the object to be measured with illumination light; a first retroreflective prism disposed on the opposite side of the illumination unit; a second retroreflective prism disposed on the same side as the illumination unit; a light receiving unit that receives the illumination light that has passed through the object to be measured multiple times between the first prism and the second prism; and a first light guiding unit disposed on the same side as the first prism that guides the illumination light toward the light receiving unit, wherein the centers of the first prism and the second prism are eccentric to each other in the first direction, and the multiple passages of the illumination light on each optical surface are arranged in two rows along the first direction.

[0007] This allows for improvements in various characteristics of absorption spectroscopy using multiple reflections. The measuring device has a light-receiving unit that receives the irradiated light that has passed through the object to be measured multiple times between a first prism and a second prism, each of which has retroreflective properties. This allows the measuring device to position the multiple reflection cell, composed of the first and second prisms, relative to the object to be measured, thereby increasing the optical path length of the irradiated light. In addition, in the measuring device, the centers of the first and second prisms in the first direction are eccentric to each other, and the multiple passages of the irradiated light on each optical surface are arranged in two rows along the first direction. Therefore, compared to conventional techniques where the multiple passages are arranged in a single row along the first direction, the measuring device can further increase the optical path length of the irradiated light relative to the object to be measured. Consequently, the measuring device can double the number of reflections and thus the optical path length of the irradiated light without narrowing the beam spacing of the irradiated light, thereby doubling the measurement sensitivity in measuring the state of the object to be measured. As a result, the measuring device can also improve the measurement accuracy of the state of the object to be measured.

[0008] In one embodiment of the measuring device, the first light guide may include a first optical component that reflects the irradiated light toward the second prism. This makes it possible for the measuring device to realize not only a forward path but also a return path for the irradiated light in the multiple reflection cell, and to further increase the optical path length of the irradiated light based on the forward and return paths. With respect to the multiple reflection cell composed of prisms, the measuring device can widely utilize the prism surface, including the first optical surface and the second optical surface, and further increase the number of reflections. As a result, the measuring device can further improve the measurement sensitivity and measurement accuracy in measuring the state of the object to be measured.

[0009] In one embodiment of the measuring device, the irradiation unit and the light receiving unit may be arranged in parallel in a second direction intersecting the first direction, on the same side as the second prism. This allows the measuring device to have the emission point of the irradiation unit and the incidence point of the light receiving unit on the same side, without having to place them on opposite sides of the object to be measured. The light receiving unit can be placed on the same side as the irradiation unit. Therefore, the measuring device can also be made easier to install by facilitating the placement of each component included in the measuring device relative to the object to be measured. The measuring device can be made into a single unit on the irradiation side and the light receiving side, which allows for miniaturization in addition to ease of installation.

[0010] In one embodiment of the measuring device, the first optical component may be retroreflective. This allows the measuring device to accurately reflect the illumination light emitted from the second prism and incident on the first optical component in a 180-degree direction. For example, the measuring device can accurately reflect the illumination light incident on the first optical component from the negative Z-axis direction to the positive Z-axis direction back in the negative Z-axis direction. As a result, the measuring device can accurately realize not only the forward path but also the return path of the illumination light in the multiple reflection cell.

[0011] In one embodiment of the measuring device, the first optical component may include a right-angle prism. This makes it possible for the measuring device to accurately fold the irradiated light back toward the second prism, for example, with the return path of the irradiated light offset in a second direction relative to the forward path. Therefore, the measuring device can be configured such that, not only in the forward path of the irradiated light but also in the return path, multiple passages of the irradiated light are arranged in two rows along the first direction on each optical surface of the prism.

[0012] In one embodiment of the measuring device, the first light guide may include a second optical component that separates the optical path of the irradiated light emitted from the second prism from the first prism along the first direction. This allows the measuring device to increase the distance between the incident position of the irradiated light onto the light-receiving section and the first prism body in a prism multiple reflection cell, thereby reducing interference between the light-receiving section and the first prism. Even when the displacement between the first prism and the second prism along the first direction is small, the measuring device facilitates the placement of the light-receiving section while propagating the irradiated light over a narrow area. Compared to, for example, when the light-receiving section is positioned at a position shifted in the positive Z-axis direction from the first prism without bending the optical path of the irradiated light, the measuring device can reduce the amount of irradiated light passing outside the measurement area where the object to be measured does not exist. This allows the measuring device to reduce error factors in measuring the state of the object to be measured.

[0013] In one embodiment of the measuring device, the irradiation unit may be positioned such that the emission surface of the irradiation light faces the optical surface of the first prism and is coordinating with the optical surface of the second prism. This allows the measuring device to position the irradiation unit so that the emission surface of the irradiation light in the irradiation unit is in contact with the object to be measured. The measuring device can also irradiate the object to be measured with irradiation light at the shortest distance from the irradiation unit and cause the irradiation light to be incident on the first optical surface of the first prism at the shortest distance along the optical axis of the irradiation unit. As a result, the measuring device can reduce error factors in measuring the state of the object to be measured, such as when the irradiation light emitted from the irradiation unit passes outside the measurement area where the object to be measured does not exist. For example, when the measuring device measures oxygen concentration, the irradiation light may be absorbed by oxygen gas components unrelated to the object to be measured due to oxygen contained in the atmosphere. As a result, an error occurs in the oxygen concentration of the object to be measured. The measuring device can also reduce such errors and improve measurement accuracy.

[0014] In one embodiment, the measuring device may further include a second light guide that brings the optical path of the irradiated light emitted from the irradiating unit closer to the second prism along the first direction. This allows the measuring device to increase the distance between the emission position of the irradiating light in the irradiating unit and the second prism body in a prism multiple reflection cell, thereby reducing interference between the irradiating unit and the second prism. The measuring device facilitates the placement of the irradiating unit while propagating the irradiated light in a narrow area, even when the displacement along the first direction between the first prism and the second prism is small. Compared to, for example, when the irradiating unit is positioned at a location shifted in the negative Z-axis direction relative to the second prism without bending the optical path of the irradiated light, the measuring device can reduce the amount of irradiated light passing outside the measurement area where the object to be measured does not exist. This allows the measuring device to reduce error factors in measuring the state of the object to be measured.

[0015] In one embodiment, the measuring device comprises multiple sets of the first prism and the second prism, whose centers in the first direction are eccentric to each other, along the first direction, and in each set, the first prism and the second prism may have multiple light passages in their respective optical surfaces arranged in two rows along the first direction.

