• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a gas detector comprising a plane mirror (2); a concave spherical mirror (4) facing the plane mirror (2), with an optical axis (6) orthogonal to the plane mirror, the distance (D) between the plane and spherical mirrors being equal to 0.75 times the radius of curvature spherical mirror, within 10%; a radiation emitter / receiver (E) disposed at the point of intersection of the spherical mirror (4) and the optical axis (6); and a radiation receiver / transmitter (R) disposed at the point of intersection of the plane mirror (2) and the optical axis (6).
    公开号:FR3016214A1
    申请号:FR1450069
    申请日:2014-01-07
    公开日:2015-07-10
    发明作者:Sergio Nicoletti；Mickael Brun；Serge Gidon
    申请人:Commissariat a lEnergie Atomique CEA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    [0001] BACKGROUND OF THE INVENTION The present application relates to an optical detector for the presence and optionally content of a gas in an atmosphere, as well as a method of manufacturing such a detector. BACKGROUND OF THE PRIOR ART It is known to use optical detectors for the presence of a gas, for example carbon dioxide, carbon monoxide, methane or possibly various toxic gases such as xylene or toluene. cleared by the paintings. It should be noted that a presence detector of an excess of carbon dioxide and / or carbon monoxide may constitute a fire detector. Optical detectors will be investigated here which detect the presence of a gas by measuring the absorption of a light beam at one or more wavelengths corresponding to one or more absorption lines of the gas in question. In such detectors, a radiation emitter produces a light beam in a wavelength range including the characteristic absorption line wavelength (s) of the gas to be detected. A radiation receiver preceded by a filter at the wavelength of the absorption line B12921 - DD14102 2 to be detected indicates absorption at this wavelength, and the presence and content of the gas can be deduced therefrom. considered. The filter or filters may correspond to an alternation of thin dielectric layers. It can also be an alternation of metal and insulating strips whose pitch determines the filtering wavelength. In order for the entire gas detector system to be compact, it is often expected that the light beam propagating between the transmitter and the receiver will make one or more round trips via mirrors, generally mirrors. curves. In general, existing gas detector systems involving at least one round of light beam between the radiation emitter and the radiation receiver have the disadvantage of being relatively difficult to manufacture. Indeed, the transmitter, the receiver and the mirrors require precise positioning with respect to each other. Summary There is a need for an absorption gas optical detector which is particularly simple to manufacture. It is also desired that this detector be tolerant to positioning defects of the transmitter, the mirrors and the receiver relative to each other.
    [0002] Thus, an embodiment provides a gas detector comprising a plane mirror; a concave spherical mirror facing the plane mirror, of optical axis orthogonal to the plane mirror, the distance between the planar and spherical mirrors being equal to 0.75 times the radius of curvature of the spherical mirror, to within 10%; a radiation emitter / receiver disposed at the point of intersection of the spherical mirror and the optical axis; and a radiation receiver / emitter disposed at the point of intersection of the plane mirror and the optical axis.
    [0003] According to one embodiment, the plane mirror and the receiver / emitter form a single assembly comprising a support plate whose central part comprises the receiver / transmitter and whose remaining part constitutes the plane mirror. B12921 - DD14102 According to one embodiment, the plane mirror comprises a metal reflective coating comprising at least two parts insulated from each other, each part of the coating being in contact with a metal track connected to a terminal of the receiver / transmitter. According to one embodiment, the receiver / transmitter is disposed on a membrane suspended above a central cavity of the support plate. According to one embodiment, the gas detector further comprises at least one insulating layer comprising a central portion extended by arms connected to the remainder of said at least one layer, the central portion of said at least one layer constituting the membrane, the remainder of said at least one layer resting on the support plate.
    [0004] According to one embodiment, the metal tracks rest on the arms. Another embodiment provides a method of manufacturing a single set consisting of a planar mirror and a radiation receiver / transmitter, comprising the following steps: a) forming a receiver / transmitter in the central portion of a support plate ; and b) forming a reflective coating on the support plate except for said central portion. According to one embodiment, the reflective coating is metallic, the method further comprising c) in step a) forming metal tracks connected to terminals of the receiver / transmitter; and d) in step b), forming two parts in the reflective coating, each portion being connected to one of the metal tracks.
