Slim atr sensor with a measuring and reference signal

Abstract

The invention relates to an ATR sensor (10) comprising a sensor housing (12), wherein at least the following sensor components are accommodated in the sensor housing (12): an infrared radiation source (22), an ATR element (24), wherein the ATR element (24) is designed to transmit infrared radiation via reflection on at least one boundary surface of the ATR element (24); an infrared measuring sensor (32) which detects infrared radiation emitted by the infrared radiation source (22) after its transmission via the ATR element (24), and which outputs a measuring detection signal depending on the infrared radiation detected by the infrared measuring sensor (32); and infrared reference sensor (34) which detects infrared radiation emitted by the infrared radiation source (22) that is not transmitted by the ATR element (24), and which outputs a reference detection signal depending on the infrared radiation detected by the infrared reference sensor (34). According to the invention, the infrared radiation source (22) is designed and arranged to radiate an infrared measuring radiation portion (56) detected by the infrared measuring sensor (32) in a measuring radiation direction, and to simultaneously radiate an infrared reference radiation portion (60) detected by the infrared reference sensor (34) in a reference radiation direction that is different to the measuring radiation direction.

Description

[0001] Slim ATR sensor with measurement and reference signal

[0002] Description

[0003] The present invention relates to an ATR sensor comprising a sensor housing, wherein at least the following sensor components are accommodated in the sensor housing: an infrared radiation source, an ATR element, wherein the ATR element is designed as an ATR measuring element to transmit infrared radiation with reflection at at least one boundary surface of the ATR measuring element, an infrared measuring sensor which is arranged in the sensor housing in such a way that it detects infrared radiation emitted by the infrared radiation source after its transmission through the ATR measuring element, and which is designed to output a measurement detection signal depending on the infrared radiation detected by the infrared measuring sensor, an infrared reference sensor which is arranged in the sensor housing in such a way that it detects infrared radiation emitted by the infrared radiation source which is not transmitted by the ATR measuring element, and which is designed toto output a reference detection signal depending on the infrared radiation detected by the infrared reference sensor.

[0004] Such an ATR sensor is known from US 2021 / 165123 A1. "ATR" stands for "Attenuated Total Reflection," a measuring principle based on attenuated total reflection. This measuring principle is well known. The physical properties used by this measuring principle to gain knowledge and their metrological application are very well explained in the publication DE 103 16 514 A1, to whose description we refer here to explain the measuring principle.

[0005] Further ATR sensors with both an infrared measuring sensor and an infrared reference sensor are known, for example, from US Pat. No. 7,593,107 B2 and EP 3 026 426 A1. In all of the above-mentioned prior art documents, which disclose an ATR sensor with both an infrared measuring sensor and an infrared reference sensor, the infrared radiation component supplied to the infrared reference sensor is obtained by beam splitting an infrared radiation emitted by the infrared radiation source.

[0006] While this beam splitting allows for a very good comparison of the infrared measurement radiation component detected by the infrared measurement sensor with the infrared reference radiation component detected by the infrared reference sensor, the infrared measurement radiation component is reduced by the infrared reference radiation component diverted from it, increasing the risk of an undesirably increased signal-to-noise ratio. Furthermore, a beam splitter, as a physical component, requires installation space in an infrared measurement sensor, thus counteracting the desired miniaturization or compact design of the infrared measurement sensor.

[0007] The object of the present invention is therefore to provide an ATR sensor that, with the same radiation power, is capable of delivering a more advantageous signal-to-noise ratio than prior art ATR sensors. In a further aspect, the present invention also aims to provide an ATR sensor with the smallest possible installation space.

[0008] The present invention achieves the stated object by means of an ATR sensor having the features mentioned at the outset in that the infrared radiation source is designed and arranged to radiate an infrared measuring radiation portion of the infrared radiation emitted by the infrared radiation source, which portion is detected by the infrared measuring sensor, in a measuring radiation direction and at the same time to radiate an infrared reference radiation portion of the infrared radiation emitted by the infrared radiation source, which portion is detected by the infrared reference sensor, in a reference radiation direction different from the measuring radiation direction.

[0009] The simultaneous emission of the infrared reference radiation component on the one hand and the infrared measurement radiation component on the other ensures the excellent reference quality of the infrared reference radiation component. This is because the infrared measurement radiation component and the infrared reference radiation component are emitted by the infrared radiation source with the same emission characteristics. Due to the simultaneous emission, a change in the emission characteristics between the emission of the infrared measurement radiation component and the emission of the infrared reference radiation component is impossible.

