Apparatus, system, and method of operation for emitting thermal radiation

Abstract

A device (12) for emitting thermal radiation, the device (12) comprising a substrate (24), a membrane (26) (wherein the substrate (24) provides a frame for the membrane (26)), an electrically resistive structure (28) on the membrane (26), and an emitter (32) of thermal radiation arranged above the structure (28), wherein the emitter (32) comprises at least two emitter elements (36) comprising a central emitter element (40) surrounded by one or more peripheral emitter elements (42), and wherein the device (12) is adapted to emit a broad-spectrum thermal radiation. Furthermore, a system (10) and a method (90) for optical gas analysis are disclosed.

Description

Technical Field

[0001] This invention relates to an apparatus for emitting thermal radiation and a method for operating such an apparatus. Such an apparatus may also be referred to as a thermal emitter or an infrared source. Background Technology

[0002] Thermal emitters are key components in gas analysis, utilizing microelectromechanical systems (MEMS) technology to efficiently emit thermal radiation, similar to that of a blackbody. A blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, making it an excellent reference for thermal radiation. MEMS-based thermal emitters typically consist of miniature structures that can be heated to elevated temperatures, enabling them to emit infrared radiation. These devices are precisely designed to achieve desired spectral characteristics, allowing for accurate and selective gas analysis based on the unique absorption and emission spectra of different gases.

[0003] The key advantages of MEMS-based thermal emitters lie in their compact size, rapid electrical modulation, and low power consumption. The integration of MEMS technology allows for the production of miniaturized and energy-efficient thermal emitters, making them ideal for portable and field-deployable gas analysis systems. Precise control over the emission spectrum also enhances the selectivity and sensitivity of these devices, enabling the high-precision detection and analysis of specific gases.

[0004] Thermal emitters have a wide range of applications in gas analysis across various industries. A significant application is in environmental monitoring, where they are used to detect and quantify airborne pollutants. Additionally, thermal transmitters are invaluable in industrial processes such as combustion control and emissions monitoring. They play a crucial role in ensuring the efficiency and compliance of manufacturing processes by providing real-time data on gas composition. In medical applications, thermal emitters are used for respiratory analysis, monitoring of anesthetic gases, and monitoring of patient respiratory status during surgery or intensive care, enabling non-invasive diagnostics through the detection of specific biomarkers. The versatility, compactness, and accuracy of MEMS-based thermal emitters make them indispensable for enhancing gas analysis technologies for a wide range of applications.

[0005] Furthermore, the scalability and versatility of MEMS-based thermal emitters facilitate their widespread applicability to various gas sensing platforms. These emitters can be integrated into sensor arrays, enabling the simultaneous detection of multiple gases in complex environments. For example, in healthcare, the applications of MEMS-based thermal emitters extend beyond respiratory analysis. They are used in medical devices to detect trace gases associated with metabolic processes and diseases.

[0006] With continuous technological advancements, MEMS-based thermal emitters will play a crucial role in the development of next-generation gas sensing technologies. Continued improvements in manufacturing processes and materials used in MEMS devices are expected to further enhance the performance and reliability of thermal emitters. This will, in turn, promote the further development of gas analysis technologies and impact environmental monitoring, industrial processes, medical diagnostics, and more. The combination of MEMS technology and thermal emitters represents a promising prospect in the pursuit of more efficient, portable, and accurate gas sensing solutions.

[0007] The thermal emitter or infrared (IR) source described herein is a micromachined, electrically modulated thermal infrared emitter characterized by true blackbody radiation properties, rapid electrical modulation, low power consumption, high emissivity, and long lifetime. A suitable design is based on a resistance heating element deposited on a thin dielectric membrane suspended on a micromachined silicon structure. Summary of the Invention

[0008] The object of the present invention is to provide an improved device for emitting thermal radiation, an improved system for emitting thermal radiation, and an improved method for operating the device for emitting thermal radiation.

[0009] According to a first aspect, an apparatus for emitting thermal radiation is provided, the apparatus comprising: - Base, - A diaphragm, wherein the substrate provides a framework for the diaphragm. - The resistive structure on the diaphragm, and - Heat radiation emitters arranged above the structure. The transmitter includes at least two transmitter elements. This device is suitable for emitting broadband thermal radiation, and The transmitter element includes a central transmitter element surrounded by one or more peripheral transmitter elements.

