Compact injection molded optical module for gas sensing

Abstract

The invention relates to a compact injection molded optical module for gas sensing. An optical module assembly 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 connected together and when connected together form a substantially cylindrical optical cavity. The optical module assembly may further include a first opening to receive light from the light source; at least one second opening for passing light from the optical cavity to a detector; a first curved reflective element configured to direct the light from the light source to the optical cavity; and a second curved reflective element configured to direct the light from the optical cavity to the detector. In particular, an optical axis of the first curved reflective element and an optical axis of the second curved reflective element may be inclined with respect to a diametral plane of the optical cavity.

Description

Technical Field

[0001] The present disclosure generally relates to gas sensor modules, such as those using non-dispersive infrared (NDIR) sensing technology, and more particularly to NDIR gas sensors having a compact optical cavity structure for gas detection. Background Art

[0002] NDIR gas sensors are widely used to detect the presence and concentration of various gases. Instead of using a dispersive element (such as a prism or diffraction grating) to split broadband light into narrow spectral bands suitable for gas sensing, NDIR sensors employ a broadband light source and an optical filter to select a narrow spectral band that overlaps with the absorption region of the gas of interest. Generally, NDIR sensors operate in the infrared (IR) range between a wavelength of 780 nm and a wavelength of 1 mm, where IR light from the broadband light source is directed through a sample chamber towards the IR detector of the NDIR sensor. At the same time, the gas of interest is provided in the sample chamber, which results in the absorption of specific wavelengths of the IR light. Thus, the presence and concentration of the gas can be determined by measuring the attenuation of the (multiple) absorbed wavelengths using the detector. The wavelength of the gas of interest can be selected by an optical filter placed in front of the IR detector.

[0003] In this way, NDIR sensors provide high sensitivity and stability for gas measurement and detection. On the other hand, in order to achieve accurate measurements, traditional NDIR gas sensors require expensive IR optical elements and components, such as filters and detectors. In addition, in order to achieve better gas absorption, traditional NDIR gas sensors typically have a relatively large chamber size. Therefore, due to the complexity and high implementation cost of NDIR gas sensors, their applications are limited. Manufacturing small and compact NDIR gas sensors has also been a long-standing challenge.

[0004] Therefore, there is a need for an inexpensive and compact NDIR gas sensor. Thus, the focus of the present disclosure is to propose techniques and / or mechanisms for improving the design and / or manufacture of NDIR gas sensors, more specifically in a compact and cost-effective manner. Summary of the Invention

[0005] In view of the above-described technical problems in part or in whole, the present disclosure generally provides a compact injection-molded optical module for gas sensing, specifically an optical module assembly for a gas sensor, and a gas sensor having the features of the corresponding independent claims.

[0006] According to one aspect of the present disclosure, an optical module assembly for a gas sensor is provided. The optical module assembly 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, when connected together, form a substantially cylindrical optical cavity. Specifically, the lower inner surface of the optical cavity may be formed by the first housing portion, and the upper inner surface of the optical cavity may be formed by the second housing portion. Additionally, the optical module assembly may further include: a first opening for receiving light from a light source; and at least one second opening for transmitting light from the optical cavity to a detector. Additionally, the optical module assembly may further include: a first curved reflecting element configured to direct light from the light source towards the optical cavity; and a second curved reflecting element configured to direct light from the optical cavity towards the detector. Specifically, the optical axis of the first curved reflecting element and the optical axis of the second curved reflecting element may be inclined with respect to the diameter plane of the optical cavity.

[0007] It should be noted that the positions of the first opening and the second opening and the positions of the first curved reflecting element and the second reflecting element with respect to the first housing portion and the second housing portion may be determined according to various embodiments. For example, the first opening and the second opening may be formed in the first housing portion. For example, the first curved reflecting element and the second curved reflecting element may be formed in any one of the first housing portion and the second housing portion.

[0008] Configured as described above, the optical shaping structure according to the present disclosure provides an effective 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, the configurations of the miniaturized optical conical reflector and the curved 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 more effectively direct the light into the optical cavity.

[0009] In some embodiments, the optical module assembly may further include a guiding reflector for coupling light from a light source into the optical cavity. The guiding reflector may have a specific optimal shape for guiding light into the optical cavity. For example, the guiding reflector may have a frustum shape. Specifically, the guiding reflector may be arranged such that the smaller diameter portion of the frustum shape points towards the light source. In some embodiments, the first housing portion may include a flat surface and a guiding reflector for coupling light from the light source into the optical cavity. Additionally, the second housing portion may include a cylindrical structure and a first curved reflecting element and a second curved reflecting element. Specifically, the flat surface of the first housing portion may be positioned to connect to the peripheral wall of the cylindrical structure of the second housing portion. Similarly, a first opening and a second opening may be provided at 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 connect to the peripheral wall of the cylindrical structure of the first housing portion, and the first opening and the second opening may be provided in the cylindrical structure of the first housing portion, optionally at the peripheral wall of the cylindrical structure.

[0010] In some embodiments, the first curved reflecting element and the second curved reflecting element may be provided outside the circumferential inner surface portion of the optical cavity. Specifically, the first curved reflecting element may further be arranged to direct light originating from a first position below the lower inner surface of the optical cavity towards the optical cavity. Similarly, the second curved reflecting element may further be arranged to direct light from the optical cavity towards a second position below the lower inner surface of the optical cavity.

[0011] In some embodiments, the first opening and the second opening may be horizontal openings located on the lower inner surface of the optical cavity. The first curved reflecting element may extend from the upper inner surface of the optical cavity towards the first opening, and the second curved reflecting element may extend from the upper inner surface of the optical cavity towards at least one second opening. The first curved reflecting element and the second curved reflecting element may be provided as corresponding extensions of the second housing portion, or as parts of the corresponding extensions. Specifically, the first curved reflecting element and the second curved reflecting element may be arranged according to the positions of the first opening and the second opening respectively, such that light is directed by the first curved reflecting element from the light source through the first opening towards the optical cavity, and by the second curved reflecting element from the optical cavity through at least one second opening towards the detector.

[0012] In some embodiments, the corresponding extensions of the second housing portion or parts of the corresponding extensions may have inclined surfaces on which the corresponding first curved reflecting element and second curved reflecting element are formed. Specifically, the inclined surfaces may be positioned to correspond to the positions of the first opening and the second opening respectively.

[0013] In some embodiments, the first housing portion and the second housing portion may be formed by injection molding. Additionally, the inner surface of the optical cavity may be coated with an optical reflective material. Specifically, the reflective material may be reflective at the 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 an optical reflective material that is reflective at the wavelength of the light source. In some embodiments, the optical module assembly may further include an optical filter configured to filter light from the optical cavity before it reaches the detector. The optical filter may then be disposed in at least one of the second openings and / or on top of the guiding reflector, as described above. In some embodiments, the first opening and the second opening may be positioned relative to each other at a 90-degree azimuthal angle within the diameter plane of the optical cavity.