    [0005] According to one embodiment, step a) comprises the following steps: e) depositing a first insulating layer on the surface of the support plate; and f) depositing and etching a metal layer to form concentric rings connected to the metal tracks, the rings and metal tracks constituting the receiver / transmitter. According to one embodiment, the method further comprises the following step g) etching the support plate locally to form a central cavity under a central portion of the insulating layer, the central portion carrying the receiver / transmitter. BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages will be set forth in detail in the following description of particular embodiments in a non-limiting manner with reference to the accompanying figures in which: FIG. schematic section of an embodiment of an optical gas detector, FIGS. 2A and 2B are schematic views of an embodiment of a planar-receiver mirror assembly, and FIGS. 3A to 3C, 4A to 4C, SA at 5C and 6A and 6B are schematic views illustrating steps of an embodiment of a method of manufacturing a planar-to-receiver mirror assembly, FIGS. 3B and 3C, 4B and 4C, 5B and 5C and 6B being sectional views along the BB and CC planes of the corresponding A-indexed figures. For the sake of clarity, the same elements have been designated by the same references in the various figures and, in addition, the various figures are not drawn to scale. DETAILED DESCRIPTION Fig. 1 is a schematic sectional view of an embodiment of an absorption gas optical detector. The detector comprises a plane mirror 2 facing a concave spherical mirror 4 of radius of curvature RC, a radiation emitter 35, and a radiation receiver R. The optical axis B12921 - DD14102 of the system corresponds to the optical axis of the spherical mirror 4 and is orthogonal to the plane mirror 2. The emitter E is disposed at the intersection of the spherical mirror 4 with the optical axis 6 and the receiver R is disposed at the intersection of the plane mirror 2 and the optical axis 6. The emitter E is preferably a little or no directional emitter (divergent emitter) facing the plane mirror 2. The emitter E and the receiver R are respectively connected to the mirrors 2 and 4 by means not shown in FIG.
    [0006] The mirrors 2 and 4 are arranged so that the distance D between the respective intersections of the mirrors 2 and 4 with the optical axis 6 is equal to 1%, or even within 5%, or even 10%, three-quarters the radius of curvature RC of the spherical mirror 4 (D = 0.75 * Rc). Under these conditions, when a beam, of which a ray 8 has been represented, is emitted by the emitter E, it is reflected by the plane mirror 2 and then by the spherical mirror 4 before reaching the receiver R. The beam travels so three times the cavity. The magnification of the system is equal to 0.5, that is to say that the image of the emitter E on the receiver R has a dimension half that of the emitter E. A gas detector comprising mirrors , such as the detector of Figure 1, is well suited to the detection of gas whose absorption line or lines are in the infrared.
    [0007] The emitter may then be a filament heated to a temperature capable of emitting a sufficient quantity of radiation in a range of wavelengths including the absorption line to be detected, for example a temperature of between 350 ° C. and 650 ° C. for a detection wavelength of 4.25 pin corresponding to a carbon dioxide absorption line. By way of example, the receiver R comprises a passive component (resistor) or an active component (diode or transistor) whose characteristics change as a function of their heating due to the reception of infrared rays.
