Compact injection-molded optical module for gas detection

Abstract

An optical module component for a gas sensor may include a first housing portion and a second housing portion. The first housing portion and the second housing portion may be configured to be joined together and form a substantially cylindrical optical cavity when joined together. The optical module component may further include: a first opening for receiving light from a light source; at least one second opening for directing light from the optical cavity to a detector; a first curved reflective element configured to direct the light from the light source into the optical cavity; and a second curved reflective element configured to direct the light from the optical cavity to the detector.In particular, optical axes of the first and second curved reflecting elements may be inclined with respect to a diametrical plane of the optical cavity.

Description

Technical FieldThe present disclosure is generally directed to gas sensor modules using, for example, non-dispersive infrared (NDIR) sensing techniques, and more particularly to NDIR gas sensors having a compact optical cavity structure for gas sensing.BackgroundNDIR gas sensors are widely used for detecting the presence and concentration of various gases. Instead of using a dispersive element such as a prism or diffraction grating to separate broadband light into a narrow spectrum suitable for gas sensing, NDIR sensors use a broadband lamp source and an optical filter to select a narrow band spectral range that overlaps with the absorption range of the gas of interest. Generally, NDIR sensors are operated in the infrared (IR) range between 780 nm and 1 mm wavelengths, with the IR light from the broadband lamp source being directed through a sample chamber to an IR detector of the NDIR sensors. Meanwhile, the NDIR sensors are provided with the gas of interest in the sample chamber, causing absorption of certain wavelengths of the IR light. Accordingly, the presence and concentration of the gas can be determined by measuring the attenuation of the absorbed wavelength(s) using the detector. The wavelength for which the gas of interest can be selected can be selected via an optical filter placed in front of the IR detector.In this way, NDIR sensors provide high sensitivity and stability for gas measurement and sensing. On the other hand, conventional NDIR gas sensors require expensive IR optics and components such as filters and detectors to achieve precise measurement. In addition, conventional NDIR gas sensors typically have a large chamber size to achieve better gas absorption. Therefore, the applications of NDIR gas sensors are limited due to their complexity and high implementation costs. It has also long been the challenge to produce NDIR gas sensors of small and compact size.There is a need for an improved, low cost, and compact NDIR gas sensor. Accordingly, the focus of the present disclosure is to propose techniques and / or mechanisms for improving the design and / or manufacture of NDIR gas sensors, and in particular in a compact and cost-effective manner.SummaryIn view of some or all of the above technical problems, the present disclosure generally provides a compact injection molded optical module for gas detection, and more particularly, an optical module component for a gas sensor and a gas sensor having the features of the respective independent claims. According to an aspect of the disclosure, an optical module component for a gas sensor is provided. The optical module component may include a first housing portion and a second housing portion. The first housing portion and the second housing portion may be configured to be connected together and form a substantially cylindrical optical cavity when connected together. In particular, a lower inner surface of the optical cavity may be formed by the first housing portion and an upper inner surface of the optical cavity may be formed by the second housing portion. In addition, the optical module component may further include a first opening for receiving light from a light source and at least one second opening for guiding light from the optical cavity to a detector. In addition, the optical module component may also include a first curved reflective element configured to direct the light from the light source into the optical cavity and a second curved reflective element configured to direct the light from the optical cavity toward the detector. In particular, optical axes of the first and second curved reflective elements may be inclined with respect to a diametrical plane of the optical cavity.It should be noted that the positions of the first and second openings and the positions of the first and second curved reflective elements with respect to the first and second housing portions may be determined according to a wide variety of implementations. For example, the first and second openings may be formed in the first housing portion. For example, the first and second curved reflective members may be formed in the first or second housing portion.As configured above, the optical mold structure according to the present disclosure provides an efficient way to improve the coupling efficiency of the light source into the optical cavity to maximize the light absorption of the gas while keeping the light source relatively far from the main body of the optical cavity. To this end, a configuration of a miniaturized cone optical reflector and a curved reflection mirror may be connected and placed at a very close distance above the light source to reduce the divergence angle of the light beam and guide the light more efficiently into the optical cavity.In some embodiments, the optical module component may further include a guide reflector for coupling the light from the light source into the optical cavity. The guide reflector may have a specific optimum shape for guiding the light to the optical cavity. For example, the guide reflector may have a truncated cone shape. In particular, the guide reflector can be arranged such that a smaller diameter patof the cone shape points to the light source. In some embodiments, the first housing portion may include a flat surface and the guide reflector for coupling the light from the light source into the optical cavity. Further, the second housing portion may include a cylindrical structure and the first and second curved reflective members. In particular, the flat surface of the first housing portion may be positioned to be connected to a circumferential wall of the cylindrical structure of the second housing portion. In addition, the first opening and the second opening may be disposed on the flat surface of the first housing portion. Alternatively, the first housing portion may include a cylindrical structure and the second housing portion may include a flat surface. In this case, the flat surface of the second housing portion may be positioned to be connected to a circumferential wall of the cylindrical structure of the first housing portion, and the first opening and the second opening may be disposed in the cylindrical structure of the first housing portion, optionally at the circumferential wall of the cylindrical structure.In some embodiments, the first and second curved reflective elements may be disposed outside a circumferential inner surface portion of the optical cavity. In particular, the first curved reflective element may be further arranged to direct light originating from a first location below the lower inner surface of the optical cavity into the optical cavity. In addition, the second curved reflective element may be further arranged to direct the light from the optical cavity to a second location below the lower inner surface of the optical cavity.In some embodiments, the first and second openings may be horizontal openings located on the lower inner surface of the optical cavity. The first curved reflective element may extend from the upper inner surface of the optical cavity toward the first opening and the second curved reflective element may extend from the upper inner surface of the optical cavity toward the at least one second opening. The first curved reflective element and the second curved reflective element may be arranged as a respective extending part of the second housing portion or as part of the respective extending part. In particular, the first curved reflective element and the second curved reflective element may be arranged according to a position of the first opening and a position of the second opening, respectively, such that the light is directed through the first curved reflective element from the light source into the optical cavity through the first opening and is directed through the second curved reflective element from the optical cavity through the at least one second opening to the detector.In some embodiments, the respective extending part or a part of the respective extending part of the second housing portion may have an inclined surface on which the respective first and second curved reflecting members are formed. In particular, the inclined surfaces may be positioned corresponding to the position of the first opening and the position of the second opening, respectively.In some embodiments, the first housing portion and the second housing portion may be formed by injection molding. Moreover, the inner surfaces of the optical cavity may be coated with optically reflective material. In particular, the reflective material can be reflective at a wavelength of the light source. For example, the first curved reflective element and the second curved reflective element may each include a respective curved mirror coated with optically