[0014] Configured as described above, the optical cavity may have a cylindrical shape that is coated with a reflective material at the wavelength of the light source to propagate the coupled light towards 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 will interact with the flowing gas within the cavity and may be absorbed by it. Additionally, a miniaturized curved mirror above the detector may direct the light from the optical cavity through an aperture (opening) onto the detector on an external printed circuit board (PCB). In this way, single-channel gas sensing may be achieved in an accurate and efficient manner because the light propagation path within the cavity may be increased, thereby enhancing the light absorption by the gas.

[0015] In some embodiments, the optical module assembly may further include one or more additional second openings and respective optical filters disposed at predefined angular positions on the first housing portion. Similarly, one or more respective optical filters may be configured to filter light from the optical cavity. In such a case, the optical module assembly may further include one or more additional second curved reflective elements that are associated with the one or more additional second openings and are arranged to direct light of respective wavelengths of the light source from the optical cavity through the respective additional second openings having the respective optical filters towards respective detectors. In such embodiments, the first opening and the second opening may be positioned relative to each other at a 30-degree or 60-degree azimuthal angle within the diameter plane of the optical cavity. Although examples are explicitly mentioned of positioning the first opening and the second opening relative to each other at a 30-degree or 60-degree azimuthal angle within the diameter plane of the optical cavity, azimuthal angles other than 30 degrees or 60 degrees may also be applicable for multi-channel gas sensing applications.

[0016] In some embodiments, the optical module assembly may further include at least one gas port for serving as a gas inlet and / or a gas outlet for 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.

[0017] According to another aspect of the present disclosure, a gas sensor is provided. The gas sensor may have an optical module assembly according to any one of the above aspects and their embodiments and be implemented based on (e.g., by using) the optical module assembly, which has an optical cavity. The gas sensor may further include a printed circuit board (PCB) arrangement attached to the optical module assembly. The PCB arrangement may include a light source configured to emit light to propagate in the optical cavity of the optical module assembly. The PCB arrangement may further include an optical detector configured to detect light from the optical cavity of the optical module assembly.

[0018] For example, the optical module may include a bottom and a top. The bottom of the device may include a cylindrical wall having a certain height (e.g., dimensions in the range of a few millimeters) and two openings for transmitting light from the light source to the optical detector. The opening above the light source may be a conical reflector having a certain height (e.g., in the range of a few millimeters) and an angle relative to each other (e.g., 90 degrees) to couple light into the cavity structure. On the other hand, the top of the module may include: a flat plate that closes the cylindrical structure to create an optical cavity; and additionally, two mirrors that reflect light, one from the light source to the cavity and the other from the cavity to the optical filter and detector.

[0019] For example, the optical module according to the present disclosure may include two reflective curved mirrors having specific physical dimensions and curvatures. The optical module according to the present disclosure may further include a frustoconical reflector that has appropriate circular diameters at the top and bottom and has an appropriate height from the optical body to a very close distance above the light source. Additionally, the optical module may further include two openings for a dedicated light source and detector, positioned at an angle of, for example, 90 degrees to each other. However, the positions of the apertures may also be placed at any predefined angle to each other in the cylindrical structure for other embodiments. It should also be noted that the optical module may further include a cylindrical structure having a predefined cylindrical diameter and wall height, and the cavity may include a reflective inner coating surface at the wavelength of the light source.

[0020] In certain embodiments, a guiding reflector and a first curved reflective element may be provided to be substantially close to the light source. In certain embodiments, the PCB arrangement may further include an optical filter configured to filter light from the optical cavity before reaching the detector. In certain embodiments, the PCB arrangement may further include a controller configured to drive the light source and process the optical signal of the detected light. The light source may include a light source suitable for gas detection / measurement using NDIR, such as a filament. The optical detector may include a light detector suitable for gas detection / measurement using NDIR, such as 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.

[0021] Configured as described above, the present disclosure provides a compact NDIR gas sensor module for detecting a predetermined gas of interest using a compact optical cavity structure. The sensor module includes an injection-molded optical cavity structure that is clamped / glued onto a printed circuit board (PCB) arrangement to provide the entire module. The PCB includes a filament as a light source, a thermopile as an optical detector, and a microcontroller for driving the filament and processing the detected signal. In this way, by integrating miniaturized optical components into an optical body, an efficient gas sensing method can be provided to improve detection performance while maintaining a very compact size of the housing.

[0022] According to another aspect of the present disclosure, a method of manufacturing an optical module assembly for a gas sensor is provided. The method may include providing a first housing portion and a second housing portion of the optical module assembly. The method may further include connecting the first housing portion to the second housing portion to form a substantially cylindrical optical cavity. Specifically, the lower inner surface of the optical cavity may be formed by the first housing portion, and the upper inner surface of the optical cavity may be formed by the second housing portion. The method may further include providing a first opening for receiving light from a light source, and providing at least one second opening for transmitting light from the optical cavity to a detector. Specifically, the method may additionally include providing a first curved reflecting element between the first housing portion and the second housing portion for directing light from the light source into the optical cavity, and providing a second curved reflecting element between the first housing portion and the second housing portion for directing light from the optical cavity to the detector. Specifically, the optical axis of the first curved reflecting element and the optical axis of the second curved reflecting element may be inclined with respect to the diameter plane of the optical cavity.

[0023] In certain embodiments, the method may further include determining an inclination angle of the first curved reflecting element with respect to the diameter plane of the optical cavity and an inclination angle of the second curved reflecting element with respect to the diameter plane of the optical cavity such that light from the light source is directed into the optical cavity by the first curved reflecting element through the first opening, and light from the optical cavity is directed to the detector by the second curved reflecting element through the at least one second opening. In certain embodiments, the method may further include providing a guiding reflector having a frustum shape for coupling light from the light source into the optical cavity. In certain embodiments, the method may further include providing a flat surface and a guiding reflector for the first housing portion, and providing a cylindrical structure as well as the first curved reflecting element and the second curved reflecting element for the second housing portion. In this case, the flat surface of the second housing portion may be positioned to connect to the peripheral wall of the cylindrical structure of the first housing portion, and the method may further include setting the first opening and the second opening at the flat surface of the first housing portion.

[0024] 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 such a case, the flat surface of the second housing portion may be positioned to connect to the peripheral wall of the cylindrical structure of the first housing portion, and the method may further include providing the first opening and the second opening in the cylindrical structure of the first housing portion, optionally at the peripheral wall of the cylindrical structure.

[0025] In some embodiments, the first curved reflecting element and the second curved reflecting element may be provided outside the circumferential inner surface portion of the optical cavity. Additionally, the first curved reflecting element may be arranged to direct light from a first position below the lower inner surface of the optical cavity towards the optical cavity, and the second curved reflecting element may be arranged to direct light from the optical cavity towards a second position below the lower inner surface of the optical cavity.

[0026] In some embodiments, the first opening and the second opening may be horizontal openings located on the lower inner surface of the optical cavity. Additionally, the first curved reflecting element may extend from the upper inner surface of the optical cavity towards the first opening, and the second curved reflecting element may extend from the upper inner surface of the optical cavity towards at least one second opening.

[0027] In some embodiments, the method may further include providing the first curved reflecting element and the second curved reflecting element as respective extension portions of the second housing portion, or as parts of the respective extension portions. The method may further include setting the first curved reflecting element and the second curved reflecting element respectively according to the positions of the first opening and the second opening, such that light is directed from the light source through the first opening towards the optical cavity by the first curved reflecting element, and from the optical cavity through at least one second opening towards the detector by the second curved reflecting element.

