Gas analyzer

Abstract

Gas analyzer (100) which has the following features: a gas chamber (102) designed to hold a gas that is to be analyzed; a radiation source (104, 204) designed to emit electromagnetic radiation into the gas chamber (102), wherein the electromagnetic radiation is adapted to disperse gas molecules of a specific type contained in the gas, that is recorded in the gas chamber (102), to be analyzed, selectively excited, wherein the radiation source (104, 204) has a cavity radiator designed as an electrically heatable body or is designed as such; a collimator (122, 222) designed to collimate the electromagnetic radiation emitted by the radiation source (104, 204), wherein the collimator (122, 222) has a concave mirror (234) which is arranged on one side of the radiation source (104, 204) opposite the gas chamber (102), wherein the radiation source (104, 204) has one or more perforations (204a) so that electromagnetic radiation reflected by the collimator (122, 222) can pass through the radiation source (104, 204); a base section (230); a carrier (232) coupled to the base section (230) and supporting the radiation source (104, 204), wherein the carrier (232) is transparent to the electromagnetic radiation emitted by the radiation source (104, 204); and a sensor (106) designed to detect a physical quantity that indicates the degree of interaction between the electromagnetic radiation emitted by the radiation source (104, 204) and the gas to be analyzed.

Description

[0001] Various designs generally relate to a gas analysis measuring device.

[0002] Gas analyzers, designed either as photoacoustic gas sensors or as non-dispersive radiation spectrometers, provide a simple way to analyze the composition of gases. As the analysis of ambient air composition, for example due to pollution, becomes increasingly important, it is desirable to have a gas analyzer with a simple design that is capable of measuring gas composition in a highly efficient manner.

[0003] US 2010 / 0118301A1 discloses a gas analysis system comprising a light source assembly, a fluorescence reaction assembly, and a detector, wherein the light source assembly includes a light source and a collimator located between the light source and the fluorescence reaction assembly.

[0004] US 2016 / 0 356 700 A1 discloses various methods for coupling a photonic circuit, which includes a chamber filled with gas to be analyzed, to a light source, wherein a collimator system is arranged between the light source and the photonic circuit. US 5 616 826 A discloses a photoacoustic device with a light source that provides a pulsed beam of light to a measuring chamber, wherein the light source comprises an incandescent lamp attached to a parabolic reflector as the emitter and a rotating bell for providing the pulsed beam of light. US 4 787 750 A, US 2003 / 0 209 669 A1,

[0005] US 8 415 626 B1, and WO 93 / 09 422 A1 each disclose a gas analysis device.

[0006] According to various embodiments of the present disclosure, a gas analyzer is provided. The gas analyzer may comprise: a gas chamber designed to hold a gas to be analyzed; a radiation source designed to emit electromagnetic radiation into the gas chamber, the electromagnetic radiation being adapted to selectively excite gas molecules of a certain type to be detected in the gas held in the gas chamber, the radiation source comprising or being designed as a cavity radiator configured as an electrically heatable body; and a collimator designed to collimate the electromagnetic radiation emitted by the radiation source, the collimator comprising a concave mirror arranged on one side of the radiation source opposite the gas chamber.wherein the radiation source has one or more perforations such that electromagnetic radiation reflected by the collimator can pass through the radiation source; a base section, a support coupled to the base section and supporting the radiation source, the support being transparent to the electromagnetic radiation emitted by the radiation source; and a sensor designed to detect a physical quantity indicating the degree of interaction between the electromagnetic radiation emitted by the radiation source and the gas to be analyzed.

[0007] In the drawings, the same reference points generally denote the same parts in the different views. The drawings are not necessarily to scale; instead, the focus is generally on illustrating the principles of the invention. The following description presents various embodiments of the invention with reference to the following drawings, in which: Fig. 1 is a schematic view of a gas analyzer which has a source unit; Fig. 2 is a schematic view of a modified source unit; Fig. 3A to 3G an example method for manufacturing a collimator of the source unit from Fig. 2 represents; Fig. 4. A flowchart of the example procedure, which is described in the Fig. 3A to 3G is shown; Fig. 5 is a schematic view of another modified source unit.

[0008] The following detailed description refers to the accompanying drawings, which illustrate certain details and embodiments in which the invention can be implemented.

[0009] The term "exemplary" is used here to mean "serving as an example or illustration." Each embodiment or configuration described here as "exemplary" is not necessarily to be understood as preferred or advantageous over other embodiments or configurations.

[0010] The term "collimated electromagnetic radiation" means, as used here, electromagnetic radiation with a low degree of dispersion in its propagation.

[0011] The term "collimator", as used here, refers to a device designed to focus a beam of electromagnetic radiation.

[0012] The term "optical axis", as used here, refers to an imaginary line that defines a path along which electromagnetic radiation propagates through a system up to a first approximation.

[0013] The term "focal point of the collimator" refers to a characteristic point on the optical axis of a collimator where parallel rays of electromagnetic radiation converge or from which they split into parallel rays after refraction or reflection through the collimator.