[0010] By radiating in different spatial directions, the infrared measurement radiation component emitted in the measurement direction can be used with its full signal strength to gain metrological knowledge. Likewise, the infrared reference radiation component emitted in the reference radiation direction different from the measurement direction can be fully utilized to provide a high-quality reference for evaluating the infrared measurement radiation component detected by the infrared measurement sensor. With the same emission power, a higher useful signal level is thus achieved on both the infrared measurement sensor and the infrared reference sensor. Overall, the ATR sensor can therefore offer a higher signal-to-noise ratio at the same rated power.

[0011] An advantageously slim ATR sensor can be obtained in that the sensor housing extends along a sensor housing longitudinal axis defining an axial direction, wherein the infrared measuring sensor and the infrared reference sensor are arranged at an axial distance from one another in the sensor housing. The sensors can be arranged in a particularly space-saving manner if they have a substantially identical design. Preferably, the infrared measuring sensor and the infrared reference sensor have a housing that is prismatic, conical, or cylindrical over at least 80%, more preferably predominantly 90%, of its housing length. The housings of the infrared reference sensor, on the one hand, and the infrared measuring sensor, on the other, can have entirely different housing shapes.For example, a sensor consisting of an infrared reference sensor and an infrared measurement sensor can have a housing with a shape consisting of a prism, cone, truncated cone, or cylinder, while the other sensor can have a different shape consisting of a prism, cone, truncated cone, or cylinder. In this case, the design of the housing shape is less important than the design of the end faces. The design of the housing's outer surface running around the housing axis is therefore not necessary. The housings are nevertheless considered prismatic, conical, or cylindrical if their outer surface is that of a prism, cone, truncated cone, or cylinder.

[0012] The housings of the infrared reference sensor and the infrared measuring sensor preferably each extend along a housing axis, which, depending on the housing shape, can preferably be a prism axis, a conical axis, or a cylindrical axis. To achieve the slimmest possible ATR sensor, the infrared reference sensor, on the one hand, and the infrared measuring sensor, on the other, are preferably arranged in the sensor housing with coaxial housing axes. For this purpose, the housing axes are preferably oriented parallel or coaxially to the sensor housing's longitudinal axis. This allows the dimensions of the sensor housing of the ATR sensor to be kept small, orthogonal to its sensor housing's longitudinal axis.

[0013] Any connecting contacts extending from the housing of the infrared reference sensor and the infrared measuring sensor are not included in the length of the housings of these sensors.

[0014] Preferably, the infrared reference sensor on the one hand and the infrared measuring sensor on the other hand are arranged in the sensor housing with sensor detection surfaces facing each other.

[0015] Advantageously, the infrared radiation source can be arranged axially, relative to the sensor housing's longitudinal axis, between the infrared measuring sensor and the infrared reference sensor. This allows the radiation paths from the infrared radiation source to the infrared measuring sensor and the infrared reference sensor to be set to approximately the same length, which further increases the quality of the reference signal relative to the measurement signal.

[0016] To achieve the slimmest possible ATR sensor, i.e., one with the smallest possible projection orthogonal to its sensor housing's longitudinal axis, according to an advantageous development of the present invention, the ATR measuring element can be arranged axially between the infrared measuring sensor and the infrared reference sensor. Since the infrared radiation source emits the infrared measuring radiation component and the infrared reference radiation component in different spatial directions, arranging the ATR measuring element axially between the infrared reference sensor and the infrared measuring sensor is not a problem.

[0017] The infrared measuring sensor and / or the infrared reference sensor is preferably a multi-channel sensor, particularly preferably a four-channel sensor. Multi-channel sensors, which generally require a separate detection surface for each channel and a radiation filter assigned to the respective detection surface, with the detection surfaces, usually also the radiation filters, lying in a common plane for the detection surfaces or for the radiation filters, take up a relatively large amount of space due to their design. Due to the previously described radiation of infrared radiation by the infrared radiation source in different, preferably opposite, spatial directions, the infrared measuring sensor and the infrared reference sensor can be arranged at different locations within the sensor housing, spaced apart from one another.This allows both the infrared measurement sensor and the infrared reference sensor to be designed as multi-channel sensors, in particular as four-channel sensors, without requiring a sensor housing with an undesirably large size, in particular with an undesirably large diameter. The sensor housing can nevertheless remain slim, preferably with a diameter of no more than 12 mm.