[0028] In some embodiments, the respective extension portions of the second housing portion or parts of the respective extension portions may have inclined surfaces on which the respective first curved reflecting element and second curved reflecting element are formed. Specifically, the inclined surfaces may be positioned to correspond to the positions of the first opening and the second opening respectively.

[0029] 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 surface of the optical cavity with an optical reflective material. In some embodiments, the method may further include providing respective curved mirrors as the first curved reflecting element and the second curved reflecting element, and coating the respective curved mirrors with a light reflective material.

[0030] In some embodiments, the method may further include providing an optical filter for filtering light from the optical cavity before it reaches the detector. Specifically, the optical filter may be disposed in at least one second opening and / or on top of the guiding reflector, as described above. In some embodiments, the method may further include positioning the first opening and the second opening at a 90-degree azimuth angle relative to each other in the diameter plane of the optical cavity.

[0031] In some embodiments, the method may further include providing one or more additional second openings and corresponding optical filters at predefined angular positions in the first housing portion for filtering light from the optical cavity, and providing one or more additional second curved reflecting elements associated with the one or more additional second openings for directing light of a corresponding wavelength of the light source from the optical cavity through the corresponding additional second openings having the corresponding optical filters to the corresponding detectors. In this case, the first opening and the second opening may be positioned at a 30-degree or 60-degree azimuth angle relative to each other in the diameter plane of the optical cavity.

[0032] In some embodiments, the method may further include 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 and / or a gas outlet of the optical cavity.

[0033] Configured as described above, the method of manufacturing an optical module for a gas sensor according to the present disclosure provides an efficient and precise way to perform gas sensing because the efficiency of coupling the light source into the optical cavity can be improved, thereby maximizing the light absorption by 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 combining a miniaturized optical conical reflector and a curved mirror can be applied, which will be placed at a very close distance above the light source to reduce the divergence angle of the light beam and thus more effectively guide the light into the optical cavity.

[0034] Specifically, the optical cavity may be provided with a cylindrical shape that is coated with a reflective material at the wavelength of the light source to propagate the coupled light towards the detector. When the light propagates, it will interact with the flowing gas in the cavity and can be absorbed by it. In addition, the miniaturized curved mirror above the detector can direct the light from the optical cavity through the aperture (opening) onto the detector disposed on an external printed circuit board (PCB). In this way, single-channel gas sensing can be achieved in an accurate and effective manner because the light propagation path in the cavity can be increased, thereby enhancing the light absorption performed by the gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Example embodiments of the present disclosure are described below with reference to the accompanying drawings; where like reference numerals indicate the same or similar elements; and where

[0036] Figure 1 A schematic top view illustrates an exemplary structure of an optical module assembly 100 for a gas sensor according to an embodiment of the present disclosure;

[0037] Figure 2 Schematically illustrates along Figure 1 a cross-sectional view corresponding to the view along line A-A shown;

[0038] Figure 3A A three-dimensional (3D) view schematically illustrates an exemplary arrangement within the optical module assembly 100 for a first housing portion 101 according to an embodiment of the present disclosure;

[0039] Figure 3B A three-dimensional (3D) view schematically illustrates an exemplary arrangement within the optical module assembly 100 for a second housing portion 102 according to an embodiment of the present disclosure;

[0040] Figure 3C A detailed three-dimensional (3D) view schematically illustrates an exemplary structure of an optical module assembly 100 having a first housing portion 101 fixed to a second housing portion 102 according to an embodiment of the present disclosure;

[0041] Figure 4 Schematically illustrates along Figure 1 a cross-sectional view corresponding to the view along line B-B shown;

[0042] Figure 5 A flowchart is schematically shown, illustrating an example of a method 500 for manufacturing an optical module assembly for a gas sensor according to an embodiment of the present disclosure;

[0043] Figure 6 A cross-sectional view schematically illustrates a gas sensor 200 according to an embodiment of the present disclosure, the gas sensor 200 including the above optical module assembly 100; having a PCB arrangement 112 along Figure 1 the line A-A shown;

[0044] Figure 7 A cross-sectional view schematically illustrates a gas sensor 200 according to an embodiment of the present disclosure, the gas sensor 200 including the above optical module assembly 100; having a PCB arrangement 112 along Figure 1 the line B-B shown;

[0045] Figure 8A A PCB arrangement 112 to be combined with the optical module assembly 100 for implementing a gas sensor 200 according to an embodiment of the present disclosure is schematically illustrated;

[0046] Figure 8BSchematically illustrates a PCB layout 112 according to an embodiment of the present disclosure for use in combination with an optical module assembly 100 to implement a gas sensor 200;

[0047] Figure 9A Schematically illustrates in a top view another exemplary structure of an optical module assembly 100 for a gas sensor according to an embodiment of the present disclosure;

[0048] Figure 9B Schematically illustrates in relation to Figure 9A a cross-sectional view corresponding to the view along line A-A shown;

[0049] Figure 9C Schematically illustrates in relation to Figure 9A a cross-sectional view corresponding to the view along line B-B shown;

[0050] Figure 10A Schematically illustrates in a three-dimensional view an exemplary arrangement within an optical module assembly 100 for a first housing part 101 according to an embodiment of the present disclosure Figure 9A thereof;

[0051] Figure 10B Schematically illustrates in a three-dimensional (3D) view an exemplary arrangement within an optical module assembly 100 for a second housing part 102 according to an embodiment of the present disclosure Figure 9A thereof;

[0052] Figure 10C Schematically illustrates a detailed three-dimensional view of an exemplary structure of an optical module assembly 100 having a first housing part 101 fixed to a second housing part 102; and Figure 9A

[0053] Figure 11 Schematically illustrates in relation to Figure 9A a PCB layout 112 for use in combination with an optical module assembly 100 to implement a gas sensor 200. DETAILED DESCRIPTION

[0054] As described above, unless otherwise specified, the same or similar reference numerals in the present disclosure may indicate the same or similar elements, such that for the sake of brevity, the repeated description thereof may be omitted.

[0055] ​A non-dispersive infrared (NDIR) gas sensor can detect the presence and concentration of various gases by selecting a narrowband spectral region that overlaps with the absorption region of the gas of interest. As described above, the use of a broadband light source and an optical filter integrated with the sample chamber can allow the NDIR sensor to be a good candidate for gas measurement. However, such NDIR sensors are very complex and expensive, which limits their applications.

[0056] Thus, generally speaking, the present disclosure generally proposes techniques and / or mechanisms for improving the design and / or manufacture of NDIR gas sensors, more specifically in a compact and cost-effective manner.

[0057] Figure 1 The exemplary structure of an optical module assembly 100 for a gas sensor according to an embodiment of the present disclosure is schematically illustrated in a top view. Among other things, the optical module assembly 100 may include 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 reflecting element 105-1, and a second curved reflecting element 105-2. Specifically, the first housing portion 101 and the second housing portion 102 may be connected together by injection molding to form a substantially cylindrical optical cavity 103 when the two housing portions are connected together. Thus, the lower inner surface of the optical cavity 103 may be formed by the first housing portion 101, and the upper inner surface of the optical cavity 103 may be formed by the second housing portion 102. Here, for illustrative purposes, Figure 1 the first housing portion 101 of the optical module assembly 100 in is shown opaquely, while the second housing portion 102 of the optical module assembly 100 is shown in a transparent view for illustrating the structural combination of the two housing portions 101, 102 that form the gas sensor optical cavity 103 of the optical module.