[0014] Fig. Figure 1 is a schematic view of a gas analyzer 100. The gas analyzer 100 may comprise: a gas chamber 102 designed to hold a gas to be analyzed, a radiation source 104 designed to emit electromagnetic radiation into the gas chamber 102, the electromagnetic radiation being adapted to selectively excite gas molecules of a certain type to be detected in the gas held in the gas chamber 102, and a sensor 106 designed to detect a physical quantity indicating the degree of interaction between the electromagnetic radiation emitted by the radiation source 104 and the gas to be analyzed.The degree of interaction between the electromagnetic radiation emitted by the radiation source 104 and the gas to be analyzed can indicate the concentration of gas molecules of a certain type to be detected in the gas taken up in the gas chamber 102.

[0015] The gas analyzer 100 can be designed as a photoacoustic gas analyzer. In such a gas analyzer, the physical quantity that indicates the degree of interaction between the electromagnetic radiation emitted by the radiation source 104 and the gas to be analyzed is acoustic waves. These acoustic waves are generated as a result of the excitation of gas molecules of the type to be detected in the gas contained in the gas chamber 102 by the electromagnetic radiation emitted by the radiation source 104. The operating principle of the photoacoustic gas analyzer is described below.

[0016] In a photoacoustic gas analyzer, the radiation source 104 is designed to emit electromagnetic radiation in a time-varying manner, for example, periodically, that is, with a time-varying intensity. The electromagnetic radiation emitted by the radiation source 104 can be adapted to trigger specific atomic and / or molecular transitions in gas molecules of the type to be detected in the gas held in the gas chamber 102 and / or to excite various vibrational and / or rotational states of the gas molecules. During the subsequent de-excitation of the thus excited gas molecules, heat is generated, leading to a local expansion of the gas held in the gas chamber 102, which produces a positive pressure pulse.

[0017] The excess heat generated in this way is subsequently dissipated to a heat sink, causing the gas to contract and generating a negative pressure pulse. A heat sink can be provided by a holder in physical contact with the photoacoustic gas analyzer 100.

[0018] Since the electromagnetic radiation is emitted in a time-varying manner, the gas molecules of the type to be detected are excited in a time-varying manner, for example, periodically. In this way, a time-varying, for example, periodic, pressure fluctuation is generated in the gas contained in gas chamber 102, which contains the gas molecules of the type to be detected. Thus, acoustic waves are generated in this way. In a photoacoustic gas analyzer, the sensor 106 can be an acoustic wave sensor designed to detect, or be configured as such, acoustic waves generated in gas chamber 102 by the interaction of the electromagnetic radiation emitted by the radiation source 104 with the gas molecules of the type to be detected.

[0019] The acoustic wave sensor 106 can be arranged within the gas chamber 102. In a gas analyzer 100 designed in this way, the sensor response increases with increasing concentration of the gas molecules of interest, i.e., the gas molecules of the type to be detected. A photoacoustic gas analyzer 100 of this type is referred to in this description as a direct detection photoacoustic gas analyzer 100.

[0020] Alternatively, the photoacoustic gas analyzer 100 can be designed as a photoacoustic gas analyzer of the differential detection type, meaning that the sensor 106 for acoustic waves is not located within the gas chamber 102, but in a reference gas chamber 108, in which the gas is separated from the gas chamber 103 by a window 110 that is transparent to the electromagnetic radiation emitted by the radiation source 104. A reference gas with a well-defined composition, containing the gas molecules of interest, is contained in the reference gas chamber 108.

[0021] In a photoacoustic gas analyzer 100 of the differential detection type, the electromagnetic radiation emitted by the radiation source 104 passes through the gas chamber 102 and selectively interacts with gas molecules of interest. Through this selective interaction with the molecules of interest, the intensity of the electromagnetic radiation is attenuated in the gas chamber 102 depending on the concentration of the molecules of interest in the gas to be analyzed; that is, the attenuation increases with increasing concentration of the molecules of interest. Accordingly, the attenuation of the electromagnetic radiation indicates the concentration of the gas molecules of interest. After passing through the gas chamber 102, the electromagnetic radiation enters the reference gas chamber 108 through the window 110 and selectively excites gas molecules of interest in the reference gas.The more the electromagnetic radiation is attenuated in gas chamber 102, the lower the intensity in the comparison gas chamber 108 and the lower the response of the sensor 106 to acoustic waves. Accordingly, in a photoacoustic gas analyzer 100 of the differential detection type, the response of the sensor 106 to acoustic waves decreases with increasing concentration of the gas molecules of interest in gas chamber 102. The actual concentration of the molecules of interest in gas chamber 102 can be determined by comparison with a calibrated maximum response of the sensor 106 to acoustic waves at a decreasing concentration of the molecules of interest in gas chamber 102.

[0022] The radiation source 104 can be designed to emit electromagnetic radiation in the infrared, visible, and / or ultraviolet frequency range. Infrared light is suitable for exciting molecular vibrational states. For example, infrared light with a wavelength between approximately 4.170 and 4.370 µm and between approximately 14 and 16 µm is suitable for exciting vibrational states of CO2 molecules.

[0023] The radiation source 104 can comprise at least one of a group consisting of a cavity radiator, a photodiode, and a laser. Power supply lines 105 of such a radiation source 104 are in Fig. 1 shown.