[0010] This means that the transmitter has partitions along the direction from the center outwards, while the central transmitter element itself is not partitioned. This is believed to be beneficial in terms of mechanical properties and mechanical optimization. If the transmitter has a circular shape, the radial direction is understood as this outward direction.

[0011] Typically, emitters are fully connected layers (i.e., monolithic structures) to maximize the radiating surface area. However, the inventors recognized a problem: when the device is rapidly cycled through temperature variations exceeding 500°C, significant amounts of thin-film stress accumulate. This can lead to deformation of the emitter layer and subsequent delamination.

[0012] Therefore, the inventors have recognized a solution to this problem: dividing a relatively thick emitter layer into at least two emitter elements. Each emitter element is smaller than the emitter, and all emitter elements together form the emitter. The technical advantage is that the emitter is configured such that different regions can expand and contract according to their respective local temperatures without causing device failure. Furthermore, if the emitter and the resistive structure are in electrical contact (and both are conductive), segmenting the emitter reduces electrical interactions between the two elements, such as current flow. Preferably, the upper surface of the resistive structure is at least generally arranged in a plane (e.g., the XY plane). Segmentation or partitioning generally allows for a reduction in the influence of the emitter layer on the mechanical and electrical properties of the system. Since the two layers (i.e., the emitter layer and the resistive structure layer) are connected, there will always be some interaction, but by introducing spacing (especially spacing only in the emitter material), its dominance is reduced.

[0013] In a preferred embodiment, the emitter is positioned at the center of the diaphragm. The device is configured such that the thermal radiation provided by the device has a spectrum similar to that of Planck's blackbody radiation. The device has various applications, including safety applications in medical gas sensing, toxic gas detection, explosive gas leak detection, and refrigerant gas detection (toxic or contaminant). The device can provide an approximately constant spectral emissivity greater than 0.80 or greater than 0.85 over a wide wavelength range (at least 2 µm to 15 µm in the preferred embodiment).

[0014] In a preferred embodiment, the size of the transmitter is smaller than the size of the diaphragm. Additionally, the size of the transmitter can be at least 60% of the size of the diaphragm. It should be noted in this context that the term "size" as used herein does not refer to volume, but rather to a two-dimensional area, particularly an area, perpendicular to the main emission direction from the transmitter.

[0015] In a preferred embodiment, at least two transmitter elements have substantially the same surface area for each of these elements. In this context, the terminology generally indicates a maximum deviation of + / - 20%, preferably + / - 10%, and particularly + / - 5%.

[0016] It is important to note that the feature of the transmitter element, including the central transmitter element surrounded by one or more peripheral transmitter elements, is optional. This feature can be omitted if the desired beneficial technical effect is not intended to be achieved. Elements of the invention can be practiced without this feature.

[0017] According to the improvements, the device is suitable for emitting a broadband infrared spectrum between 1 µm and 15 µm, particularly between 2 µm and 12 µm, and particularly between 2 µm and 7 µm.

[0018] This is the preferred spectrum of thermal radiation, and the corresponding wavelength range is such that at least about 90% or at least about 95% of the total emitted light power is taken into account.

[0019] According to further improvements, the transmitter includes at least four, particularly at least five, particularly at least six, particularly at least seven elements.

[0020] As explained above, existing technologies suggest that the emitter is a monolithic structure to maximize the radiating surface area. This general principle can also be applied to this device, namely, the number of emitter elements should be as small as possible to maximize the radiating surface area. However, contrary to this assumption, the inventors have found that some division into multiple emitter elements is beneficial, given the recognized advantages that different regions can expand and contract according to their respective local temperatures without causing device failure. Furthermore, it is believed that the growth of the emitter layer, especially when manufactured using electrochemical processes, can be improved.

[0021] With further improvements, the transmitter has a circular shape.

[0022] This circular shape allows for a uniform temperature distribution in all directions of the emitter.

[0023] As a further improvement, a transmitter element with a circular symmetrical pattern was designed.

[0024] Circular symmetrical patterns can advantageously achieve or improve uniform growth.

[0025] With further improvements, the transmitter has a square or octagonal shape.