[0058] The first opening 104-1 of the optical module assembly 100 can receive light from a light source. For example, the light source may include a filament ( Figure 1 not shown in ) outside the optical module assembly 100. The second opening 104-2 of the optical module assembly 100 can allow light to be transmitted from the optical cavity 103 to a detector outside the optical module assembly 100. Without intended limitation, the detector may include, for example, a thermopile as an optical detector outside the optical module assembly 100 ( Figure 1 not shown in ). The light source may also include other types of light sources, such as light-emitting diodes (LEDs), and the optical detector may also include other types of detectors, such as solid-state detectors.

[0059] In addition, the first curved surface reflecting element 105-1 can direct light from an (external) light source towards the optical cavity 103, and the second curved surface reflecting element 105-2 can direct light from the optical cavity 103 towards an (external) detector.

[0060] For better understanding, reference is made to Figure 2 and Figure 4 which schematically illustrate corresponding side views of the optical module group 100 according to an embodiment of the present disclosure: Figure 1 is a cross-sectional view corresponding to the view along line A-A shown in Figure 2 and Figure 1 is a cross-sectional view corresponding to the view along line B-B shown in Figure 4 That is, Figure 1 and Figure 2 are the respective cross-sections of the two housing parts 101, 102. Figure 4 Reference numerals shown in Figure 2 and Figure 4 which are the same as those in Figure 1 may represent the same or similar structures or components and will not be repeated herein for the sake of brevity.

[0061] As Figure 2 shown, the first opening 104-1 of the optical module assembly 100 is arranged to receive light from an external light source (such as the filament 107). As Figure 4 shown, the second opening 104-2 of the optical module assembly 100 is arranged to transfer light from the optical cavity 103 to an external detector (such as the thermopile 109). In an embodiment, the filament 107 is not part of the optical module assembly 100 but is part of an (external) electronic board (such as a printed circuit board (PCB) as Figure 6 more clearly shown in FIGS. 7 to 8), to which the optical module 100 is attached (e.g., by shearing or gluing to fix the light module to the PCB). Similarly, the thermopile 109 is not part of the optical module assembly 100 but is part of the PCB to which the optical module assembly 100 is attached.

[0062] Since different gases have different self-absorption wavelengths (e.g., the absorption wavelength for CO2 is 4.26 μm), corresponding optical filters can be used to filter out the absorption wavelengths of the gas of interest from the broad spectrum of the filament light to avoid detecting gases other than the gas of interest. As Figure 4As shown, an optical filter 110 is additionally placed on the thermopile detector 109 to filter the light from the optical cavity 103 before it reaches the detector 109. Although in this example, the optical filter 110 is provided on the detector as part of an external PCB, in some embodiments, if the gas sensor module is to be designed to a smaller size, the optical filter 110 can alternatively be placed inside the optical module assembly 100 (as shown by the dashed circle in Figure 4 ). In this case, the optical module assembly 100 can also include the optical filter 110, arranged to filter the light from the optical cavity 103.

[0063] As Figure 2 and Figure 4 shown, further note that the optical axes of the first curved reflecting element 105-1 and the second curved reflecting element 105-2 are inclined with respect to the diameter plane of the optical cavity 103 (indicated by the plane P). The respective inclination angles of the first curved reflecting element 105-1 and the second curved reflecting element 105-2 can be adjusted to direct the light from the light source 107 to 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), respectively. To improve the gas detection efficiency, a guiding reflector 106 can be provided inside the optical module assembly 100 for coupling the light from the light source 107 into the optical cavity 103. For example, the guiding reflector 106 can have a frustum shape, with its smaller diameter part pointing towards the light source 107 to increase the coupling efficiency.

[0064] As Figure 1 shown, the first housing part 101 can have a cylindrical structure, and the second housing part 102 can be in the form of a flat surface (e.g., a plate). When the two housing parts are combined at the connection position, the second housing part 102 is positioned to connect to the peripheral wall of the cylindrical structure of the first housing part 101. In an embodiment, a first opening 104-1 and a second opening 104-2 are provided in the cylindrical structure of the first housing part 101, and optionally in the peripheral wall of the cylindrical structure, also as Figure 2 and Figure 4 shown. In some embodiments, the first curved reflecting element 105-1 and the second curved reflecting element 105-2 can be provided outside the circumferential inner surface part of the optical cavity 103. Specifically, the first curved reflecting element 105-1 can also be arranged to direct the light from a first position below the lower inner surface of the optical cavity to the optical cavity 103, and the second curved reflecting element 105-2 can also be arranged to direct the light from the optical cavity 103 to a second position below the lower inner surface of the optical cavity 103.

[0065] It should be noted that the arrangement of the optical module assembly 100 shown in the above figures is merely illustrative, and other possible arrangements that allow light from the light source to be transmitted and propagated within the optical cavity 103 to reach the detector for gas measurement / detection should not be excluded from the embodiments of the inventive concept proposed in the present disclosure. For example, the first opening 104-1 and the second opening 104-2 may be formed in the first housing part 101, and the first curved reflecting element 105-1 and the second curved reflecting element 105-2 may be formed in any one of the first housing part 101 and the second housing part 102.

[0066] For example, the first opening 104-1 and the second opening 104-2 may be horizontal openings located on the lower inner surface (i.e., at the bottom) of the optical cavity 103. Similarly, the first curved reflecting element 105-1 may extend from the upper inner surface of the optical cavity 103 towards the first opening 104-1, and the second curved reflecting element 105-2 may extend from the upper inner surface of the optical cavity 103 towards the second opening 104-2. For example, the first curved reflecting element 105-1 and the second curved reflecting element 105-2 may be arranged as corresponding extensions or parts of corresponding extensions of the second housing part 103, or may be provided according to the positions of the first opening 104-1 and the second opening 104-2 respectively, such that light is directed by the first curved reflecting element 105-1 from the light source 107 through the first opening 104-1 into the optical cavity 103 (see the light propagation path a), and is directed by the second curved reflecting element 105-2 from the optical cavity 103 through the second opening 104-2 towards the detector 109 (see the light propagation path b).

[0067] In some embodiments, the corresponding extension or part of the corresponding extension of the second housing part 102 may have an inclined surface on which the corresponding first curved reflecting element 105-1 and the second curved reflecting element 105-2 are formed. Thus, the inclined surface may be positioned to correspond to the positions of the first opening 104-1 and the second opening 104-2 respectively. Note that the inclined surface may be (exclusively) formed in the part of the optical module assembly 100 that overlaps with the light source 107 (such as a filament) and the optical detector 109 (such as an infrared sensor). In other words, except where the openings 104-1 and 104-2 are located, the cylindrical structural wall (i.e., the peripheral wall) has a vertical form rather than an inclined form, so as to increase the path length of the light propagating within the cavity 103.