reflective material reflective at a wavelength of the light source. In some embodiments, the optical module component may further comprise an optical filter arranged to filter the light from the optical cavity before reaching the detector. The optical filter can then be arranged in the at least one second opening and / or on top of the guide reflector, as mentioned above. In some embodiments, the first aperture and the second aperture may be positioned relative to each other at a 90 degree azimuth angle in the diameter plane of the optical cavity.As configured above, the optical cavity may have a cylindrical shape coated with reflective material at the wavelength of the light source to propagate the coupled-in light to the detector. The optical housing may include a gas inlet / outlet port through which gas and air may flow into the cavity. As the light propagates, it interacts with and can be absorbed by the flowing gases within the cavity. In addition, a miniaturized curved mirror over the detector can direct the light from the optical cavity through an opening (aperture) onto the detector on an external printed circuit board (PCB). In this way, single channel gas sensing can be achieved in a precise and efficient manner, as the light propagation path within the cavity can be increased, thereby improving light absorption by the gas.In some embodiments, the optical module component may further comprise one or more further second openings together with a respective optical filter arranged at predefined angular locations in the first housing portion. Likewise, the one or more respective optical filters may be arranged to filter the light from the optical cavity. In this case, the optical module component may further comprise one or more further second curved reflective elements associated with the one or more further second openings and arranged to direct the light of a respective wavelength of the light source from the optical cavity through the respective further second opening with the respective optical filter to a respective detector. In such embodiments, the first aperture and the second aperture may be positioned relative to each other at a 30-degree or 60-degree azimuth angle in the diameter plane of the optical cavity. Although examples of positioning the first aperture and the second aperture at a 30-degree or 60-degree azimuth angle in the optical cavity diameter plane relative to each other are explicitly mentioned, other azimuth angles instead of 30-degree or 60-degree may also be applied for multi-channel gas sensing applications.In some embodiments, the optical module component may further comprise at least one gas port for serving as a gas inlet to and / or a gas outlet from the optical cavity. The at least one gas port may be disposed on the lower inner surface or the upper inner surface of the optical cavity.According to another aspect of the present disclosure, a gas sensor is provided. The gas sensor may include and be implemented based on (e.g., using) the optical module component having an optical cavity according to the above aspect and any of the embodiments thereof. The gas sensor may also include a printed circuit board (PCB) assembly attached to the optical module component. The PCB arrangement may comprise a light source configured to emit light for propagation in the optical cavity of the optical module component. The PCB arrangement may further comprise an optical detector configured to detect light from the optical cavity of the optical module component.For example, the optical module may include a lower part and an upper part. The lower part of the device may comprise a cylindrical wall having a certain height (e.g. having dimensions in a range of a few millimetres) and two openings for transmitting the light from the light source to the optical detector. The openings above the light source may be a cone reflector having a certain height (e.g., in a range of a few millimeters) and an angle (e.g., 90 degrees) relative to each other for coupling the light into the cavity structure. On the other hand, the upper part of the module may comprise a flat plate closing the cylindrical structure to create an optical cavity and additionally two mirrors reflecting light, one from the light source to the cavity and one from the cavity to the optical filter and detector.For example, the optical module according to the present disclosure may include two curved reflection mirrors having specific physical dimensions and curvatures. The optical module according to the present disclosure may also include a frustoconical reflector having a suitable circular diameter at the top and bottom and having a suitable height from the optical body to a very close distance above the light source. In addition, the optical module may also include two openings positioned, e.g., 90 degrees to each other for the dedicated light source and the detector. However, the position of the openings may also be placed at any predefined angle to each other in the cylinder structure for other implementations. It should be further noted that the optical module may also include a cylindrical structure having a predefined cylinder diameter and wall height, and the cavity may include reflective interior coating surfaces at the light source wavelength.In some embodiments, the guide reflector and the first curved reflecting member may be arranged to be substantially close to the light source. In some embodiments, the PCB arrangement may further comprise an optical filter arranged to filter the light from the optical cavity before reaching the detector. In some embodiments, the PCB arrangement may further comprise a controller configured to drive the light source and process an optical signal of the detected light. The light source may comprise an optical source suitable for gas sensing measurement using NDIR, for example a filament. The optical detector may comprise a light detector suitable for gas detection measurement using NDIR, for example a thermopile. It should be noted that other types of detectors and sources may be used to implement the gas sensor according to the present disclosure.As configured above, the disclosure provides a compact NDIR gas sensor module to detect a predetermined gas of interest using a compact optical cavity structure. The sensor module includes an injection molded optical cavity structure that is clamped / bonded to a printed circuit board (PCB) assembly to provide the entire module. The PCB contains a filament as the optical source, a thermopile as the optical detector, and a microcontroller to drive the filament and process the detected signal. In this way, by integrating miniaturized optical components into the optical body, an efficient gas sensing approach can be provided to improve sensing performance while keeping the housing in a very compact size.According to still another aspect of the present disclosure, a method of manufacturing an optical module component for a gas sensor is provided. The method may include providing a first housing portion and a second housing portion of the optical module component. The method may also include connecting the first housing portion to the second housing portion to form a substantially cylindrical optical cavity. In particular, a lower inner surface of the optical cavity may be formed by the first housing portion and an upper inner surface of the optical cavity may be formed by the second housing portion. The method may further comprise providing a first aperture for receiving light from a light source and providing at least one second aperture for guiding light from the optical cavity to a detector. In particular, the method may additionally comprise providing a first curved reflective element between the first housing portion and the second housing portion for directing the light from the light source into the optical cavity and providing a second curved reflective element between the first housing portion and the second housing portion for directing the light from the optical cavity to the detector. In particular, optical axes of the first and second curved reflective elements may be inclined with respect to a diametrical plane of the optical cavity.In some embodiments, the method may further comprise determining an angle of inclination of the first curved reflective element with respect to the diametrical plane of the optical cavity and an angle of inclination of the second curved reflective element with respect to the diametrical plane of the optical cavity such that the light from the light source is directed through the first curved reflective element into the optical cavity through the first opening and the light from the optical cavity is directed through the second curved reflective element to the detector through the at least one second opening. In some embodiments, the method may further include providing a guide reflector having a frustoconical shape for coupling the light from the light source into the optical cavity. In some embodiments, the method may further include providing a flat surface and the guide reflector for the first housing portion and a cylindrical structure and the first and second curved reflective elements for the second housing portion. In this case, the flat surface of the second housing portion may be positioned to be connected to a peripheral wall of the cylindrical structure of the first housing portion, and the method may further include disposing the first opening and the second opening on the flat surface of the first housing portion.In some embodiments, the method may further include providing a cylindrical structure for the first housing portion and a flat surface for the second housing portion. In