    [0008] B12921 - DD14102 6 Thus, the receiver R can be a bolometric or pyrometric sensor, or a thermopile. Simulations have been carried out by the inventors and show that such a system is insensitive to maladjustments. By way of example, when the distance D between the mirrors 2 and 4 is varied by 10%, the image of the transmitter is enlarged and overflows the receiver; the received energy then decreases by only 10% compared to the energy received in the ideal case where the entire image of the transmitter occupies the surface of the receiver. When one inclines by 0.05 ° or that is moved laterally 20 pin one of the mirrors 2 or 4 with respect to the optical axis 6, the image of the transmitter on the receiver is moved and the energy received on the receiver also decreases by only 10% compared to the ideal case. This positioning tolerance is particularly related to the fact that the receiver R and the emitter E are respectively integral with the mirror 2 and the mirror 4. In addition, because one of the mirrors constituting the optical system of the gas detector described previously is a plane mirror rather than a curved mirror, the system is simpler to manufacture. Figs. 2A and 2B schematically show an embodiment of a planar-receiver mirror assembly, Fig. 2B being a sectional view of Fig. 2A taken along the plane of section BB. The assembly comprises: - a support plate 10 provided with a cavity 12 on one of its faces; a layer or set of layers 14, generally insulating, comprising a central portion 16, an outer portion 18, and arms 20 and 21 interconnecting the portions 16 and 18; the portion 16 constitutes a membrane above the cavity 12 and the portion 18 covers the support plate 10 around the cavity 12; B12921 - DD14102 7 - a reflective coating 22 coating most of the portion 18 of the layer 14; commonly the coating is metallic, for example a layer of gold; a receiver R integral with the membrane 16; and metal tracks 24 and 25 for electrically connecting the receiver. In the example shown, the reflective coating 22 is in the form of a disk divided into two half-disks 22a and 22b separated and isolated from each other. The metal tracks 24 and 25 respectively rest on the arm 20 and on the arm 21. The metal tracks 25 and 24 extend from the receiver R, respectively under the part 22a and under the part 22b of the coating 22. Thus the coating 22, in addition to constituting the reflecting surface of the plane mirror 2, is used to electrically connect the receiver R, the portions 22a and 22b constituting electrodes. Advantageously, the heat losses at the receiver R are limited because the membrane 16 supporting the receiver is suspended above a cavity.
    [0009] The receiver R and the plane mirror 2 constitute an assembly making it possible to eliminate the assembly step of these two elements and to ensure a precise and stable positioning of the receiver R with respect to the plane mirror 2. FIGS. 3A to 6B are schematic views of an example of the central portion of a receiver plane mirror assembly at different stages of an exemplary manufacturing method. Figure 3A is a schematic and top view of the central portion of the planar-receiver mirror assembly 30 after first steps, Figures 3B and 3C being sectional views along the BB and CC planes, respectively. These figures represent a support plate 10, for example made of silicon, after a step of depositing an insulating layer 30, for example SiO 2 or Si 3 N 4, followed by a deposition step of a metal layer. The metal layer has been etched to form concentric metal rings 34 interconnected by rectilinear metal tracks 24 and 25 resting on the insulating layer 30. The set of concentric rings 34 and metal tracks 24 and 25 form a radiation receiver 5 R. The metal rings 34 and the metal tracks 24 and 25 are, for example, platinum or titanium nitride. Thus, the voltage between tracks 24 and 25 depends on the strength of the metal rings. This resistance is temperature dependent and is an indication of the intensity of radiation striking metal rings 34. FIGS. 4B and 4C are sectional views of FIG. 4A, respectively along planes BB and CC. FIGS. 4A to 4C schematically represent the structure of FIGS. 3A to 3C after the following successive steps: deposition of an insulating layer 38, for example of SiO 2 or Si 3 N 4, and etching of the layer 38 to form openings 40 which reveal the ends of the metallic tracks 24 and 25 of the receiver R. In FIG. 4A and in the following figures, the portions of the radiation receiver R covered with the layer 38 are shown in dotted lines. Figures 5B and 5C are sectional views of Figure 5A respectively along the planes BB and CC. FIGS. 5A to 5C schematically represent the structure of FIGS. 4A to 4C after the following successive steps: deposition of a reflective coating 22 and etching of the coating 22 to discover a central portion of the layer 38 and to separate the coating 22 in two parts 22a and 22b. As indicated above, the coating 22 is preferably a metal layer, each of the two parts 22a and 22b of the coating 22 being connected respectively to the end of the track 25 and the end of the track 24 of the 35 receiver R to electrically connect the latter.
