Optical concentration meter

Abstract

Provided is an optical concentration measuring device for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet and accommodating gas introduced through the gas inlet; an optical component installed in the acoustic cavity; and an acoustic transducer installed in the acoustic cavity, wherein the optical component has one or more of: a light source that emits light including a wavelength that is absorbed by the target component; and an optical waveguide that is optically connected to the light source, through which light from the light source propagates and at least a portion of which is exposed to the space within the acoustic cavity.

Description

[Technical Field]

[0001] The present invention relates to an optical concentration measuring instrument. [Background technology]

[0002] Patent Document 1 states, “The proposed photoacoustic gas sensor device, as eg shown in FIG. 1, may be built with a small form factor, such that it has an overall size of eg 1×1×0.7 cm 3 " (0040) [Prior art document] [Patent Documents] [Patent Document 1] US 2022 / 0187193 A1 Summary of the Invention

[0003] In a first aspect, there is provided an optical concentration meter for measuring the concentration of a target component in a gas, the optical concentration meter comprising: an acoustic cavity having a gas inlet and accommodating the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; and an acoustic transducer disposed within the acoustic cavity, the optical component including one or more light sources that emit light including wavelengths absorbed by the target component; and one or more optical waveguides optically connected to the light sources, through which the light from the light sources propagates and at least a portion of which is exposed to the space within the acoustic cavity.

[0004] In the optical concentration measuring instrument described above, the acoustic transducer may output an electrical signal corresponding to a pressure fluctuation in the acoustic cavity that occurs when an evanescent wave that seeps out of the optical waveguide as the light from the light source propagates through the optical waveguide is absorbed by the target component contained in the gas that is present around the optical waveguide and has a refractive index smaller than that of the optical waveguide.

[0005] Any of the above optical density measuring instruments is 10 mm 3 In any of the optical concentration measuring instruments described above, the optical waveguide may have an effective optical path length of 10 mm or more.

[0006] In any of the optical concentration measuring instruments described above, the optical component may have one or more substrates that support the light source and the optical waveguide.

[0007] In any of the optical concentration measuring instruments described above, the light source and the optical waveguide may be provided together on the same substrate and may be in direct contact with each other.

[0008] In any of the optical concentration measuring instruments described above, the light source and the optical waveguide may both be provided on the same substrate, and may be optically coupled to each other via a photocoupler.

[0009] In any of the optical concentration measuring instruments described above, the light source and the optical waveguide may be provided on different substrates, and may be optically coupled to each other via a photocoupler.

[0010] In any of the above optical concentration measuring instruments, at least a portion of the optical waveguide in the propagation direction of the light propagating within the optical waveguide may have its entire surface exposed to the space within the acoustic cavity without contacting the substrate.

[0011] In any of the above optical concentration measuring instruments, a space may be provided between the light source and the substrate.

[0012] In any of the optical concentration measuring instruments described above, the optical waveguide may at least partially include a bending portion that bends the propagation direction of the light propagating within the optical waveguide.

[0013] In any of the optical concentration measuring instruments described above, the optical waveguide may at least partially include one or more pairs of reflecting means that reverse the propagation direction of the light propagating within the optical waveguide and then return it to its original direction.

[0014] In any of the optical concentration measuring instruments described above, the optical waveguide may at least partially include an elliptical circulation portion that causes the light propagating within the optical waveguide to circulate in an ellipse.

[0015] In any of the optical concentration measuring instruments described above, the optical waveguide may at least partially include a ring-shaped circulating portion that causes the light propagating within the optical waveguide to circulate in an ellipse or a circle.

[0016] In any of the optical concentration measuring instruments described above, the optical component may include a light receiver that detects the light from the light source. In any of the optical concentration measuring instruments described above, the light source may adjust the output of the light it emits in accordance with the detection result of the light receiver.

[0017] In any of the optical concentration measuring instruments described above, the optical component may include an optical filter that transmits the wavelength of the light from the light source and blocks wavelengths other than the wavelength of the light.

[0018] In any of the optical concentration measuring instruments described above, the optical component may include a plurality of the optical waveguides optically connected to one of the light sources.

[0019] In any of the optical concentration measuring instruments described above, the optical component may include a plurality of the light sources optically connected to one or more of the optical waveguides.

[0020] In any of the above optical concentration measuring instruments, the average optical path length of the light from the light source that is emitted into the space within the acoustic cavity without entering the optical waveguide and reflected by the inner wall of the acoustic cavity may be shorter than the effective optical path length of the optical waveguide.

[0021] In any of the above optical concentration measuring instruments, the average reflectance of the inner wall of the acoustic cavity may be 70% or less.

[0022] In any of the optical concentration measuring instruments described above, the acoustic cavity may have a base on which the optical component and the acoustic transducer are mounted, and the acoustic cavity may have a lid in which the gas inlet is formed and attached to the base.

[0023] In any of the above optical concentration measuring instruments, the lid portion may be adhered to the base portion, thereby allowing the internal space of the acoustic cavity to communicate with the external space of the acoustic cavity only through the gas inlet.

[0024] In any of the optical concentration measuring devices described above, the base may have a conductive portion. In any of the optical concentration measuring devices described above, the conductive portion may include an inner contact end formed on the surface and electrically connected to at least one of the light source and the acoustic transducer. In any of the optical concentration measuring devices described above, the conductive portion may include an outer contact end exposed to the external space of the acoustic cavity.

[0025] Any of the optical concentration measuring instruments described above may include a dust filter attached to the gas inlet to seal the gas contained in the acoustic cavity.

[0026] Any of the optical concentration measuring devices described above may include an electrical circuit disposed within the acoustic cavity and in wired or wireless communication with the light source and / or the acoustic transducer.