this case, the flat surface of the second housing portion may be positioned to be connected to a circumferential wall of the cylindrical structure of the first housing portion, and the method may further include disposing the first opening and the second opening in the cylindrical structure of the first housing portion, and optionally on the circumferential wall of the cylindrical structure.In some embodiments, the first and second curved reflective elements may be disposed outside a circumferential inner surface portion of the optical cavity. In addition, the first curved reflective element may be further arranged to direct light originating from a first location below the lower inner surface of the optical cavity into the optical cavity, and the second curved reflective element may be further arranged to direct the light from the optical cavity to a second location below the lower inner surface of the optical cavity.In some embodiments, the first and second openings may be horizontal openings located on the lower inner surface of the optical cavity. Moreover, the first curved reflective element may extend from the upper inner surface of the optical cavity toward the first opening and the second curved reflective element may extend from the upper inner surface of the optical cavity toward the at least one second opening.In some embodiments, the method may further comprise providing the first curved reflective element and the second curved reflective element as a respective extending part of the second housing portion or as part of the respective extending part. The method may further include arranging the first curved reflective element and the second curved reflective element according to a position of the first opening and a position of the second opening, respectively, such that the light is directed through the first curved reflective element from the light source into the optical cavity through the first opening and is directed through the second curved reflective element from the optical cavity through the at least one second opening to the detector.In some embodiments, the respective extending part or a part of the respective extending part of the second housing portion may have an inclined surface on which the respective first and second curved reflecting members are formed. In particular, the inclined surfaces may be positioned corresponding to the position of the first opening and the position of the second opening, respectively.In some embodiments, the first housing portion and the second housing portion may be provided by injection molding. In some embodiments, the method may further include coating the inner surfaces of the optical cavity with optically reflective material. In some embodiments, the method may further include providing a respective curved mirror as the first and second curved reflective elements and coating the respective curved mirrors with optically reflective material.In some embodiments, the method may further comprise providing an optical filter for filtering the light from the optical cavity before reaching the detector. In particular, the optical filter can be arranged in the at least one second opening and / or on top of the guide reflector, as mentioned above. In some embodiments, the method may further comprise positioning the first aperture and the second aperture relative to each other at a 90 degree azimuth angle in the diameter plane of the optical cavity.In some embodiments, the method may further comprise providing one or more further second openings together with a respective optical filter at predefined angular locations in the first housing portion for filtering the light from the optical cavity and providing one or more further second curved reflective elements associated with the one or more further second openings for directing the light of a respective wavelength of the light source from the optical cavity through the respective further second opening with the respective optical filter to a respective detector. In this case, the first opening and the second opening may be positioned relative to each other at a 30-degree or 60-degree azimuth angle in the diameter plane of the optical cavity.In some embodiments, the method may further comprise providing at least one gas port on the lower inner surface or the upper inner surface of the optical cavity for serving as a gas inlet to and / or a gas outlet from the optical cavity.As configured above, the method for manufacturing an optical module component for a gas sensor according to the present disclosure provides an efficient and accurate way of gas detection because the efficiency of coupling the light source into the optical cavity can be improved, thereby maximizing light absorption of the gas. On the other hand, the light source can be kept relatively far from the main body of the optical cavity. To this end, a configuration of combining a miniaturized cone optical reflector with a curved reflection mirror to be placed at a very close distance above the light source may be adopted to reduce the divergence angle of the light beam and thus guide the light into the optical cavity more efficiently. In particular, the optical cavity may be provided with a cylindrical shape coated with reflective material at the wavelength of the light source to propagate the coupled-in light to the detector. As the light propagates, it interacts with and can be absorbed by the flowing gases within the cavity. In addition, a miniaturized curved mirror over the detector can direct the light from the optical cavity through an opening (aperture) onto the detector on an external printed circuit board (PCB). In this way, single channel gas sensing can be achieved in a precise and efficient manner, as the light propagation path within the cavity can be increased, thereby improving light absorption by the gas.Brief Description of the DrawingsExemplary embodiments of the disclosure will be explained below with reference to the accompanying drawings, wherein like reference numerals indicate like or similar elements, and wherein FIG. 1 schematically illustrates, in a plan view, an exemplary structure of an optical module component 100 for a gas sensor according to embodiments of the present disclosure, FIG. 2 schematically illustrates a cross-sectional view corresponding to a drawing along the line A-A indicated in FIG. 1 , FIG. 3A schematically illustrates, in a three-dimensional (3D) view, an exemplary arrangement within the optical module component 100 for the first housing portion 101 according to embodiments of the present disclosure, FIG. 3B schematically illustrates, in a three-dimensional (3D) view, an exemplary arrangement within the optical module component 100 for the second housing portion 102, according to embodiments of the present disclosure, FIG. 3C schematically illustrates a detailed three-dimensional (3D) view of an exemplary structure of the optical module component 100 with the first housing portion 101 attached to the second housing portion 102, according to embodiments of the present disclosure, FIG. 4 schematically illustrates a cross-sectional view corresponding to a drawing along the line B-B indicated in FIG. 1 , FIG. 5 schematically shows a flow chart illustrating an example of a method 500 for manufacturing an optical module component for a gas sensor according to embodiments of the present disclosure, FIG. 6 schematically illustrates a cross-sectional view of a gas sensor 200 including the optical module component 100 described above with a PCB assembly 112 along line A-A indicated in FIG. 1, according to embodiments of the present disclosure, FIG. 7 schematically illustrates a cross-sectional view of a gas sensor 200 including the optical module component 100 described above with a PCB assembly 112 along the line B-B indicated in FIG. 1, according to embodiments of the present disclosure, FIG. 8A schematically illustrates the PCB assembly 112 to be combined with the optical module component 100 for implementing the gas sensor 200 according to embodiments of the present disclosure, FIG. 8B schematically illustrates the PCB arrangement 112 to be combined with the optical module component 100 for implementing the gas sensor 200 according to embodiments of the present disclosure, FIG. 9A schematically illustrates, in a plan view, another exemplary structure of an optical module component 100 for a gas sensor according to embodiments of the present disclosure, FIG. 9B schematically illustrates a cross-sectional view corresponding to a drawing along the line A-A indicated in FIG. 9A , FIG. 9C schematically illustrates a cross-sectional view corresponding to a drawing along the line B-B indicated in FIG. 9A , FIG. 10A schematically illustrates, in a three-dimensional view, an exemplary arrangement within the optical module component 100 of FIG. 9A for the first housing portion 101 according to embodiments of the present disclosure, FIG. 10B schematically illustrates, in a three-dimensional (3D) view, an exemplary arrangement within the optical module component 100 of FIG. 9A for the second housing portion 102, according to embodiments of the present disclosure, FIG. 10C schematically illustrates a detailed three-dimensional view of an exemplary structure of the optical module component 100 of FIG. 9A with the first housing portion 101 attached to the second housing portion 102, in accordance with embodiments of the present disclosure; and FIG. 11 schematically illustrates the PCB assembly 112 to be combined with the optical module component 100 of FIG. 9A for implementing the gas sensor 200 according to embodiments of the present disclosure.Detailed DescriptionAs indicated above, identical or like