Connecting device for analyzing gas or gas mixture by means of Raman scattering, and gas spectrometer

Abstract

The invention relates to a connection device (10) for analysing a gas or a gas mixture by means of Raman scattering (11), the connection device (10) being provided for guiding the gas or the gas mixture through the connection device (10), comprising: a first connection element (12) for connecting the gas or the gas mixture to the first connection element (12); the first connecting element is tubular and has a first end (14), a second end (16) and at least one opening (18, 60, 68, 72) arranged between the first end (14) and the second end (16), and a second connecting element (20), the invention relates to a connecting device (10) comprising a first connecting element (22), a second connecting element (24), which is tubular and has a first end (22), a second end (24) and at least one opening (26, 62, 66, 72) arranged between the first end (22) and the second end (24), and an intermediate element (28), which is tubular and has a first end (30) and a second end (32), according to the invention, the intermediate element (28) is at least partially composed of a transparent material, in particular transparent to Raman scattering (11), in particular in the visible frequency range, in an assembled state (34) of the connecting device (10), the intermediate element (28) is arranged in a radial direction (13) between the first connecting element (12) and the second connecting element (20) and between the opening (18, 60, 68, 72) of the first connecting element (12) and the opening (26, 62, 66, 72) of the second connecting element (20), the opening (18, 60, 68, 72) of the first connecting element (12) and the opening (26, 62, 66, 72) of the second connecting element (20) are arranged at least partially aligned with each other in the assembled state (34) of the connecting device (10).

Description

Technical Field

[0001] The present invention relates to a connecting device for analyzing a gas or a gas mixture having the features of claim 1, and a gas spectrometer for analyzing a gas or a gas mixture having the features of the dependent claims. Background Art

[0002] Raman spectroscopy can be used to identify and quantify gases in a gas mixture. Each gas has a characteristic Raman spectrum. By analyzing and evaluating the corresponding Raman spectrum, the gas can be identified and its concentration determined. EP3 961 195A1 discloses a measuring device for gases based on Raman spectroscopy. Summary of the Invention

[0003] The present invention provides a connecting device for analyzing a gas or a gas mixture by means of Raman scattering. The connecting device is arranged to guide the gas or the gas mixture through the connecting device. In other words, the connecting device is suitable for allowing the gas or the gas mixture to pass through. The gas or the gas mixture can be under pressure or not under pressure.

[0004] The connecting device includes a first connecting element. The first connecting element is configured in a tubular shape and has a first end, a second end, and at least one opening arranged between the first end and the second end. The opening is formed in the wall of the first connecting element. The connecting device further includes a second connecting element. The second connecting element is configured in a tubular shape and has a first end, a second end, and at least one opening arranged between the first end and the second end. The opening is also formed in the wall of the second connecting element here. The first connecting element and / or the second connecting element can have a plurality of, in particular at least two, especially at least four such openings. The openings can be configured differently in terms of their (geometric) shape and size. It is also conceivable that the openings are configured identically in terms of their shape and size.

[0005] In the present invention, "tubular" refers to an elongate structure (but not necessarily straight) whose longitudinal extension scale is much larger than its transverse extension scale. The connecting device further includes an intermediate element. The intermediate element is configured in a tubular shape and has a first end and a second end. The intermediate element is at least partially made of a material that is particularly transparent to Raman scattering, especially transparent in the visible frequency range. The intermediate element can also be configured to be colored. The intermediate element can have, for example, a hue that results in a 25% reduction in transparency.

[0006] In the assembled state of the connecting device, the intermediate element is arranged between the first connecting element and the second connecting element in the radial direction. In the present invention, the axial direction refers to the direction oriented parallel to the longitudinal extension of the intermediate element. Correspondingly, in the present invention, the radial direction refers to the direction oriented perpendicular to the axial direction. The intermediate element is furthermore arranged between the opening of the first connecting element and the opening of the second connecting element.