[0016] This allows the measuring device to increase the number of reflections in the multiple reflection cell, thereby improving measurement sensitivity by increasing the optical path length. For example, if the spacing of the optical paths in the X direction of the irradiated light at the object under measurement is the same for one set of prisms and two sets of prisms, the number of optical paths along the X direction of the irradiated light nearly doubles with two sets of prisms. The measuring device can easily achieve high sensitivity even when, for example, the number of reflections is limited by the beam diameter of the irradiated light with one set of prisms.

[0017] In one embodiment of the measuring device, each of the first prism and the second prism may include a corner cube or a right-angle prism. This makes it possible for the measuring device to be less susceptible to the influence of vibrations of the multiple reflection cell on the optical path of the irradiated light, even when the optical path becomes long due to repeated multiple reflections in the multiple reflection cell, due to retroreflective properties. The measuring device facilitates the adjustment of the number of reflections in the multiple reflection cell and the adjustment of the optical axis. [Effects of the Invention]

[0018] According to this disclosure, it is possible to provide a measuring device that can improve various characteristics in absorption spectroscopy using multiple reflections. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram showing an example of the configuration of a measuring device according to the first embodiment of this disclosure. [Figure 2] Figure 1 is a schematic diagram showing an example of the first optical surface of the first prism. [Figure 3] Figure 1 is a schematic diagram showing an example of the second optical surface of the second prism. [Figure 4] It is a schematic diagram showing an example of the configuration on the other side of the measuring device in FIG. 1. [Figure 5] It is a schematic diagram corresponding to FIG. 1, showing an example of the configuration of the measuring device according to a modified example of the present disclosure. [Figure 6] It is a schematic diagram corresponding to FIG. 2, showing an example of the first optical surface of the first prism in FIG. 5. [Figure 7] It is a schematic diagram corresponding to FIG. 3, showing an example of the second optical surface of the second prism in FIG. 5. [Figure 8] It is a schematic diagram corresponding to FIG. 4, showing an example of the configuration on the other side of the measuring device in FIG. 5. [Figure 9] It is a schematic diagram for explaining the effect of the measuring device in FIG. 5. [Figure 10] It is a schematic diagram showing an example of the configuration of the measuring device according to the second embodiment of the present disclosure. [Figure 11] It is a schematic diagram showing a first example of the second optical component used for each of the first light guiding portion and the second light guiding portion in FIG. 10. [Figure 12] It is a schematic diagram showing a second example of the second optical component used for each of the first light guiding portion and the second light guiding portion in FIG. 10. [Figure 13] It is a schematic diagram showing a third example of the second optical component used for each of the first light guiding portion and the second light guiding portion in FIG. 10.

Mode for Carrying Out the Invention

[0020] The background and problems of the prior art will be described in more detail.

[0021] The method for measuring the gas concentration using laser light is a method for measuring the absorbance of the irradiated laser light and the concentration of the substance by utilizing the characteristic that molecules absorb light of a specific wavelength in laser absorption spectroscopy. The absorbance depends on the number of molecules present in the space through which the laser light passes. If the gas density is uniform, the longer the optical path of the laser light, the higher the signal intensity regarding the absorbance. As a result, the accuracy of the measurement regarding the absorbance is improved.

[0022] A conventional measurement method using multiple reflection is known, in which a laser beam is passed back and forth multiple times within a sample containing gas or other materials to lengthen the optical path. For example, a method using a prism multiple reflection cell is also known as a method of multiple reflection. This method involves placing two prisms opposite each other and arranging them so that their centerlines in a predetermined direction are offset from each other in a predetermined direction.

[0023] In conventional prism multiple reflection cells, when the light trails from multiple reflections are arranged in a line along a predetermined direction on the optical surface, which is the input and output surface of the prism, the number of reflections was determined based on the prism diameter and the beam diameter of the laser light. On the other hand, in order to achieve the predetermined number of reflections, the laser light had to maintain the required beam diameter throughout the entire optical path length obtained by multiple reflections.

[0024] However, when the optical path length is particularly long, the beam diameter tends to broaden due to the diffraction phenomenon of light. This broadening of the beam diameter becomes more pronounced as the beam diameter as parallel light narrows. Realizing a narrow and long laser beam is not easy. Therefore, there is a lower limit to the beam diameter, which is one of the factors that determine the number of reflections. As a result, when the points where the laser light enters and exits are arranged in a line on the optical surface of a finite-sized prism, there is a limit to how much the number of reflections can be increased.

[0025] In addition, in conventional prism multiple reflection cells, the laser light source was placed on one of the two prisms, and the photodetector was placed on the other prism. Therefore, when the measurement area between the prisms became long, it was necessary to separate the laser light source and the photodetector and install them so that they were on either side of the measurement area. As a result, the ease of installation of the measurement device was reduced.

[0026] This disclosure aims to provide a measuring device that can improve various characteristics in absorption spectroscopy using multiple reflections in order to solve the problems described above. For example, this disclosure relates to a prism multiple reflection cell used in a gas concentration measuring device using laser light.

[0027] The following description will primarily focus on one embodiment of this disclosure, with reference to the attached drawings. In the following description, the X, Y, and Z directions refer to the directions of the arrows in the figures. The directions of each arrow are consistent across different drawings. The X direction corresponds to the "first direction" described in the claims. The Y direction corresponds to the "second direction intersecting the first direction" described in the claims. In some figures, the X, Y, and Z directions are omitted for the sake of simplicity.

[0028] (First Embodiment) Figure 1 is a schematic diagram showing an example of the configuration of the measuring device 1 according to the first embodiment of this disclosure. An example of the configuration and function of the measuring device 1 according to the first embodiment will be mainly described with reference to Figure 1.

[0029] The measuring device 1 measures the state of the object to be measured S by absorption spectroscopy using a prism multiple reflection cell. In this disclosure, "object to be measured S" includes, for example, any object that is the target of detection or measurement using the measuring device 1. The object to be measured S includes, for example, a gas. "State of the object to be measured S" includes the presence or absence of the object to be measured S or the concentration of the object to be measured S. The measuring device 1 arranges the prism multiple reflection cells so as to sandwich the object to be measured S from both sides, and passes the irradiating light L through the object to be measured S multiple times by reflecting it multiple times with the prism multiple reflection cells. The measuring device 1 increases the number of reflections of the irradiating light L in the prism multiple reflection cell compared to the conventional technology, thereby increasing the optical path length of the irradiating light L to the object to be measured S and improving the measurement sensitivity.