[0027] The above summary of the invention does not list all of the features of the present invention. Subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic side view of an optical concentration measuring device 100 according to an embodiment. [Figure 2] FIG. 2 is a schematic plan view of the optical concentration measuring instrument 100 shown in FIG. [Figure 3] FIG. 2 is a schematic side view of an optical component 220 according to one embodiment. [Figure 4] 1 is a schematic side view of an optical concentration measuring device 300 according to an embodiment. [Figure 5] FIG. 3 is a schematic side view of an optical component 321 according to one embodiment. [Figure 6] FIG. 3 is a schematic side view of an optical component 322 according to one embodiment. [Figure 7] FIG. 3 is a schematic side view of an optical component 323 according to one embodiment. [Figure 8] FIG. 4 is a schematic side view of an optical concentration measuring device 400 according to an embodiment. [Figure 9] FIG. 4 is a schematic side view of an optical concentration measuring device 401 according to an embodiment. [Figure 10] FIG. 4 is a schematic side view of an optical concentration measuring device 402 according to one embodiment. [Figure 11] FIG. 1 is a schematic side view of an optical concentration measuring device 500 according to an embodiment. [Figure 12] FIG. 6 is a schematic side view of an optical concentration measuring device 600 according to one embodiment. [Figure 13] FIG. 6 is a schematic side view of an optical component 621 according to one embodiment. [Figure 14] FIG. 6 is a schematic side view of an optical component 622 according to one embodiment. [Figure 15] FIG. 7 is a schematic plan view of an optical waveguide 741 according to one embodiment. [Figure 16] FIG. 7 is a schematic plan view of an optical waveguide 742 according to one embodiment. [Figure 17] FIG. 7 is a schematic plan view of an optical waveguide 743 according to one embodiment. [Figure 18] 8 is a schematic side view of a light guide 840 and a light source 130 of an optical component 820 according to one embodiment. [Figure 19]FIG. 9 is a schematic plan view of an optical component 920 according to one embodiment. [Figure 20] FIG. 9 is a schematic plan view of an optical component 921 according to one embodiment. [Figure 21] FIG. 21 is a schematic side view of the optical component 921 shown in FIG. 20. [Figure 22] FIG. 1 is a schematic plan view of an optical component 1021 according to one embodiment. [Figure 23] 1 is a schematic plan view of an optical waveguide 1140 and a light source 130 of an optical component 1120 according to one embodiment. [Figure 24] FIG. 12 is a schematic plan view of a light guide 1240 and a light source 130 of an optical component 1220 according to one embodiment. [Figure 25] FIG. 13 is a schematic plan view of an optical concentration measuring device 1300 according to one embodiment. [Figure 26] FIG. 26 is a schematic side view of the optical concentration measuring instrument 1300 shown in FIG. 25. [Figure 27] FIG. 14 is a schematic plan view of an optical concentration measuring device 1400 according to one embodiment. [Figure 28] FIG. 28 is a schematic side view of the optical concentration measuring instrument 1400 shown in FIG. 27. [Figure 29] FIG. 15 is a schematic plan view of an optical component 1520 according to one embodiment. [Figure 30] FIG. 16 is a schematic plan view of an optical component 1620 according to one embodiment. [Figure 31] FIG. 31 is a schematic side view of the optical component 1620 shown in FIG. [Figure 32] FIG. 18 is a schematic plan view of an optical concentration measuring device 1800 according to one embodiment. [Figure 33] FIG. 18 is a schematic plan view of an optical filter 1881, a light source 1831, and an optical waveguide 140 of an optical component 1821 according to one embodiment. [Figure 34] FIG. 18 is a schematic plan view of an optical filter 1882, a light source 1832, and an optical waveguide 140 of an optical component 1822 according to one embodiment. [Figure 35]FIG. 18 is a schematic plan view of an optical filter 1883, a light source 1833, and an optical waveguide 140 of an optical component 1823 according to one embodiment. [Figure 36] FIG. 19 is a schematic plan view of an optical concentration measuring device 1900 according to one embodiment. [Figure 37] FIG. 19 is a schematic plan view of an optical concentration measuring device 1901 according to one embodiment. [Figure 38] FIG. 2 is a schematic plan view of an optical concentration measuring device 2000 according to one embodiment. [Figure 39] FIG. 2 is a schematic plan view of an optical concentration measuring device 2001 according to one embodiment. [Figure 40] FIG. 7 is a schematic side view of the optical concentration measuring instrument 600 shown in FIG. [Figure 41] FIG. 21 is a schematic side view of an optical concentration meter 2100 according to one embodiment. [Figure 42] FIG. 21 is a schematic side view of an optical concentration meter 2100 according to one embodiment. [Figure 43] FIG. 22 is a schematic side view of an optical concentration measuring device 2200 according to one embodiment. [Figure 44] FIG. 23 is a schematic side view of an optical concentration meter 2300 according to one embodiment. [Figure 45] FIG. 24 is a schematic plan view of an optical concentration measuring device 2400 according to one embodiment. [Figure 46] 18 is a diagram illustrating an example of a method for calculating the overall length of the optical waveguide 743 shown in FIG. 17, which has a curved, round shape in plan view. [Figure 47] 7 is a graph showing the relationship between the length of one side of a square surrounding an optical waveguide 743 in a plan view and the overall length and effective optical path length of the optical waveguide 743. [Figure 48] 10 is a graph showing the relationship between the length of one side of the square occupied area and the effective optical path length of the optical waveguide 743 in an optical concentration measuring instrument 600 or the like equipped with the optical waveguide 743. [Figure 49] 49 is a graph showing the relationship between the volume of the optical concentration measuring instrument 600 and the effective optical path length of the optical waveguide 743 in the example of FIG. 48. DETAILED DESCRIPTION OF THE INVENTION

[0029] The following embodiments do not limit the scope of the invention as claimed, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0030] FIG. 1 is a schematic side view of an optical concentration meter 100 according to one embodiment. FIG. 2 is a schematic plan view of the optical concentration meter 100 shown in FIG. 1. FIG. 1 shows X, Y, and Z axes that are orthogonal to each other. In FIG. 1, the X axis extends left and right into the paper, with the right side of the paper being the X axis positive side. The Y axis extends deep into the paper, with the far side of the paper being the Y axis positive side. The Z axis extends up and down into the paper, with the upper side of the paper being the Z axis positive side. In FIG. 2 and subsequent figures, the X, Y, and Z axes corresponding to the X, Y, and Z axes in FIG. 1 are also shown, and redundant explanations will be omitted below.

[0031] The optical concentration meter 100 includes an acoustic cavity 110 that contains a gas, and an optical component 120 and an acoustic transducer 190 that are installed within the acoustic cavity 110. In the side view of Fig. 1 and the plan view of Fig. 2, a portion of the acoustic cavity 110 is shown as being see-through. This also applies to the side views and plan views from Fig. 3 onwards, and redundant explanations will be omitted below.

[0032] The optical concentration meter 100 is a device that uses the photoacoustic effect to measure the concentration of a target component in a gas contained in an acoustic cavity 110. The photoacoustic effect is a phenomenon in which molecules that absorb light energy release heat, and the volumetric expansion caused by the heat generates an acoustic wave. The optical concentration meter 100 can also be called a photoacoustic gas sensor.

[0033] The acoustic cavity 110 has a gas inlet 111 and contains a gas introduced through the gas inlet 111. The inner walls of the acoustic cavity 110 may or may not be light reflective.

[0034] The optical component 120 has a light source 130, an optical waveguide 140, and a substrate 150. The optical component 120 may have one or more light sources 130, one or more optical waveguides 140, and one or more substrates 150, and in this example, has one of each.

[0035] Light source 130 emits light having a wavelength that is absorbed by a target component in the gas. The wavelength of the light emitted by light source 130 can be set according to the target component whose concentration is to be measured by optical concentration meter 100. For example, if the target component is carbon dioxide molecules (CO2), the wavelength of the light may be on the order of several μm, i.e., the light may be mid-infrared. Note that in FIG. 1 and subsequent figures, the light from light source 130 is schematically shown by a straight dashed line, and redundant explanations will be omitted below.