reference numerals in the present disclosure may indicate identical or like elements unless otherwise indicated, so repeated description thereof may be omitted for brevity.Non-dispersive infrared (NDIR) gas sensors can detect the presence and concentration of various gases by selecting a narrow band spectral range that overlaps with the absorption range of the gas of interest. As mentioned above, the use of a broadband lamp source and an optical filter integrated into a sample chamber can allow an NDIR sensor to serve as a good candidate for gas measurement. However, such an NDIR sensor is very complex and expensive, which limits its applications.In view of this, the present disclosure generally proposes, in a broad sense, techniques and / or mechanisms for improving the design and / or manufacture of NDIR gas sensors, and in particular in a compact and cost-effective manner.FIG. 1 schematically illustrates, in a plan view, an exemplary structure of an optical module component 100 for a gas sensor according to embodiments of the present disclosure. The optical module component 100 may include, among other things, a first housing portion 101 (not shown), a second housing portion 102, a first opening 104- 1, a second opening 104- 2, a first curved reflective element 105- 1, and a second curved reflective element 105- 2. In particular, the first housing portion 101 and the second housing portion 102 may be connected to each other by injection molding to form a substantially cylindrical optical cavity 103 when both housing portions are connected to each other. Thus, a lower inner surface of the optical cavity 103 may be formed by the first housing portion 101 and an upper inner surface of the optical cavity 103 may be formed by the second housing portion 102. Herein, for illustrative purposes, the first housing portion 101 of the optical module component 100 is shown opaque in FIG. 1, while the second housing portion 102 of the optical module component 100 is shown in a transparent view to illustrate the structural combination of the two housing portions 101, 102 forming the optical gas sensor cavity 103 of the optical module. The first opening 104- 1 of the optical module component 100 may receive light from a light source. The light source may comprise, for example, a filament outside the optical module component 100 (not shown in FIG. 1 ). The second opening 104- 2 of the optical module component 100 may allow light to be directed from the optical cavity 103 to a detector external to the optical module component 100. Without intended limitation, the detector may include, for example, a thermopile as an optical detector external to the optical module component 100 (not shown in FIG. 1 ). The light source may also include other types of optical sources, such as light emitting diodes (LEDs), and the optical detector may also include other types of detectors, such as solid state detectors.Further, the first curved reflective element 105- 1 may direct the light from the (external) light source into the optical cavity 103, and the second curved reflective element 105- 2 may direct the light from the optical cavity 103 to the (external) detector.For better understanding, reference is made to FIGS. 2 and 4, which schematically illustrate a respective side view of the optical module component 100 of FIG. 1 according to embodiments of the present disclosure: FIG. 2 is a cross-sectional view corresponding to a drawing along the line A-A indicated in FIG. 1, and FIG. 4 is a cross-sectional view corresponding to a drawing along the line B-B indicated in FIG. 1. That is, FIGS. 2 and 4 show a respective cross section of both housing sections 101, 102. The same reference numerals shown in FIGS. 2 and 4 as in FIG. 1 may represent the same or similar structure or components that are not repeated here for brevity. As illustrated in FIG. 2, the first opening 104- 1 of the optical module component 100 is arranged to receive light from an external light source, such as a filament 107. As illustrated in FIG. 4, the second opening 104- 2 of the optical module component 100 is arranged to direct light from the optical cavity 103 to an external detector, such as a thermopile 109. In the embodiment, the filament 107 is not part of the optical module component 100, but is part of an (external) electronic board (e.g., a printed circuit board (PCB) as more clearly illustrated in FIGS. 6-8 ) to which the optical module 100 is attached (e.g., by clamping or bonding to attach the optical module to the PCB). Likewise, thermopile 109 is not part of optical module component 100, but is part of the PCB to which optical module component 100 is attached.Since different gases have different absorption wavelengths of their own (e.g., an absorption wavelength of 4.26 mm for CO 2), a corresponding optical filter can be used to filter out the absorption wavelength of the gas of interest from a broad spectrum of the filament light to avoid detecting gases other than the gas of interest. As shown in FIG. 4, an optical filter 110 is additionally placed on the thermopile detector 109 for filtering the light from the optical cavity 103 before reaching the detector 109. Although the optical filter 110 is disposed on the detector as part of the external PCB in the present example, the optical filter 110 may alternatively be placed inside the optical module component 100 (as shown by the dotted circle in FIG. 4 ) in some embodiments if a gas sensor module is to be designed in a smaller size. In this case, the optical module component 100 may also include an optical filter 110 arranged to filter the light from the optical cavity 103.Further, as shown in FIGS. 2 and 4, it is to be noted that optical axes of the first and second curved reflecting members 105- 1, 105- 2 are inclined with respect to a diametrical plane (indicated by the plane P) of the optical cavity 103. The respective inclination angles of the first curved reflecting element 105- 1 and the second curved reflecting element 105- 2 may be adjusted to respectively direct the light from the light source 107 into the optical cavity 103 (as shown by the light propagation path a) and to direct the light from the optical cavity 103 to the detector 109 (as shown by the light propagation path b). In order to improve the efficiency in gas detection, a guide reflector 106 may be provided within the optical module component 100 for coupling the light from the light source 107 into the optical cavity 103. For example, the guide reflector 106 may have a truncated cone shape with a smaller diameter pat facing the light source 107 to increase the coupling efficiency.As illustrated in FIG. 1, the first housing portion 101 may have a cylindrical structure, and the second housing portion 102 may be in the form of a flat surface (e.g., a plate). When both housing portions are combined in a joined position, the flat surface of the second housing portion 102 is positioned to be joined to a circumferential wall of the cylindrical structure of the first housing portion 101. In the embodiment, the first opening 104- 1 and the second opening 104- 2 are arranged in the cylindrical structure of the first housing portion 101 and optionally on the circumferential wall of the cylindrical structure, as also shown in FIGS. 2 and 4. In some embodiments, the first and second curved reflective elements 105- 1, 105- 2 may be disposed outside a circumferential inner surface portion of the optical cavity 103. In particular, the first curved reflective element 105- 1 may be further arranged to direct light originating from a first location below the lower inner surface of the optical cavity into the optical cavity 103, and the second curved reflective element 105- 2 may be further arranged to direct the light from the optical cavity 103 to a second location below the lower inner surface of the optical cavity 103.It should be noted that the arrangement of the optical module component 100 as shown in the above-mentioned figures is merely illustrative and other possible arrangements that allow the light from the light source to be guided within the optical cavity 103 and propagate to reach the detector for the purpose of gas measurement / detection are not excluded from the implementation of the inventive concept proposed by the present disclosure. For example, the first and second openings 104- 1, 104- 2 may be formed in the first housing portion 101, and the first and second curved reflective elements 105- 1, 105- 2 may be formed in the first or second housing portions 101, 102.For example, the first and second openings 104- 1, 104- 2 may be horizontal openings located on the lower inner surface (i.e., bottom) of the optical cavity 103. In addition, the first curved reflective element 105- 1 may extend from the upper inner surface of the optical cavity 103 toward the first opening 104- 1, and the second curved reflective element 105- 2 may extend from the upper inner surface of the optical cavity 103 toward the second opening 104- 2. For example, the first curved reflective element 105- 1 and the second curved reflective element 105- 2 may be arranged as a respective extending part of the second housing portion 102 or as part of the respective extending part and arranged according to a position of the first opening 104- 1 and a position of the second opening 104- 2, respectively, such that the light is directed through the first curved reflective element 105- 1 from the light source 107 through the first opening 104- 1 into the optical cavity 103 (see light propagation path a) and is directed through the second curved reflective element 105- 2 from the optical cavity 103 through the second opening 104- 2 to the detector 