[0007] The opening of the first connecting element and the opening of the second connecting element are arranged at least partially aligned with each other (e.g., corresponding to each other) in the assembled state of the connecting device. Thus, for example, a laser beam can be introduced into the interior of the connecting device and the intermediate element through two corresponding or at least partially aligned openings of the first and second connecting elements and the intermediate element. Raman scattering emitted by a gas or gas mixture can in this case be emitted outwards from the interior of the connecting device through two (additional) corresponding or at least partially aligned openings of the first and second connecting elements and the intermediate element.

[0008] The first connecting element, the second connecting element and / or the intermediate element can be arranged coaxially with each other in the assembled state of the connecting device. The first connecting element, the second connecting element and / or the intermediate element can each be constructed in one piece or integrally.

[0009] In the assembled state of the connecting device, the first connecting element, the second connecting element and / or the intermediate element can be arranged at least partially nested with each other. In other words, in the assembled state of the connecting device, the first connecting element, the second connecting element and / or the intermediate element can be arranged successively in the radial direction (in a sandwich manner, where the intermediate element is arranged between the first and second connecting elements). In the assembled state of the connecting device, the second connecting element can be inserted at least partially, in particular through its first end portion, into the first connecting element.

[0010] The connecting device can at least partially serve as a measuring chamber for Raman spectroscopy or is a Raman measuring unit. Thus, the connecting device can connect a gas inlet and a gas outlet to each other. In particular, the first end portion of the first connecting element can be connected to a gas inlet for introducing a gas or gas mixture into the connecting device. In particular, the second end portion of the second connecting element can be connected to a gas outlet for discharging a gas or gas mixture from the connecting device.

[0011] Thus, a structurally simple connecting device can be realized with a small number of components, which can be applied, for example, as a measurement chamber for Raman spectroscopy in a gas spectrometer. Here, direct in-line measurement is possible, i.e., during the actual process operation, without changing or affecting the medium to be examined (such as a gas or a gas mixture). Therefore, sampling or retaining a sample (such as a gas or a gas mixture) during the process is not required. The complexity of the part for guiding the medium (such as guiding a gas or a gas mixture) is also reduced. The actual medium path (or gas path or gas mixture path) can mainly consist of metal, and the remaining measurement unit (or Raman measurement unit) can be manufactured, for example, as a plastic injection molding.

[0012] According to a further extension, the intermediate element can be made of glass, industrial glass, or sapphire glass. Thus, a high compressive strength or pressure resistance of the intermediate element can be ensured, while maintaining the transparent property.

[0013] According to a further extension, the intermediate element can be constructed at least partially polished. The intermediate element can be constructed polished at its first end and / or at its second end. The intermediate element can be constructed polished on one or both of its end faces. In the present invention, the end face refers to the face of the intermediate element that is oriented orthogonally to the axial direction (arranged at the two ends of the intermediate element). The intermediate element can be constructed polished on the inner side and / or the outer side of the wall of the intermediate element. Alternatively or additionally, the intermediate element can at least locally have an anti-reflection coating, especially anti-reflection for the visible frequency range. Alternatively or additionally, the intermediate element can at least locally have a tint for reducing transparency, especially for the visible frequency range.

[0014] Thus, fluorescence and / or interfering rays or their reflections can be avoided or at least reduced. Thus, a clearer or better measurement signal can be achieved and the measurement result can be optimized. Weak signals can also be detected better.

[0015] According to a further extension, the intermediate element can have an opaque coating sectionally, especially opaque for the visible frequency range. The coating that is especially opaque for the visible frequency range can be arranged in the region of the first end of the intermediate element and / or in the region of the second end of the intermediate element. Thus, interfering rays or their reflections can be avoided or at least reduced. Thus, a clearer or better measurement signal can be achieved and the measurement result can be optimized. Weak signals can be detected better.

[0016] According to a further expansion, the first connecting element, the second connecting element and / or the intermediate element may have a circular, elliptical or square cross-section. It is also conceivable that the cross-section of the first connecting element, the second connecting element and / or the intermediate element has a cross-section with other geometric shapes. The intermediate element may have at least one integrated lens. The geometric shape of the cross-section of the intermediate element may be determined or influenced by the integrated lens. Thus, the connecting device can be flexibly applied and adapted to different requirements determined by the use respectively.