[0036] The optical waveguide 140 is optically connected to the light source 130, and light from the light source 130 propagates therethrough. At least a portion of the optical waveguide 140 is exposed to the space within the acoustic cavity 110. The total length of the optical waveguide 140 is, for example, about 2 cm. If the optical component 120 has multiple optical waveguides 140, the total length of the multiple optical waveguides 140 may be about 2 cm. The width of the optical waveguide 140 is, for example, about 3 μm. These dimensions may vary depending on the design of the optical concentration meter 100, the optical waveguide 140, etc.

[0037] The substrate 150 supports the light source 130 and the light guide 140. In this example, the light source 130 and the light guide 140 are both provided on one substrate 150 and are in direct contact with each other.

[0038] The optical concentration meter 100 can measure the concentration of a target component by detecting an acoustic wave generated by the target component absorbing light from the optical component 120 using the acoustic transducer 190, and measuring the concentration of the target component based on the intensity of an electrical signal output from the acoustic transducer 190 that detected the acoustic wave. More specifically, the acoustic transducer 190 outputs an electrical signal corresponding to a pressure fluctuation in the acoustic cavity 110 that occurs when the target component, contained in a gas that has a refractive index smaller than that of the optical waveguide 140 and that surrounds the optical waveguide 140, absorbs evanescent waves that leak out of the optical waveguide 140 as light from the light source 130 propagates through the optical waveguide 140. In FIG. 1 and subsequent figures, the evanescent waves are schematically represented by dots, and the acoustic waves are schematically represented by straight dashed lines, and redundant explanations will be omitted below.

[0039] The optical concentration measuring device 100 separates the optical path of light absorbed by the target component in the gas from the acoustic cavity 110 that contains the gas and resonates the sound generated by the absorption of light by the target component, thereby making it possible to reduce the volume, i.e., to make it more compact, than a measuring device for comparison in which the optical path and the acoustic cavity 110 are not separated. As an example, the optical concentration measuring device 100 has a size of 10 mm. 3 While optical concentration measuring instrument 100 is thus miniaturized, it still ensures an effective optical path length of 10 mm or more for optical waveguide 140. The relationship between the volume of optical concentration measuring instrument 100 and the effective optical path length will be described in detail later.

[0040] Furthermore, optical concentration measuring instrument 100 has greater flexibility in design and manufacturing than the measuring instrument of the comparative example described above, by separating the optical path and acoustic cavity 110. The measuring instrument of the comparative example described above may be, for example, the measuring instrument disclosed in Patent Document 1.

[0041] 1 and subsequent figures, the optical component 120 and the acoustic transducer 190 of the optical concentration meter 100 are shown with similar dimensions simply for the purpose of clarity, but it should be noted that the dimensional ratio of these components is not limited to the dimensional ratio shown. In the optical concentration meter 100, the optical component 120 may not have the substrate 150. In this case, the light source 130 and the optical waveguide 140 of the optical component 120 may be directly installed in the acoustic cavity 110.

[0042] 3 is a schematic side view of an optical component 220 according to one embodiment. The optical concentration meter 100 according to one embodiment shown in FIGS. 1 and 2 may include, instead of the optical component 120, an optical component 220 in which the light source 130 is formed on the positive side of the optical waveguide 140 along the Z axis. In the optical component 220, similar to the optical component 120, the light source 130 and the optical waveguide 140 are both provided on a single substrate 150 and are in direct contact with each other. By including the optical components 120 and 220 configured in this manner, the optical concentration meter 100 can efficiently propagate light from the light source 130 to the optical waveguide 140 and can reduce the size of the optical components 120 and 220.

[0043] In addition, for the embodiments described using the drawings from Figure 3 onwards, only the differences from the embodiment described using Figures 1 and 2 will be described. In the following embodiments, components corresponding to those in the embodiment of Figures 1 and 2 will be given the same reference numerals, and duplicated descriptions will be omitted.

[0044] FIG. 4 is a schematic side view of an optical concentration meter 300 according to one embodiment. Optical concentration meter 300 differs from optical concentration meter 100 in that optical component 320 includes a photocoupler 360 instead of optical component 120. In optical component 320, light source 130 and optical waveguide 140 are both provided on a single substrate 150 and are optically coupled to each other via photocoupler 360. By including optical component 320 configured in this manner, optical concentration meter 300 allows light source 130, photocoupler 360, and optical waveguide 140 to be designed independently, thereby increasing design flexibility. Furthermore, by including optical component 320 configured in this manner, optical concentration meter 300 can reduce the size of optical component 320.

[0045] 5 is a schematic side view of an optical component 321 according to one embodiment. Instead of the optical component 320, the optical concentration meter 300 may include an optical component 321 having a photocoupler 361 formed of a grating, i.e., a diffraction grating, enclosed in a dashed line frame in FIG.

[0046] 6 is a schematic side view of an optical component 322 according to one embodiment. Instead of the optical component 320, the optical concentration meter 300 may include an optical component 322 having a photocoupler 362, surrounded by a dashed line in FIG. 6, which is composed of two sets of gratings with an intermediate cladding interposed therebetween.

[0047] 7 is a schematic side view of an optical component 323 according to one embodiment. The optical concentration meter 300 may include, instead of the optical component 320, an optical component 323 having a photocoupler 363 formed of a directional coupler with an intermediate clad interposed therebetween, as enclosed by a dashed line in FIG.

[0048] 8 is a schematic side view of an optical concentration meter 400 according to one embodiment. Optical concentration meter 400 differs from optical concentration meter 100 in that optical component 420 includes two substrates 451 and 452 and a photocoupler 460 instead of optical component 120. In optical component 420, light source 130 and optical waveguide 140 are provided on separate substrates 451 and 452, respectively, and are optically coupled to each other via photocoupler 460. By including optical component 420 configured in this manner, optical concentration meter 400 allows light source 130 to be designed separately from other components such as photocoupler 460 and optical waveguide 140, thereby increasing the degree of design freedom.

[0049] 9 is a schematic side view of an optical concentration meter 401 according to one embodiment. Optical concentration meter 401 differs from optical concentration meter 400 in that optical component 421 is provided instead of optical component 420. In optical component 420, light from light source 130 is emitted from the side surface on the positive side of light source 130 along the X axis, but in optical component 421, light from light source 130 is emitted from the surface on the negative side of substrate 451 along the Z axis. Optical component 421 has a substrate support 453 that holds substrate 451 at a predetermined position.

[0050] 10 is a schematic side view of an optical concentration meter 402 according to one embodiment. Optical concentration meter 402 differs from optical concentration meter 401 in that optical component 422 is provided instead of optical component 421. In optical component 421, light from light source 130 is emitted from the surface of substrate 451 on the negative side in the Z axis direction, while in optical component 422, light from light source 130 is emitted from the surface of light source 130 on the negative side in the Z axis direction.