109 (see light propagation path b).In some embodiments, the respective extending part or part of the respective extending part of the second housing portion 102 may have an inclined surface on which the respective first and second curved reflective elements 105- 1, 105- 2 are formed. Accordingly, the inclined surfaces may be positioned corresponding to the position of the first opening 104- 1 and the position of the second opening 104- 2, respectively. Note that the inclined surface may be formed (excluding) on a portion of the optical module component 100 that overlaps the light source 107 (e.g., the filament) and the optical detector 109 (e.g., an infrared sensor). In other words, the cylindrical structural wall (i.e., the peripheral wall) has a vertical shape instead of an inclined shape except where the openings 104- 1 and 104- 2 are located, in order to increase the path length of the light propagating inside the cavity 103.It is further noted that the inner surfaces 103- 1, 103- 2 of the optical cavity 103 may be coated with optically reflective material. The reflective material may be reflective at a wavelength of the light source. In addition, the first curved reflective element 105- 1 and the second curved reflective element 105- 2 may each include a respective curved mirror coated with the optically reflective material. In this way, the light reflected from the curved mirror over the filament 107 can circulate within the cylindrical structure (i.e., the optical cavity 103) through multiple reflections from the vertical wall of the cavity 103 to maximize light absorption. Since light absorption depends on the optical path length between the filament 107 and the detector 109, the absorption can be increased by increasing the path length, which further provides a higher sensitivity in gas detection.Moreover, the first opening 104- 1 and the second opening 104- 2 may be positioned relative to each other at a 90-degree azimuth angle in the diameter plane of the optical cavity 103, as shown in FIG. 1. That is, the light source 107 (e.g., the filament) and the optical detector 109 (e.g., an infrared sensor) may not be arranged in series to allow multiple reflections within the cavity 103. This contributes to increasing the optical path length to improve the sensitivity of the gas sensor module.In the above-mentioned embodiments, as illustrated in FIGS. 1 to 4, a second opening for single-channel gas detection is provided. However, in some other embodiments, the optical module component may be implemented as a multi-channel gas sensor by adding, for example, multiple detectors with different optical filters and multiple openings (openings) in the cylinder structure with predetermined angular locations. Accordingly, the optical module component 100 may further include one or more further second openings 104- 2 together with a respective optical filter 110 arranged at predefined angular locations in either the first or the second housing portion 101, 102. Similar to the optical filter as mentioned above, the additional one or more respective optical filters may be arranged to filter the light from the optical cavity 103. In particular, the optical module component 100 further comprises one or more further second curved reflective elements 105- 2 associated with the one or more further second openings 104- 2 and arranged to direct the light of a respective wavelength of the light source 107 from the optical cavity 103 through the respective further second opening 104- 2 with the respective optical filter 110 to a respective detector 109.For example, the optical module component may include another aperture and detector for the reference measurement such that the sensor may be used for two-channel NDIR gas sensing. In the multi-channel NDIR case, the first aperture and the second aperture(s) may be positioned relative to each other at a predefined angle, e.g., a 30-degree or 60-degree azimuth angle in the diameter plane of the optical cavity 103.It is noted that the first housing portion 101 and the second housing portion 102 may be formed by injection molding. As shown in the embodiment of FIGS. 1, 2, and 4, the optical module component 100 of the gas sensor is formed by the first housing portion 101 (as the lower part of the optical cavity 103) and the second housing portion 102 (as the upper part of the optical cavity 103). That is, the optical module component 100 may be provided with a combination of miniaturized optical components integrated into the optical cavity 103 manufactured by injection molding. Thus, the entire optical assembly for the gas sensor may be made from two separate injection molded parts, which are then assembled to form a one-piece optical module component 100. It is further noted that by manufacturing the optical module component in two parts, gas sensor modules can be manufactured by injection molding (e.g., polymer type resin, thermosetting type epoxy resin) to achieve high volume production and low manufacturing cost. For example, the polymer-type resin may be polymethylmethacrylate, referred to as "PMMA", or any other similar polymer-based material. In addition, it is also possible to coat the surface of the optical components (e.g., the shaded portion indicated by the dashed line C in FIG. 1 ) within the optical module component.It is noted that, in addition to injection molding, other suitable techniques for fabricating the internal configuration / structure of the optical module component as described above may also be used without departing from the scope of the present disclosure.In addition, the optical module component 100 may further comprise at least one gas port 108 configured to let gas into the optical cavity 103 and / or to let gas out of the optical cavity 103. The at least one gas port 108 may be arranged on the lower inner surface or the upper inner surface of the optical cavity 103. The at least one gas port 108 of sufficiently large size may function for both the inlet and outlet of gas. In addition, the optical module component 100 may optionally be provided with recessed portions 111- 1, 111- 2 (see FIGS. 2 and 4 ) in the vicinity of the first and second curved reflective members 105- 1, 105- 2 to assist in manufacturing precise curved mirrors (as the first and second curved reflective members 105- 1, 105- 2) in injection molding.A more detailed three-dimensional (3D) view of the proposed gas sensor module is shown in FIGS. 3A to 3C. FIG. 3A schematically illustrates, in a 3D plan view, an exemplary arrangement within the optical module component 100 for the first housing portion 101 according to embodiments of the present disclosure. FIG. 3B schematically illustrates, in a 3D plan view, an exemplary arrangement within the optical module component 100 for the second housing portion 102, according to embodiments of the present disclosure. The same reference numerals shown in FIGS. 3A and 3B as in FIGS. 1, 2, and 4 may represent the same or similar structure or components that are not repeated here for brevity. Here, the first housing portion 101 may be referred to as the lower part of the optical module component 100 forming the lower inner surface of the optical cavity 103, and the second housing portion 102 may be referred to as the upper part of the optical module component 100 forming the upper inner surface of the optical cavity 103. In this embodiment, curved mirrors as the first and second curved reflecting members 105-1, 105-2 are located at the upper part (the first portion 101), while the cylindrical wall 122 and the openings 104-1, 104-2 connected to the cone reflector 106 are located at the lower part (the second portion 102). However, in other embodiments, the positions of the curved reflective elements and the apertures may vary to optimize / minimize the size of the optical module component. For example, the curved reflective elements may alternatively or additionally be arranged together with the openings on the lower part (the second portion 102).In some embodiments, the upper part of the injection molded optical cavity (i.e., the second housing portion 102) may be provided with respective inclined surfaces on which the respective curved mirrors may be formed as the first and second curved reflecting members 105- 1, 105- 2. In this case, the inclined surfaces may be formed mainly or exclusively at portions (of the second housing portion 102) above the light source (filament) 107 shown in FIG. 2 and the optical detector 109 shown in FIG. 4, respectively. In other words, other portions of the upper part of the injection moulded optical cavity may not be provided with an inclined curved surface, but instead with a horizontal flat surface connected to the rest of the cylindrical wall which is vertical.Thus, the flat portion / surface (plate) of the second housing portion 102 may be positioned corresponding to a vertical circumferential wall of the cylindrical structure of the first housing portion 101, and the first and second curved reflective elements 105- 1, 105- 2 are arranged as a respective extending part of the second housing portion 102 or as a part of the respective extending part extending from the flat portion / surface and arranged according to the positions of the first and second openings, respectively, of the first housing portion 101, such that the light is directed through the first curved reflective element 105- 1 from the light source 107 into the optical cavity 103 through the first opening 104- 1 and is directed through the second curved reflective element 105- 2 from the optical cavity 103 to the detector 109 through the second opening 104- 2.As mentioned above, the inner surfaces 103- 1, 103- 2 of the optical