[0024] A cavity radiator is designed to emit electromagnetic radiation according to Planck's radiation law; that is, the radiation spectrum is determined by the temperature and not by the shape or composition. Radiation source 104 can incorporate a cavity radiator designed as an electrically heatable body, such as a membrane. In operation, the electrically heatable body can be heated electrically to a temperature exceeding 450 °C.

[0025] The acoustic wave sensor 106 can be a capacitive acoustic wave sensor comprising two spaced-apart diaphragms with a capacitor between them. One of the diaphragms can be fixed, while the other can be displaced by the acoustic wave to be detected. Displacement of the diaphragm can indicate a characteristic of the acoustic wave to be detected and can trigger a change in the capacitor's capacitance. This change can be detected by a suitable readout circuit that provides an electrical signal indicating characteristics of the acoustic wave to be detected, such as sound pressure.

[0026] Additionally or alternatively, the acoustic wave sensor 106 can include, or be designed as, a piezoelectric acoustic wave sensor comprising a piezoelectric thin film that can be deformed by the acoustic waves to be detected. Deformation of the piezoelectric thin film can generate an electrical voltage within it, which indicates characteristics of the acoustic waves to be detected. The induced electrical voltage can be read out by a suitable readout circuit that provides an electrical signal indicating characteristics of the acoustic waves to be detected, such as sound pressure.

[0027] In Fig. Reference numeral 1 denotes the signal and / or power supply lines of sensor 106. Sensor 106 can be connected to a processing unit, which is designed, for example, as an application-specific integrated circuit (ASIC) or as a microprocessor, and is designed to determine the concentration of gas molecules of interest in gas chamber 102 from signals received by sensor 106.

[0028] Alternatively, the gas analyzer 100 can be designed as a non-dispersive radiation sensor, in particular as a non-dispersive infrared sensor (NDIR - Non-dispersive Infrared Detector). In a gas analyzer 100 of this type, the sensor 106 is designed as an electromagnetic radiation sensor, such as an infrared sensor, and the physical quantity that indicates the degree of interaction between the electromagnetic radiation emitted by the radiation source 104 and the gas molecules of interest is the intensity of the electromagnetic radiation detected by the radiation sensor 106. The higher the concentration of the molecules of interest in the gas taken up in the gas chamber 102, the lower the intensity of the electromagnetic radiation detected by the sensor 106.The actual concentration of the molecules of interest in gas chamber 102 can be determined by comparing the detected intensity with a calibrated maximum intensity at a decreasing concentration of the molecules of interest in gas chamber 102.

[0029] The gas analyzer 100 can further have a window 112 which is transparent to the electromagnetic radiation emitted by the radiation source 104 and is arranged between the radiation source 104 and the gas chamber 102.

[0030] Window 112 can be configured as a filter. Using filter 112, the spectrum of the radiation emitted by radiation source 104 can be limited to a narrow energy range, including a single excitation energy, to ensure that only molecules of a single type are excited at any given time. This prevents the unintentional excitation of molecules of different types from those intended for detection in the gas contained in gas chamber 102. In this way, the measurement sensitivity can be improved compared to a gas analyzer without a filter.

[0031] If only a single type of gas molecule is to be detected in the gas contained in gas chamber 102, the filter 112 can be designed to exhibit a specific transmission property. Alternatively, if gas molecules of different types with different excitation energies are to be detected in the gas to be analyzed, a tunable filter 112 with tunable transmission properties can be used. In operation, the transmission properties of the filter 112 can be varied to excite gas molecules of different types. The filter 112 can be a plasmonic filter and / or a Fabry-Perot interferometer, such as a Fabry-Perot etalon, or be designed as such.

[0032] The gas analyzer can be used to monitor the composition of ambient air, for example, to determine the concentration of CO2 and / or toxic gases, such as CO. Methane and / or water molecules (humidity) in the ambient air can also be detected in this way. Alternatively or additionally, the Gas Analyzer 100 can be designed and used as a breath gas analyzer to measure the concentration of alcohol and / or acetone, which indicates blood sugar levels.

[0033] As in Fig. As specified in Figure 1, the gas chamber 102 can be bounded by a gas chamber wall 114. A through-hole 116, serving as a gas inlet and outlet, can be provided in the gas chamber wall 114. The through-hole 116 can be temporarily and / or permanently open. In this way, the gas chamber 102 can be temporarily or even permanently in gas flow communication with the outer surface 118 of the gas analyzer 100. Gas exchange between the gas chamber 102 and the outer surface 118 of the gas analyzer 100 by diffusion can thus be provided so that the composition of the ambient air can be monitored by means of the gas analyzer 100.

[0034] A high degree of excitation of gas molecules of interest in gas chamber 102 can be achieved by providing a reflector 120 on the gas chamber wall 114. The reflector 120 can have a reflectance in the infrared and / or visible and / or ultraviolet frequency range of at least 20%, or at least 50%, or even at least 80%.

[0035] A high degree of excitation can also be provided by means of a collimator 112, which is designed to collimate electromagnetic radiation emitted by the radiation source 104.