[0017] According to a further expansion, the connecting device may have at least one seal. The seal may be dispensed with in the case of non-critical gases or gas mixtures and in the very low pressure range. The seal may be configured as an O-ring or in particular as a molded seal element for thermochemical connection. In the assembled state of the connecting device, at least one seal may be arranged on the first end or the second end of the intermediate element. The seal may be arranged on the end face side of the intermediate element in the assembled state of the connecting device. The connecting device may have two or more seals. The seal may be configured as an O-ring. In the assembled state of the connecting device, at least one seal may be arranged respectively on the first end or the second end of the intermediate element. In the assembled state of the connecting device, at least one seal may be arranged respectively on the two end face sides of the intermediate element. Thus, the sealing performance of the connecting device can be achieved by simple means. Complicated seals and / or sealing systems may be dispensed with.

[0018] According to a further expansion, the first connecting element may have an internal thread. The internal thread may be arranged on the second end of the connecting element. The second connecting element may have an external thread corresponding to the internal thread. In the assembled state of the connecting device, the first connecting element and the second connecting element may be screwed together, in particular to locking, by means of the internal thread and the external thread. By means of this threaded connection, the assembled state of the connecting device can be achieved by simple means. Here, the connecting device can be quickly and safely converted into the assembled state or the assembled state can be loosened.

[0019] According to a further expansion, the second connecting element may have a receiving area for receiving the intermediate element. The receiving area of the second connecting element may extend from the first end of the second connecting element to the protrusion of the second connecting element. In other words, the second connecting element may have a protrusion, wherein the receiving area of the second connecting element is arranged between the protrusion and the first end of the second connecting element. One or more of the openings of the second connecting element may be arranged in the receiving area of the second connecting element. If the intermediate element is received in the receiving area of the second connecting element, the intermediate element is arranged between the first end of the second connecting element and the protrusion of the second connecting element. Thus, the intermediate element can be quickly and safely received and placed in the connecting device.

[0020] According to a further refinement, the first connecting element can have a receiving area for receiving the intermediate element and / or the second connecting element, in particular the receiving area of the second connecting element. The receiving area of the first connecting element can extend from the projection of the first connecting element to the second end of the first connecting element. In other words, the first connecting element can have a projection, wherein the receiving area of the first connecting element is arranged between the projection and the second end of the first connecting element. One or more of the openings of the first connecting element can be arranged in the receiving area of the first connecting element. Thus, the second connecting element can be received and positioned quickly and safely in the connecting device together with the intermediate element.

[0021] According to a further refinement, one or more of the openings of the first connecting element and / or one or more of the openings of the second connecting element can be configured as circular and / or elliptical. It is also conceivable that the openings of the first and / or second connecting elements have other geometric shapes. Thus, the openings and thus the connecting device can be generally adapted to different focal geometries (e.g., elliptical, circular) of the laser. Thus, the connecting device can be used flexibly.

[0022] According to a further refinement, the first connecting element and / or the second connecting element can have a coating. The coating of the first and / or second connecting element can be configured as multilayered. In other words, the coating can include multiple layers or strata. The coating can be configured as antireflective, hydrophobic, and / or corrosion-resistant. Thus, moisture adhesion inside the connecting device can be avoided, so that, for example, moisture in a gas or gas mixture can be measured. In addition, corrosion formation can be prevented or at least reduced.

[0023] According to a further refinement, the first connecting element and / or the second connecting element can be made of metal, in particular made of 316 stainless steel or 316L stainless steel. The first connecting element and / or the second connecting element can be configured as a nickel-iron-chromium alloy with molybdenum additive, copper additive, and titanium additive, for example configured as 2.4858 10NiCr21MoF55 or 1.4401 X5CrNiMo17-12-2. Thus, high gas resistance and surface quality of the first connecting element and / or the second connecting element can be achieved. Thus, adhesion of gas molecules can be avoided and an effective coating can be obtained. Plastics or generally steel can also be used as raw materials in the case of non-critical gases such as N2 in a low pressure range.

[0024] According to the invention, it is also proposed that a gas spectrometer for analyzing a gas or gas mixture by means of Raman scattering includes at least one connecting device according to the above-described embodiments. The gas or gas mixture can be under pressure or not under pressure.