[0068] Further note that the inner surfaces 103-1, 103-2 of the optical cavity 103 can be coated with an optical reflective material. The reflective material can be reflective at the wavelength of the light source. In addition, the first curved reflecting element 105-1 and the second curved reflecting element 105-2 can each include a respective curved mirror coated with an optical reflective material. In this way, the light reflected from the curved mirror above the filament 107 can circulate inside the cylindrical structure (i.e., the optical cavity 103) through multiple reflections off the vertical walls 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, which also improves the sensitivity of gas detection.

[0069] In addition, the first opening 104-1 and the second opening 104-2 can be positioned relative to each other in the diameter plane of the optical cavity 103 at an azimuth angle of 90 degrees, as Figure 1 shown. That is, the light source 107 (e.g., a filament) and the optical detector 109 (e.g., an infrared sensor) can be non-aligned such that multiple reflections inside the cavity 103 are facilitated. This helps to increase the optical path length to enhance the sensitivity of the gas sensor module.

[0070] In the above embodiment, as Figures 1 to 4 shown, a second opening is provided for single-channel gas detection.. However, in some other embodiments, the optical module assembly can be implemented as a multi-channel gas sensor by, for example, adding multiple detectors and multiple apertures (openings) with different optical filters in a cylindrical structure having pre-specified angular positions. Thus, the optical module assembly 100 can also include one or more additional second openings 104-2 and corresponding optical filters 110 disposed at predefined angular positions in any one of the first housing portion 101 and the second housing portion 102. Similar to the above optical filters, the additional one or more corresponding optical filters can be arranged to filter the light from the optical cavity 103. Specifically, the optical module assembly 100 further includes one or more additional second curved reflecting elements 105-2, which are associated with the one or more additional second openings 104-2 and are arranged to direct light of a corresponding wavelength of the light source 107 from the optical cavity 103 through the corresponding additional second openings 104-2 having the corresponding optical filters 110 to the corresponding detectors 109.

[0071] For example, the optical module assembly can include additional openings and additional detectors for reference measurements such that the sensor can be used for dual-channel NDIR gas detection. In the case of multi-channel NDIR, the (multiple) first openings and second openings can be positioned relative to each other in the diameter plane of the optical cavity 103 at a predefined angle, such as 30 degrees or 60 degrees.

[0072] Note that the first housing part 101 and the second housing part 102 can be formed by injection molding. As Figure 1 , Figure 2 and Figure 4 illustrated in the embodiments of, the optical module assembly 100 of the gas sensor is formed by a first housing part 101 (as the bottom of the optical cavity 103) and a second housing part 102 (as the top of the optical cavity 103). That is, the optical module assembly 100 can be provided with a combination of miniaturized optical components integrated in the optical cavity 103 manufactured by injection molding. Thus, the entire optical fitting for the gas sensor can be made of two separate injection-molded parts, which are then joined together to form an integral optical module assembly 100. Further note that by producing the optical module assembly in two parts, the gas sensor module can be manufactured by injection molding (e.g., polymer-based resin, thermosetting epoxy resin) to achieve high-volume production and low manufacturing costs. For example, the polymer-based resin can be polymethyl methacrylate (so-called "PMMA") or any other similar polymer-based material. Additionally, it is also allowed to coat the surfaces of the optical components (e.g., the shaded part indicated by the dashed line C in Figure 1 ) within the optical module assembly.

[0073] It should be noted that, without departing from the scope of the present disclosure, other suitable techniques for producing the internal configuration / structure of the above-described optical module assembly can be utilized in addition to injection molding.

[0074] In addition, the optical module assembly 100 may further include at least one gas port 108 configured to input gas into and / or output gas from the optical cavity 103. The at least one gas port 108 can be provided on the lower inner surface or the upper inner surface of the optical cavity 103. The at least one gas port 108 having a sufficiently large size can be used for both gas input and output simultaneously. Similarly, the optical module assembly 100 can optionally be provided with groove portions 111-1, 111-2 (see Figure 2 and Figure 4 ) near the first curved reflecting element 105-1 and the second curved reflecting element 105-2 to assist in manufacturing precise curved mirrors (as the first curved reflecting element 105-1 and the second curved reflecting element 105-2) by injection molding.

[0075] Figures 3A to 3C A more detailed three-dimensional (3D) view of the proposed gas sensor module is shown. Figure 3A A schematic illustration of an exemplary arrangement within the optical module assembly 100 for the first housing part 101 according to an embodiment of the present disclosure is shown in a 3D top view. Figure 3BA 3D top view schematically illustrates an exemplary arrangement within the optical module assembly 100 for the second housing part 102 according to an embodiment of the present disclosure. Figure 3A and Figure 3B shown in Figure 1 、 Figure 2 and Figure 4 The same reference numerals may represent the same or similar structures or components, and for the sake of brevity, they will not be repeated herein. Here, the first housing part 101 may refer to the bottom of the optical module assembly 100 that forms the lower inner surface of the optical cavity 103, and the second housing part 102 may refer to the top of the optical module assembly 100 that forms the upper inner surface of the optical cavity 103. In this embodiment, the curved mirrors as the first curved reflecting element 105-1 and the second curved reflecting element 105-2 are located at the top (the first part 101), while the cylindrical wall 122 and the openings 104-1, 104-2 connected to the conical reflector 106 are located at the bottom (the second part 102). However, in other embodiments, the positions of the curved reflecting elements and the openings may vary to optimize / minimize the size of the optical module assembly. For example, the curved reflecting elements may alternatively or additionally be arranged at the bottom (the second part 102) together with the openings.

[0076] In some embodiments, the top of the injection-molded optical cavity (i.e., the second housing part 102) may be provided with corresponding inclined surfaces on which corresponding curved mirrors may be formed as the first curved reflecting element 105-1 and the second curved reflecting element 105-2. In this case, the inclined surfaces may be mainly or exclusively formed respectively on Figure 2 the lamp source (filament) 107 shown in Figure 4 and the part (the second housing part 102) above the optical detector 109 shown in. In other words, other parts of the top of the injection-molded optical cavity may not be provided with inclined curved surfaces but with horizontal flat surfaces to connect with the rest of the vertical cylindrical wall.

[0077] Therefore, the flat part / surface (plate) of the second housing part 102 may be positioned to correspond to the peripheral vertical wall of the cylindrical structure of the first housing part 101, and the first curved reflecting element 105-1 and the second curved reflecting element 105-2 are arranged as corresponding extension parts or parts of the corresponding extension parts of the second housing part 102 extending from the flat part / surface, and are respectively arranged according to the positions of the first opening and the second opening of the first housing part 101, such that light is directed from the light source 107 by the first curved reflecting element 105-1 through the first opening 104-1 into the optical cavity 103, and is directed from the optical cavity 103 by the second curved reflecting element 105-2 through the second opening 104-2 to the detector 109.