[0018] Since the ATR element, as the ATR measuring element, is generally arranged on the sensor housing such that one side surface of the ATR measuring element is accessible from a fluid outside the sensor housing for its metrological detection using an ATR method, the ATR measuring element is preferably located at a distance from the virtual sensor housing longitudinal axis, which is conceived to pass centrally through the sensor housing. To achieve the greatest possible freedom in arranging at least one sensor consisting of an infrared measuring sensor and an infrared reference sensor in the sensor housing, an infrared measuring radiation reflector is preferably arranged axially between the ATR measuring element and the infrared measuring sensor, and / or an infrared reference radiation reflector is preferably arranged axially between the infrared radiation source and the infrared reference sensor.In principle, the infrared reference radiation component can be guided from the infrared radiation source to the infrared reference sensor via a radiation guide, such as an ATR element. However, the radiation guide used for this purpose is not the ATR measuring element of the ATR sensor.

[0019] The ATR measuring element can in principle have any desired shape, as long as it has spaced-apart boundary surfaces that can totally reflect infrared radiation, allowing the infrared radiation to propagate within the ATR measuring element. Preferably, the ATR measuring element is prismatic, at least in sections. The design of a single boundary surface as a totally reflecting measuring surface facing the outside environment of the ATR sensor is generally sufficient. Preferably, opposing, particularly preferably parallel outer surfaces of the ATR measuring element form the boundary surfaces that totally reflect the infrared radiation coupled into the ATR measuring element. As a result, infrared radiation coupled into the ATR measuring element can be reflected multiple times between the boundary surfaces and thus transmitted through the ATR measuring element over a greater distance.The infrared radiation is preferably coupled in via a side surface running between the totally reflecting interfaces. To facilitate the coupling of the infrared radiation, this side surface can be inclined at an angle other than a right angle to the totally reflecting, opposite, preferably parallel, interfaces. To ensure reliable coupling of the infrared radiation from the ATR measuring element, the ATR measuring element is preferably designed with mirror symmetry, which also helps prevent assembly errors.The output surface of the ATR measuring element, which is mirror-symmetrical to the input surface, enables an infrared partial beam, after multiple total reflections – neglecting the attenuation of the infrared radiation at the interface serving as the measuring surface, which is a surface of the ATR measuring element facing the outside environment of the ATR sensor – to exit the ATR measuring element between the parallel interfaces through the output surface at the same or a similar angle as the angle at which it was coupled into the ATR measuring element through the input surface. To achieve the desired slim ATR sensor, an infrared radiation source with the smallest possible spatial dimension is preferably used, for example, a thread- or rod-shaped infrared filament source.For precise and safe positioning of the infrared radiation source regardless of its respective shape, the infrared radiation source is preferably arranged on a carrier component.

[0020] To ensure that the infrared radiation source can reliably emit the infrared measurement radiation component and the infrared reference radiation component not just in slightly different spatial directions, but in significantly different spatial directions, the carrier component can have a recess penetrating the carrier component in the direction away from the infrared radiation source. The infrared radiation source can then be arranged on the carrier component to emit infrared radiation through the recess. In particular, the infrared radiation source can be designed and arranged to emit only one infrared radiation component consisting of the infrared reference radiation component and the infrared measurement radiation component through the recess in the carrier component, and to emit the respective other infrared radiation component in a direction away from the carrier component, but not through it.The infrared radiation source is preferably located in the recess or in the direction in which the recess penetrates the support component, above or below the recess.

[0021] Since the infrared radiation source is usually arranged close to a boundary surface of the ATR measuring element in order to couple the infrared measuring radiation component emitted by it into the ATR measuring element as well as possible, the infrared radiation source preferably emits the infrared reference radiation component through the recess in the carrier component.

[0022] The recess may be a hole in the support component that is completely surrounded by the material of the support component or may be a recess that extends from an edge of the support component into the support component.