[0030] The measuring device 1 includes an irradiation unit 10, a plurality of prisms 20 including a first prism 21 and a second prism 22, a light receiving unit 30, and a first light guiding unit 40.

[0031] The irradiation unit 10 has a light source including a laser such as a semiconductor laser. However, it is not limited to this, and the light source of the irradiation unit 10 may be, for example, a lamp light source or an LED (Light-Emitting Diode) light source. The irradiation unit 10 irradiates the object to be measured S with irradiation light L. The irradiation unit 10 irradiates the irradiation light L towards the space including the region where the object to be measured S exists, for example, through any optical system included in the irradiation unit 10. The irradiation unit 10 is positioned so that the emission surface of the irradiation light L faces the first optical surface 23 of the first prism 21 (described later) and is on the same plane as the second optical surface 24 of the second prism 22 (described later).

[0032] The object to be measured S is located, for example, in the space between the first prism 21 and the second prism 22. The wavelength of the illumination light L irradiated by the illumination unit 10 is included in the light absorption band of the object to be measured S. In this disclosure, "light absorption band" includes any wavelength range, for example, the visible region or the infrared region. The wavelength of the illumination light L irradiated by the illumination unit 10 includes the wavelength absorbed by the object to be measured S.

[0033] The first prism 21 is positioned on the opposite side of the irradiating section 10 and is retroreflective. In this disclosure, “retroreflective” means, for example, the property of reflecting light in a direction 180 degrees to the direction from which it was incident, regardless of the direction from which the light was incident. The first prism 21 includes, for example, a corner cube or a right-angle prism. In Figure 1, the first prism 21 is shown as a corner cube as an example. The corner cube, which is the first prism 21, is a prism whose tip is cut with three planes. The corner cube, which is the first prism 21, may be made of glass.

[0034] The first prism 21 has a first optical surface 23 facing the illumination unit 10 and the second prism 22. The positive X-axis end of the first optical surface 23 faces the Z-direction of the emission surface of the illumination light L in the illumination unit 10, with the object to be measured S in between. The first optical surface 23 guides the illumination light L, which is irradiated from the illumination unit 10 and has passed through the object to be measured S, into the interior of the first prism 21. The first optical surface 23 causes the illumination light L, which has been reflected multiple times inside the first prism 21, to be emitted towards the object to be measured S and guided through the object to be measured S to the second prism 22 or the light receiving unit 30.

[0035] The second prism 22 is positioned on the same side as the irradiating section 10 and is retroreflective. The second prism 22 includes, for example, a corner cube or a right-angle prism. In Figure 1, the second prism 22 is shown as a corner cube as an example. The corner cube, which is the second prism 22, is a prism whose tip is cut with three planes. The corner cube, which is the second prism 22, may be made of glass.

[0036] The second prism 22 has a second optical surface 24 facing the first prism 21 and the first light guide 40. The negative X-axis end of the second optical surface 24 faces the first light guide 40 in the Z-direction, with the object to be measured S in between. The second optical surface 24 guides the illumination light L emitted from the first prism 21 and passing through the object to be measured S into the interior of the second prism 22. The second optical surface 24 is folded back by the first light guide 40, guiding the illumination light L that has passed through the object to be measured S into the interior of the second prism 22. The second optical surface 24 causes the illumination light L, which has been reflected multiple times inside the second prism 22, to be emitted towards the object to be measured S and guided through the object to be measured S to the first prism 21 or the first light guide 40.

[0037] The light-receiving unit 30 has a photodetector that includes a light-receiving element such as a photodiode. The light-receiving unit 30 receives the irradiation light L that is irradiated onto the object to be measured S by the irradiation unit 10. The light-receiving unit 30 receives the irradiation light L that has passed through the object to be measured S multiple times between the first prism 21 and the second prism 22. At least a portion of the wavelength band that can be received by the light-receiving unit 30 is included in the light absorption band of the object to be measured S. The photodetector in the light-receiving unit 30 has detection sensitivity at the wavelength of the irradiation light L.

[0038] The measuring device 1 may calculate the absorbance of the irradiated light L from the intensity of the irradiated light L received by the light receiving unit 30. The measuring device 1 may also calculate the concentration of the substance to be measured S from the absorbance of the irradiated light L. The light receiving unit 30 may be included in the measuring device 1 or connected to a separate computing device. The computing device may calculate the absorbance of the irradiated light L and the concentration of the substance to be measured S based on the light received signal corresponding to the intensity of the irradiated light L output from the light receiving unit 30. The computing device may be, for example, a dedicated computer, a general-purpose PC (Personal Computer), or a server.

[0039] The first light guide 40 is positioned on the same side as the first prism 21 and guides the irradiated light L toward the light receiving unit 30. The first light guide 40 includes, for example, a first optical component that reflects the irradiated light L toward the second prism 22. The first optical component is, for example, retroreflective. The first optical component includes, for example, a right-angle prism. The first light guide 40 reflects the irradiated light L, which is incident from the negative Z-axis toward the positive Z-axis, toward the negative Z-axis direction by the first optical component.

[0040] The first prism 21 and the second prism 22 have their centers in the first direction eccentric to each other. For example, the center line L1 of the first prism 21 in the first direction and the center line L2 of the second prism 22 in the first direction do not coincide, but are offset along the first direction. As an example, the center lines L1 and L2 are parallel to each other along the Z direction. That is, the first optical surface 23 of the first prism 21 and the second optical surface 24 of the second prism 22 may be opposite each other in the Z direction so that they are parallel to each other along the XY direction.

[0041] The object to be measured S is interposed between a first prism 21 and a second prism 22 that are opposite each other in the Z direction. The first optical surface 23 of the first prism 21 may be, for example, parallel to the XY plane. The second optical surface 24 of the second prism 22 may be, for example, parallel to the XY plane. Each of the first optical surface 23 and the second optical surface 24 may be in contact with the object to be measured S.

[0042] Figure 2 is a schematic diagram showing an example of the first optical surface 23 of the first prism 21 in Figure 1. Referring to Figure 2, we will mainly explain an example of the arrangement of multiple passages for the irradiated light L in the first optical surface 23.