[0078] As described above, the inner surfaces 103-1, 103-2 of the optical cavity 103 can be coated with an optically reflective material, as shown in the shaded area of ​​FIG. 3. Note that the inner surface 103-1 formed by the first shell portion 101 can also include the (inner) surface of the conical reflector 106, which can also be coated with an optically reflective material. The reflective material can include a metallic material that is reflective at the wavelength of the light source, such as aluminum. Therefore, in order to manufacture an optical module for gas sensing such as proposed in the present disclosure, injection molding of a polymer material (e.g., a resin) can be used to form two separate parts of the module (e.g., a bottom and a top), and then the inner surfaces of the two parts are coated with, for example, aluminum (as shown in the shaded area) to allow light to be reflected inside the cavity. Subsequently, the two separate parts (i.e., the first shell portion and the second shell portion) can be combined together via one or more connecting elements 120-1, 120-2 thereof. As Figure 3A and Figure 3B As shown, the connecting element 120-2 of the second housing part (top / upper part) 102 can be inserted into the connecting element 120-1 of the first housing part (bottom / lower part) 101 to fix the second housing part 102 to the first housing part 101. In this way, an optical cavity 103 having a cylindrical shape can be formed, which is coated with an optically reflective material at the wavelength of the light source so that the coupled light is guided from the light source to the detector. Figure 3C A detailed 3D top view of an exemplary structure having a first housing portion 101 secured to a second housing portion 102 according to an embodiment of the present disclosure is schematically illustrated.

[0079] As described above, the guide reflector 106 may have a truncated cone shape, with a smaller diameter portion pointing toward the light source (not shown). Likewise, the coated portion of the module is shown as a shaded area. In an embodiment, the truncated cone reflector 106 may have a certain circular diameter on its top side or bottom side, and may have a certain height from the body of the optical module assembly (e.g., the first opening) to a very close distance above the light source, so as to better couple the light from the light source into the cavity 103 of the optical module assembly. The top side of the conical reflector 106 may be connected to the first opening 104-1 at the first housing portion 101, while the bottom side of the conical reflector 106 may be positioned away from the first opening 104-1 and just above the light source. For example, the circular diameter at the bottom side of the conical reflector 106 (e.g., in the millimeter range) may be smaller than the circular diameter at the top side of the conical reflector 106 (e.g., also in the millimeter range). For example, the conical reflector 106 may have a certain height (e.g., in the range of several millimeters) from the first opening of the optical module assembly to a very close distance above the light source (e.g., also in the millimeter range or less).

[0080] In some embodiments, the cylindrical structure 103 of the optical module assembly 100 may have a predefined cylinder diameter (e.g., in the range of several millimeters or several centimeters) and wall height (e.g., in the range of several millimeters). Accordingly, the optical module assembly for a gas sensor proposed in the present disclosure may have dimensions such as length (L) and width (W) in the range of several millimeters to several centimeters and height (H) in the range of several millimeters, as Figure 3C shown. A more compact optical module assembly with smaller dimensions can be achieved by adopting the techniques disclosed in the present application. For example, by arranging the openings and the curved reflecting element in different ways, it is also possible to reduce the dimensions of the cylindrical structure 103 of the optical module assembly 100 from the centimeter range to the millimeter range (depending on the predefined cylinder diameter), so that the optical module assembly for a gas sensor has reduced dimensions, for example, in the range where the length (L) and width (W) are less than 10 mm and the height (H) is less than 5 mm. It should be noted that the above dimensions of the optical module assembly according to the present disclosure are provided for illustrative purposes only and are not intended to be construed as limiting. It is also possible to reduce the size of the guiding reflector to minimize the overall size of the optical module assembly.

[0081] It should also be noted that the above structure of the optical module assembly and the above arrangement of the elements (i.e., the internal configuration) within the optical module assembly according to the present disclosure are provided for illustrative purposes only and are not intended to be construed as limiting. For example, the cylindrical structure may be located at the upper part / top of the optical module assembly, and / or the optical filter may be located elsewhere than on top of the detector. According to the present disclosure, various arrangements of the elements within the optical module assembly are possible and are within the scope of the present disclosure.

[0082] The optical module described in the above embodiments can be attached (e.g., by shear / bonding) to a printed circuit board (PCB) to provide a complete module / device for gas detection / measurement, as Figure 6 and Figure 7 shown. Figure 6 Corresponding to Figure 2 , a cross-sectional view of a gas sensor 200 according to an embodiment of the present disclosure is schematically illustrated, and the gas sensor 200 includes the above optical module assembly 100 having a PCB arrangement 112 along the Figure 1 shown line A-A. Figure 7 Corresponding to Figure 4 , a cross-sectional view of a gas sensor 200 according to an embodiment of the present disclosure is schematically illustrated, and the gas sensor 200 includes the above optical module assembly 100 having a PCB arrangement 112 along the Figure 1 shown line B-B. Figure 6 and Figure 7 shown in Figure 1 ,Figure 2 and Figure 4 Like reference numerals may represent like or similar structures or components, and for the sake of brevity, they will not be repeated herein.

[0083] Specifically, the PCB arrangement 112 can be attached to the optical module assembly 100 by cutting or gluing, and includes: a light source (such as the filament 107), configured to emit light for propagation in the optical cavity 103 of the optical module assembly 100; and an optical detector (such as the thermopile 109), configured to direct the light from the optical cavity 103 to the optical module assembly 100. The PCB arrangement 112 may also include a controller (such as a microcontroller) 113, configured to drive the light source 107 and process the optical signals of the detected light. In some embodiments, the PCB arrangement 112 may also include an optical filter 110, arranged to filter the light from the optical cavity 103 (such as on top of the optical detector 109) before reaching the detector 109. The PCB arrangement 112 itself can be implemented in a layer-stacked manner, as shown in FIG. 8. For example, in Figure 8A and Figure 8B the example of, the PCB arrangement 112 can be regarded as including corresponding layers of the light source 107, the optical detector 109, the optical filter 110 (optional), and the microcontroller 113 (optional). These layers can be copper layers or layers of any other suitable material. As described above, in order to implement a more compact gas sensor device 200, the guiding reflector 106 for coupling the light from the light source 107 into the optical cavity 103 of the optical module assembly 100 can be arranged to be substantially close to the light source 107 on the PCB arrangement 112.

[0084] Therefore, the gas sensor device 200 proposed in the present disclosure can be provided by, for example, attaching an injection-molded optical cavity structure (i.e., the optical module assembly 100) to the PCB arrangement 112, which can include a filament as the light 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 certain specific applications, the PCB arrangement 112 may also include other additional components (such as a humidity sensor). It should be noted that Figure 8A and Figure 8B the positions of the elements (such as the light source 107, the optical detector 109, and optionally the microcontroller 113 and the optical filter 110) on the PCB arrangement shown are merely illustrative and are not intended to be construed as limiting the scope of the present disclosure. Specifically, the optional microcontroller 113 can be placed at any position on the PCB, or at the optimal position on the PCB for purposes such as size minimization.

[0085] In some (other) embodiments, as shown in FIGS. 9 to Figure 11 shown, in order to reduce the size (e.g., diameter and height) of the cylindrical structure and the size of the guiding reflector, the upper housing portion 102 may include a cylindrical structure 122 and reflecting elements (105-1, 105-2), as Figure 10B shown, while the lower portion 101 of the optical module may include a flat surface having (two) openings (104-1, 104-2) and a guiding reflector 106, as Figure 10A shown. Similarly, 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 assembly 100. An optical filter plate may also be placed on top of the guiding (conical) reflector.