[0051] 11 is a schematic side view of an optical concentration meter 500 according to one embodiment. Optical concentration meter 500 differs from optical concentration meter 100 in that, instead of optical component 120, optical component 520 is provided in which at least a portion of optical waveguide 140 is spaced from substrate 550 by a support portion 551 of substrate 550. In optical component 520, at least a portion of optical waveguide 140 in the propagation direction of light propagating within optical waveguide 140 does not come into contact with substrate 550, and the entire surface is exposed to the space within acoustic cavity 110. In optical component 520, at least a portion of optical waveguide 140 can also be defined as being floating.

[0052] By including the optical component 520 configured as described above, the optical concentration meter 500 can prevent light leakage and light absorption from the optical waveguide 140 to the substrate 550, thereby improving the light propagation efficiency in the optical waveguide 140. To achieve this effect, the distance between the optical waveguide 140 and the substrate 550 may be greater than the seepage length of evanescent waves that seep out of the optical waveguide 140 during the process of light from the light source 130 propagating through the optical waveguide 140, and may be, for example, 2 μm or more. Furthermore, the optical concentration meter 500 including the optical component 520 can increase the contact between the evanescent waves that seep out of the optical waveguide 140 during the process of light from the light source 130 propagating through the optical waveguide 140 and the target component contained in a gas that is present around the optical waveguide 140 and has a refractive index smaller than that of the optical waveguide 140. This allows the optical concentration measuring device 500 to make more target components absorb the evanescent waves, increasing the pressure fluctuation range within the acoustic cavity 110 and increasing the output of the acoustic transducer 190.

[0053] 12 is a schematic side view of an optical concentration meter 600 according to one embodiment. Optical concentration meter 600 differs from optical concentration meter 500 in that, instead of optical component 520, optical component 620 is provided in which at least a portion of light source 130 and optical waveguide 140 are spaced from substrate 650 by support portion 651 of substrate 650. In optical component 620, a space is provided between light source 130 and substrate 650. It can also be defined that at least a portion of light source 130 and optical waveguide 140 are floating in optical component 620.

[0054] By including optical component 620 configured in this manner, optical concentration meter 600 can prevent light leakage and light absorption from light source 130 and optical waveguide 140 to substrate 650, thereby efficiently propagating light from light source 130 to optical waveguide 140 and increasing the light propagation efficiency in optical waveguide 140. To achieve this effect, the separation distance between light source 130 and substrate 650 may be greater than the seepage length of evanescent waves, which is the length of light from light source 130 seeping into the space between light source 130 and substrate 650, and may be, for example, 2 μm or greater.

[0055] 13 is a schematic side view of an optical component 621 according to one embodiment. The optical concentration meter 600 may include, instead of the optical component 620, an optical component 621 in which the light source 130 is formed on the positive side of the optical waveguide 140 in the Z axis direction.

[0056] FIG. 14 is a schematic side view of an optical component 622 according to one embodiment. Instead of optical component 320, optical concentration meter 600 may include optical component 622 in which light source 130 is formed on the positive side of optical waveguide 640 along the Z axis, and in which the film thickness of optical waveguide 640 is relatively thin, located on the positive side of support 651 closest to light source 130 along the Z axis. As shown in FIG. 14 , optical waveguide 640 may have a step so that the film thickness is thin only at that position, or the film thickness may increase in multiple steps or smoothly from that position toward the positive side of the X axis. By including optical component 622 having optical waveguide 640 with a film thickness that is thin at that position, optical concentration meter 600 can prevent light from leaking to substrate 650 through support 651.

[0057] In the following embodiments, as an example, a space is provided between the light source 130 and the substrate 650, as in the example of Figure 12, and the optical waveguide 140 is supported by a support portion 651 or the like of the substrate 650 so that the entire surface is exposed without at least a portion of the optical waveguide 140 coming into contact with the substrate 650 or the like.

[0058] Fig. 15 is a schematic plan view of an optical waveguide 741 according to one embodiment. In Figs. 1 to 14, the shapes of the optical waveguide 140 and the like are shown simply in a plan view for the purpose of clarity of explanation. The optical component 120 of the optical concentration meter 100 and the like may have an optical waveguide 741 instead of the optical waveguide 140. The optical waveguide 741 has a zigzag shape in a plan view.

[0059] 16 is a schematic plan view of an optical waveguide 742 according to one embodiment. The optical component 120 of the optical concentration meter 100 may have the optical waveguide 742 instead of the optical waveguide 140. The optical waveguide 742 has a circular shape in plan view with alternating straight lines and curves.

[0060] 17 is a schematic plan view of an optical waveguide 743 according to one embodiment. The optical component 120 of the optical concentration measuring instrument 100 may have the optical waveguide 743 instead of the optical waveguide 140. The optical waveguide 743 has a curved, round shape in a plan view.

[0061] 15 to 17 may also be defined as including at least a bent portion that bends the propagation direction of light propagating within optical waveguide 741. Optical waveguide 741 and the like may also be defined as having at least a portion that is not linear in a planar view. By including optical component 120 and the like having optical waveguide 741 and the like, optical concentration meter 100 and the like can increase the optical path length per unit area on the surface of substrate 150 and the like.

[0062] Figure 18 is a schematic side view of an optical waveguide 840 and a light source 130 of an optical component 820 according to one embodiment. In Figure 18, other components included in optical component 820 are omitted for the sole purpose of clarifying the invention. For the same purpose, some components are also omitted from the subsequent figures, and redundant explanations will be omitted hereafter.

[0063] The optical concentration meter 100 and the like may include an optical component 820 instead of the optical component 120 and the like. In the optical component 820, the optical waveguide 840 includes one or more pairs of reflecting means 841 that at least partially reverse the propagation direction of light propagating within the optical waveguide 840 and then return it to its original direction. The reflecting means 841 may be, for example, a grating, a metal, or a reflection between a high-refractive index material and a low-refractive index material. The optical waveguide 840 can also be defined as having at least a section sandwiched between mirrors. By including the optical component 820, the optical concentration meter 100 and the like can increase the optical path length per unit area on the surface of the substrate 150 and the like.

[0064] 19 is a schematic plan view of an optical component 920 according to one embodiment. The optical concentration meter 100 or the like may include the optical component 920 instead of the optical component 120 or the like. In the optical component 920, an optical waveguide 940 partially includes an elliptical winding portion 941 that causes light propagating within the optical waveguide 940 to circulate in an ellipse. The linear portion of the optical waveguide 940 other than the elliptical winding portion 941 is referred to as a linear waveguide.

[0065] By including optical component 920, optical concentration measuring instrument 100 and the like can increase the optical path length per unit area on the surface of substrate 150 and the like. Furthermore, when a straight waveguide is connected to input light to elliptical circulation portion 941, as in the example of FIG. 19 , optical concentration measuring instrument 100 and the like can control the mode of the input light by the waveguide width, and can efficiently circulate the light in elliptical circulation portion 941. Furthermore, when the straight waveguide that inputs light to elliptical circulation portion 941 is connected at an angle along the tangent of the ellipse, optical concentration measuring instrument 100 and the like can efficiently circulate the light in elliptical circulation portion 941.