[0025] Reference is made to the explanations regarding the connecting device in terms of the advantages thus achievable. The explanations related to the connecting device and / or the measures to be further explained below can be used to further configure the gas spectrometer.

[0026] The gas spectrometer can include a laser for generating a laser beam. The gas spectrometer, in particular the laser and / or the connecting device, can be arranged such that the laser beam of the laser enters the interior of the connecting device through two mutually corresponding or aligned openings of a first and a second connecting element and an intermediate element and irradiates a gas or gas mixture inside the connecting device.

[0027] The gas spectrometer can include at least one detector for detecting Raman scattering. The gas spectrometer, in particular the detector and / or the connecting device, can be arranged such that Raman scattering emitted from the interior of the connecting device by the gas or gas mixture exits through two mutually corresponding or aligned openings of the first and the second connecting element and the intermediate element and irradiates the detector.

[0028] Here, the opening through which the laser beam enters the interior of the connecting device is the same as the opening through which the Raman scattering exits and is detected. It is also conceivable that the opening through which the laser beam enters the interior of the connecting device is different from the opening through which the Raman scattering exits and is detected. Description of the Drawings

[0029] Embodiments of the present invention are explained below with reference to the drawings. The drawings show:

[0030] Figure 1 : Longitudinal section of the connecting device for analyzing a gas or gas mixture by means of Raman scattering in the assembled state,

[0031] Figure 2 : According to Figure 1 Longitudinal section of the first connecting element of the connecting device,

[0032] Figure 3 : According to Figure 1 Longitudinal section of the second connecting element of the connecting device,

[0033] Figure 4 : According to Figure 1 Schematic side view of the intermediate element of the connecting device,

[0034] Figure 5 : Having a connecting device according to Figure 1 Schematic gas spectrometer. Detailed Description of the Invention

[0035] The connecting device in Figure 1The overall reference numeral 10 is provided. The connecting device 10 is arranged for analyzing a gas or a gas mixture by means of Raman scattering 11. The connecting device 10 can be configured as part of a gas spectrometer 54 (see Figure 5 ).

[0036] The connecting device 10 can at least partially be a Raman measuring unit or a measuring chamber for Raman spectroscopy. In Figure 1 the assembled state 34 of the connecting device 10 is shown. The connecting device 10 is arranged for guiding a gas or a gas mixture through the connecting device 10. This is indicated in Figure 1 by means of two thick arrows. The connecting device 10 can be connected at its left end in Figure 1 to a gas inlet for guiding the gas or the gas mixture into the connecting device 10 and at its right end in Figure 2 to a gas outlet for guiding the gas or the gas mixture out of the connecting device 10.

[0037] In the present invention, the connecting device 10 comprises a first connecting element 12, a second connecting element 20 and an intermediate element 28. In the present invention, the connecting device 10 comprises, by way of example, two seals 40 which are, by way of example, configured as O-rings in the present invention.

[0038] In the present invention, the intermediate element 28 is arranged between the first connecting element 12 and the second connecting element 20 along a radial direction 13. The intermediate element 28 is, by way of example, arranged between the two seals 40 along an axial direction 15 in the present invention.

[0039] In the assembled state 34 of the connecting device 10, the first connecting element 12, the second connecting element 20, the intermediate element 28 and the two seals 40 are, by way of example, arranged coaxially with one another in the present invention.

[0040] Figure 2 Shows a longitudinal section of the first connecting element 12 of the connecting device 10 according to Figure 1 . The first connecting element 12 is configured as tubular and has a first end 14, a second end 16 and, by way of example, four openings 18 in the present invention. The openings 18 are arranged between the first end 14 and the second end 16 of the first connecting element 12.

[0041] The first connecting element 12 has, by way of example, an internal thread 42 at its second end 16 in the present invention. The second connecting element 20 has an external thread 44 corresponding to the internal thread 42 (see Figure 1 or 3). The internal thread 42 and the external thread 44 form a threaded connection by means of which the connecting device 10 is converted into the combined state 34 and can be held in the combined state 34. By unscrewing or loosening this threaded connection, the combined state 34 of the connecting device 10 can be loosened again.