[0086] It should be understood that FIGS. 9 to Figure 11 depict another exemplary aspect for implementing an optical module assembly and a gas sensor according to the present disclosure. Figures 9A to 9C may respectively correspond to Figure 1 , Figure 2 and Figure 4 , illustrating a top view and corresponding side views of the optical module assembly according to the figures along lines A-A and B-B shown in the top view. Similarly, Figures 10A to 10C may respectively correspond to Figures 3A to 3C , illustrating three-dimensional (3D) views of the first housing portion 101, the second housing portion 102, and the first housing portion 101 fixed to the second housing portion 102 of the optical module assembly 100. Similarly, Figure 11 may correspond to Figure 8A , illustrating a PCB layout 112 to be combined with the optical module assembly 100 for implementing a gas sensor 200. Obviously, the embodiments shown in FIGS. 9 to Figure 11 may have similar components / structures of the optical module assembly / gas sensor, which may be denoted by the same reference numerals, and for the sake of brevity, will not be repeated herein.

[0087] It should also be understood that compared with the embodiments of Figure 1 to FIG. 8, in the embodiments of FIGS. 9 to Figure 11 , the positions of the openings (104-1, 104-2) and the reflector 106 may be moved from the middle of the module side to the (multiple) corners of the module, so that more space can be provided for the reflector 106. Therefore, the positions of the thermopile (109) and the filament (light source 107) on the PCB may be changed such that they can be placed in the optimal positions for guiding light within the optical cavity (e.g., exactly below the corresponding openings 104-1, 104-2). In addition, in Figure 1In the embodiments of FIGS. 1 to 8, the filter 110 is located on the thermopile (i.e., on the PCB board), while in the embodiments of FIGS. 9 to Figure 11 In the embodiments of, the filter 110 is placed in the opening of the detector opening 104-2, as Figure 9C clearly shown in FIGS.

[0088] In all embodiments, other optical components, such as the conical reflector 106 and the curved mirrors 105-1, 105-2, may have almost the same dimensions. However, it should be noted that in the embodiments of FIGS. 9 to Figure 11 In the embodiments of, the curved mirrors 105-1, 105-2 may be part of the top 102, and / or the cylindrical sidewall 122 may be part of the top 101. Similarly, compared with the embodiments of FIGS. 1 to 8, in the embodiments of FIGS. 9 to Figure 1 In the embodiments of, the cylindrical cavity 103 may have a smaller diameter and height. With the arrangement shown in the embodiments of FIGS. 9 to Figure 11 In the embodiments of, the size of the optical module assembly for the gas sensor can also be reduced, for example, the length (L) and width (W) are reduced to 10 mm. In addition, as described above, the groove portions 111-1, 111-2 are optional and may not have to appear in the examples of Figure 11 In the embodiments of. Figure 10C In the embodiments of.

[0089] It should be noted that Figures 1 to 11 The above structure of the optical module assembly shown, the above arrangement of the elements within the optical module assembly, and the positions of the elements on the PCB arrangement are merely exemplary and are not intended to be construed as limiting the scope of the present disclosure.

[0090] Figure 5 A flowchart is schematically shown, illustrating an example of a method 500 for manufacturing an optical module assembly for a gas sensor according to an embodiment of the present disclosure. For example, the optical module assembly can be implemented as the optical module assembly 100 in FIGS. 9 to 10, Figures 1 to 4 etc. In some embodiments, the method 500 can be implemented by injection molding, as understood by those of ordinary skill in the art. Alternatively, those of ordinary skill in the art can also use other means other than injection molding to manufacture the internal configuration / structure of the optical module assembly, and the present disclosure should not limit the implementation manner of the method 500 to any specific manufacturing technology.

[0091] Specifically, the method 500 may include: in step S510, providing the first housing portion 101 of the optical module assembly 100. The method 500 may also include: in step S520, providing the second housing portion of the optical module assembly 100. Here, according to one of the embodiments, as Figure 5As shown, step S520 is performed after step 510. However, step 520 may be performed before step S510, or may be performed simultaneously with step S510. Meanwhile, the first housing portion 101 provided in step S510 has a first opening 104-1 for receiving light from the light source 107 and at least one second opening 104-2 for transmitting light from the optical cavity to the detector 109. According to one embodiment, the first housing portion 101 having the first opening 104-1 and the second opening 104-2 is formed by injecting a material (such as a polymer resin) into a mold and cooling the material with pressure. That is, the first housing portion 101, and the first opening 104-1 and the second opening 104-2 are formed in one step. However, the first housing portion 101, and the first opening 104-1 and the second opening 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 the first housing portion 101 is provided. Similarly, the second housing portion 102 provided in step S520 has a first curved mirror and a second curved mirror. According to one embodiment, like the first housing portion 101, the second housing portion 102 having the first curved mirror and the second curved mirror is formed by injecting a material (such as a polymeric resin) into a mold or by cooling the material with pressure. That is, the second housing portion 102, and the first curved mirror and the second curved mirror are formed in one step. However, the second housing portion 102, and the first curved mirror and the second curved mirror may be formed in different steps or at different times. That is, the first curved mirror and the second curved mirror may be formed in the second housing portion 102 after the second housing portion 102 is provided.

[0092] Specifically, the optical axis of each of the first curved reflecting element and the second curved reflecting element (i.e., the first curved mirror and the second curved mirror) can be inclined with respect to the diameter plane of the optical cavity. As described above, the manufacturing of these elements / portions of the optical module assembly 100 can be performed by, for example, injection molding or other suitable techniques, which can form the internal configuration / structure of the optical module assembly proposed in the present disclosure.

[0093] Method 500 may further include: in step S530, providing a reflective coating on the surface of the first housing portion 101 of the optical module assembly 100. Method 500 may further include: in step S540, providing a reflective coating on the surface of the second housing portion 102 of the optical module assembly 100. According to one embodiment, in step S530, after releasing the first housing portion 101 from the molding die, a reflective coating is formed on the surface inside each of the first opening 104-1 and the second opening 104-2. Similarly, in step S540, in one embodiment, after releasing the second housing portion 102 from the molding die, a reflective coating is formed on the surface of the second housing portion 102 including the surface of each of the first curved mirror and the second curved mirror. By performing this step S540, a first curved mirror coated with an optical reflective material is formed as the first curved reflecting element 105-1 for directing light from the light source 107 into the optical cavity. Similarly, by this step S540, a second curved mirror coated with an optical reflective material is formed as the second curved reflecting element 105-2 for directing light from the optical cavity to the detector 109. Here, according to one embodiment, as Figure 5 shown, step S540 is performed after step 530. However, step 540 may be performed before step S530, or may be performed simultaneously with step S530.

[0094] Method 500 may further include: in step S550, placing the optical filter 110 in the second opening 104-2 within the first housing portion 101, the second opening 104-2 being located above the detector 109, as Figure 9C shown. Here, the optical filter 110 may be placed on the detector 109, as Figure 4 shown. In this case, step S550 may be skipped.

[0095] Method 500 may further include: in step S560, 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. Specifically, the lower inner surface of the optical cavity may be formed by the first housing portion 101, and the upper inner surface of the optical cavity may be formed by the second housing portion 102.