[0043] The first optical surface 23 has a circular shape, for example, in the XY plane. On the first optical surface 23 of the first prism 21, the multiple passages of the irradiated light L are arranged in two rows along the first direction. For example, the multiple first passages of the irradiated light L are spaced a distance C from the center line in the Y direction of the first optical surface 23 to one side in the Y direction. The multiple first passages include passages P1, P3, P5, P7, P9, P13, P15, P17, P19, and P21. The multiple second passages of the irradiated light L are spaced a distance C from the center line in the Y direction of the first optical surface 23 to the other side in the Y direction. The multiple second passages include passages P2, P4, P6, P8, P10, P14, P16, P18, P20, and P22.

[0044] The irradiated light L passing through the first optical surface 23 of the first prism 21 in the optical path of multiple reflections is reflected alternately in two rows around the X axis in the order of passing sections P1, P2, P3, P4, P5, P6, P7, P8, P9, and P10. For example, the irradiated light L irradiated from the irradiating section 10 onto the object to be measured S first enters the interior of the first prism 21 from passing section P1. The irradiated light L is reflected repeatedly inside the first prism 21 and exits from passing section P2 towards the object to be measured S. The irradiated light L reflected by the second prism 22 enters the interior of the first prism 21 again from passing section P3.

[0045] Similarly, the illumination light L that enters the interior of the first prism 21 from the passage section P3 exits from the passage section P4. The illumination light L that enters the interior of the first prism 21 from the passage section P5 exits from the passage section P6. The illumination light L that enters the interior of the first prism 21 from the passage section P7 exits from the passage section P8. The illumination light L that enters the interior of the first prism 21 from the passage section P9 exits from the passage section P10.

[0046] The irradiated light L, which is emitted from the passing section P10 to the object S to be measured and reflected by the second prism 22, enters the interior of the first light guide section 40 from the passing section P11 of the first light guide section 40. The irradiated light L is reflected repeatedly inside the first light guide section 40 and folded back, and is emitted from the passing section P12 toward the object S to be measured. At this time, the irradiated light L is emitted from the first light guide section 40 with the passing section P12 being the emission position, which is located at a distance of twice C in the Y direction from the incidence position of the first light guide section 40 in the passing section P11.

[0047] The illuminated light L, reflected back by the first light guide 40, undergoes multiple reflections in the order of passing sections P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, and P22, filling the gaps between the passing sections P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, and P11, which constitute the forward path. For example, the illuminated light L that exits from the first light guide 40 at passing section P12 and is reflected by the second prism 22 enters the interior of the first prism 21 from passing section P13. The illuminated light L repeatedly reflects inside the first prism 21 and exits from passing section P14 towards the object to be measured S. The illuminated light L reflected by the second prism 22 enters the interior of the first prism 21 again from passing section P15.

[0048] Similarly, the illumination light L that enters the interior of the first prism 21 from the passing section P15 exits from the passing section P16. The illumination light L that enters the interior of the first prism 21 from the passing section P17 exits from the passing section P18. The illumination light L that enters the interior of the first prism 21 from the passing section P19 exits from the passing section P20. The illumination light L that enters the interior of the first prism 21 from the passing section P21 exits from the passing section P22. The illumination light L that exits from the passing section P22, which is located at a distance C from the X axis, passes through the object to be measured S and enters the light receiving section 30.

[0049] Figure 3 is a schematic diagram showing an example of the second optical surface 24 of the second prism 22 in Figure 1. Referring to Figure 3, we will mainly explain an example of the arrangement of multiple passages for the irradiated light L on the second optical surface 24.

[0050] The second optical surface 24 has, for example, a circular shape in the XY plane. On the second optical surface 24 of the second prism 22, the multiple passages of the irradiated light L are arranged in two rows along the first direction. For example, the multiple third passages of the irradiated light L are spaced a distance C from the center line in the Y direction of the second optical surface 24 to one side in the Y direction. The multiple third passages include passages P2, P4, P6, P8, P10, P12, P14, P16, P18, and P20. The multiple fourth passages of the irradiated light L are spaced a distance C from the center line in the Y direction of the second optical surface 24 to the other side in the Y direction. The multiple fourth passages include passages P3, P5, P7, P9, P11, P13, P15, P17, P19, and P21.

[0051] The irradiated light L passing through the second optical surface 24 of the second prism 22 in the optical path of multiple reflections is reflected alternately in two rows around the X axis in the order of passing sections P2, P3, P4, P5, P6, P7, P8, P9, P10, and P11. For example, the irradiated light L that is emitted from the irradiating section 10, passes through passing section P1, and is reflected by the first prism 21 first enters the interior of the second prism 22 from passing section P2. The irradiated light L is reflected repeatedly inside the second prism 22 and is emitted from passing section P3 towards the object to be measured S. The irradiated light L reflected by the first prism 21 enters the interior of the second prism 22 again from passing section P4.

[0052] Similarly, the illumination light L that enters the interior of the second prism 22 from the passage section P4 exits from the passage section P5. The illumination light L that enters the interior of the second prism 22 from the passage section P6 exits from the passage section P7. The illumination light L that enters the interior of the second prism 22 from the passage section P8 exits from the passage section P9. The illumination light L that enters the interior of the second prism 22 from the passage section P10 exits from the passage section P11.

[0053] The irradiated light L, which is emitted from the passing section P11 to the object S under measurement and reflected back by the first light guide section 40, undergoes multiple reflections in the order of passing sections P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, and P22, filling the gaps between the passing sections P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, and P11, which constitute the forward path. For example, the irradiated light L emitted from the first light guide section 40 enters the interior of the second prism 22 from the passing section P12. The irradiated light L is reflected repeatedly inside the second prism 22 and emitted from the passing section P13 towards the object S under measurement. The irradiated light L reflected by the first prism 21 enters the interior of the second prism 22 again from the passing section P14.

[0054] Similarly, the illumination light L that enters the interior of the second prism 22 from the passing section P14 exits from the passing section P15. The illumination light L that enters the interior of the second prism 22 from the passing section P16 exits from the passing section P17. The illumination light L that enters the interior of the second prism 22 from the passing section P18 exits from the passing section P19. The illumination light L that enters the interior of the second prism 22 from the passing section P20 exits from the passing section P21. The illumination light L that exits from the passing section P21 and is reflected by the first prism 21 passes through the passing section P22 and enters the light receiving section 30.

[0055] Figure 4 is a schematic diagram showing an example of another configuration of the measuring device 1 shown in Figure 1. The example of another configuration of the measuring device 1 shown in Figure 1 will be mainly described with reference to Figure 4.