cavity 103 may be coated with optically reflective material, as shown in the shaded portion of FIG. 3. It is noted that the inner surface 103- 1 formed by the first housing portion 101 may also include the (inner) surface of the cone reflector 106, which may also be coated with the optically reflecting material. The reflective material may include metal material reflective at a wavelength of the light source, such as aluminum. Accordingly, to fabricate such an optical module for gas sensing as proposed in the present disclosure, injection molding of polymeric material (e.g., resin) may be employed to form the two separate parts (e.g., the lower and upper parts) of the module, followed by coating the inner surfaces of the two parts with, e.g., aluminum (as shown in the shaded area) to allow the light to reflect within the cavity. Subsequently, the two separate parts (i.e. the first and the second housing portion) may be combined with each other via one or more connection elements 120- 1, 120- 2 thereof. As shown in FIGS. 3A and 3B, the connector 120- 2 of the second housing portion (the upper / upper part) 102 may be inserted into the connector 120- 1 of the first housing portion (the lower / upper part) 101 to fix the second housing portion 102 to the first housing portion 101. In this way, the optical cavity 103 may be formed with a cylindrical shape coated with optically reflective material at a wavelength of the light source to guide the input light from the light source to the detector. FIG. 3C schematically illustrates a detailed 3D top view of an exemplary structure of the optical module component 100 having the first housing portion 101 attached to the second housing portion 102, in accordance with embodiments of the present disclosure.As mentioned above, the guide reflector 106 may have a truncated cone shape with a smaller diameter pat facing the light source (not shown). Again, the coated portion of the module is shown in the shaded area. In the embodiment, the frustoconical reflector 106 may have a particular circular diameter at its top and bottom and may have a particular height from the optical module component body (e.g., the first opening) to a very close distance above the light source to better couple the light from the light source into the optical module component cavity 103. The top of the cone reflector 106 may be connected to the first opening 104- 1 at the first housing portion 101, while the bottom of the cone reflector 106 may be remote from the first opening 104- 1 and close above the light source. For example, the circular diameter (e.g., in a millimeter range) at the bottom of cone reflector 106 may be less than the circular diameter at the top of cone reflector 106 (e.g., also in the millimeter range). For example, the cone reflector 106 may have a certain height (e.g., in a range of a few millimeters) from the first opening of the optical module component to a very close distance (e.g., also in the millimeter range or less) above the light source.In some embodiments, the cylindrical structure 103 of the optical module component 100 may have a predefined cylinder diameter (e.g. in a range of a few millimeters to a few centimeters) and a predefined wall height (e.g. in a range of a few millimeters). Accordingly, the optical module component for a gas sensor as proposed in the present disclosure may have, for example, a dimension in a range of a few millimeters to a few centimeters in length (L) and in width (W), and a dimension in a range of a few millimeters in height (H), as illustrated in FIG. 3C. For example, by arranging the openings and the curved reflective members in another manner, it is possible to further reduce the size of the cylindrical structure 103 of the optical module component 100 from the centimeter range to the millimeter range (depending on the predetermined cylinder diameter) to have a reduced-size optical module component for the gas sensor having a dimension, for example, within a range below 10 mm in length (L) and in width (W) and within a range below 5 mm in height (H). It should be noted that the above-mentioned dimensions of the optical module component according to the present disclosure are provided for exemplary purposes only and should not be construed as limiting. It is also possible to reduce the size of the guide reflector to minimize the overall size of the optical module component.It should be further noted that the above-mentioned structure of the optical module component and the above-mentioned arrangement of elements (i.e., internal configuration) within the optical module component according to the present disclosure are provided for exemplary purposes only and are not to be construed as limiting. For example, the cylindrical structure may be located at the upper / upper part of the optical module component and / or the optical filter may be located at a different location than on the detector. According to the present disclosure, various arrangements of the elements within the optical module component and within the scope of the disclosure are possible.The optical module component as described in the previous embodiments may be attached (e.g., by clamping / gluing) to a printed circuit board (PCB) to provide a complete module / apparatus for gas sensing / measurement as shown in FIGS. 6 and 7. FIG. 6 corresponds to FIG. 2, which schematically illustrates a cross-sectional view of a gas sensor 200 including the above-described optical module component 100 having a PCB assembly 112 along the line A-A indicated in FIG. 1, according to embodiments of the present disclosure. FIG. 7 corresponds to FIG. 4, which schematically illustrates a cross-sectional view of a gas sensor 200 including the above-described optical module component 100 having a PCB assembly 112 along the line B-B indicated in FIG. 1, according to embodiments of the present disclosure. The same reference numerals shown in FIGS. 6 and 7 as in FIGS. 1, 2, and 4 may represent the same or similar structure or components that are not repeated here for brevity. In particular, the PCB arrangement 112 may be attached to the optical module component 100 by clamping or gluing and may include a light source (e.g. the filament 107) configured to emit light for propagation in the optical cavity 103 of the optical module component 100 and an optical detector (e.g. the thermopile 109) configured to detect light from the optical cavity 103 of the optical module component 100. The PCB arrangement 112 may also include a controller (e.g., microcontroller) 113 configured to drive the light source 107 and process an optical signal of the detected light. In some embodiments, the PCB arrangement 112 may further include an optical filter 110 arranged (e.g., on the optical detector 109) to filter the light from the optical cavity 103 before reaching the detector 109. The PCB arrangement 112 itself may be implemented in a stacked-layer manner, as shown in FIG. 8. For example, in the example of FIGS. 8A and 8B, the PCB arrangement 112 may be seen to include a respective layer of a light source 107, an optical detector 109, an optical filter 110 (optional), and a microcontroller 113 (optional). These layers may be copper layers or any other suitable material. As mentioned above, in order to achieve a more compact gas sensor device 200, the guide reflector 106 of the optical module component 100 for coupling the light from the light source 107 into the optical cavity 103 may be arranged to be substantially close to the light source 107 on the PCB assembly 112.Accordingly, the gas sensor device 200 as proposed in the present disclosure may be provided, for example, by attaching an injection molded optical cavity structure (i.e., the optical module component 100) to the PCB assembly 112, which may include a filament as the optical source 107, a thermopile as the optical detector 109, and optionally a microcontroller 113 for controlling / driving the light source 107 and the optical detector 109. The PCB arrangement 112 may also include an optical filter 110 disposed on the optical detector 109. In some specific applications, other additional components (e.g., a humidity sensor) may also be included in the PCB assembly 112. It should be noted that the positions of the elements on the PCB assemblies (such as the light source 107, the optical detector 109, and optionally the microcontroller 113 and the optical filter 110) as illustrated in FIGS. 8A and 8B are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. In particular, the optional microcontroller 113 may be placed at any position on the PCB or at an optimal position on the PCB for the purpose of e.g. size minimization.In some (other) embodiments, as illustrated in FIGS. 9 to 11, to reduce the dimensions of the cylindrical structure (e.g., diameter and height) and the guide reflector dimension, the upper housing portion 102 may include the cylindrical structure 122 and the reflective elements ( 105- 1, 105- 2) as shown in FIG. 10B, while the lower part 101 of the optical module may include the flat surface with the (two) openings ( 104- 1, 104- 2) and the guide reflectors 106 as shown in FIG. 10A. Also, the optical filter 110 may optionally be placed in the opening 104- 2 above the detector 109 within the first housing 101 to further reduce the size of the optical module component 100. It is also possible to place the optical filter plate on top of the guiding (cone) reflector.It should be understood that FIGS. 9 to 11 illustrate another exemplary aspect for implementing the optical module component and the gas sensor according to the present disclosure. FIGS. 9A to 9C may correspond to FIGS. 1, 2, and 4, respectively, illustrating a