[0023] Typically, the infrared radiation source emits an infrared radiation component as a radiation cone from the infrared radiation source. The radiation direction of the respective infrared radiation component is then the cone axis or another radiation axis centrally penetrating the infrared radiation component in its spatial region. A solid angle between the radiation directions of the infrared measurement radiation component and the infrared reference radiation component is then the smallest angle between the radiation axes of the said radiation components. The solid angle between the radiation directions of the infrared measurement radiation component and the infrared reference radiation component is preferably 90° to 180°. The infrared reference radiation component preferably has a propagation component that is directed opposite to a propagation component of the infrared measurement radiation component.Particularly preferably, the infrared radiation source emits the infrared measuring radiation component and the infrared reference radiation component in opposite directions, i.e. with radiation axes which enclose an angle of 180° between them.

[0024] In principle, the carrier component can be any component on or in which the infrared radiation source is directly mounted. Preferably, the carrier component is a printed circuit board. In this case, the infrared radiation source can be an SMD radiation source, which can be soldered, welded, or bonded to a surface of the carrier component.

[0025] To maximize the effective use of space in the sensor housing, at least one additional electronic component is preferably arranged on the circuit board. This additional electronic component can be a control device that controls the operation of the infrared radiation source. A temperature measuring element, preferably an NTC measuring element, can also be arranged on the circuit board, for example, to detect a temperature of the infrared radiation source or close to it.

[0026] The carrier component, as a circuit board, is preferably electrically connected, or at least connectable, to the external environment of the sensor housing via a line arrangement, so that electrical energy can be supplied to the circuit board via this line arrangement in order to supply the infrared radiation source and, if appropriate, the at least one further electronic component, in particular the control device, with electrical energy. Additionally or alternatively, signals can be transmitted via the line arrangement to the control device, which processes them to control the operation of the infrared radiation source. The control device can comprise an integrated circuit.

[0027] In principle, the support component can be arranged in any desired manner in the sensor housing. An arrangement with advantageously low installation space requirements can be achieved by holding or at least supporting the support component on a reflector arrangement, of which the infrared measurement radiation reflector or the infrared reference radiation reflector forms at least one component. The support component can be held directly by the infrared measurement radiation reflector or the infrared reference radiation reflector, or it can be held by a structural component that, in addition to the support component and preferably at a distance from it, holds a reflector comprising an infrared measurement radiation reflector and an infrared reference radiation reflector.

[0028] The ATR sensor is generally used for the metrological analysis of a fluid. The fluid may contain suspended particles that could interfere with the measurement results of the ATR sensor if they enter the detection range of the ATR measuring element. Such suspended particles can be, for example, cell membranes or cell membrane sections. To prevent unwanted suspended particles from interfering with the measurement results of the ATR sensor, according to a preferred embodiment of the present invention, a membrane is arranged on the sensor housing, which at least partially, preferably completely, covers an outer side of the ATR measuring element facing away from the housing interior. The membrane is permeable to the respective fluid to be measured, but not to solids contained in the fluid, such as the aforementioned suspended particles. The membrane preferably lies gap-free against an outer surface forming a measuring surface of the ATR measuring element.If the membrane is arranged at a distance from the outer surface acting as the measuring surface, this distance is preferably greater than the dimension, extending in the direction of the distance, of an evanescent field that forms on the outer surface during measuring operation. Desirably, the ATR sensor is a slender sensor extending along the sensor housing's longitudinal axis, with dimensions that are preferably at least 3 to 4 times larger along the sensor housing's longitudinal axis than orthogonal to the sensor housing's longitudinal axis. To achieve this, the sensor housing can have at least one section extending along the sensor housing's longitudinal axis with a polyhedral outer surface or one curved around the sensor housing's longitudinal axis.

[0029] In the case of a polyhedral outer surface of the section, this is preferably a regular polyhedral outer surface whose immediately adjacent planar outer surface sections meet along an edge that lies in a common plane with the sensor housing's longitudinal axis. Preferably, in sections orthogonal to the sensor housing's longitudinal axis, the polyhedral outer surface in the section displays a regular polygon as its outer edge, particularly preferably with equally long edges. The polyhedral outer surface can taper in the section along the sensor housing's longitudinal axis, for example in the manner of a truncated pyramid, although this is not preferred. Preferably, the planar outer surface sections of the polyhedral outer surface run parallel to the sensor housing's longitudinal axis.

[0030] The outer surface curved around the sensor housing's longitudinal axis preferably has the sensor housing's longitudinal axis as the axis of curvature in the section or has at least one axis of curvature parallel to the sensor housing's longitudinal axis. The outer surface curved around the sensor housing's longitudinal axis in this section can also taper in the axial direction, for example, as a truncated cone, but preferably extends along the sensor housing's longitudinal axis with an outer edge that is constant in size and shape. The outer edge can have an elliptical or oval shape in sections orthogonal to the sensor housing's longitudinal axis, but is preferably circular.