[0056] The light-receiving section 30, together with the illuminating section 10, is on the same side as the second prism 22 and is arranged in parallel in a second direction intersecting the first direction. The vertex Q of the right-angle prism, which serves as the first light guide section 40, and the central axis L3 of the prism 20, which is parallel to the Z direction, are located in the same XZ plane perpendicular to the Y direction. That is, in the side view of Figure 4, the vertex Q of the right-angle prism is located on the central axis L3 of the prism 20, which is parallel to the Z direction.

[0057] In Figure 4, the multiple first optical paths OP1 of the irradiating light L passing through the interior of the object under measurement S, which are arranged between the multiple first passing sections of the first prism 21 and the multiple fourth passing sections of the second prism 22, overlap in the X direction, spaced apart by a distance C on one side in the Y direction with respect to the central axis L3. Similarly, the multiple second optical paths OP2 of the irradiating light L passing through the interior of the object under measurement S, which are arranged between the multiple second passing sections of the first prism 21 and the multiple third passing sections of the second prism 22, overlap in the X direction, spaced apart by a distance C on the other side in the Y direction with respect to the central axis L3.

[0058] According to the measuring device 1 of the above embodiment, various characteristics in absorption spectroscopy using multiple reflections can be improved. The measuring device 1 has a light-receiving unit 30 that receives the irradiated light L that has passed through the object to be measured S multiple times between a first prism 21 and a second prism 22, each of which has retroreflective properties. As a result, the measuring device 1 can position the multiple reflection cell composed of the first prism 21 and the second prism 22 relative to the object to be measured S, thereby increasing the optical path length of the irradiated light L. In addition, in the measuring device 1, the centers of the first prism 21 and the second prism 22 are eccentric relative to each other in the first direction, and the multiple passages of the irradiated light L in each optical surface are arranged in two rows along the first direction. Therefore, the measuring device 1 can further increase the optical path length of the irradiated light L to the object to be measured S compared to the conventional technology in which the multiple passages are arranged in one row along the first direction. Therefore, the measuring device 1 can double the number of reflections and thus the optical path length of the irradiated light L without narrowing the beam spacing of the irradiated light L, thereby doubling the measurement sensitivity in measuring the state of the object S under measurement. As a result, the measuring device 1 can also improve the measurement accuracy of the state of the object S under measurement.

[0059] In the measuring device 1, the first light guide 40 includes a first optical component that reflects the irradiated light L toward the second prism 22. This makes it possible for the measuring device 1 to realize not only a forward path but also a return path for the irradiated light L in the multiple reflection cell, and to further increase the optical path length of the irradiated light L based on the forward and return paths. With respect to the multiple reflection cell composed of the prism 20, the measuring device 1 can widely utilize the prism surfaces, including the first optical surface 23 and the second optical surface 24, and further increase the number of reflections. As a result, the measuring device 1 can further improve the measurement sensitivity and measurement accuracy in measuring the state of the object S under measurement.

[0060] In the measuring device 1, the irradiation unit 10 and the light receiving unit 30 are arranged in parallel in a second direction intersecting the first direction, on the same side as the second prism 22. This allows the measuring device 1 to have the emission point of the irradiation light L in the irradiation unit 10 and the incidence point in the light receiving unit 30 on the same side, without having to place them on opposite sides of the object to be measured S. The light receiving unit 30 can be placed on the same side as the irradiation unit 10. Therefore, the measuring device 1 can also improve the ease of installation of the device itself by facilitating the placement of each component included in the measuring device 1 relative to the object to be measured S. The measuring device 1 can be integrated into a single device on the irradiation side and the light receiving side, which allows for miniaturization in addition to ease of installation.

[0061] The first optical component of the first light guide section 40 is retroreflective. This allows the measuring device 1 to accurately reflect the illumination light L that has been emitted from the second prism 22 and incident on the first optical component in a 180-degree direction. For example, the measuring device 1 can accurately reflect the illumination light L that has been incident on the first optical component from the negative Z-axis to the positive Z-axis in the negative Z-axis direction. As a result, the measuring device 1 can accurately realize not only the forward path but also the return path of the illumination light L in the multiple reflection cell.

[0062] The first optical component of the first light guide section 40 includes a right-angle prism. This allows the measuring device 1 to accurately fold the irradiated light L towards the second prism 22, for example, when the return path of the irradiated light L is offset in a second direction relative to the forward path. Therefore, the measuring device 1 can be configured such that, not only in the forward path of the irradiated light L but also in the return path, multiple passages of the irradiated light L are arranged in two rows along the first direction on each optical surface of the prism 20.

[0063] The irradiation unit 10 is positioned such that the emission surface of the irradiation light L faces the first optical surface 23 of the first prism 21 and is coordinating with the second optical surface 24 of the second prism 22. This allows the measuring device 1 to position the irradiation unit 10 so that the emission surface of the irradiation light L in the irradiation unit 10 is in contact with the object to be measured S. The measuring device 1 can also irradiate the object to be measured S from the irradiation unit 10 at the shortest distance and cause the irradiation light L to be incident on the first optical surface 23 of the first prism 21 at the shortest distance along the optical axis of the irradiation unit 10. As a result, the measuring device 1 can reduce error factors in measuring the state of the object to be measured S, such as when the irradiation light L emitted from the irradiation unit 10 passes outside the measurement area where the object to be measured S does not exist. For example, when the measuring device 1 measures oxygen concentration, it is conceivable that the irradiation light L may be absorbed by oxygen gas components unrelated to the object to be measured S due to oxygen contained in the atmosphere. As a result, an error occurs in the oxygen concentration of the object to be measured S. The measuring device 1 can also reduce such errors and improve measurement accuracy.

[0064] Each of the first prism 21 and the second prism 22 includes a corner cube or a right-angle prism. This makes it possible for the measuring device 1 to be less susceptible to the influence of vibrations of the multiple reflection cell on the optical path of the irradiated light L, even when the optical path becomes longer due to repeated multiple reflections in the multiple reflection cell, due to retroreflective properties. The measuring device 1 facilitates the adjustment of the number of reflections and the optical axis in the multiple reflection cell.

[0065] In the first embodiment described above, the irradiating unit 10 and the light-receiving unit 30 are arranged in parallel in a second direction intersecting the first direction on the same side as the second prism 22, but this is not the only way. The irradiating unit 10 and the light-receiving unit 30 do not have to be arranged in parallel in a second direction on the same side as the second prism 22. Alternatively, the irradiating unit 10 and the light-receiving unit 30 do not have to be arranged on the same side as each other, as in the arrangement in the second embodiment described later.