[0036] By collimating the beam, a greater amount of electromagnetic radiation can be directed into gas chamber 102 compared to a gas analyzer 100 without a collimator. This increases the intensity of the electromagnetic radiation in gas chamber 102. Consequently, gas molecules of interest can be excited more efficiently than with a gas analyzer 100 without a collimator. This increases the sensitivity of the gas analyzer 100.

[0037] As in Fig. As specified in Figure 1, the collimator 122 can be designed as a convex lens, in particular as a biconvex lens. The radiation source 104 can be located at a focal point FP of the biconvex lens 122 on one side of the biconvex lens 122 that faces the gas chamber 102, or overlap it. In this way, the beam of electromagnetic radiation emitted by the radiation source 104 can be parallelized by the biconvex lens 122; that is, the beams of electromagnetic radiation emitted by the radiation source 104 are converted into parallel beams by the collimator 122. In this way, the amount of radiation emitted to the inner surface of the gas chamber wall 114 is minimized, thereby minimizing absorption losses in the gas chamber wall 114.Additionally, a well-defined angle of incidence between the parallel beam of electromagnetic radiation and the surface of the filter 112 facing the radiation source 104 can be ensured, thereby reducing the intensity of the electromagnetic beam due to reflection, particularly total internal reflection, at the surface of the filter 112. Accordingly, a high degree of excitation of the gas molecules of interest in the gas chamber 102 can be ensured. The parallel radiation beam is denoted by the reference symbol P in . Fig. 1 is designated.

[0038] The collimator 122 can have an optical axis OA that intersects the collimator 122 and / or the radiation source 104.

[0039] As in Fig. As specified in Figure 1, the radiation source 104 and the collimator 122 can be integrated into a source unit 124. The source unit 124 can include a holder 126 that supports the radiation source 104 and the collimator 122. The source unit 124 can further include a source unit filter 128, which is separate from the collimator 122 and supported by the holder 126. The source unit filter 128 can be designed as a filter with fixed transmission properties or as a tunable filter whose transmission properties can be adjusted.

[0040] What's next in Fig. As shown in Figure 1, a collimator filter 129, which is physically connected to the collimator 122, can be provided additionally or alternatively. For example, the collimator filter 129 can be designed as a layer applied to a surface of the biconvex lens 122, for instance, on a surface of the biconvex lens 122 facing the radiation source 104. Alternatively, a filter layer can be provided on a surface of the biconvex lens 122 opposite the radiation source 104. A biconvex lens 122 with a filter layer on both sides is also conceivable.

[0041] The Source Unit 124 can be supplied as a pre-assembled unit. In this way, the Gas Analyzer 100 can be manufactured in a simple manner.

[0042] Fig. Figure 2 shows a modified source unit in greater detail compared to the source unit shown in Fig. 1 is shown. Fig. 2 are parts that are parts of the source unit 124 from Fig. 1 corresponds to, with the same reference symbol, but plus 100.

[0043] The Source Unit 224, which is in Fig. Figure 2 shows a holder 226 with a base section 230 and a support 232 coupled to the base section 230 and carrying the radiation source 204. The support 232 can be transparent to the electromagnetic radiation emitted by the radiation source 204. Additionally, the support 232 can be configured as a source-unit filter designed to selectively transmit electromagnetic radiation emitted by the radiation source 204.

[0044] As in Fig. As shown in Figure 2, the base section 230 of the holder 226 can have a substantially ring-shaped form. The support 232 can be designed as a membrane coupled to a radial inner circumferential portion of the base section 230 and can optionally be made of a material with a low thermal conductivity of, for example, less than 5 W / (mK). In this way, the radiation source 204 can be thermally decoupled from the holder 226 and thus from the gas to be analyzed.

[0045] In Fig. 2 are the radial and axial directions of the source unit 224, each designated with the reference numeral Round A.

[0046] The source unit 224 can further comprise a collimator 222. The collimator 222 can have a concave mirror 234 or be designed as such. The radiation source 204 can be arranged at a focal point FP of the concave mirror 234 or overlap it. In this way, radiation reflected by the mirror 234 can be parallelized. The parallelized radiation beam is denoted by the reference symbol P in Fig. 2. The mirror 234 can be coupled to a radial inner part of the base section 230.

[0047] The collimator 222 can have an optical axis OA that intersects the collimator 222 and / or the radiation source 204.

[0048] The mirror 234 can be in physical contact with a transparent layer 234a, which is arranged on one side of the mirror 234 facing the radiation source 204 and is designed to transmit electromagnetic radiation emitted by the radiation source 204. The window 234 can be designed as a metallic layer. The transparent layer 234a can be designed as a collimator filter 229, for example, as a filter that is in physical contact with the collimator 222.

[0049] Alternatively, the collimator 222 can be designed as a Bragg mirror, for example as a reflector with several transparent layers having different refractive indices. In a reflector of this type, a metallic reflective layer can be omitted.

[0050] In the case that the radiation source 204 is designed as a cavity radiator, the radiation source 204 can have at least one or more perforations 204a in order to reduce the absorption rate of radiation reflected by the collimator 222 by the radiation source 204 itself, compared to an identical radiation source without perforations. In this way, electromagnetic radiation reflected by the collimator 222 can pass through the radiation source 204, thereby increasing the output of electromagnetic radiation compared to a radiation source 204 without perforations 204a.