plan view and a side view of the optical module component according to a drawing along the line A-A and the line B-B, respectively, as indicated in the plan view. Also, FIGS. 10A to 10C may correspond to FIGS. 3A to 3C, respectively, illustrating a three-dimensional (3D) view of the first housing portion 101, the second housing portion 102, and the first housing portion 101 fixed to the second housing portion 102 for the optical module component 100. Similarly, FIG. 11 may correspond to FIG. 8A illustrating the PCB assembly 112 to be combined with the optical module component 100 for implementing the gas sensor 200. In particular, the embodiments shown in FIGS. 9 to 11 may have a similar component / structure for the optical module component / gas sensor, which may be represented by the same reference numerals and which are not repeated here for brevity.It is further understood that, as compared to the embodiments of FIGS. 1 to 8, in the embodiments of FIGS. 9 to 11, the positions of the openings ( 104- 1, 104- 2) and the reflector 106 can be shifted from the center of the module side to the corner(s) of the module, so that more space can be provided for the reflector 106. Accordingly, the position of the thermopile (detector 109) and the filament (optical source 107) on the PCB may be changed so that they may be placed at optimal locations for guiding the light within the optical cavity (e.g., to be placed just under the respective openings 104- 1, 104- 2). Further, in the embodiments of FIGS. 1-8, the position of the filter 110 is on the thermopile (i.e., on the printed circuit board), while in the embodiments of FIGS. 9-11, the filter 110 is placed in the cutout of the detector aperture 104- 2, as clearly shown in FIGS. 9C and 10A.The other optical components, such as cone reflector 106 and curved mirrors 105- 1, 105- 2, may be nearly the same size in all embodiments. However, it is noted that the curved mirrors 105- 1, 105- 2 may be a portion of the top surface 102 and / or the cylindrical sidewall 122 may be a portion of the top portion 101 in the embodiments of FIGS. 9-11. Also, the cylindrical cavity 103 may have a smaller diameter and a smaller height in the embodiments of FIGS. 9 to 11 compared to the embodiments of FIGS. 1 to 8. With the arrangement as shown in the embodiments of FIGS. 9 to 11, the size of the optical module component for the gas sensor can be further reduced, for example, up to 10 mm in length (L) and width (W). In addition, as mentioned above, the recess portions 111- 1, 111- 2 are optional and need not necessarily be present as in the example of FIG. 10C.It should be noted that the above-mentioned structure of the optical module component and the above-mentioned arrangement of the elements within the optical module component, as well as the positions of the elements on the PCB arrangements as illustrated in FIGS. 1 to 11, are for illustrative purposes only and should not be construed as limiting the scope of the disclosure.FIG. 5 schematically illustrates a flow chart illustrating an example of a method 500 of manufacturing an optical module component for a gas sensor according to embodiments of the present disclosure. The optical module component may be implemented as, for example, the optical module component 100 in FIGS. 9 to 10, 1 to 4, or the like. In some embodiments, the method 500 may be implemented by injection molding, as appreciated by one of ordinary skill in the art. Alternatively, one of ordinary skill in the art would also be able to use other ways besides injection molding to fabricate the internal configuration / structure of the optical module component, and the present disclosure is not intended to limit the implementation of the method 500 to a particular fabrication technique.In particular, the method 500 may comprise, at step S 510, providing a first housing section 101 of the optical module component 100. The method 500 may further comprise, in step S 520, providing a second housing section 102 of the optical module component 100. Here, according to one of the embodiments, step S 520 is performed after step 510, as shown in FIG. 5. However, step 520 may be performed before step S 510, or may be performed simultaneously with step S 510. In addition, the first housing portion 101 provided in step S 510 comprises the first opening 104- 1 for receiving light from the light source 107 and at least one second opening 104- 2 for guiding light from the optical cavity to the detector 109. According to one of the embodiments, the first housing portion 101 having the first and second openings 104- 1, 104- 2 is formed by injecting a material such as a polymer type resin into a mold and cooling the material with a pressure. That is, the first housing portion 101 and the first and second openings 104- 1, 104- 2 are formed in one step. However, the first housing portion 101 and the first and second openings 104- 1, 104- 2 may be formed in different steps or at different times. That is, the first opening 104- 1 and the second opening 104- 2 may be formed in the first housing portion 101 after providing the first housing portion 101. In addition, the second housing portion 102 provided in step S 520 includes the first curved mirror and the second curved mirror. According to one of the embodiments, like the first housing portion 101, the second housing portion 102 having the first and second curved mirrors is formed by injecting a material such as a polymer type resin into a mold and cooling the material with a pressure. That is, the second housing portion 102 and the first and second curved mirrors are formed in one step. However, the second housing portion 102 and the first and second curved mirrors may be formed in different steps or at different times. That is, the first and second curved mirrors may be formed in the second housing portion 102 after providing the second housing portion 102.Specifically, an optical axis of each of the first and second curved reflecting members (namely, the first and second curved mirrors) may be inclined with respect to a diametrical plane of the optical cavity. As indicated above, the fabrication of these elements / portions of the optical module component 100 may be performed, for example, by injection molding or other suitable techniques that may form the internal configuration / structure of the optical module component as suggested by the present disclosure.The method 500 may further include, at step S 530, providing a reflective coating layer on the surface of the first housing portion 101 of the optical module component 100. The method 500 may further comprise, at step S 540, providing a reflective coating layer on the surface of the second housing portion 102 of the optical module component 100. According to one of the embodiments, at step S 530, the reflective coating layer is formed on the surface of the first housing portion 101 including an inner side of each of the first and second openings 104- 1, 104- 2 after releasing the first housing portion 101 from the molding die. In addition, at step S 540, the reflective coating layer is formed on the surface of the second housing portion 102 including a surface of each of the first and second curved mirrors after releasing the second housing portion 102 from the molding die in one of the embodiments. By performing this step S 540, the first curved mirror coated with the optically reflecting material is formed as the first curved reflecting member 105- 1 for guiding the light from the light source 107 into the optical cavity. Moreover, through this step S 540, the second curved mirror coated with the optically reflecting material is formed as the second curved reflecting member 105- 2 for guiding the light from the optical cavity to the detector 109. Here, according to one of the embodiments, step S 540 is performed after step 530, as shown in FIG. 5. However, step 540 may be performed before step S 530 or may be performed simultaneously with step S 530.The method 500 may further include, at step S 550, placing the optical filter 110 in the second opening 104- 2 located above the detector 109 within the first housing portion 101, as shown in FIG. 9C. Here, the optical filter 110 may be placed on the detector 109 as shown in FIG. 4. In this case, this step S 550 may be skipped.The method 500 may further comprise, at step S 560, connecting the first housing portion 101 to the second housing portion 102. By connecting the first housing portion 101 and the second housing portion 102 to each other, a substantially cylindrical optical cavity is formed. In particular, a lower inner surface of the optical cavity may be formed by the first housing portion 101 and an upper inner surface of the optical cavity may be formed by the second housing portion 102.As configured above, the optical module component having an optical mold structure, the gas sensor, and the method for manufacturing the optical module component according to the present disclosure provide an efficient way to improve the coupling efficiency of the light source into the optical cavity and thus maximize the light absorption of the gas while keeping the light source relatively far from the optical cavity.By arranging the openings and the curved reflective elements at appropriate positions (e.g., at a predefined angle relative to each other), single channel as well as multi-channel gas sensing can be achieved in a precise and efficient manner. In particular, the light propagation path within the cavity can be increased, thereby improving light absorption by the gas. Accordingly, a compact NDIR gas sensor module may also be provided to detect a predetermined gas of interest using a compact optical cavity structure. By