[0026] It is worth noting that, generally speaking, emitters with a circular shape best fit the isopleths of the temperature field, where the temperature isopleths on a circular diaphragm will be circular due to symmetry. Following the geometry of these isopleths is expected to reduce stress. In particular, the corners of the diaphragm often experience stress peaks. Square diaphragms can be easily fabricated using KOH etching (wet etching). On a square diaphragm, the isopleths will be circular at the center and become squarish-circular (square with rounded edges) outwards. The inventors have found that partitioning along the isopleths is a good guiding method, where deviations from the idealized shape in the diagram are acceptable. Furthermore, the inventors have found that an octagon is an approximation of a circle within a square diaphragm, and that an octagon uses a larger surface area than a circle when placed within the same square diaphragm. Therefore, this shape represents a previously unrecognized tradeoff between symmetry, uniform temperature distribution, and filling the diaphragm with emitter material to improve output power. This is especially true if the octagon is irregular (e.g., a square with chamfered corners).

[0027] With further improvements, the transmitter elements are arranged in a spoked wheel configuration.

[0028] This arrangement is beneficial for certain applications and, depending on the characteristics being focused on (especially when optimizing mechanical properties).

[0029] With further improvements, the ratio of the area of ​​the central component to the area of ​​the peripheral components is between 50% and 150%, particularly between 75% and 125%.

[0030] The ratio between the areas of the central portion and one of the outer portions can play a significant role in the uniformity of platinum black growth on the chip. Additionally, thermal stress depends on the characteristic dimensions of the different partitions passing through the emitter layer. To further minimize membrane stress, the entire diaphragm should be able to deform slightly with temperature. It is noteworthy that mechanical deformation (e.g., bending) is much greater than the diaphragm thickness. As an example, in actual testing, approximately 20 µm of deformation was observed in a 0.5 µm thick diaphragm at a peak temperature of approximately 500 °C.

[0031] According to further improvements, the separation gap between the two transmitter elements has the same shape as the periphery of the transmitter.

[0032] This improvement can help decouple the properties of the transmitter and the resistive element (i.e., the heater).

[0033] According to further improvements, the separation gap between the first transmitter element and the second transmitter element has a width between 1 µm and 80 µm, particularly between 2 µm and 60 µm, particularly between 3 µm and 40 µm, and particularly between 5 µm and 30 µm.

[0034] These values ​​were determined to be a technically advantageous compromise between achieving the narrowest possible separation for a high fill factor and high efficiency, and the necessary wide separation to provide electrical insulation / prevention of current flow and reduced stress.

[0035] With further improvements, the transmitter is segmented in both the radial and circumferential directions.

[0036] To further minimize membrane stress, the entire diaphragm should be able to deform slightly with temperature (see above). Therefore, it is recommended that the emitter be partitioned along a first direction outward from the center and a second direction perpendicular to the first direction. If the emitter has a circular shape, the first direction can be understood as the radial direction, and the second direction can be understood as the circumferential or tangential direction.

[0037] In a preferred embodiment, the transmitter is segmented along a first direction (particularly the radial direction) into, for example, at least two, particularly at least three transmitter elements, and along a second direction (particularly the tangential direction) into, for example, at least two, particularly at least three, particularly at least four, particularly at least five, particularly at least six, particularly at least eight elements.

[0038] According to further improvements, the size of the transmitter is at least 70%, particularly at least 80%, particularly at least 85%, particularly at least 90% of the size of the diaphragm.

[0039] These values ​​have been found to be beneficial in terms of efficiency.

[0040] According to further improvements, the emitter may include or be made of metallic black (especially platinum black).

[0041] Metallic black, and especially platinum black, exhibits advantageous properties for the intended use (meaning the intended emission of thermal radiation). In some preferred embodiments, the emitter is made of metallic black (particularly platinum black).

[0042] According to a second aspect, a system for optical gas analysis is provided, the system comprising: - The apparatus as described above is adapted to emit first light through the gas to be analyzed; - At least one optical sensor; and - An analyzer, wherein the analyzer is adapted to determine the concentration of at least one gas of at least one component of a gas based on a second light detected by at least one optical sensor, wherein passing through the gas causes the first light to change into the second light.

[0043] According to a third aspect, a method for optical gas analysis is provided, the method comprising the following steps: - Use the device described above to emit thermal radiation as a first light through the gas to be analyzed; - Detecting the second light, wherein passing through the gas causes the first light to change into the second light; and - Based on the detected second light, determine the concentration of at least one gas of at least one component of the gas.