[0051] The source unit 224 can further comprise a source unit filter 228', which is distinct from the support 232 and is arranged on one side of the radiation source 204 opposite the collimator 222. The source unit filter 228' can be supported by several posts 236 arranged on one axial side of the support 226. The source unit filter 228' can comprise several filter layers 228a', 228b'. The filter layers 228a', 228b' can have distinct, well-defined transmission characteristics in respective narrow frequency bands. Accordingly, by integrating the filter layers 228a' and 228b' with a single filter, a filter with well-defined transmission characteristics over a wider frequency range can be provided in this way compared to a single layer.

[0052] In an exemplary embodiment, one of the layers 228a', 228b' can be formed from SiO2 and the corresponding other layer from polycrystalline silicon. Even if the source unit filter 228' in Fig. Figure 2 shows the component having only two layers, 228a' and 228b'. It is evident that the number of layers can be changed as desired. In an exemplary embodiment, a source unit filter can have more than two alternating layers of polycrystalline silicon and SiO2.

[0053] The posts 236 can be coupled to the holder 226 and / or the source unit filter 228 by gluing or anodic bonding. At least one of the posts 236 can be provided with a reflector 237 on an outer surface, designed to reflect electromagnetic radiation emitted by the radiation source 204. In this way, a high output of electromagnetic radiation can be ensured.

[0054] The following is an exemplary procedure for manufacturing a collimator designed as a concave mirror, with reference to Fig. 3A to 3G, as well as with reference to the flowchart that is in Fig. As shown in section 4, it is described.

[0055] The exemplary procedure 1000 can exhibit the following:

[0056] Application of a sacrificial layer 12, for example a SiO2 layer, onto a substrate 10, for example a silicon substrate ( Fig. 3A, Fig. 3B and S1100 in Fig. 4);

[0057] Applying at least one prestressing element 14 to the sacrificial layer 12 ( Fig. 3C and S1200 in Fig. 4);

[0058] Applying a reflective layer 16 to the sacrificial layer 12 and to the at least one prestressing element 14 ( Fig. 3D and S1300 in Fig. 4);

[0059] Application of an optically transparent layer 18 to the sacrificial layer 16 ( Fig. 3E and S1400 in Fig. 4);

[0060] Removing a part of the substrate 10, at least from one section thereof, opposite the at least one prestressing element 14 ( Fig. 3F and S1500 in Fig. 4); and

[0061] Removing part of the sacrificial layer 12, at least from a section thereof, which faces the at least one prestressing element 14 ( Fig. 3G and S1600 in Fig. 4).

[0062] As in Fig. As shown in Figures 3C to 3G, several prestressing elements 14 can be applied to the surface of the sacrificial layer 12 opposite the substrate 10.

[0063] The at least one prestressing element 14 is designed to exert mechanical stress on the reflective layer 16 and on the optically transparent layer 18. This can be achieved by manufacturing the at least one prestressing element 14 from a material with a high or low coefficient of thermal expansion of the material of the reflective layer 16 and / or the optically transparent layer 18. The reflective layer 16 and the optically transparent layer 18 can be manufactured at elevated temperatures, for example, at temperatures substantially higher than those encountered when using a gas analyzer employing a collimator of this type.During subsequent cooling of the reflective layer 16, the optically transparent layer 18 and the at least one prestressing element 14, a bending deflection of the reflective layer 16 and the optically transparent layer 18 occurs due to the different thermal expansion properties.

[0064] In an exemplary embodiment, the optically transparent layer 16 can be made of polycrystalline silicon, and the at least one prestressing element 14 can be made of Si3N4. The portion of the substrate 10 opposite the at least one prestressing element 14 can be removed by deep reactive ion etching (DRIE), for example, if the substrate 10 is made of silicon and the sacrificial layer 12 is made of SiO2. In this case, the substrate 10 can be selectively etched by DRIE, while the sacrificial layer 12 acts as an etch-stop layer.

[0065] The etched substrate 10' can be used as in Fig. 3F and Fig. 3G is specified as having an essentially ring-shaped form.

[0066] The sacrificial layer 12 can subsequently be removed, for example by HF etching. The sacrificial layer is designated with the reference symbol 12' in Fig. 3G is designated. Depending on the thickness of the sacrificial layer 12 and / or the thickness of the reflective layer 16 and the optically transparent layer 18 and / or the configuration of the prestressing elements 14, the bending deflection of the reflective layer 16 and the optically transparent layer 18 can only occur after the removal of a portion of the sacrificial layer 12 facing the at least one prestressing element 14. The respective thickness of the sacrificial layer 12 and / or the reflective layer 16 and / or the optically transparent layer 18 can range from approximately 100 nm to approximately 1 µm.

[0067] The reflective layer 16 can be made of a metal, such as aluminium or gold.

[0068] The reflective layer 16 can be called the mirror 234 as in Fig. 2 shown function and the optically transparent layer 18 can be considered the transparent layer 234a as in Fig. 2 shown function.