[0042] In the present invention, the first connecting element 12 exemplarily has a receiving area 50 for receiving the intermediate element 28 and at least part of the second connecting element 20. The first connecting element 12 has a protrusion 52. The receiving area 50 of the first connecting element 12 extends from the protrusion 52 to the second end 16 of the first connecting element 12.

[0043] In the present invention, the openings 18 of the first connecting element 12 are exemplarily arranged inside the receiving area 50 of the first connecting element 12. An angle of 90° is arranged between the respective openings 18 of the first connecting element 12. In other words, every two adjacent openings 18 are arranged or oriented orthogonally to each other.

[0044] Figure 3 Shows a longitudinal section of the second connecting element 20 of the connecting device 10 according to Figure 1 . The second connecting element 20 is configured as a tube and has a first end 22, a second end 24 and, in the present invention, exemplarily four openings 26 arranged between the first end 22 and the second end 24 of the second connecting element 20.

[0045] In the present invention, the second connecting element exemplarily has a receiving area 46 for receiving the intermediate element 28. The second connecting element 20 has a protrusion 48. The receiving area 46 of the second connecting element 20 extends from the protrusion 48 to the second end 22 of the second connecting element 20.

[0046] In the present invention, the openings 26 of the second connecting element 20 are exemplarily arranged inside the receiving area 46 of the second connecting element 20. An angle of 90° is arranged between the respective openings 26 of the second connecting element 20. In other words, every two adjacent openings 26 are arranged or oriented orthogonally to each other.

[0047] In the assembled state 34 of the connecting device 10 (see Figure 1 ), the intermediate element 28 is arranged in the two receiving areas 46, 50 and is arranged in the radial direction 13 between the openings 18, 26 of the first connecting element 12 and the second connecting element 20. In the assembled state 34 of the connecting device 10, the second connecting element 20 in particular projects into the receiving area 50 of the first connecting element 12 through its receiving area 46 and the intermediate element 28 received therein. The receiving area 50 of the first connecting element 12 currently exemplarily surrounds the receiving area 46 of the second connecting element 20 together with the intermediate element 28 radially outwards.

[0048] The openings 18, 26 of the first connecting element 12 and / or the second connecting element 20 can have a circular and / or elliptical shape.

[0049] The first connecting element 12 and / or the second connecting element 20 can have a particularly multi-layer coating. The coating can be configured to be anti-reflective, hydrophobic, and / or corrosion-resistant.

[0050] The first connecting element 12 and / or the second connecting element 20 can be made of metal, in particular 316 stainless steel or 316L stainless steel. The first connecting element 12 and / or the second connecting element 20 can be configured as a nickel-chromium-iron alloy with molybdenum additive, copper additive, and titanium additive.

[0051] Figure 4 Schematically shows a side view of the intermediate element 28 of the connecting device 10 according to Figure 1 . The intermediate element 28 is configured tubular, having a first end 30 and a second end 32. The intermediate element 28 is made of a transparent material. The intermediate element 28 is configured to be transparent particularly for Raman scattering 11, particularly in the visible frequency range. The intermediate element 28 can be made of glass, industrial glass, or sapphire glass.

[0052] The intermediate element 28 can be configured to be polished on its first end 30 and / or on its second end 32. The intermediate element 28 can be particularly configured to be polished on one or both of its end faces 36. Similarly, the intermediate element 28 can be configured to be polished on the inner side 17 and / or the outer side 19 of the wall 21 of the intermediate element 28. The intermediate element 28 can have an anti-reflective coating, particularly an anti-reflective coating for the visible frequency range.

[0053] In the assembled state of the connecting device 10 (see Figure 1 ), in the present invention, a seal 40 is respectively arranged on two end faces 36 of the intermediate element 28 by way of example.

[0054] The intermediate element 28 has a coating 38 that is opaque particularly for the visible frequency range in the region of its first end 30 and in the region of its second end 32 in the present invention by way of example. These two sections of the intermediate element 28 provided with the opaque coating 38 are arranged at a distance from each other such that a transparent region is retained between the regions provided with the opaque coating 38, and through this transparent region, for example, laser and / or Raman scattering 11 can be transmitted.