[0044] It should be understood that the above features and the features to be explained below can be used not only in the combinations specified in each case, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description

[0045] Embodiments of the present invention are shown in the accompanying drawings and explained in more detail in the following description. In the accompanying drawings: Figure 1An embodiment of a system for optical gas analysis is shown.

[0046] Figure 2 A cross-section of the overall structure of the device for emitting thermal radiation is shown.

[0047] Figure 3 First, second, and third embodiments of a device for emitting thermal radiation are shown.

[0048] Figure 4 Fourth, fifth, and sixth embodiments of a device for emitting thermal radiation are shown.

[0049] Figure 5 The seventh, eighth, and ninth embodiments of a device for emitting thermal radiation are shown.

[0050] Figure 6 The tenth, eleventh, and twelfth embodiments of a device for emitting thermal radiation are shown.

[0051] Figure 7 The thirteenth, fourteenth, and fifteenth embodiments of a device for emitting thermal radiation are shown.

[0052] Figure 8 The sixteenth, seventeenth, and eighteenth embodiments of the device for emitting thermal radiation are shown.

[0053] Figure 9 An embodiment of a method for optical gas analysis is shown. Detailed Implementation

[0054] Figure 1 An embodiment of a system 10 for optical gas analysis is shown. System 10 includes a device 12 for emitting thermal radiation in the form of a first light 14, here in the infrared range. The device 12 emits the first light 14 through the gas 16 to be analyzed (shown as a small dot in the figure).

[0055] System 10 also includes at least one light sensor 18 and an analyzer 20. The analyzer 20 determines the concentration of at least one gas of at least one component of gas 16 based on a second light 22 detected by the at least one light sensor 18.

[0056] The relationship between the first light 14 and the second light 22 is that the first light 14 transforms into the second light 22 when it passes through a gas. This transformation occurs because certain wavelengths contained in the first light are attenuated by the gas, thus producing the second light. Since different gases attenuate the first light in different ways, the second light can provide an indication of the type and concentration of the gas.

[0057] Figure 2A cross-section of the overall arrangement of a device 12 for emitting thermal radiation (especially infrared light) is shown. The device 12 includes a substrate 24 and a diaphragm 26, wherein the substrate 24 provides a frame for the diaphragm 26. It can be seen that the substrate 24 has a cavity that exposes a region at the bottom of the diaphragm 26. The cavity in the substrate 24 is typically formed by etching, giving the substrate 24 a frame-like shape.

[0058] A resistive structure 28 is disposed on a diaphragm 26. The resistive structure 28 is embedded in an optional passivation layer 30. The structure 28 is at least generally disposed in a plane. In this description, this plane is perpendicular to the drawing layer, i.e., it extends toward the observer of the drawing. Along a given orientation, this plane is the XY plane.

[0059] A thermal radiation emitter 32 is disposed above structure 28. Emitter 32 is typically covered by a passivation layer (not shown). The resistive structure 28 is heated by allowing current to flow through it. Heat from structure 28 is received by emitter 32 and then emitted as infrared light or transferred as heat to the surrounding air or gas and other structures. Emitter 32 is configured to provide desired radiation characteristics. Emitter 32 has an upper surface 48.

[0060] Figure 3 (a) A first embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a circular shape and is divided into two emitter elements 36 by a separating gap 34, wherein each emitter element 36 has a semi-circular shape. The separating gap 34 passes through the center 38 of the emitter 32.

[0061] Figure 3 (b) A second embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a circular shape and is divided into four emitter elements 36 by two separating gaps 34, wherein each emitter element 36 has a shape resembling a quarter circle. The separating gaps 34 pass through the center 38 of the emitter 32.

[0062] Figure 3 (c) A third embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a circular shape and is divided into six emitter elements 36 by three dividing gaps 34, wherein each emitter element 36 has a shape resembling a 60° circular sector. The dividing gaps 34 pass through the center 38 of the emitter 32. This arrangement is considered to be a spoked wheel configuration.