[0069] As previously mentioned with reference to Fig. As mentioned in section 2, the collimator 222 can alternatively be designed as a Bragg mirror. A collimator of this type can be produced by applying several alternating optically transparent layers with different refractive indices, for example, several alternating layers of S2 and polycrystalline silicon, to the reflecting layer 16 or to the sacrificial layer 12 and to the at least one prestressing element 14 without applying it to the reflecting layer. Bending deflection of the several layers of the Bragg mirror can be achieved by the prestressing element 14 as described above.

[0070] Fig. Figure 5 shows a modified source unit. In Fig. 5 are parts that are parts of the source unit 124 from Fig. 1 corresponds to, with the same reference symbol, but plus 200.

[0071] The Source Unit 324, which is in Fig. Figure 5 shows a holder 326 with a base section 330 and a support 332 coupled to the base section 330 and carrying the radiation source 304.

[0072] As in Fig. As shown in Figure 5, the base section 330 of the holder 326 can have a substantially ring-shaped form. The support 332 can be designed as a membrane coupled to a radial inner circumferential portion of the base section 330 and can optionally be made of a material with a low thermal conductivity of, for example, 5 W / (mK). In this way, the radiation source 304 can be thermally decoupled from the holder 326 and thus from the gas to be analyzed.

[0073] In Fig. 5 The radial and axial directions are each designated with the reference symbols R and A.

[0074] The source unit 324 can further comprise a collimator 322. The collimator 322 can have a Fresnel lens 323 or be designed as such. The radiation source 304 can be arranged at a focal point FP of the Fresnel lens 323 or overlap it. In this way, beams of electromagnetic radiation emitted by the radiation source 304 are parallelized by the Fresnel lens 323, for example, converted into a beam of parallel electromagnetic beams. The parallelized radiation beam is designated by the reference symbol P.

[0075] The collimator 322 may also have an optical axis OA that intersects the collimator 322 and / or the radiation source 304.

[0076] The collimator 322 can be coupled to an axial end face of the base section 330 of the holder 326 by means of several posts 336. The posts 336 can be coupled to the holder 326 and / or the collimator 322 by adhesive bonding or anodic bonding. Similar to the posts 236 of the source unit 224 as in Fig. As shown in 2, the posts 336 of the source unit 324 can be as in Fig. Figure 5 shows a reflector 337 attached to an outer surface thereof. In this way, a source unit with a high output of electromagnetic radiation can be provided.

[0077] The collimator 322 can be equipped with a collimator filter 329, which is in physical contact with a surface of the Fresnel lens 323 opposite the radiation source 304.

[0078] What's next in Fig. As shown in Figure 5, the source unit 324 can be provided with a source unit filter 328, which is located on one side of the collimator 322 opposite the radiation source 304. As shown in Fig. As shown in Figure 5, the source unit filter 328 can have several filter layers 328a, 228b. In an exemplary embodiment, one of the layers 328a, 328b can be made of SiO2 and the corresponding other layer of polycrystalline silicon. As with reference to the source unit 224 as shown in Figure 5, the source unit filter 328 can be made of SiO2. Fig. As shown in Figure 2, a source unit filter 328 with defined filter properties can be provided by the layers.

[0079] The source unit filter 328 can be coupled to the collimator 322 by means of several posts 338 arranged on radial outer sections of the source unit filter 328. The posts 338 can be coupled to the source unit filter 328 and / or the collimator 322 by adhesive bonding or anodic bonding. The posts 338 supporting the source unit filter 328 can be provided with a reflector 339 on an outer surface thereof, designed to reflect electromagnetic radiation emitted by the collimator 322.

[0080] The Fresnel lens 323 can be produced by etching several rings, for example concentric rings, into a surface of a flat substrate made of a material that is transparent to the radiation emitted by the radiation source 104, for example glass or plastic.

[0081] It should be noted that the present invention is not limited to the collimator arrangements disclosed above. Alternatively or additionally, the collimator can be designed as a plasmonic arrangement, a collimator lens arrangement, a Fresnel lens arrangement with more than a single layer (trench) to increase contrast, or hollow fibers.

[0082] The following are various examples of the present revelation.

[0083] Example 1 is a gas analyzer. The gas analyzer may comprise: a gas chamber designed to hold a gas to be analyzed; a radiation source designed to emit electromagnetic radiation into the gas chamber, the electromagnetic radiation being adapted to selectively excite gas molecules of a certain type to be detected in the gas held in the gas chamber, the radiation source comprising or being designed as a cavity radiator configured as an electrically heatable body; a collimator designed to collimate the electromagnetic radiation emitted by the radiation source, the collimator comprising a concave mirror arranged on one side of the radiation source opposite the gas chamber, the radiation source having one or more perforations.so that electromagnetic radiation reflected by the collimator can pass through the radiation source; a base section, a support coupled to the base section and supporting the radiation source, the support being transparent to the electromagnetic radiation emitted by the radiation source, and a sensor designed to detect a physical quantity indicating the degree of interaction between the electromagnetic radiation emitted by the radiation source and the gas to be analyzed.

[0084] In Example 2, the object from Example 1 may optionally further include the collimator having an optical axis. The radiation source may be arranged on the optical axis.

[0085] In Example 3, the object may, in addition to one from Example 1 or 2, optionally have the optical axis intersecting the collimator.