[0031] In a further development of the shape of the outer surface of the sensor housing, the sensor housing can have at least one measuring section extending along the sensor housing's longitudinal axis with an outer surface that is polyhedral or curved around the sensor housing's longitudinal axis, in which the infrared measuring sensor is accommodated. Additionally or alternatively, the sensor housing can have at least one reference section extending along the sensor housing's longitudinal axis with an outer surface that is polyhedral or curved around the sensor housing's longitudinal axis, in which the infrared reference sensor is accommodated. The measuring section and the reference section can be formed at an axial distance from one another on the sensor housing. In this case, the measuring section contains the infrared measuring sensor but not the infrared reference sensor, and the reference section contains the infrared reference sensor but not the infrared measuring sensor.

[0032] A particularly easy-to-handle sensor housing can be obtained if the sensor housing has, at least in sections, a prismatic and / or cylindrical outer surface and / or a prismatic or cylindrical envelope. Regarding the prismatic and / or cylindrical outer surface, we refer to what was said above regarding the sections with a polyhedral or curved outer surface. In the preferred embodiment with an ATR measuring element arranged axially between the infrared measuring sensor and the infrared reference sensor, the sensor housing will have an axial section in which a preferably flat outer surface of the ATR measuring element, as its measuring surface, is accessible to a fluid to be measured in the external environment of the sensor housing.At the location where the outer surface of the ATR measuring element is accessible, the sensor housing is preferably only partially prismatic or partially cylindrical due to the accessible outer surface of the ATR measuring element, but preferably in such a way that the entire sensor housing has a prismatic or cylindrical envelope over the two sections mentioned and the axially intermediate area of ​​the receptacle of the ATR measuring element.

[0033] Particularly preferably, the ATR sensor does not exceed a dimension orthogonal to the sensor housing's longitudinal axis of 12 mm over at least 75% of the axial length of an axial section of the sensor housing containing the infrared radiation source, the ATR measuring element, the infrared measuring sensor, and the infrared reference sensor, particularly preferably over at least 85% of said length, more preferably over at least 95% of said length, and most preferably over the entire length. This enables the use of the ATR sensor in commercially available sensor holders.

[0034] The present invention will be explained in more detail below with reference to the accompanying drawing. It shows:

[0035] Figure 1 is a schematic longitudinal sectional view through an inventive embodiment of an ATR sensor of the present application.

[0036] In Figure 1, an embodiment of an ATR sensor according to the invention is generally designated 10. The ATR sensor 10 comprises a sensor housing 12 with a tube 13, which is preferably formed in one piece. The sensor housing 12, in particular its tube 13, can generally be made of plastic, but is preferably made of stainless steel in order to permanently withstand even aggressive chemical environments.

[0037] In the example shown, the sensor housing 12 is designed as a cylindrical housing with a cylindrical envelope 14. The cylindrical envelope 14 is indicated by a dash-dotted line in the region of a recess 16 of the otherwise cylindrical sensor housing 12. The sensor housing 12 extends along a sensor housing longitudinal axis L, which, as the sensor housing longitudinal axis L, conceived as passing centrally through the sensor housing 12, is also the cylinder axis of the cylindrical sensor housing 12. Outside the recess 16, the cylindrical envelope 14 coincides with the outer surface 13a of the cylindrical tube 13.

[0038] A printed circuit board 18 is arranged in the sensor housing 12 as a carrier component 20 for an infrared radiation source 22. To accommodate the printed circuit board 18, an installation space in the axial extension area of ​​an ATR element 24, the ATR measuring element 24, is used. This installation space is available because the ATR measuring element 24, with its flat outer surface 24a serving as the measuring surface 26, must be accessible to a fluid to be measured in the external environment U of the sensor housing 12. Therefore, the ATR measuring element 24 is arranged in the sensor housing 12 at a distance from the sensor housing's longitudinal axis L.