[0066] Fig. 20 is a schematic plan view of an optical component 921 according to one embodiment. Fig. 21 is a schematic side view of the optical component 921 shown in Fig. 20. In Fig. 20, a support portion 951 of a substrate 950 of the optical component 921 is indicated by a dashed line. The optical concentration meter 100 and the like may be provided with the optical component 921 instead of the optical component 920.

[0067] In the optical component 921, the optical waveguide 940 generally includes an elliptical circulation portion 941 that causes light propagating within the optical waveguide 940 to circulate in an ellipse; that is, the optical waveguide 940 is an elliptical waveguide. The light source 130 is disposed at a position that overlaps with the elliptical circulation portion 941 in a plan view. When the light source 130 is disposed within the elliptical circulation portion 941, as in the example shown in FIGS. 20 and 21 , the optical concentration meter 100 or the like can more efficiently input the light emitted from the light source 130 into the elliptical circulation portion 941. In this case, the optical concentration meter 100 or the like can efficiently circulate the light through the elliptical circulation portion 941 by disposing the light source 130 outside the elliptical focus of the elliptical circulation portion 941, as shown in FIG. 20 .

[0068] Furthermore, in the optical component 921, in a plan view, the support portion 951 of the substrate 950 supports the inside of the elliptical focus of the elliptical circumferential portion 941, so that the entire surface outside the elliptical focus of the elliptical circumferential portion 941 is exposed to the space within the acoustic cavity 110 without coming into contact with the substrate 950. This allows the optical concentration measuring instrument 100, etc. to increase the propagation efficiency of light circulating outside the elliptical focus of the elliptical circumferential portion 941, and to increase contact between the evanescent wave that seeps out of the optical waveguide 940 as the light from the light source 130 propagates through the optical waveguide 940 and the target component contained in the gas that is present around the optical waveguide 940 and has a refractive index smaller than that of the optical waveguide 940. Furthermore, the optical concentration measuring instrument 100, etc., allows the support portion 951 of the substrate 950 to support at least a portion of the region inside the elliptical focus of the elliptical circumferential portion 941, so that the optical waveguide 940 can be stably supported.

[0069] FIG. 22 is a schematic plan view of an optical component 1021 according to one embodiment. In FIG. 22, a support portion 951 of a substrate 950 of the optical component 1021 is indicated by a dashed line. The optical concentration meter 100 and the like may include, instead of the optical component 921, an optical component 1021 having a light source 1130 configured so that part of its outer shape roughly follows the outer shape of the elliptical orbital portion 941. As in the example of FIG. 22 , the optical concentration meter 100 and the like can increase the amount of light input to the elliptical orbital portion 941 by placing the light source 1130 outside the elliptical focus of the elliptical orbital portion 941 and increasing the surface area of ​​the light source 1130.

[0070] 23 is a schematic plan view of an optical waveguide 1140 and a light source 130 of an optical component 1120 according to one embodiment. The optical concentration meter 100 or the like may include the optical component 1120 instead of the optical component 120 or the like. In the optical component 1120, the optical waveguide 1140 at least partially includes a ring-shaped circulating portion 1141 that causes light propagating within the optical waveguide 1140 to circulate in an ellipse or a circle. The linear portion of the optical waveguide 1140 other than the ring-shaped circulating portion 1141 is referred to as a linear waveguide. In the optical waveguide 1140, a connection portion between the ring-shaped circulating portion 1141 and the linear waveguide is a directional coupler, and the separation distance between the ring-shaped circulating portion 1141 and the linear waveguide at this connection portion is adjustable.

[0071] By including optical component 1120, optical concentration measuring instrument 100 and the like can increase the optical path length per unit area on the surface of substrate 150 and the like. Furthermore, optical concentration measuring instrument 100 and the like can efficiently introduce light into ring-shaped circulating portion 1141 by controlling the distance between the linear waveguide and ring-shaped circulating portion 1141, as in one embodiment of FIG.

[0072] 24 is a schematic plan view of optical waveguide 1240 and light source 130 of optical component 1220 according to one embodiment. Optical concentration meter 100 and the like may be provided with optical component 1220 instead of optical component 1120. In optical component 1220, there is no gap between ring-shaped circumferential portion 1241 and the linear waveguide; that is, they are integrally formed. By providing optical component 1220, optical concentration meter 100 and the like can eliminate the need for microfabrication to dimensions smaller than the waveguide width, and can be easily manufactured.

[0073] Fig. 25 is a schematic plan view of an optical concentration meter 1300 according to one embodiment. Fig. 26 is a schematic side view of the optical concentration meter 1300 shown in Fig. 25. Optical concentration meter 1300 differs from optical concentration meter 100 in that, instead of optical component 120, optical component 1320 additionally includes a light receiver 1370.

[0074] The light receiver 1370 detects light from the light source 130. In this example, the light receiver 1370 is provided in direct contact with one of the ends of the optical waveguide 140, opposite the end directly contacted by the light source 130. The light source 130 may adjust the output of the light it emits based on the detection result of the light receiver 1370. By including such optical component 1320, the optical concentration meter 1300 can detect the optical output of the light source 130 and perform signal processing according to the optical output, such as adjusting the optical output of the light source 130. In this example, the light receiver 1370 is mounted on a single substrate 650 together with other components such as the light source 130. This allows the optical concentration meter 1300 to be miniaturized.

[0075] FIG. 27 is a schematic plan view of an optical concentration meter 1400 according to one embodiment. FIG. 28 is a schematic side view of the optical concentration meter 1400 shown in FIG. 27. The optical concentration meter 1400 differs from the optical concentration meter 1300 in that it includes an optical component 1420 instead of the optical component 1320. In the optical component 1420, the light receiver 1470 is provided on a substrate 1452 separate from the substrate 1450 on which the other components such as the light source 130 are provided. The light receiver 1470 is provided next to the light source 130 and detects leakage light from the light source 130 located on a support portion 1451 of the substrate 1450, as shown by the dashed line in FIG. 28. By including such an optical component 1420, the optical concentration meter 1400 can design only the light receiver 1470 separately from the other components such as the light source 130.

[0076] Fig. 29 is a schematic plan view of optical component 1520 according to one embodiment. Fig. 30 is a schematic plan view of optical component 1620 according to one embodiment. Optical concentration meter 1300 may include optical components 1520 and 1620 in which light receivers 1570 and 1670 are provided next to light source 130, instead of optical component 1320. In optical component 1520 in the example of Fig. 29, light receiver 1570 is connected to light source 130 via a waveguide. On the other hand, in optical component 1620 in the example of Fig. 30, light receiver 1670 is not connected to light source 130.