[0086] In Example 4, the object may optionally further comprise, in addition to one from Example 1 to 3, that the collimator further comprises at least one from a group consisting of a convex lens, a Bragg mirror and a Fresnel lens.

[0087] In Example 5, the object from Example 4 may optionally further have a concave mirror with a reflectance in the infrared and / or visible and / or ultraviolet frequency range of at least 20% or at least 50% or at least 80%.

[0088] In Example 6, the object from Examples 1 to 5 may optionally further include the fact that the collimator has at least one focal point. The radiation source may be located at one of the collimator's focal points.

[0089] In Example 7, the object may optionally further comprise a filter, in addition to one from Example 1 to 6, which is designed to selectively transmit electromagnetic radiation emitted by the radiation source.

[0090] In Example 8, the subject of Example 7 may optionally further include the filter being designed as a tunable filter whose transmission properties are tunable.

[0091] In Example 9, the subject of Example 8 may optionally further include the tunable filter having or being designed as a plasmonic filter and / or a Fabry-Perot interferometer.

[0092] In Example 10, the item may, if different from one of Examples 7 to 9, further have the feature that the filter is a collimator filter in physical contact with the collimator or is designed as such.

[0093] In Example 11, the object of Example 10 may optionally further include the collimator being designed as a filter layer applied to a surface of the collimator.

[0094] In Example 12, the object may optionally include a source unit from one of the examples 1 to 11, which has a holder that supports the radiation source and / or the collimator. The source unit may be designed as a pre-assembled unit.

[0095] In Example 13, the item may optionally further include, in addition to one from Examples 7 to 12, that the filter is carried as a source unit filter separate from the collimator and the holder, or is designed as such.

[0096] In Example 14, the object may, if different from Example 12 to 13, optionally further have that the base section is substantially ring-shaped and the support is plate-like, and that the holder has the substantially ring-shaped base section and the plate-like support that carries the radiation source.

[0097] In Example 15, the object of Example 14 may optionally also have the support made of a material with a thermal conductivity of less than 5 W / (mK).

[0098] In Example 16, the object may, if different from Example 14 or 15, further have the feature that the carrier is designed to transmit electromagnetic radiation emitted by the radiation source.

[0099] In Example 17, the subject of Examples 13 and 16 may optionally further exhibit that the carrier has a source unit filter or is designed as such.

[0100] In Example 18, the object may optionally further comprise, in addition to one from Example 1 to 17, that the radiation source further comprises at least one from a group consisting of a photodiode and a laser.

[0101] In Example 19, the object from Example 18 may optionally have the cavity radiator having multiple perforations.

[0102] In Example 20, the object may optionally further comprise one of those from Examples 1 to 19, in that the gas chamber is bounded by a reflector designed to reflect electromagnetic radiation emitted by the radiation source.

[0103] In Example 21, the object from Example 20 may optionally further have a reflector with a reflectance in the infrared and / or visible and / or ultraviolet frequency range of at least 20% or at least 50% or at least 80%.

[0104] In Example 22, the object may, in addition to one from Example 1 to 21, optionally have the gas chamber in permanent gas flow connection with the outside of the gas analyzer.

[0105] In Example 23, the object may optionally further comprise one from Examples 1 to 22 such that the radiation source is designed to selectively excite gas molecules of a specific type, which are to be detected in the gas contained in the gas chamber, in a time-varying manner, thereby generating acoustic waves as the physical quantity that indicates the degree of interaction between the electromagnetic radiation emitted by the radiation source and the gas molecules of the type which are to be detected in the gas contained in the gas chamber. The sensor may include, or be designed as, an acoustic wave sensor designed to detect acoustic waves generated by the electromagnetic radiation.

[0106] In Example 24, the object of Example 23 may optionally further have the sensor arranged inside the gas chamber.

[0107] In Example 25, the object of Example 23 may optionally further include the sensor being arranged in a reference gas chamber which is gas-tight and separated from the gas chamber and filled with a reference gas which has a well-defined quantity of gas molecules of the type to be detected in the gas chamber.

[0108] In Example 26, the object may optionally further comprise one of those from Examples 1 to 25, namely that the sensor has or is designed to be an optical sensor capable of detecting electromagnetic radiation emitted by the radiation source.

[0109] Example 27 is a mobile device that includes a gas analyzer from one of Examples 1 to 26.

[0110] In Example 28, the mobile device from Example 27 may also be designed as a mobile phone.

[0111] Even though the invention has been shown and described specifically with reference to certain embodiments, it is obvious to those skilled in the art that various changes to the form and details can be made without departing from the spirit and scope of protection of the invention as defined in the appended claims. The scope of protection of the invention is thus specified by the appended claims, and all modifications that fall within the meaning and scope of equivalence of the claims are therefore considered to be included therein.