[0066] In the first embodiment described above, the first optical component of the first light guide 40 was described as having retroreflective properties, but it is not limited to this. The first optical component does not have to have retroreflective properties.

[0067] In the first embodiment described above, the first optical component of the first light guide 40 was described as including a right-angle prism, but is not limited thereto. The first optical component may include any other component that can realize the function of reflecting the illuminated light L. For example, the first optical component may include a retroreflective corner cube.

[0068] In the first embodiment described above, the illumination unit 10 is positioned such that the emission surface of the illumination light L faces the first optical surface 23 of the first prism 21 and is coordinating with the second optical surface 24 of the second prism 22. However, it is not limited to this. As described in the second embodiment below, the illumination unit 10 may be positioned such that the emission surface of the illumination light L is offset in a first direction from the first optical surface 23 of the first prism 21 and does not face the first optical surface 23. The illumination unit 10 does not have to be positioned coordinating with the second optical surface 24 of the second prism 22. For example, if it is difficult to accommodate the illumination unit 10 in the gap offset in a first direction between the first prism 21 and the second prism 22, it may be positioned offset in the negative direction of the Z axis from the position coordinating with the second optical surface 24.

[0069] In the first embodiment described above, the first prism 21 and the second prism 22 each include, but are not limited to, a corner cube or a right-angle prism. The first prism 21 and the second prism 22 each may include any other prism having retrospective properties. The first prism 21 and the second prism 22 may be the same type of prism as in the first embodiment, or they may be different types of prisms.

[0070] In the first embodiment described above, the through portions P1, P3, P5, P7, P9, P11, P13, P15, P17, P19, and P21 are arranged in a line on the same straight line along the first direction on the first optical surface 23 of the first prism 21, but are not limited to this. The through portions P1, P3, P5, P7, P9, P11, P13, P15, P17, P19, and P21 may be arranged in a line along the first direction at positions offset from each other on the same straight line.

[0071] In the first embodiment described above, the through portions P2, P4, P6, P8, P10, P12, P14, P16, P18, P20, and P22 are arranged in a line on the same straight line along the first direction on the first optical surface 23 of the first prism 21, but are not limited to this. The through portions P2, P4, P6, P8, P10, P12, P14, P16, P18, P20, and P22 may be arranged in a line along the first direction at positions offset from each other on the same straight line.

[0072] In the first embodiment described above, the through portions P1, P3, P5, P7, P9, P11, P13, P15, P17, P19, and P21 are arranged in a line on the same straight line along the first direction on the second optical surface 24 of the second prism 22, but are not limited to this. The through portions P1, P3, P5, P7, P9, P11, P13, P15, P17, P19, and P21 may be arranged in a line along the first direction at positions offset from each other on the same straight line.

[0073] In the first embodiment described above, the through portions P2, P4, P6, P8, P10, P12, P14, P16, P18, P20, and P22 are arranged in a line on the same straight line along the first direction on the second optical surface 24 of the second prism 22, but are not limited to this. The through portions P2, P4, P6, P8, P10, P12, P14, P16, P18, P20, and P22 may be arranged in a line along the first direction at positions offset from each other on the same straight line.

[0074] In the first embodiment described above, the first optical surface 23 of the first prism 21 and the second optical surface 24 of the second prism 22 were described as facing each other in the Z direction so as to be parallel to each other along the XY direction, but the invention is not limited to this. The first optical surface 23 of the first prism 21 and the second optical surface 24 of the second prism 22 may face each other in the Z direction so as to be non-parallel to each other along at least one of the XY directions. That is, the first prism 21 and the second prism 22 may face each other at an angle. This makes it possible for the measuring device 1 to reduce the influence of reflected light generated at the first optical surface 23 or the second optical surface 24.

[0075] Figure 5 is a schematic diagram corresponding to Figure 1, showing an example of the configuration of the measuring device 1 according to a modified example of the present disclosure. Figure 6 is a schematic diagram corresponding to Figure 2, showing an example of the first optical surfaces 23a and 23b of the first prisms 21a and 21b in Figure 5. Figure 7 is a schematic diagram corresponding to Figure 3, showing an example of the second optical surfaces 24a and 24b of the second prisms 22a and 22b in Figure 5. Figure 8 is a schematic diagram corresponding to Figure 4, showing an example of the configuration of the measuring device 1 in Figure 5 from another side. An example of the configuration and function of the measuring device 1 according to a modified example will be mainly described with reference to Figures 5 to 8.

[0076] In the first embodiment described above, the prism 20 includes, but is not limited to, a pair of first prisms 21 and second prisms 22. The measuring device 1 may have multiple pairs of first prisms 21 and second prisms 22 whose centers in the first direction are eccentric to each other along the first direction. For example, the measuring device 1 may have a configuration in which a pair of first prisms 21a and second prisms 22a and a pair of first prisms 21b and second prisms 22b are arranged sequentially from the positive side to the negative side in the X direction. As shown in Figures 6 and 7, in each pair, the first prism 21 and second prism 22 may have multiple passages for the irradiated light L in two rows along the first direction on their respective optical surfaces.

[0077] For example, a plurality of first passing sections may be arranged on the first optical surface 23a of the first prism 21a. The plurality of first passing sections may include passing sections P1, P3, P15, and P17. For example, a plurality of first passing sections may be arranged on the first optical surface 23b of the first prism 21b. The plurality of first passing sections may include passing sections P5, P7, P11, and P13.

[0078] For example, a plurality of second passing sections may be arranged on the first optical surface 23a of the first prism 21a. The plurality of second passing sections may include passing sections P2, P4, P16, and P18. For example, a plurality of second passing sections may be arranged on the first optical surface 23b of the first prism 21b. The plurality of second passing sections may include passing sections P6, P8, P12, and P14.

[0079] For example, a plurality of third passing sections may be arranged on the second optical surface 24a of the second prism 22a. The plurality of third passing sections may include passing sections P2, P4, P14, and P16. For example, a plurality of third passing sections may be arranged on the second optical surface 24b of the second prism 22b. The plurality of third passing sections may include passing sections P6, P8, P10, and P12.