[0055] In the present invention by way of example, the first connecting element 12, the second connecting element 20, and the intermediate element 28 have respectively circular cross-sections. It is also conceivable that the cross-section of at least one of these elements can have a square or other geometric shape. The intermediate element 28 can have at least one integrated lens. The geometric shape of the cross-section of the intermediate element 28 can be affected or changed due to this lens.

[0056] Figure 5 Schematically shows having according toFigure 1 The gas spectrometer 54 of the connecting device 10. The gas spectrometer 54 is arranged such that a gas or gas mixture can be guided through the connecting device 10. For this purpose, the gas or gas mixture can be introduced into the interior 64 of the connecting device 10 through the first end 14 of the first connecting element 12 of the connecting device 10. The first end 14 of the first connecting element 12 can be connected to a gas inlet for this purpose. This is indicated by a thick arrow on the Figure 5 left side in Figure 5 The gas or gas mixture can be guided through the connecting device 10 and discharged from the interior 64 of the connecting device 10 at the second end 24 of the second connecting element 20. For this purpose, the second end 24 of the second connecting element 20 can be connected to a gas outlet. This is indicated by a thick arrow on the Figure 5 right side in Figure 5 as shown.

[0057] The gas spectrometer 54 exemplarily has a laser 56 for generating a laser beam 58 in the present invention. The gas spectrometer 54 is exemplarily arranged in the present invention such that the laser beam 58 of the laser 56 passes through the first opening 60 of the second connecting element 20, through the intermediate element 28, and through the first opening 62 of the first connecting element 12 into the interior 64 of the connecting device 10 and thus irradiates the gas or gas mixture present in the interior 64 of the connecting device 10.

[0058] In the interior 64 of the connecting device 10, the gas or gas mixture irradiated by the laser beam 58 emits Raman scattering 11. The Raman scattering 11 can leave the interior 64 of the connecting device 10 through the second opening 66 of the second connecting element 20, through the intermediate element 28, and through the second opening 68 of the first connecting element. The Raman scattering 11 then irradiates on the detector 70 of the gas spectrometer 54, and the detector is arranged to detect the Raman scattering 11.

[0059] The first openings 60, 62 of the first connecting element 12 and the second connecting element 20 are exemplarily arranged aligned with each other in the present invention. Similarly, the second openings 66, 68 of the first connecting element 12 and the second connecting element 20 are exemplarily arranged aligned with each other in the present invention. The first openings 60, 62 and the second openings 66, 68 are exemplarily directed or arranged at an angle of 180° to each other in the present invention. It is also conceivable that the Raman scattering 11 is emitted from the interior 64 of the connecting device 10 through further openings 72 of the first connecting element 12 and the second connecting element 20 and is then (respectively) detected by another detector (not shown) of the gas spectrometer 54, and these further openings are also arranged aligned with each other and at an angle of 90° with respect to the first openings 60, 62 or with respect to the second openings 66, 68.

Claims

1. Connecting device (10) for analyzing a gas or gas mixture by means of Raman scattering (11), wherein, The connecting device (10) is arranged to guide a gas or a gas mixture through the connecting device (10), and the connecting device comprises: - A first connecting element (12), which is configured to be tubular and has a first end (14), a second end (16), and at least one opening (18, 60, 68, 72) arranged between the first end (14) and the second end (16); - A second connecting element (20), which is configured to be tubular and has a first end (22), a second end (24), and at least one opening (26, 62, 66, 72) arranged between the first end (22) and the second end (24); and - An intermediate element (28), which is configured to be tubular and has a first end (30) and a second end (32); wherein the intermediate element (28) is at least partially made of a transparent material that is particularly transparent to Raman scattering (11), especially transparent in the visible frequency range; wherein, in the assembled state (34) of the connecting device (10), the intermediate element (28) is arranged between the first connecting element (12) and the second connecting element (20) along the radial direction (13) and is arranged between the opening (18, 60, 68, 72) of the first connecting element (12) and the opening (26, 62, 66, 72) of the second connecting element (20), and wherein the opening (18, 60, 68, 72) of the first connecting element (12) and the opening (26, 62, 66, 72) of the second connecting element (20) are arranged at least partially aligned with each other in the assembled state (34) of the connecting device (10).