Claims

[1] Gas analyzer (100) comprising the following: a gas chamber (102) designed to hold a gas that is to be analyzed; a radiation source (104, 204) designed to emit electromagnetic radiation into the gas chamber (102), wherein the electromagnetic radiation is adapted to disperse gas molecules of a specific type contained in the gas, that is recorded in the gas chamber (102), to be analyzed, selectively excited, wherein the radiation source (104, 204) has a cavity radiator designed as an electrically heatable body or is designed as such; a collimator (122, 222) designed to collimate the electromagnetic radiation emitted by the radiation source (104, 204), wherein the collimator (122, 222) has a concave mirror (234) which is arranged on one side of the radiation source (104, 204) opposite the gas chamber (102), wherein the radiation source (104, 204) has one or more perforations (204a) so that electromagnetic radiation reflected by the collimator (122, 222) can pass through the radiation source (104, 204); a base section (230); a carrier (232) coupled to the base section (230) and supporting the radiation source (104, 204), wherein the carrier (232) is transparent to the electromagnetic radiation emitted by the radiation source (104, 204); and a sensor (106) designed to detect a physical quantity that indicates the degree of interaction between the electromagnetic radiation emitted by the radiation source (104, 204) and the gas to be analyzed. [2] Gas analyzer (100) according to claim 1, wherein the collimator (122, 222) has an optical axis, wherein the radiation source (104, 204) is arranged on the optical axis; where optionally the optical axis intersects the collimator (122, 222). [3] Gas analyzer (100) according to claim 1 or 2, wherein the collimator (122, 222) further comprises at least one from the group consisting of a convex lens, a Bragg mirror and a Fresnel lens; wherein optionally the concave mirror (234) has a reflectance in the infrared and / or visible and / or ultraviolet frequency range of at least 20% or at least 50% or at least 80%. [4] Gas analyzer (100) according to one of claims 1 to 3, wherein the collimator (122, 222) has at least one focal point, wherein the radiation source (104, 204) is arranged in a focal point of the collimator (122, 222). [5] Gas analyzer (100) according to any one of claims 1 to 4, further comprising a filter (112) designed to selectively transmit electromagnetic radiation emitted by the radiation source (104, 204). [6] Gas analyzer (100) according to claim 5, wherein the filter (112) is designed as a tunable filter (112) whose transmission properties are tunable; where optionally the tunable filter (112) includes or is designed to include a plasmonic filter and / or a Fabry-Perot interferometer. [7] Gas analyzer (100) according to claim 5 or 6, wherein the filter (112) has a collimator filter (129, 229) in physical contact with the collimator (122, 222) or is designed as such; where optionally the collimator filter (129, 229) is designed as a filter layer applied to a surface of the collimator (122, 222). [8] Gas analyzer (100) according to any one of claims 1 to 7, further comprising a source unit (124, 224) which has a holder (126, 226) which carries the radiation source (104, 204) and / or the collimator (122, 222), wherein the source unit (124, 224) is designed as a pre-assembled unit; wherein optionally the gas analyzer (100) further comprises a filter designed to selectively transmit electromagnetic radiation emitted by the radiation source (104, 204), wherein the filter is a source unit filter (128, 228) which is carried separately from the collimator (122, 222) and from the holder (126, 226) or is designed as such. [9] Gas analyzer (100) according to claim 8, wherein the base section (230) is essentially ring-shaped and the support (232) is plate-like; and wherein the holder (126, 226) comprises the substantially ring-shaped base section (230) and the plate-like support (232) which carries the radiation source (104, 204). [10] Gas analyzer (100) according to claim 9, wherein the support (232) is made of a material with a thermal conductivity of less than 5 W / (mK). [11] Gas analyzer (100) according to claim 9 or 10, wherein the carrier (232) is designed to selectively transmit electromagnetic radiation emitted by the radiation source (104, 204). [12] Gas analyzer (100) according to one of claims 1 to 11, wherein the radiation source (104, 204) further comprises at least one of a group consisting of a photodiode and a laser. [13] Gas analyzer (100) according to any one of claims 1 to 12, wherein the gas chamber (102) is bounded by a reflector (120) designed to reflect electromagnetic radiation emitted by the radiation source (104, 204), where optionally the reflector (120) has a reflectance in the infrared and / or visible and / or ultraviolet frequency range of at least 20% or at least 50% or at least 80%. [14] Gas analyzer (100) according to any one of claims 1 to 13, wherein the gas chamber (102) is in permanent gas flow connection with the outside of the gas analyzer (100). [15] Gas analyzer (100) according to any one of claims 1 to 14, wherein the radiation source (104, 204) is designed to selectively excite gas molecules of a certain type, which are to be detected in the gas which is taken up in the gas chamber (102), in a time-varying manner, thereby generating acoustic waves as the physical quantity which indicates the degree of interaction between the electromagnetic radiation emitted by the radiation source (104, 204) and the gas molecules of the type which are to be detected in the gas which is taken up in the gas chamber (102), wherein the sensor (106) comprises or is designed as an acoustic wave sensor which is designed to detect acoustic waves which are generated by the electromagnetic radiation. [16] Gas analyzer (100) according to claim 15, wherein the sensor (106) is arranged inside the gas chamber (102). [17] Gas analyzer (100) according to claim 15, wherein the sensor (106) is arranged in a reference gas chamber (108) which is gas-tight and separated from the gas chamber (102) and is filled with a reference gas which has a well-defined quantity of gas molecules of the type to be detected in the gas chamber (102). [18] Gas analyzer (100) according to any one of claims 1 to 17, wherein the sensor (106) comprises or is designed to detect electromagnetic radiation emitted by the radiation source (104, 204).

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