[0077] Fig. 31 is a schematic side view of the optical component 1620 shown in Fig. 30. The optical receiver 1670 is provided next to the light source 130 on one substrate 650 and detects leaked light from the light source 130 located on the support portion 651 of the substrate 650, as indicated by the dashed line in Fig. 31. As shown in Fig. 31, the leaked light detected by the optical receiver 1670 may include direct light that reaches the optical receiver 1670 directly from the light source 130, as well as reflected light that reaches the optical receiver 1670 after being reflected on the front or back surface of the substrate 650. By including such an optical component 1620, the optical concentration meter 1300 can detect the optical output of the light source 130 without reducing the amount of light from the light source 130 that is used to measure the concentration of a target component in a gas.

[0078] 32 is a schematic plan view of an optical concentration meter 1800 according to one embodiment. Optical concentration meter 1800 differs from optical concentration meter 100 in that, instead of optical component 120, optical component 1820 is provided which additionally has optical filter 1880 disposed between light source 130 and optical waveguide 140.

[0079] Optical filter 1880 transmits wavelengths of light from light source 130 that are absorbed by the target component in the gas, and blocks wavelengths other than these. By including such optical component 1820, optical concentration meter 1800 can prevent components in the gas other than the target component from absorbing light from light source 130 and generating acoustic waves, thereby improving the accuracy of measuring the concentration of the target component.

[0080] 33 is a schematic plan view of an optical filter 1881, a light source 1831, and an optical waveguide 140 of an optical component 1821 according to one embodiment. Optical concentration meter 1800 may include, instead of optical component 1820, optical component 1821 having optical filter 1881 made of a grating enclosed in a dashed line frame in FIG. 33 and light source 1831 optically connected to optical filter 1881.

[0081] 34 is a schematic plan view of an optical filter 1882, a light source 1832, and an optical waveguide 140 of an optical component 1822 according to one embodiment. Optical concentration meter 1800 may include, instead of optical component 1820, optical component 1822 having optical filter 1882 formed of a side grating enclosed in a dashed line frame in FIG. 34 and light source 1832 optically connected to optical filter 1882.

[0082] 35 is a schematic plan view of an optical filter 1883, a light source 1833, and an optical waveguide 140 of an optical component 1823 according to one embodiment. Optical concentration meter 1800 may include, instead of optical component 1820, optical component 1823 having optical filter 1883 formed of a focusing grating enclosed in a dashed line frame in FIG. 35 and light source 1833 optically connected to optical filter 1883.

[0083] 33 to 35, wavelengths not selected by the grating may be emitted into the acoustic cavity 110. However, for example, by designing the reflected optical path length within the acoustic cavity 110 to be sufficiently shorter than the optical path length of the optical waveguide 140, it is possible to prevent components other than the target component in the gas from absorbing the light emitted into the acoustic cavity 110 and generating acoustic waves, thereby improving the accuracy of measuring the concentration of the target component. This will be described later using FIG. 40.

[0084] 36 is a schematic plan view of an optical concentration meter 1900 according to one embodiment. Optical concentration meter 1900 differs from optical concentration meter 100 in that, instead of optical component 120, optical component 1920 is provided, which has multiple optical waveguides 1940 optically connected to one light source 130 on one substrate 650. As described above, the total length of multiple optical waveguides 1940 is, for example, about 2 cm.

[0085] When light propagates a long distance through a waveguide, the light is attenuated due to propagation loss. However, the optical concentration meter 1900 is equipped with an optical component 1920 in which each short optical waveguide 1940 is connected to multiple light sources 130, thereby reducing such propagation loss while maintaining the total optical path length.

[0086] 37 is a schematic plan view of an optical concentration meter 1901 according to one embodiment. Optical concentration meter 1901 differs from optical concentration meter 1900 in that, instead of optical component 1920, optical component 1921 is provided in which multiple optical waveguides 1941 optically connected to one light source 130 are arranged to extend radially from light source 130. Optical concentration meter 1901 equipped with such optical component 1921 can also reduce propagation loss while ensuring the total optical path length.

[0087] 38 is a schematic plan view of an optical concentration meter 2000 according to one embodiment. Optical concentration meter 2000 differs from optical concentration meter 100 in that, instead of optical component 120, optical component 2020 is provided which has multiple light sources 2030 optically connected to multiple optical waveguides 2040 on a single substrate 650.

[0088] 39 is a schematic plan view of an optical concentration meter 2001 according to one embodiment. Optical concentration meter 2001 differs from optical concentration meter 2000 in that, instead of optical component 2020, optical component 2021 is provided, which has multiple light sources 2031 optically connected to one optical waveguide 2041 on one substrate 650.

[0089] When multiple light sources are used, the amount of light emitted increases, the photoacoustic signal becomes larger, and gas sensitivity improves. However, the power consumption required to drive the light sources is large. On the other hand, when a small number of light sources are used, the amount of light emitted decreases, the photoacoustic signal becomes smaller, and gas sensitivity decreases. However, the power consumption required to drive the light sources is small. According to the optical concentration measuring instruments 2000 and 2001 shown in Figures 38 and 39, by including the above-mentioned optical components 2020 and 2021, it is possible to adjust the light amount and power consumption by selectively driving one or more of the multiple light sources 2030 and 2031.

[0090] 40 is a schematic side view of the optical concentration meter 600 shown in FIG. 6. Unlike FIG. 6, FIG. 40 indicates leakage light from the light source 130 with a dashed line. In the optical concentration meter 600 and the like, the average optical path length of light from the light source 130 that is emitted into the space within the acoustic cavity 110 without entering the optical waveguide 140 and is reflected by the inner wall of the acoustic cavity 110 may be shorter than the effective optical path length of the optical waveguide 140. By designing the optical concentration meter 600 and the like in this manner, it is possible to prevent components other than the target component in the gas from absorbing the leakage light that is emitted into the space within the acoustic cavity 110 and reflected by the inner wall, thereby improving the accuracy of measuring the concentration of the target component.

[0091] To shorten the average optical path length of the leaked light compared to the optical path length of the optical waveguide 140, for example, the average reflectance of the inner wall of the acoustic cavity 110 may be set to 70% or less. Specifically, if the average reflectance of the inner wall of the acoustic cavity 110 is R, and the leaked light is reflected N times by the inner wall, the intensity of the leaked light is R×N. The number of reflections by the inner wall required to reduce the intensity of the leaked light to, for example, one-tenth or less is 22 when R=0.9, 11 when R=0.8, 7 when R=0.7, 5 when R=0.6, and 4 when R=0.5. Therefore, in the optical concentration meter 600, etc., by setting the average reflectance of the inner wall to 70% or less, the average optical path length of the leaked light can be reduced to one-third or less compared to when the average reflectance is 90%. Thus, it can be seen that when the average reflectance of the inner wall is set to 70% or less, the effect of reducing the optical path length of the leaked light relative to the reduction in reflectance is significant.