[0039] The infrared radiation source 22 is soldered or welded onto the printed circuit board 18 as a surface-mounted device (SMD). The printed circuit board 18 is a printed circuit board 18 printed with conductive traces in a conventional manner. It also carries a control device 27 that controls the operation of the infrared radiation source 22. The printed circuit board 18 and the electronic components soldered, welded, or otherwise connected thereto: infrared radiation source 22 and control device 27, are connectable via a ribbon cable 28 to a power source and / or to a higher-level control device of a piece of laboratory equipment in which the ATR sensor 10 is used.

[0040] The ATR sensor 10 has a connection end 10a and a head end 10b axially opposite the sensor housing's longitudinal axis L. The ribbon cable 28 and a connection assembly 30 are electrically contactable at the connection end 10a. The connection assembly 30 serves to output measurement signals from an infrared measurement sensor 32 and an infrared reference sensor 34. At the head end 10b, the tube 13 is closed by a plug 35.

[0041] The infrared measurement sensor 32 and the infrared reference sensor 34 can be essentially identical sensor devices, which may differ, but need not differ, in the infrared band detectors 36 and 38 arranged therein. The output of reference detection signals by the infrared reference sensor 34 or their output from the sensor housing 12 is not shown in Figure 1 for the sake of simplicity, but does occur.

[0042] In the example shown, both the infrared measuring sensor 32 and the infrared reference sensor 34 each have four detectors 40 and 42, respectively, in front of which an infrared band filter 36 and 38, respectively, is arranged in the beam path coming from the infrared radiation source 22. The infrared measuring sensor 32 has a total of four detectors 40, of which only the two detectors 40 located behind the longitudinal sectional plane containing the sensor housing's longitudinal axis L can be seen in Figure 1. The other two detectors 40 are located orthogonally to the plane of the drawing in Figure 1, in front of this plane and in front of the two detectors 40 shown. The same applies to the infrared band filters 36, which are arranged in front of the incident side of the detectors 40 in order to allow only infrared radiation with a wavelength defined by the respective infrared band filter 36 to fall on a detector 40.

[0043] The infrared bandpass filters 36 preferably each have different wavelengths or wavelength ranges in which they are exclusively permeable to infrared radiation. Without limitation to the given example, the individual infrared bandpass filters 36 can transmit the following bandwidth of infrared radiation, specified by a respective central wavelength and its tolerances: 9.852 pm ±0.024 pm, 9.569 pm ±0.023 pm, 9.756 pm ±0.024 pm, and 8.032 pm ±0.016 pm. The infrared measuring sensor 32 is thus a four-channel measuring sensor. The infrared reference sensor 34 can be constructed identically, so that for the presently presented example, the description given for the infrared measuring sensor 32 can also be used to explain the infrared reference sensor 34.

[0044] The infrared measuring sensor 32 has a housing 44, which is cylindrical over at least 75% of its extension along the sensor housing's longitudinal axis L, with a cylinder axis Z32 that is coaxial with the sensor housing's longitudinal axis L. The housing 44 of the infrared measuring sensor 32 therefore also has a cylindrical shape over at least 75% of its axial extension along the cylinder axis Z32. The statements regarding the housing 44 apply mutatis mutandis to the housing 46 of the infrared reference sensor 34 and its cylinder axis Z34.

[0045] The sensor housing 12 has an axial measuring section 48, which, as a cylindrical measuring section 48, is delimited by an axial section of the cylindrical outer surface 13a of the tube 13 of the sensor housing 12. The infrared measuring sensor 32 is accommodated in the measuring section 48. At an axial distance from the measuring section 48, the sensor housing 12 has an axial reference section 50. This is also a cylindrical reference section 50 and is delimited by an axial section of the cylindrical outer surface 13a of the tube 13 of the sensor housing 12. The infrared reference sensor 34 is accommodated in the reference section 50.

[0046] The respective infrared sensors, infrared measuring sensor 32 and infrared reference sensor 34, are accommodated in the respective sections: measuring section 48 and reference section 50, by means of a substantially identically designed positioning element 52. The positioning element 52 is an annular element, which preferably has a groove formed on its radially outer surface for the passage of the ribbon cable 28. At the positioning element 52 of the reference section 50, the groove is empty in the illustration. The ribbon cable 28 is guided through the groove of the positioning element 52 of the measuring section 48. However, a conductor (not shown in Fig. 1) for outputting measurement signals from the infrared reference sensor 34 from the sensor housing 12 can run through the groove of the positioning element 52 of the reference section 50 and, in its further course, also through the groove of the positioning element 52 of the measuring section 48.