    [0010] Figure 6B is a sectional view of Figure 6A along the plane BB. FIGS. 6A and 6B schematically represent the structure of FIGS. 5A to 5C after the following successive steps: etching of the layers 30 and 38 to form an opening 48 around all the rings 34 of the receiver R, etching of the support plate 10 from the opening 48 to form a central cavity 12 under a membrane 16 carrying the receiver R.
    [0011] The membrane consists of a central portion 42 of the layer 38 and a central portion 50 of the layer 30, the central portion 50 facing the central portion 42. The central portions 42 and 50 are extended by arms 20 and 21 visible in FIG. 6A. The arms 20 and 21 carry part of the tracks 24 and 25, respectively. These arms connect the central portions 50 and 42 of the layers 30 and 38 to the remainder of the layers 30 and 38 resting on the support plate 10. The arms 20 and 21 make it possible to hold the membrane 16 in place. For example, if wants the optical path between the transmitter and receiver is 8 cm, the distance D between the mirrors 2 and 4 will be equal to about one third of this value, D = 2.67 cm. The dimensions of the emitter E, the receiver R and the mirrors 2 and 4 will be chosen by those skilled in the art according to the desired size and as a function of the desired performance of the detector. For example, we can choose a transmitter diameter equal to 150 fun and a receiver diameter equal to 75 gm. For flat and spherical mirrors, diameters equal to 0.45 cm and 0.9 cm, respectively, may be chosen. The gas sensor thus obtained is very compact. Particular embodiments have been described. Various variations and modifications will be apparent to those skilled in the art. The receiver can be divided into several elementary receivers, each associated with a specific filter. B12921 - DD14102 10 different elementary receivers can provide a reference indication and / or detect several different gases. The reference serves in particular to take account of environmental fluctuations and / or intensity fluctuations of the transmitter. Those skilled in the art can modify the order of the steps and / or add or delete steps in the manufacturing method described above. Although it has been described a gas detector whose emitter E is integral with the spherical mirror 4 and whose receiver R is integral with the plane mirror 2, because of the principle of the inverse return of light it is possible to exchange the positions of the emitter E and the receiver R. The receiver R is then disposed at the spherical mirror 4, the emitter E being disposed on the plane mirror 2. In this case, the magnification of the system is equal to 2. It will be chosen to arrange the transmitter or the receiver on the spherical mirror side and to arrange the receiver or the transmitter on the side of the plane mirror according to specific manufacturing requirements. This choice will also be dictated by dimensional constraints. Indeed the device (receiver or transmitter) disposed at the plane mirror is twice smaller than the device at the spherical mirror. Finally, although a gas detector has been described in which the receiver is held by a membrane over a cavity, it will be appreciated by those skilled in the art that depending on the type of transmitter or receiver selected such a cavity may not be useful.
    权利要求:
    Claims (10)
    [0001]
    REVENDICATIONS1. A gas detector comprising: a plane mirror (2); a concave spherical mirror (4) facing the plane mirror (2), of optical axis (6) orthogonal to the plane mirror, the distance (D) between the plane and spherical mirrors being equal to 0.75 times the radius of curvature of the spherical mirror, within 10%; a radiation emitter / receiver (E) disposed at the point of intersection of the spherical mirror (4) and the optical axis (6); and a radiation receiver / transmitter (R) disposed at the point of intersection of the plane mirror (2) and the optical axis (6).
    [0002]
    A detector according to claim 1, wherein the plane mirror (2) and the receiver / transmitter (R) form a single unit comprising a support plate (10), a central part of which comprises the receiver / transmitter and the remaining part of which constitutes the plane mirror (2).
    [0003]
    The detector of claim 2, wherein the plane mirror (2) comprises a metal reflective coating (22) comprising at least two mutually isolated portions (22a, 22b), each portion of the coating being in contact with each other. contact with a metal track (24, 25) connected to a terminal of the receiver / transmitter (R). 25
    [0004]
    4. Detector according to claim 2 or 3, wherein the receiver / transmitter (R) is disposed on a membrane (16) suspended above a central cavity (12) of the support plate (10).