[0080] For example, a plurality of fourth passing sections may be arranged on the second optical surface 24a of the second prism 22a. The plurality of fourth passing sections may include passing sections P3, P5, P15, and P17. For example, a plurality of fourth passing sections may be arranged on the second optical surface 24b of the second prism 22b. The plurality of fourth passing sections may include passing sections P7, P9, P11, and P13.

[0081] The measurement device 1 according to the above modified example can increase the number of reflections in the multiple reflection cell, thereby improving measurement sensitivity by increasing the optical path length. For example, if the spacing A in the X direction of the optical path of the irradiating light L at the object under measurement S is the same for one set of prisms 20 and two sets of prisms 20, the number of optical paths of the irradiating light L along the X direction nearly doubles in the two sets of prisms 20. The measurement device 1 can easily achieve high sensitivity even when, for example, the number of reflections is limited by the beam diameter of the irradiating light L in one set of prisms 20.

[0082] In addition, the measuring device 1 can be made smaller and lighter by reducing the volume of the prism 20. Figure 9 is a schematic diagram illustrating the effect of the measuring device 1 in Figure 5. Figure 9 corresponds to Figure 5. For example, focusing on one prism 20, the width along the X direction in Figure 9 is width B, whereas in Figure 5, the width along the X direction is width B / 2. Similarly, focusing on one prism 20, the width along the Z direction in Figure 9 is width D, whereas in Figure 5, the width along the Z direction is width D / 2.

[0083] Therefore, if the same number of reflections is achieved with one set of prisms 20 as shown in Figure 9 and two sets of prisms 20 as shown in Figure 5, the volume of one prism 20 is reduced to 1 / 4 of that of the two sets of prisms 20. Consequently, the multiple reflection cell of the measuring device 1 becomes smaller, and the heavy prisms 20 made of glass material can be made lighter.

[0084] The measuring device 1 can also reduce the attenuation of the light intensity of the irradiated light L. For example, when the same number of reflections is achieved with one set of prisms 20 as shown in Figure 9 and two sets of prisms 20 as shown in Figure 5, as described above, one prism 20 is miniaturized in the configuration of two sets of prisms 20, so the optical path length of the irradiated light L passing through the inside of the glass of the prism 20 is shortened. Therefore, the amount of attenuation of the light intensity of the irradiated light L due to the attenuation rate of the glass material is improved.

[0085] (Second Embodiment) Figure 10 is a schematic diagram showing an example of the configuration of the measuring device 1 according to the second embodiment of this disclosure. Figure 11 is a schematic diagram showing a first example of a second optical component used in the first light guide section 40 and the second light guide section 50, respectively, of Figure 10. Figure 12 is a schematic diagram showing a second example of a second optical component used in the first light guide section 40 and the second light guide section 50, respectively, of Figure 10. Figure 13 is a schematic diagram showing a third example of a second optical component used in the first light guide section 40 and the second light guide section 50, respectively, of Figure 10. An example of the configuration and function of the measuring device 1 according to the second embodiment will be mainly described with reference to Figures 10 to 13.

[0086] The measuring device 1 according to the second embodiment of this disclosure differs from the first embodiment in that the first light guide 40 has an offset function instead of a folding function for the optical path of the irradiated light L. Other configurations, functions, effects, and modifications are the same as in the first embodiment, and corresponding descriptions also apply to the measuring device 1 according to the second embodiment. In the following, components the same as in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted. The differences from the first embodiment will be mainly described.

[0087] In the first embodiment described above, the first light guide 40 was described as including a first optical component that folds the irradiated light L toward the second prism 22, but it is not limited to this. The first light guide 40 may include, instead of the first optical component, a second optical component that moves the optical path of the irradiated light L emitted from the second prism 22 away from the first prism 21 along a first direction. In addition, the measuring device 1 may further include a second light guide 50 that moves the optical path of the irradiated light L emitted from the irradiation unit 10 closer to the second prism 22 along a first direction. The second light guide 50 may include the same type of second optical component as the first light guide 40, or it may include a different type of second optical component.

[0088] For example, as shown in Figure 11, the second optical component included in each of the first light guide section 40 and the second light guide section 50 may be a component formed by combining a pair of right-angle prisms. For example, as shown in Figure 12, the second optical component included in each of the first light guide section 40 and the second light guide section 50 may be a component in which a hexahedral glass material is further arranged between a pair of right-angle prisms. For example, as shown in Figure 13, the second optical component included in each of the first light guide section 40 and the second light guide section 50 may be a rhomboid prism.

[0089] The second optical component, for example, shifts the first optical path S1 immediately after the illumination light L is emitted from the illumination unit 10 in the positive X-axis direction from the second optical path S2, where the illumination light L enters the first prism 21, at its positive X-axis end. The second optical component bends the optical path of the illumination light L emitted from the illumination unit 10 twice at a 90-degree angle by a pair of parallel slopes. As a result, the second optical component creates a gap along the first direction between the first optical path S1 and the second optical path S2.

[0090] The second optical component, for example, shifts the third optical path S3, just before the irradiating light L enters the light-receiving unit 30, in the negative direction of the X-axis from the fourth optical path S4, from which the irradiating light L exits the second prism 22, at its negative X-axis end. The second optical component bends the optical path of the irradiating light L entering the light-receiving unit 30 twice at a 90-degree angle by a pair of parallel slopes. As a result, the second optical component creates a gap along the first direction between the third optical path S3 and the fourth optical path S4.

[0091] The measuring device 1, by including a second optical component in the first light guide 40, can increase the distance between the incident position of the irradiated light L onto the light receiving unit 30 and the main body of the first prism 21 in a prism multiple reflection cell, thereby reducing interference between the light receiving unit 30 and the first prism 21. The measuring device 1 facilitates the placement of the light receiving unit 30 while propagating the irradiated light L in a narrow area, even when the displacement along the first direction between the first prism 21 and the second prism 22 is small. Compared to, for example, when the light receiving unit 30 is placed at a position shifted in the positive Z-axis direction from the first prism 21 without bending the optical path of the irradiated light L, the measuring device 1 can reduce the amount of irradiated light L passing outside the measurement area where the object to be measured S does not exist. As a result, the measuring device 1 can reduce error factors in measuring the state of the object to be measured S.