[0063] Figure 4(a) A fourth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a circular shape and is divided into two emitter elements 36 by a separating gap 34, specifically a central emitter element 40 having a circular shape and a peripheral emitter element 42 having an annular shape. Both emitter elements 36 have the same center, which corresponds to the center 38 of the emitter 32. The separating gap 34 is circular around the center 38 of the emitter 32. Preferably, the size of the central emitter element 40 is at least 2%, preferably at least 3%, more preferably at least 5%, and particularly greater than 10% of the total size of the emitter 32. As can be seen from this fourth embodiment and all subsequent embodiments including the central emitter element 40, the shape of each peripheral emitter element 42 is different from the shape of the central emitter element 40.

[0064] Figure 4 (b) A fifth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The fifth embodiment differs from the fourth embodiment in that, although the emitter 32 has the same dimensions, the central emitter element 40 of the fifth embodiment has a larger radius, thereby reducing the thickness of the annulus, i.e., the difference between the outer radius and the inner radius of the annulus.

[0065] Figure 4 (c) A sixth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a circular shape and is divided into three emitter elements 36 by two separating gaps 34, specifically a central emitter element 40 with a circular shape and two peripheral emitter elements 42 (each of which has an annular shape). All three emitter elements 36 have the same center, which corresponds to the center 38 of the emitter 32. The separating gaps 34 are circles with different radii around the center 38 of the emitter 32.

[0066] Figure 5 (a) shows a seventh embodiment of the emitter 32 of the device 12 for emitting thermal radiation. The emitter 32 has a circular shape and is divided into seven emitter elements 36 by seven dividing gaps 34, particularly a central emitter element 40 with a circular shape and six peripheral emitter elements 42 (each of which has a shape like a 60° annular fan). In terms of overall orientation, the dividing gaps 34 are directed toward the center 38 of the emitter 32, thereby avoiding the area of ​​the central emitter element 38.

[0067] Figure 5(b) shows an eighth embodiment of the emitter 32 of the device 12 for emitting thermal radiation. The eighth embodiment differs from the seventh embodiment in that, although the emitters 32 have the same dimensions, the central emitter element 40 of the eighth embodiment has a larger radius, thereby reducing the size of the peripheral emitter elements 42.

[0068] Figure 5 (c) A ninth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The ninth embodiment differs from the seventh embodiment in that the six peripheral emitter elements 40 are further divided by an additional circular dividing gap 34, the center of which is shared with the center 38 of the emitter 32. Thus, the ninth embodiment comprises a total of one central emitter element 40 and twelve peripheral emitter elements 42. Figure 5 All arrangements in (a)-(c) are considered as spoked wheel configurations.

[0069] Figure 6 (a) A tenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a square shape and is divided into two emitter elements 36 by a partition gap 34, wherein each emitter element 36 has a rectangular shape like a semi-square. The partition gap 34 passes through the center 38 of the emitter 32 and extends perpendicular to the corresponding side of the emitter 32.

[0070] Figure 6 (b) An eleventh embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a square shape and is divided into four emitter elements 36 by two partition gaps 34, wherein each emitter element 36 has a square shape. The partition gaps 34 pass through the center 38 of the emitter 32, extend perpendicular to the corresponding side of the emitter 32, and are perpendicular to each other.

[0071] Figure 6 (c) A twelfth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a square shape and is divided into four emitter elements 36 by two dividing gaps 34, wherein each emitter element 36 has a triangular shape. The dividing gaps 34 pass through the corners 44 of the emitter 32 and are perpendicular to each other.

[0072] Figure 7(a) A thirteenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a square shape and is divided into two emitter elements 36 by a separating gap 34, specifically a central emitter element 40 having a square shape and a peripheral emitter element 42 having a hollow square shape. The separating gap 34 has a square shape. The center of the emitter element 36 and the separating gap 34 corresponds to the center 38 of the emitter 32. This embodiment is one of the examples shown, wherein the separating gap separating the two emitter elements 36 has the same shape as the periphery 50 of the emitter 32.

[0073] Figure 7 (b) A fourteenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The emitter 32 has a square shape and is divided into three emitter elements 36 by two partition gaps 34, specifically a central emitter element 40 with a square shape and two peripheral emitter elements 42 with a hollow square shape. All three emitter elements 36 have the same center, which corresponds to the center 38 of the emitter 32. The partition gaps 34 are squares with different side lengths around the center 38 of the emitter 32.