[0047] The annular positioning elements 52 can be arranged frictionally in the tube 13 and can frictionally hold the infrared sensor 32 or 34 held by them. However, the positioning elements 52 can also be adhesively arranged in a fixed position on the tube 13 by interposing an adhesive and can be adhesively connected in a similar manner to the respective infrared sensor 32 or 34 positioned by them.

[0048] The support component 20 with the infrared radiation source 22 and the ATR measuring element 24 are arranged axially between the infrared sensors 32 and 34, which are arranged with the detector surfaces of the detectors 40 and 42 facing each other. Additionally, an infrared measuring radiation reflector 54 is arranged axially between the infrared radiation source 22 and the ATR measuring element 24. By means of its reflective surface 54a, the reflector deflects an infrared measuring radiation component 56 emitted by the infrared radiation source 22 and transmitted by the ATR measuring element 24 with reflection at its parallel boundary surfaces 24a and 24b toward the bandpass filters 36 and the detectors 40 of the infrared measuring sensor 32.

[0049] The circuit board 18 has a recess 58 at the location where the infrared radiation source 22 is mounted. The infrared radiation source 22 is arranged above the recess 58, so that it can not only emit infrared radiation as the infrared measurement radiation component 56 toward the inclined surface of the ATR measuring element 24, but in the example shown, can simultaneously emit an infrared reference radiation component 60 in the opposite direction through the recess 58 in the circuit board 18.

[0050] The infrared reference radiation portion 60 reaches the infrared reference sensor 34 via an infrared reference radiation reflector 62, whose reflective surface 62a deflects the infrared reference radiation portion 60 emitted by the infrared radiation source 22 toward the bandpass filters 38 and the detectors 42.

[0051] The infrared reference radiation reflector 62 is arranged axially between the carrier component 20 with the infrared radiation source 22 arranged thereon and the ATR measuring element 24 on the one hand and the infrared reference sensor 34 on the other hand.

[0052] The infrared reference radiation reflector 62 supports the support component 20. The support component is held by a support component 64, which is located behind the section plane of Figure 1. Another support component 64 can be located parallel to the illustrated support component 64 in front of the section plane of Figure 1.

[0053] The ATR measuring element 24, which is transparent to infrared radiation, is connected to the tube 13 by soldering by a soldering section 66 running around it.

[0054] The measuring surface 26 is covered by a membrane 68, which is directly connected to the

[0055] Measuring surface 26 is in contact and is permeable to fluid to be measured in the external environment U of the ATR sensor 10, but not to suspended matter contained in the fluid, such as cells, cell residues and the like. This prevents falsification of the measurement result due to disruptive influences from solid particles. The membrane 68 is fixed to the measuring surface 26 by a frame 70 which is positively anchored in the tube 13 or in the sensor housing 12. A seal 72 between the frame 70 and the solder section 66 prevents fluid from the external environment U from entering the interior A of the ATR sensor 10 or into its sensor housing 12. The membrane 68 is accessible to fluid in the external environment U via a recess 71 which completely penetrates the frame 70 in the direction of its thickness.

[0056] The design described above with components arranged successively in the axial direction, wherein the ATR measuring element 24, the infrared radiation source 22 and a large part of the carrier component 20 axially overlap in the axial extension area of ​​the ATR measuring element 24, allows a very slim dimensioning of the ATR sensor 20, which in its cylindrical and thus rotationally symmetrical sections 48 and 50 with respect to the sensor housing longitudinal axis L has a dimension D that is orthogonal to the sensor housing longitudinal axis L and does not exceed 12 mm.

[0057] In the area between the measuring section 48 and the reference section 50, namely in the area of ​​the recess 16, the sensor housing 12 is partially cylindrical and has a radial dimension starting from the sensor housing longitudinal axis L, which at least in the partially cylindrical area of ​​the tube 13 of the sensor housing 12 does not exceed a dimension of 6 mm.