[0096] Configured as described above, the optical module assembly, gas sensor, and method of manufacturing the optical module assembly having an optical molding structure according to the present disclosure provide an effective way to improve the coupling efficiency of the light source into the optical cavity, thus maximizing the light absorption of the gas while keeping the light source relatively far from the optical cavity.

[0097] By arranging the opening and the curved surface reflecting element in appropriate positions (e.g., at a predefined angle relative to each other), single-channel gas sensing and multi-channel gas sensing can be achieved in an accurate and efficient manner. Specifically, the optical propagation path within the cavity can be increased, thereby enhancing the light absorption of the gas.

[0098] Therefore, a compact NDIR gas sensor module can also be provided to detect a predefined gas of interest using a compact optical cavity structure. By integrating miniaturized optical components into the optical body, an efficient gas sensing method can be provided to improve the detection performance while maintaining a very compact size of the housing.

[0099] It should be noted that the above device features correspond to the corresponding method features. However, for the sake of brevity, these method features may not be explicitly described. The disclosure herein is also considered to extend to such method features. Specifically, the present disclosure is understood to relate to a method of manufacturing the above optical module assembly, and / or to providing and / or arranging the corresponding elements of the optical module assembly.

[0100] It should also be noted that, depending on the emphasized technical field, the embodiments of the present disclosure are applicable to various system configurations. In other words, the examples shown in the above figures, which serve as the basis for the above examples, are merely illustrative and do not limit the present disclosure in any way. That is, additional existing and proposed new functions available in the corresponding operating environment can be used in combination with the examples of the embodiments of the present disclosure based on the defined principles.

[0101] It should also be noted that the disclosed example embodiments can be implemented in many ways using hardware and / or software applications. For example, the disclosed embodiments can be implemented using dedicated hardware, dedicated software, and / or hardware associated with software executable thereon. The components and / or elements in the figures are merely examples and do not limit the use or the scope of the function of any hardware, software combined with hardware, firmware, embedded logic components, or a combination of two or more such components implementing a specific embodiment of the present disclosure.

[0102] Finally, it should be noted that the specification and the drawings merely illustrate the principles of the proposed device and method. Those skilled in the art will be able to implement various arrangements, although these arrangements are not explicitly described or shown herein, but they embody the principles of the present invention and are included within its spirit and scope. In addition, all the examples and embodiments outlined herein are mainly for the purpose of clear illustration to help the reader understand the principles of the proposed device and method. Moreover, all statements herein providing the principles, aspects, and embodiments of the present invention, as well as specific examples thereof, are intended to cover their equivalents.

Claims

1. An optical module assembly for a gas sensor, comprising: a first housing portion; as well as The second housing part, wherein the first housing portion and the second housing portion are configured to be connected together and to form a substantially cylindrical optical cavity when connected together; 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; The optical module assembly further comprises: a first opening for receiving light from a light source; at least one second opening for passing light from the optical cavity to a detector; a first curved reflective element configured to direct the light from the light source toward the optical cavity; and a second curved reflective element configured to direct the light from the optical cavity toward the detector; The optical axis of the first curved reflective element and the optical axis of the second curved reflective element are inclined relative to the diameter plane of the optical cavity.

2. The optical module assembly of claim 1, further comprising a guiding reflector for coupling the light from the light source into the optical cavity, wherein the guiding reflector has a truncated cone shape.

3. The optical module assembly of claim 2, wherein the first housing portion comprises: Flat surface; as well as the guiding reflector is used to couple the light from the light source into the optical cavity, The second housing portion comprises: Cylindrical structure; as well as The first curved reflective element and the second curved reflective element, wherein the flat surface of the first housing portion is positioned to be connected to a peripheral wall of the cylindrical structure of the second housing portion, and The first opening and the second opening are disposed at the flat surface of the first housing portion.

4. The optical module assembly according to 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 be connected to a peripheral wall of the cylindrical structure of the first housing portion, and The first opening and the second opening are disposed at the flat surface of the first housing portion.

5. The optical module assembly according to claim 1, wherein the first curved reflective element and the second curved reflective element are arranged outside the circumferential inner surface portion of the optical cavity; wherein the first curved reflective element is further arranged to direct light originating from a first location below the lower inner surface of the optical cavity toward the optical cavity; as well as The second curved reflective element is further arranged to direct the light from the optical cavity to a second position below the lower inner surface of the optical cavity.

6. The optical module assembly according to claim 1, Wherein the first opening and the second opening 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 to the first opening, and the second curved reflective element extends from the upper inner surface of the optical cavity to the at least one second opening.

7. The optical module assembly according to claim 1, The first curved reflective element and the second curved reflective element are arranged as corresponding extensions of the second shell part or are arranged in parts of the corresponding extensions, and are respectively set according to the position of the first opening and the position of the second opening, so that the light is directed from the light source to the optical cavity through the first opening by the first curved reflective element, and is directed from the optical cavity to the detector through the at least one second opening by the second curved reflective element.

8. The optical module assembly according to claim 7, The corresponding extension portion of the second shell part or a portion of the corresponding extension portion has an inclined surface, and the corresponding first curved reflective element and second curved reflective element are formed on the inclined surface, and the inclined surface is positioned to correspond to the position of the first opening and the position of the second opening, respectively.

9. The optical module assembly according to claim 1, The first shell part and the second shell part are formed by injection molding.

10. The optical module assembly according to claim 1, The inner surface of the optical cavity is coated with an optically reflective material.

11. The optical module assembly according to claim 1, The first curved reflective element and the second curved reflective element each include a corresponding curved mirror coated with an optical reflective material.

12. The optical module assembly of claim 2, further comprising an optical filter arranged to filter the light from the optical cavity before reaching the detector.

13. The optical module assembly according to claim 12, wherein the optical filter is arranged in the at least one second opening and / or on top of the guiding reflector.

14. The optical module assembly according to claim 1, Wherein the first opening and the second opening are positioned at a 90 degree azimuth angle relative to each other in the diametric plane of the optical cavity.

15. The optical module assembly according to claim 1 further comprises one or more additional second openings and corresponding optical filters arranged at predefined angular positions in the first housing portion, the one or more corresponding optical filters being arranged to filter the light from the optical cavity, the optical module assembly further comprising one or more additional second curved reflective elements, the one or more additional second curved reflective elements being associated with the one or more additional second openings and being arranged to direct the light of the corresponding wavelength of the light source from the optical cavity to the corresponding detector through the corresponding additional second openings using the corresponding optical filters.

16. The optical module assembly according to claim 1, further comprising at least one gas port for serving as a gas inlet and / or a gas outlet of 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.

17. A gas sensor comprising: An optical module assembly having an optical cavity according to any one of claims 1 to 16; A printed circuit board PCB device is attached to the optical module assembly and comprises: a light source configured to emit light for propagation in the optical cavity of the optical module assembly; as well as An optical detector is configured to detect light from the optical cavity of the optical module assembly.

18. A gas sensor according to claim 17 as appended to claim 2, wherein the guiding reflector and the first curved reflective element are arranged substantially close to the light source.

19. The gas sensor of claim 17, wherein the PCB device further comprises a controller configured to drive the light source and process an optical signal of the detected light.

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