[0074] Figure 7 (c) A fifteenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation is shown. The fifteenth embodiment differs from the fourteenth embodiment in that it has two additional separating gaps 34 that pass through the angle 44 of the emitter 32 and are perpendicular to each other. Therefore, the fifteenth embodiment includes a total of twelve emitter elements 36.

[0075] Figure 8 (a) shows a sixteenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation. The emitter 32 has a square shape and is divided into five emitter elements 36 by five partition gaps 34, particularly a central emitter element 40 with a square shape and four peripheral emitter elements 42 (each of which has a trapezoidal shape). In terms of overall orientation, the four partition gaps 34 are directed toward the center 38 of the emitter 32, thereby avoiding the area of ​​the central emitter element 38.

[0076] Figure 8 (b) shows a seventeenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation. The emitter 32 has an octagonal shape and is divided into eight emitter elements 36 by four dividing gaps 34. The dividing gaps 34 pass through the center 38 of the emitter 32.

[0077] Figure 8(c) shows an eighteenth embodiment of the emitter 32 of the device 12 for emitting thermal radiation. The emitter 32 has an octagonal shape and is divided into nine emitter elements 36 by nine dividing gaps 34, particularly a central emitter element 40 with an octagonal shape and eight peripheral emitter elements 42 (each of which has a trapezoidal shape). In terms of overall orientation, the dividing gaps 34 pass through the center 38 of the emitter 32 but avoid the area of ​​the central emitter element 38. Figure 8 Both arrangements in (b) and (c) are considered as spoked wheel configurations.

[0078] Figure 9 An embodiment of a method 90 for optical gas analysis is shown, the method comprising an operating device 12. In a first step, using the previously described device, thermal radiation as a first light 14 is emitted S10 through the gas 16 to be analyzed. As it passes through the gas 16, the first light 14 changes into a second light 22, i.e., the spectrum of the light (particularly with respect to the amplitude at different wavelengths) changes. This second light 22 is detected S12. Based on the detected second light 22, the concentration of at least one gas of at least one component of the gas 16 is determined S14.

[0079] According to this disclosure, a first aspect (aspect 1) includes an apparatus for emitting thermal radiation, the apparatus comprising a substrate, a diaphragm (wherein the substrate provides a frame for the diaphragm), a resistive structure on the diaphragm, and an emitter of thermal radiation disposed above the structure, wherein the emitter comprises at least two emitter elements, wherein the apparatus is adapted to emit broadband thermal radiation, and wherein the emitter elements include a central emitter element surrounded by one or more peripheral emitter elements.

[0080] In aspect 2, the apparatus of aspect 1 is optionally adapted to emit thermal radiation having a spectral width between 1 µm and 15 µm, particularly having a spectral width between 2 µm and 12 µm, particularly having a spectral width between 2 µm and 7 µm.

[0081] In aspect 3, the transmitter of one or both of aspects 1 and 2 may optionally include at least four, particularly at least five, particularly at least six, particularly at least seven transmitter elements.

[0082] In aspect 4, the transmitter of one or any combination of aspects 1-3 may optionally have a circular shape.

[0083] In aspect 5, the device of one or any combination of aspects 1-4 may optionally be provided with a transmitter element of a circular symmetrical pattern.

[0084] In aspect 6, the transmitter of one or any combination of aspects 1-5 may optionally have a square or octagonal shape.

[0085] In aspect 7, the apparatus of one or any combination of aspects 1-6 may optionally include a separating gap that separates two transmitter elements, the separating gap having the same shape as the periphery of the transmitter.

[0086] In aspect 8, the device of one or any combination of aspects 1-7 may optionally have a ratio of the area of ​​the central transmitter element to the area of ​​the peripheral transmitter element between 50% and 150%, particularly between 75% and 125%.

[0087] In aspect 9, the device of one or any combination of aspects 1-8 may optionally have a transmitter element arranged in a spoked wheel configuration.

[0088] In aspect 10, the transmitter of one or any combination of aspects 1-9 may optionally be segmented both radially and tangentially.

[0089] In aspect 11, the device of one or any combination of aspects 1-10 may optionally have a separation gap between the first transmitter element and the second transmitter element, the separation gap having a width between 1 µm and 100 µm, particularly between 5 µm and 75 µm, particularly between 10 µm and 60 µm, particularly between 15 µm and 50 µm.