[0092] 41 is a schematic side view of an optical concentration meter 2100 according to one embodiment. Optical concentration meter 2000 differs from optical concentration meter 600 in that, instead of acoustic cavity 110, optical concentration meter 2000 includes acoustic cavity 2110 having a base portion 2112 and a lid portion 2114 that are separate from each other.

[0093] In the acoustic cavity 2110, the base 2112 is a portion on which the optical component 120 and the acoustic transducer 190 are mounted on a surface 2113, and the lid 2114 is a portion in which the gas inlet 111 is formed and which is attached to the base 2112. By providing such an acoustic cavity 2110, the optical concentration meter 2100 can be easily manufactured by first mounting the components to be mounted in the acoustic cavity 2110, such as the optical component 120 and the acoustic transducer 190, on the surface 2113 of the base 2112, and then attaching the lid 2114 to the base 2112.

[0094] Fig. 42 is a schematic side view of an optical concentration meter 2100 according to one embodiment. The optical concentration meter 2100 shown in Fig. 42 differs from the optical concentration meter 2100 shown in Fig. 41 in that a lid 2114 is bonded to a base 2112 with adhesive 2115. This allows the internal space of the acoustic cavity 2110 to communicate with the external space of the acoustic cavity 2110 only via the gas inlet 111. According to the optical concentration meter 2100 shown in Fig. 42, the adhesion between the lid 2114 and the base 2112 is improved compared to when the lid 2114 is placed on the base 2112 without being bonded, and the internal space of the acoustic cavity 2110 is made more airtight. This makes it possible to prevent attenuation of pressure fluctuations within the acoustic cavity 2110.

[0095] FIG. 43 is a schematic side view of an optical concentration meter 2200 according to one embodiment. The optical concentration meter 2200 differs from the optical concentration meter 2100 shown in FIG. 41 in that a base 2212 has a conductive portion 2216. The conductive portion 2216 includes an inner contact end 2217 formed on a surface 2213 of the base 2212 and an outer contact end 2218 exposed to the external space of the acoustic cavity 2210. The inner contact end 2217 is electrically connected to at least one of the light source 130 and the acoustic transducer 190. The optical concentration meter 2200 includes such an acoustic cavity 2210, thereby enabling electrical continuity between the inside and outside of the acoustic cavity 2210.

[0096] 44 is a schematic side view of an optical concentration meter 2300 according to one embodiment. The optical concentration meter 2300 differs from the optical concentration meter 600 in that it additionally includes an anti-dust filter 2392. The anti-dust filter 2392 is attached to the gas inlet 111 of the acoustic cavity 110, and seals the gas contained in the acoustic cavity 110. By including such anti-dust filter 2392, the optical concentration meter 2300 can prevent foreign matter from entering the acoustic cavity 110.

[0097] 45 is a schematic plan view of an optical concentration meter 2400 according to one embodiment. The optical concentration meter 2400 differs from the optical concentration meter 100 in that it additionally includes an electric circuit 2494 installed in the acoustic cavity 110. The electric circuit 2494 is electrically connected to at least one of the light source 130 and the acoustic transducer 190.

[0098] The electrical circuit 2494 may function, for example, as a circuit for driving a light source, and may adjust the output of light emitted from the light source 130. Additionally or alternatively, the electrical circuit 2494 may function, for example, as a concentration calculation circuit, and may calculate the concentration of a target component in a gas based on the output of the acoustic transducer 190. Additionally or alternatively, the electrical circuit 2494 may also function as an analog-to-digital conversion circuit, a digital data transmission circuit, or the like.

[0099] In an acoustic cavity that utilizes internal reflection, such as the measuring device in the comparative example described above, if an electrical circuit is placed inside the acoustic cavity, it is difficult to control the reflectance of light on the circuit surface, so the electrical circuit is placed outside the acoustic cavity. In contrast, in optical concentration measuring device 2400, the optical path and acoustic cavity 110 are separated, so electrical circuit 2494 can be placed inside acoustic cavity 110, which makes it possible to miniaturize optical concentration measuring device 2400 and facilitates its incorporation into other devices.

[0100] 46 is a diagram illustrating an example of a method for calculating the total length of the optical waveguide 743, which has a curved, round shape in plan view, as shown in FIG. prop teeth, [Formula 1] ΔR can be calculated by the waveguide width W waveguide and the waveguide spacing W spacingwhere Rmin is the minimum radius of curvature and n is the number of turns. The footprint length Lfp, which is the length of one side of a square surrounding the optical waveguide 743 in a plan view, is twice the maximum radius of curvature Rmax plus ΔR.

[0101] 47 is a graph showing the relationship between the length of one side of a square surrounding the optical waveguide 743 in a plan view and the total length and effective optical path length of the optical waveguide 743. The horizontal axis of the graph indicates the footprint length [mm], and the vertical axis of the graph indicates the optical path length of the optical waveguide 743, i.e., the total length [mm] and the effective optical path length [mm]. In FIG. 47, the curve shown by the dashed line on the upper side indicates the total length L of the optical waveguide 743. prop The curve on the bottom represents the total length L prop is multiplied by the seepage efficiency η of the optical waveguide 743, prop , i.e., the effective optical path length. In this example, η is set to 20%.

[0102] FIG. 48 is a graph showing the relationship between the length of one side of a square occupied area of ​​an optical concentration measuring instrument such as the optical waveguide 743 and the effective optical path length of the optical waveguide 743. The horizontal axis of the graph indicates the footprint length Lfp [mm], and the vertical axis of the graph indicates the effective optical path length Leff [mm]. In FIG. 48, the dimensional range of the optical path of the measuring instrument of the comparative example described above is indicated by dots. As shown in FIG. 48, to ensure an effective optical path length Leff of 10 to 50 mm, the measuring instrument of the comparative example requires a footprint length Lfp of 10 mm to 20 mm, whereas the optical concentration measuring instrument such as the optical waveguide 743 requires only a footprint length Lfp of less than 5 mm.

[0103] 49 is a graph showing the relationship between the volume of the optical concentration measuring device 600 and the effective optical path length of the optical waveguide 743 in the example of FIG. 48. The horizontal axis of the graph represents the volume Vcell [mm 3 ], and the vertical axis of the graph indicates the effective optical path length Leff [mm]. The curve shown in Fig. 49 indicates the cell volume Vcell of optical concentration measuring device 600 or the like equipped with optical waveguide 743. In Fig. 49, the dimensional range of the measuring device of the comparative example is indicated by dots.

[0104] In an optical concentration meter 600 or the like equipped with an optical waveguide 743, the height of the acoustic cavity 110, i.e., the cell height of the optical concentration meter 600 or the like, is assumed to be 0.5 mm. In this case, in order to ensure an effective optical path length Leff of 10 to 50 mm as shown in FIG. 49, the measuring device of the comparative example described above has a height of 700 mm. 3 ~8000mm 3 In contrast, the optical concentration measuring device 600 and the like equipped with the optical waveguide 743 require a cell volume Vcell of 10 mm 3 Thus, the optical concentration measuring device 600 and the like can be made significantly smaller than the measuring device of the comparative example.