Claims

Claims 1. ATR sensor (10) comprising a sensor housing (12), wherein at least the following sensor components are included in the sensor housing (12): an infrared radiation source (22), an ATR element (24), wherein the ATR element (24) is configured as an ATR measuring element (24) to transmit infrared radiation by reflection at at least one interface of the ATR measuring element (24), an infrared measuring sensor (32), which is arranged in the sensor housing (12) such that it detects infrared radiation emitted by the infrared radiation source (22) after its transmission through the ATR measuring element (24), and which is configured to output a measurement / detection signal depending on the infrared radiation detected by the infrared measuring sensor (32), an infrared reference sensor (34), which is arranged in the sensor housing (12) such that it detects infrared radiation emitted by the infrared radiation source (22) Infrared radiation detected,which is not transmitted by the ATR measuring element (24), and which is configured to output a reference detection signal depending on the infrared radiation detected by the infrared reference sensor (34), characterized in that the infrared radiation source (22) is configured and arranged to emit an infrared measurement radiation component (56) detected by the infrared measurement sensor (32) of the infrared radiation emitted by the infrared radiation source (22) in a measurement radiation direction and simultaneously to emit an infrared reference radiation component (60) detected by the infrared reference sensor (34) of the infrared radiation emitted by the infrared radiation source (22) in a reference radiation direction different from the measurement radiation direction.

2. ATR sensor (10) according to claim 1 , characterized in that the sensor housing (12) extends along a sensor housing longitudinal axis (L) defining an axial direction, wherein the infrared measuring sensor (32) and the infrared reference sensor (34) are arranged axially apart from each other in the sensor housing (12). ATR sensor (10) according to claim 2, characterized in that the infrared radiation source (22) is arranged axially between the infrared measuring sensor (32) and the infrared reference sensor (34). ATR sensor (10) according to claim 2 or 3, characterized in that the ATR measuring element (24) is arranged axially between the infrared measuring sensor (32) and the infrared reference sensor (34). ATR sensor (10) according to claim 3 or 4, characterized in that an infrared measurement radiation reflector (54) is arranged axially between the ATR measuring element (24) and the infrared measuring sensor (32) and / or an infrared reference radiation reflector (62) is arranged axially between the infrared radiation source (22) and the infrared reference sensor (34).An ATR sensor (10) according to one of the preceding claims, characterized in that the infrared radiation source (22) is arranged on a support component (20). An ATR sensor (10) according to claim 6, characterized in that the support component (20) has a recess (58) extending through the support component (20) in the direction away from the infrared radiation source (22), wherein the infrared radiation source (22) is arranged on the support component (20) for the emission of infrared radiation through the recess (58).

8. ATR sensor (10) according to claim 6 or 7, characterized in that the carrier component (20) is a printed circuit board (18).

9. ATR sensor (10) according to claim 8, characterized in that at least one further electronic component (27) is arranged on the circuit board (18).

10. ATR sensor (10) according to one of claims 6 to 9, including claim 5, characterized in that the support component (20) is held or supported on a reflector arrangement, of which the infrared measuring radiation reflector (54) or the infrared reference radiation reflector (62) forms at least one component.

11. ATR sensor (10) according to one of claims 2 to 10, including claim 2, characterized in that a membrane (68) is arranged on the sensor housing (12) which covers at least a section of an outer surface (24a) of the ATR measuring element (24) pointing away from the interior of the housing (A).

12. ATR sensor (10) according to one of claims 2 to 11, including claim 2, characterized in that the sensor housing (12) has at least one section (48, 50) extending along the longitudinal axis (L) of the sensor housing with a polyhedral outer surface (13a) or curved about the longitudinal axis (L) of the sensor housing.

13. ATR sensor (10) according to claim 12, characterized in that the sensor housing (12) has at least one measuring section (48) extending along the longitudinal axis (L) of the sensor housing with a polyhedral or curved shape about the longitudinal axis (L) of the sensor housing. The sensor housing (12) has an outer surface (13a) in which the infrared measuring sensor (32) is accommodated, and / or the sensor housing has at least one reference section (50) extending along the longitudinal axis (L) of the sensor housing with a polyhedral outer surface (13a) or curved about the longitudinal axis (L) of the sensor housing in which the infrared reference sensor (34) is accommodated. The ATR sensor (10) according to claim 12 or 13 is characterized in that the sensor housing (12) has at least a section with a prismatic and / or cylindrical outer surface (13a) and / or a prismatic or cylindrical envelope (14).ATR sensor (10) according to one of the preceding claims, including claim 2, characterized in that the ATR sensor (10) does not exceed a dimension orthogonal to the longitudinal axis (L) of the sensor housing (12) over at least 75% of the extension length of an axial section of the sensor housing (12) containing the infrared radiation source (22), the ATR measuring element (24), the infrared measuring sensor (32) and the infrared reference sensor (34).

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