[0090] In aspect 12, one or any of the emitters of aspects 1-11 may optionally have at least 70%, particularly at least 80%, particularly at least 85%, particularly at least 90% of the size of the diaphragm.

[0091] Aspect 13 includes a system for optical gas analysis, the system comprising means of one or any combination of aspects 1-12, the means being adapted to emit a first light through a gas to be analyzed; at least one photosensitive sensor; and an analyzer, wherein the analyzer is adapted to determine the concentration of at least one gas of at least one component of the gas based on a second light detected by the at least one photosensitive sensor, wherein passing through the gas causes the first light to change into the second light.

[0092] Aspect 14 includes a method for optical gas analysis, the method comprising the steps of: emitting thermal radiation as a first light through a gas to be analyzed using a device of one or any combination of aspects 1-12; detecting a second light, wherein the first light is transformed into the second light by passing through the gas; and determining the concentration of at least one gas of at least one component of the gas based on the detected second light.

Claims

1. A device (12) for emitting thermal radiation, the device (12) comprising: - Base (24) - A diaphragm (26), wherein the substrate (24) provides a framework for the diaphragm (26). - The resistive structure (28) on the diaphragm (26), and - A heat radiation emitter (32) arranged above the structure (28), The transmitter (32) includes at least two transmitter elements (36). The device (12) is adapted to emit broadband thermal radiation. The transmitter element (36) includes a central transmitter element (40) surrounded by one or more peripheral transmitter elements (42). The size of the central transmitter element (40) is at least 3% of the total size of the transmitter (32), and The shape of each peripheral transmitter element (42) is different from that of the central transmitter element (40).

2. The apparatus (12) according to claim 1, wherein, The device (12) is adapted to emit thermal radiation with a spectral width between 1 µm and 15 µm, particularly with a spectral width between 2 µm and 12 µm, particularly with a spectral width between 2 µm and 7 µm.

3. The apparatus (12) according to claim 1, wherein, The transmitter (32) comprises at least four, particularly at least five, particularly at least six, particularly at least seven transmitter elements (36).

4. The apparatus (12) according to claim 1, wherein, The transmitter (32) has a circular shape.

5. The apparatus (12) according to claim 1, wherein, The transmitter element (36) is designed with a circular symmetrical pattern.

6. The apparatus (12) according to claim 1, wherein, The transmitter (32) has a square or octagonal shape.

7. The apparatus (12) according to claim 1, wherein, The separation gap (34) separating the two transmitter elements (36) has the same shape as the periphery (50) of the transmitter (32).

8. The apparatus (12) according to claim 1, wherein, The ratio of the area of ​​the central transmitter element (40) to the area of ​​the peripheral transmitter element (42) is between 50% and 150%, particularly between 75% and 125%.

9. The apparatus (12) according to claim 1, wherein, The transmitter element (36) is arranged in a spoked wheel configuration.

10. The apparatus (12) according to claim 1, wherein, The transmitter (32) is segmented both radially and tangentially.

11. The apparatus (12) according to claim 1, wherein, The separation gap (34) between the first transmitter element (36) and the second transmitter element (36) has a width of 1 µm and 100 µm, particularly 5 µm and 75 µm, particularly 10 µm and 60 µm, particularly 15 µm and 50 µm.

12. The apparatus (12) according to claim 1, wherein, The size of the transmitter (32) is at least 70%, particularly at least 80%, particularly at least 85%, particularly at least 90% of the size of the diaphragm (36).

13. A system (10) for optical gas analysis, the system (10) comprising: - The device (12) according to any one of claims 1 to 12 is adapted to emit a first light (14) through the gas (16) to be analyzed. - At least one optical sensor (18); and - Analyzer (20), wherein the analyzer (20) is adapted to determine the concentration of at least one gas of at least one component of the gas (16) based on a second light (22) detected by the at least one optical sensor (18), wherein the first light (14) is transformed into the second light (22) through the gas (16).

14. A method (90) for optical gas analysis, the method comprising the following steps: - Using the apparatus according to any one of claims 1 to 12, thermal radiation as a first light is emitted (S10) through the gas (16) to be analyzed; - Detect (S12) the second light, wherein passing through the gas (16) causes the first light (14) to change into the second light (22); and - Determine (S14) the concentration of at least one gas of at least one component of the gas (16) based on the detected second light (22).

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