    [0005]
    The detector of claim 4, further comprising at least one insulating layer (14; 30,38) having a central portion (16; 42,50) extended by arms (20,21) connected to the remainder of said least one layer, the central portion of said at least one layer constituting the membraneB12921 - DD14102 12 (16), the remainder of said at least one layer resting on the support plate (10).
    [0006]
    6. Detector according to claim 5, wherein the metal tracks (24, 25) rest on the arms (20, 21).
    [0007]
    A method of manufacturing a single set consisting of a plane mirror and a radiation receiver / emitter, comprising the steps of: a) forming a receiver / transmitter (R) in the central portion of a carrier plate (10); and b) forming a reflective coating (22) on the support plate (10) with the exception of said central portion.
    [0008]
    The method of claim 7, wherein the reflective coating is metallic, the method further comprising: c) in step a) forming metal tracks (24, 25) connected to receiver / transmitter terminals (R) ); and d) in step b), forming two portions (22a, 22b) in the reflective coating (22), each portion being connected to one of the metal tracks.
    [0009]
    9. The method of claim 8, wherein step a) comprises the following steps: e) depositing a first insulating layer (30) on the surface of the support plate (10); and f) depositing and then etching a metal layer to form concentric rings (34) connected to the metal tracks (24, 25), the rings and the metallic tracks constituting the receiver / transmitter (R).
    [0010]
    The method of claim 9, further comprising the step of: g) etching the support plate (10) locally to form a central cavity (12) under a central portion (42) of the insulating layer (30), the central portion carrying the receiver / transmitter (R).
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    同族专利:
    公开号 | 公开日
    EP2891876A1|2015-07-08|
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    US9134226B2|2015-09-15|
    FR3016214B1|2019-09-06|
    EP2891876B1|2020-03-18|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20070242720A1|2006-04-12|2007-10-18|Eckles Robert D|Multi-pass optical cell with actuator for actuating a reflective surface|
    US20120267532A1|2010-01-21|2012-10-25|Cambridge Cmos Sensors Limited|Ir emitter and ndir sensor|WO2018069624A1|2016-10-11|2018-04-19|Commissariat A L'energie Atomique Et Aux Energies Alternatives|Highly folding pendular optical cavity|US7535573B2|2006-02-23|2009-05-19|Picarro, Inc.|Cavity enhanced optical spectroscopy with a cavity having a predetermined deviation from a mode degeneracy condition|FR3054882B1|2016-08-04|2020-10-09|Commissariat Energie Atomique|ABSORPTION CAVITY WITH INPUT AND OUTPUT WAVE GUIDES FOR A BIOLOGICAL OR CHEMICAL SENSOR|
    US10161859B2|2016-10-27|2018-12-25|Honeywell International Inc.|Planar reflective ring|
    FR3063811B1|2017-03-10|2021-08-27|Elichens|OPTICAL GAS SENSOR|
    FR3072775B1|2017-10-23|2019-09-27|Elichens|COMPACT GAS SENSOR|
    FR3095517B1|2019-04-25|2021-05-14|Elichens|Compact gas sensor|
    法律状态:
    2016-01-25| PLFP| Fee payment|Year of fee payment: 3 |
    2017-01-31| PLFP| Fee payment|Year of fee payment: 4 |
    2018-01-31| PLFP| Fee payment|Year of fee payment: 5 |
    2019-01-30| PLFP| Fee payment|Year of fee payment: 6 |
    2020-01-30| PLFP| Fee payment|Year of fee payment: 7 |
    2021-01-28| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1450069A|FR3016214B1|2014-01-07|2014-01-07|OPTICAL DETECTOR OF A GAS|
    FR1450069|2014-01-07|FR1450069A| FR3016214B1|2014-01-07|2014-01-07|OPTICAL DETECTOR OF A GAS|
    EP14198359.3A| EP2891876B1|2014-01-07|2014-12-16|Optical gas detector|
    US14/576,794| US9134226B2|2014-01-07|2014-12-19|Optical gas detector|
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