[0105] Although the present invention has been described using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0106] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and can be realized in any order unless the output of a previous process is used in a later process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, it does not mean that it is essential to perform the process in this order. [Explanation of symbols]

[0107] 100 Optical concentration meter 110 Acoustic Cavity 111 Gas inlet 120 Optical Components 130 Light source 140 Optical waveguide 150 boards 190 Acoustic Transducer 220 Optical Components 300 Optical concentration meter 320 Optical Components 360 Photocoupler 321 Optical Components 361 Photocoupler 322 Optical Components 362 Photocoupler 323 Optical Components 363 Photocoupler 400 Optical concentration meter 420 Optical Components 451 PCB 452 board 460 Photocoupler 401 Optical concentration meter 421 Optical Components 453 Substrate support 402 Optical concentration meter 422 Optical Components 500 optical density meter 520 Optical Components 550 board 551 Support part 600 Optical concentration meter 620 Optical Components 650 board 651 Support part 621 Optical Components 622 Optical Components 640 Optical waveguide 741 Optical waveguide 742 Optical waveguide 743 Optical waveguide 820 Optical Components 840 Optical waveguide 841 Reflection means 920 Optical Components 921 Optical Components 940 Optical waveguide 941 Oval Circumference Section 950 board 951 Support part 1021 Optical Components 1130 light source 1120 Optical Components 1140 Optical waveguide 1141 Ring-shaped circumferential section 1220 Optical Components 1240 Optical waveguide 1241 Ring-shaped circumferential section 1300 Optical Density Meter 1320 Optical Components 1370 Receiver 1400 Optical Density Meter 1420 Optical Components 1450 board 1451 Support part 1452 PCB 1470 Receiver 1520 Optical Components 1570 Receiver 1620 Optical Components 1670 Receiver 1800 optical density meter 1820 Optical Components 1880 Optical Filter 1821 Optical Components 1831 light source 1881 Optical Filters 1822 Optical Components 1832 light source 1882 Optical Filters 1823 Optical Components 1833 light source 1883 Optical Filters 1900 Optical concentration meter 1920 Optical Components 1940 Optical waveguide 1901 Optical concentration meter 1921 Optical Components 1941 Optical waveguide 2000 Optical concentration meter 2020 Optical Components 2030 light source 2040 Optical waveguide 2001 Optical concentration meter 2021 Optical Components 2031 Light source 2041 Optical waveguide 2100 Optical Density Meter 2110 Acoustic Cavity 2112 Base 2113 Surface 2114 Lid 2115 Adhesive 2200 Optical Density Meter 2210 Acoustic Cavity 2212 Base 2213 Surface 2216 Conductive part 2217 Inner contact end 2218 Outer contact end 2300 Optical Density Meter 2392 Dust Filter 2400 Optical Density Meter 2494 Electrical Circuits

Claims

1. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; The acoustic transducer outputs an electrical signal corresponding to a pressure fluctuation in the acoustic cavity that occurs when an evanescent wave leaks out of the optical waveguide during propagation of the light from the light source through the optical waveguide, and the evanescent wave is absorbed by the target component contained in the gas that is present around the optical waveguide and has a refractive index smaller than that of the optical waveguide. Optical concentration meter.

2. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical component has one or more substrates that support the light source and the optical waveguide; the light source and the optical waveguide are both provided on the substrate and are optically coupled to each other via a photocoupler; Optical concentration meter.

3. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical component has one or more substrates that support the light source and the optical waveguide; the light source and the optical waveguide are provided on different substrates, and are optically coupled to each other via a photocoupler; Optical concentration meter.

4. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical component has one or more substrates that support the light source and the optical waveguide; A space is provided between the light source and the substrate. Optical concentration meter.

5. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; The optical waveguide includes, at least in part, a bending portion that bends the propagation direction of the light propagating within the optical waveguide. Optical concentration meter.

6. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical waveguide at least partially includes one or more pairs of reflecting means for reversing the propagation direction of the light propagating within the optical waveguide and then returning it to its original direction; Optical concentration meter.

7. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; The optical waveguide at least partially includes an elliptical circumferential portion that causes the light propagating within the optical waveguide to circulate in an ellipse. Optical concentration meter.

8. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; The optical waveguide at least partially includes a ring-shaped circulating portion that causes the light propagating within the optical waveguide to circulate in an ellipse or a circle. Optical concentration meter.

9. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical component has an optical filter that transmits the wavelength of the light from the light source and blocks wavelengths other than the wavelength of the light; Optical concentration meter.

10. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical component has a plurality of the optical waveguides optically connected to one of the light sources; Optical concentration meter.

11. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; the optical component has a plurality of the light sources optically connected to one or more of the optical waveguides; Optical concentration meter.

12. An optical concentration meter for measuring the concentration of a target component in a gas, comprising: an acoustic cavity having a gas inlet for containing the gas introduced through the gas inlet; an optical component disposed within the acoustic cavity; an acoustic transducer disposed within the acoustic cavity; Equipped with The optical component has one or more light sources that emit light including wavelengths that are absorbed by the target component, and one or more optical waveguides that are optically connected to the light sources, through which the light from the light sources propagates, and at least a portion of which is exposed to a space within the acoustic cavity; a mean optical path length of light emitted into a space within the acoustic cavity without entering the optical waveguide and reflected by an inner wall of the acoustic cavity, out of the light from the light source, is shorter than an effective optical path length of the optical waveguide; Optical concentration meter.

13. 10mm ３ It has a volume of The effective optical path length of the optical waveguide is 10 mm or more. The optical concentration measuring device according to any one of claims 1 to 12.

14. The average reflectivity of the inner wall of the acoustic cavity is 70% or less. The optical concentration measuring device according to any one of claims 1 to 12.

15. The acoustic cavity comprises: a base on which the optical component and the acoustic transducer are mounted; a cover portion in which the gas inlet is formed and which is attached to the base portion; having The optical concentration measuring device according to any one of claims 1 to 12.

16. the lid portion is bonded to the base portion, whereby the internal space of the acoustic cavity is in communication with the external space of the acoustic cavity only via the gas inlet; The optical concentration measuring instrument according to claim 15.

17. the base portion has a conductive portion, The conductive portion is an inner contact formed on the surface and electrically connected to at least one of the light source and the acoustic transducer; an outer contact end exposed to the external space of the acoustic cavity; Including, The optical concentration measuring instrument according to claim 15.

18. a dust filter attached to the gas inlet and sealing the gas contained in the acoustic cavity; The optical concentration measuring device according to any one of claims 1 to 12.

19. an electric circuit disposed within the acoustic cavity and electrically connected to at least one of the light source and the acoustic transducer; The optical concentration measuring device according to any one of claims 1 to 12.

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