integrating miniaturized optical components into the optical body, an efficient gas sensing approach can be provided to improve sensing performance while keeping the housing in a very compact size.It should be noted that the above-described device features correspond to respective method features for reasons of shortage, which however cannot be explicitly described. It is believed that the disclosure of the present document also extends to such method features. In particular, it is understood that the present disclosure relates to methods of manufacturing the optical module component described above and / or to the provision and / or arrangement of respective elements of the optical module component.It is further noted that examples of embodiments of the disclosure are applicable to various system configurations depending on the underline technical fields. In other words, the examples shown in the above-described figures, which are used as the basis for the examples discussed above, are merely illustrative and do not limit the present disclosure in any way. That is, additional other existing and proposed new functionalities available in a corresponding operating environment may be used in connection with examples of embodiments of the present disclosure based on the defined principles.It should also be noted that the disclosed example embodiments may be implemented in many ways using hardware and / or software configurations. For example, the disclosed embodiments may be implemented using dedicated hardware, dedicated software, and / or hardware in conjunction with software executable thereon. The components and / or elements in the figures are merely examples and do not limit the scope of use or functionality of hardware, software in combination with hardware, firmware, embedded logic component, or a combination of two or more such components that implement certain embodiments of the present disclosure.Finally, it should be noted that the description and drawings merely illustrate the principles of the proposed apparatus and methods. Those skilled in the art will be able to implement various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and embodiments outlined in the present document are, in principle, expressly intended for explanatory purposes only to aid the reader in understanding the principles of the proposed apparatus and method. Furthermore, all statements herein providing principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims

An optical module component for a gas sensor, comprising: a first housing portion; and a second housing portion, wherein the first housing portion and the second housing portion are configured to be connected to each other and form a substantially cylindrical optical cavity when connected to each other; and wherein a lower inner surface of the optical cavity is formed by the first housing portion and an upper inner surface of the optical cavity is formed by the second housing portion; wherein the optical module component further comprises: a first opening for receiving light from a light source; at least one second opening for guiding light from the optical cavity to a detector; a first curved reflective element configured to guide the light from the light source into the optical cavity; and a second curved reflective element configured to direct the light from the optical cavity to the detector, wherein optical axes of the first and second curved reflective elements are inclined with respect to a diametrical plane of the optical cavity.The optical module component of claim 1, further comprising: a guide reflector for coupling the light from the light source into the optical cavity, wherein the guide reflector has a frustoconical shape.The optical module component according to claim 2, wherein the first housing portion comprises: a flat surface; and the guide reflector for coupling the light from the light source into the optical cavity, wherein the second housing portion comprises: a cylindrical structure; and the first and second curved reflecting members, wherein the flat surface of the first housing portion is positioned to be connected to a circumferential wall of the cylindrical structure of the second housing portion, and wherein the first opening and the second opening are disposed on the flat surface of the first housing portion.The optical module component of claim 2, wherein the first housing portion comprises a cylindrical structure, wherein the second housing portion comprises a flat surface, wherein the flat surface of the second housing portion is positioned to connect to a circumferential wall of the cylindrical structure of the first housing portion, and wherein the first opening and the second opening are disposed in the cylindrical structure of the first housing portion and optionally on the circumferential wall of the cylindrical structure.The optical module component of claim 1, wherein the first and second curved reflective elements are disposed outside a circumferential inner surface portion of the optical cavity; wherein the first curved reflective element is further disposed to direct light originating from a first location below the lower inner surface of the optical cavity into the optical cavity; and wherein the second curved reflective element is further disposed to direct the light from the optical cavity to a second location below the lower inner surface of the optical cavity.The optical module component of claim 1, wherein the first and second openings are horizontal openings located on the lower inner surface of the optical cavity, and wherein the first curved reflective element extends from the upper inner surface of the optical cavity toward the first opening and the second curved reflective element extends from the upper inner surface of the optical cavity toward the at least one second opening.The optical module component of claim 1, wherein the first curved reflective element and the second curved reflective element are arranged as a respective extending part of the second housing portion or as a part of the respective extending part and are arranged according to a position of the first opening and a position of the second opening, respectively, such that the light is directed through the first curved reflective element from the light source through the first opening into the optical cavity and is directed through the second curved reflective element from the optical cavity through the at least one second opening to the detector.The optical module component according to claim 7, wherein the respective extending part or a part of the respective extending part of the second housing portion has an inclined surface on which the respective first and second curved reflecting members are formed, the inclined surfaces being positioned corresponding to the position of the first opening and the position of the second opening, respectively.The optical module component according to claim 1, wherein the first housing portion and the second housing portion are formed by injection molding.The optical module component of claim 1, wherein the inner surfaces of the optical cavity are coated with optically reflective material.The optical module component of claim 1, wherein the first curved reflective element and the second curved reflective element each comprise a respective curved mirror coated with optically reflective material.The optical module component of claim 2, further comprising: an optical filter arranged to filter the light from the optical cavity before reaching the detector.The optical module component of claim 12, wherein the optical filter is disposed in the at least one second opening and / or on top of the guide reflector.The optical module component of claim 1, wherein the first aperture and the second aperture are positioned relative to each other at a 90 degree azimuth angle in the diameter plane of the optical cavity.The optical module component of claim 1, further comprising: one or more further second apertures together with a respective optical filter disposed at predefined angular locations in the first housing portion, the one or more respective optical filters being arranged to filter the light from the optical cavity, the optical module component further comprising one or more further second curved reflective elements associated with the one or more further second apertures and arranged to direct the light of a respective wavelength of the light source from the optical cavity through the respective further second aperture with the respective optical filter to a respective detector.The optical module component of claim 1, further comprising: at least one gas port for serving as a gas inlet to and / or a gas outlet from the optical cavity, wherein the at least one gas port is disposed on the lower inner surface or the upper inner surface of the optical cavity.A gas sensor comprising: the optical module component having an optical cavity according to any one of claims 1 to 16; a printed circuit board, PCB, assembly attached to the optical module component and comprising: a light source configured to emit light for propagation in the optical cavity of the optical module component; and an optical detector configured to detect light from the optical cavity of the optical module component.The gas sensor according to claim 17 when dependent on claim 2, wherein the guide reflector and the first curved reflecting member are arranged to be substantially close to the light source.The gas sensor of claim 17, wherein the PCB assembly further comprises a controller configured to drive the light source and process an optical signal of the detected light.

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