[0092] The measuring device 1, by having a second light guide 50, can increase the distance between the emission position of the irradiating light L at the irradiating unit 10 and the second prism 22 body in a prism multiple reflection cell, thereby reducing interference between the irradiating unit 10 and the second prism 22. The measuring device 1 facilitates the placement of the irradiating unit 10 while propagating the irradiating light L in a narrow area, even when the displacement along the first direction between the first prism 21 and the second prism 22 is small. The measuring device 1 can reduce the amount of irradiating light L passing outside the measurement area where the object to be measured S does not exist, compared to, for example, when the irradiating unit 10 is placed at a position shifted in the negative Z-axis direction from the second prism 22 without bending the optical path of the irradiating light L. As a result, the measuring device 1 can reduce error factors in measuring the state of the object to be measured S.

[0093] It will be apparent to those skilled in the art that this disclosure can be implemented in other predetermined forms besides the embodiments described above without deviating from its spirit or essential features. Therefore, the prior description is illustrative and not limiting. The scope of the disclosure is defined not by the prior description but by the added claims. Any modifications within their equivalent scope are included therein.

[0094] For example, the shape, pattern, size, arrangement, orientation, type, and number of each component described above are not limited to those shown in the above description and drawings. The shape, pattern, size, arrangement, orientation, type, and number of each component may be configured arbitrarily as long as they can achieve their function. Each component of the illustrated measuring device 1 is a functional concept. The specific form of each component is not limited to those shown.

[0095] Some embodiments of the present disclosure are described below. However, it should be noted that the embodiments of the present disclosure are not limited to these. [Note 1] A measuring device for measuring the state of an object to be measured by absorption spectroscopy, An irradiation unit that irradiates the object to be measured with irradiation light, A first prism having retrospectivity is positioned on the opposite side of the irradiation section, A second prism, which is arranged on the same side as the aforementioned irradiation unit and has retrospective properties, A light receiving unit that receives the irradiated light that has passed through the object to be measured multiple times between the first prism and the second prism, A first light guide unit is positioned on the same side as the first prism and guides the irradiated light toward the light receiving unit, Equipped with, The first prism and the second prism are eccentric to each other in the first direction, and the multiple passages of the irradiated light in each optical surface are arranged in two rows along the first direction. Measuring device. [Note 2] The measuring device described in Appendix 1, The first light guide includes a first optical component that reflects the illuminated light toward the second prism, Measuring device. [Note 3] The measuring device described in Appendix 2, The irradiating section and the light receiving section are on the same side as the second prism and are arranged in parallel in a second direction that intersects the first direction. Measuring device. [Note 4] A measuring device as described in Appendix 2 or 3, The first optical component is retroreflective, Measuring device. [Note 5] The measuring device described in Appendix 4, The first optical component includes a right-angle prism, Measuring device. [Note 6] The measuring device described in Appendix 1, The first light guide includes a second optical component that separates the optical path of the irradiated light emitted from the second prism from the first prism along the first direction. Measuring device. [Note 7] A measuring device described in any one of the appendices 1 to 6, The irradiation unit is positioned such that the emission surface of the irradiation light faces the optical surface of the first prism and is coordinating with the optical surface of the second prism. Measuring device. [Note 8] A measuring device described in any one of the appendices 1 to 6, The system further includes a second light guide that brings the optical path of the irradiated light emitted from the irradiating unit closer to the second prism along the first direction. Measuring device. [Note 9] A measuring device described in any one of the appendices 1 to 8, The first prism and the second prism are provided in multiple sets along the first direction, with their centers in the first direction being eccentric to each other. In each set, the first prism and the second prism are such that the multiple passages for the irradiated light are arranged in two rows along the first direction on their respective optical surfaces. Measuring device. [Note 10] A measuring device described in any one of the appendices 1 to 9, Each of the first prism and the second prism includes a corner cube or a right-angle prism. Measuring device. [Explanation of Symbols]

[0096] 1. Measuring apparatus 10 Irradiation Department 20 プリズム 21, 21a, 21b 1st プリズム 22, 22a, 22b 2nd プリズム 23, 23a, 23b First optical surface 24, 24a, 24b Second optical surface 30 Light-receiving section 40 First Light Guide Section 50 Second light guide section A interval B C Distance D-size L Irradiation light L1 centerline L2 centerline L3 central axis OP1 First Optical Path OP2 Second Optical Path P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22 (through section) Q Vertex S is the target being measured. S1 First Optical Path S2 Second Optical Path S3 Third Optical Path S4 Fourth Optical Path

Claims

1. A measuring device for measuring the state of an object to be measured by absorption spectroscopy, An irradiation unit that irradiates the object to be measured with irradiation light, A first prism having retrospectivity is positioned on the opposite side of the irradiation section, A second prism, which is arranged on the same side as the aforementioned irradiation unit and has retroreflective properties, A light receiving unit that receives the irradiated light that has passed through the object to be measured multiple times between the first prism and the second prism, A first light guide unit is positioned on the same side as the first prism and guides the irradiated light toward the light receiving unit, Equipped with, The first prism and the second prism are eccentric to each other in the first direction, and the multiple passages of the irradiated light on each optical surface are arranged in two rows along the first direction. Measuring device.

2. A measuring device according to claim 1, The first light guide includes a first optical component that reflects the illuminated light toward the second prism. Measuring device.

3. A measuring device according to claim 2, The irradiating section and the light receiving section are on the same side as the second prism and are arranged in parallel in a second direction that intersects the first direction. Measuring device.

4. A measuring device according to claim 2 or 3, The first optical component is retroreflective, Measuring device.

5. A measuring device according to claim 4, The first optical component includes a right-angle prism, Measuring device.

6. A measuring device according to claim 1, The first light guide includes a second optical component that separates the optical path of the irradiated light emitted from the second prism from the first prism along the first direction. Measuring device.

7. A measuring device according to any one of claims 1 to 3, The irradiation unit is positioned such that the emission surface of the irradiation light faces the optical surface of the first prism and is coordinating with the optical surface of the second prism. Measuring device.

8. A measuring device according to any one of claims 1 to 3, The system further includes a second light guide that brings the optical path of the irradiated light emitted from the irradiating unit closer to the second prism along the first direction. Measuring device.

9. A measuring device according to any one of claims 1 to 3, The first prism and the second prism are provided in multiple sets along the first direction, with their centers eccentric to each other in the first direction. In each set, the first prism and the second prism are such that the multiple passages for the irradiated light are arranged in two rows along the first direction on their respective optical surfaces. Measuring device.

10. A measuring device according to any one of claims 1 to 3, Each of the first prism and the second prism includes a corner cube or a right-angle prism. Measuring device.

Images