2. The connecting device (10) according to claim 1, characterized in that, The intermediate element (28) is made of glass, industrial glass, or sapphire glass.

3. The connecting device (10) according to claim 1 or 2, characterized in that, The intermediate element (28) is configured to be polished at least partially, especially on the first end (30) of the intermediate element and / or on the second end (32) of the intermediate element, especially on one or both end faces (36) of the intermediate element, especially on the inner side (17) and / or the outer side (19) of the wall (21) of the intermediate element (28), and / or the intermediate element (28) at least partially has an anti-reflection coating especially for the visible frequency range.

4. The connecting device (10) according to at least one of the preceding claims, characterized in that, The intermediate element (28) has a light-impermeable coating (38) in sections, especially in the region of the first end (30) and / or the second end (32) of the intermediate element, which is light-impermeable especially for the visible frequency range.

5. The connecting device (10) according to at least one of the preceding claims, characterized in that, The first connecting element (12), the second connecting element (20), and / or the intermediate element (28) has a circular, elliptical, or square cross-section, especially wherein the intermediate element (28) has at least one integrated lens.

6. The connecting device (10) according to at least one of the preceding claims, characterized in that, The connecting device (10) has at least one seal (40), which is in particular designed as an O-ring or a molded sealing element. In the assembled state (34) of the connecting device (10), at least one seal (40) is arranged on the first end (30) or the second end (32) of the intermediate element (28), in particular on one of the two end faces (36) of the intermediate element. In particular, the connecting device (10) has at least two seals (40), which are in particular designed as O-rings and / or as molded sealing elements. In the assembled state (34) of the connecting device (10), at least one seal (40) is respectively arranged on the first end (30) and the second end (32) of the intermediate element (28), in particular on the two end faces (36) of the intermediate element.

7. The connecting device (10) according to at least one of the preceding claims, characterized in that The first connecting element (12) has an internal thread (42), in particular on the second end (16) of the first connecting element. The second connecting element (20) has an external thread (44) corresponding to the internal thread (42). In the assembled state (34) of the connecting device (10), the first connecting element (12) and the second connecting element (20) are screwed together by means of the internal thread (42) and the external thread (44), in particular until they are locked.

8. The connecting device (10) according to at least one of the preceding claims, characterized in that The second connecting element (20) has a receiving area (46) for receiving the intermediate element (28). The receiving area (46) of the second connecting element (20) extends from the first end (22) of the second connecting element (20) to the projection (48) of the second connecting element (20). In particular, the openings (26, 62, 66, 72) of the second connecting element (20) are arranged in the receiving area (46) of the second connecting element.

9. The connecting device (10) according to at least one of the preceding claims, characterized in that The first connecting element (12) has a receiving area (50) for receiving the intermediate element (28) and / or the second connecting element (20), in particular for receiving the receiving area (46) of the second connecting element. The receiving area (50) of the first connecting element (12) extends from the projection (52) of the first connecting element (12) to the second end (16) of the first connecting element (12). In particular, the openings (18, 60, 68, 72) of the first connecting element (12) are arranged in the receiving area (50) of the first connecting element.

10. The connecting device (10) according to at least one of the preceding claims, characterized in that, The openings (18, 60, 68, 72) of the first connecting element (12) and / or the openings (26, 62, 66, 72) of the second connecting element (20) are designed as circular and / or elliptical.

11. The connecting device (10) according to at least one of the preceding claims, characterized in that The first connecting element (12) and / or the second connecting element (20) has a coating, in particular a multi-layer coating. The coating is designed as anti-reflective, hydrophobic and / or corrosion-resistant.

12. The connecting device (10) according to at least one of the preceding claims, characterized in that, The first connecting element (12) and / or the second connecting element (20) is / are made of metal, in particular 316 stainless steel or 316L stainless steel, in particular a nickel-chromium-iron alloy with molybdenum additive, copper additive and titanium additive.

13. A gas spectrometer (54) for analyzing a gas or gas mixture by means of Raman scattering (11), comprising at least one connecting device (10) according to at least one of the preceding claims.

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