Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/02—Catoptric systems, e.g. image erecting and reversing system
  • G02B17/06—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror
  • G02B17/0605—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using two curved mirrors
  • G02B17/061—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using two curved mirrors on-axis systems with at least one of the mirrors having a central aperture
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/0066—Radiation pyrometry, e.g. infrared or optical thermometry for hot spots detection
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/0022—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiation of moving bodies
  • G01J5/0025—Living bodies
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/04—Casings
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/07—Arrangements for adjusting the solid angle of collected radiation, e.g. adjusting or orienting field of view, tracking position or encoding angular position
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/08—Optical arrangements
  • G01J5/0806—Focusing or collimating elements, e.g. lenses or concave mirrors
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/08—Optical arrangements
  • G01J5/0808—Convex mirrors
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/08—Optical arrangements
  • G01J5/0815—Light concentrators, collectors or condensers
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/08—Catadioptric systems
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/08—Catadioptric systems
  • G02B17/0804—Catadioptric systems using two curved mirrors
  • G02B17/0808—Catadioptric systems using two curved mirrors on-axis systems with at least one of the mirrors having a central aperture
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
  • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
  • G02B5/085—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal
  • G02B5/0858—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal the reflecting layers comprising a single metallic layer with one or more dielectric layers
  • G02B5/0866—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal the reflecting layers comprising a single metallic layer with one or more dielectric layers incorporating one or more organic, e.g. polymeric layers
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B13/00—Burglar, theft or intruder alarms
  • G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
  • G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
  • G08B13/19—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using infrared-radiation detection systems
  • G08B13/193—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using infrared-radiation detection systems using focusing means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/0014—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiation from gases, flames
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B13/00—Optical objectives specially designed for the purposes specified below
  • G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Definitions

• the present invention relates to the field of optical systems comprising one or more optical components suitable for reflecting or making converge or diverge infrared radiation.
• the invention aims more particularly to propose a simple and inexpensive optical device which makes it possible to modify the field of vision of an infrared detector installed on the ceiling of a room, in order to observe the layer under the ceiling of the room.
• the invention also relates to an optical accessory which can be mounted or dismounted on an existing infrared detector, the optical accessory comprising an optical device as mentioned.
• the main application targeted by the invention relates to the modification of the field of vision of an infrared detector comprising a moderate resolution sensor, comprising for example 64 ⁇ 64 or 80 ⁇ 80 sensitive elements.
• This type of detector has sufficient resolution to allow imaging applications.
• the invention applies to any type of infrared detector for which there is a need to modify the detector's field of vision in a simple and inexpensive manner.
• “Ceiling layer” means a layer located directly under the ceiling of a room, and which has a small thickness compared to the height of the room. Typically, a ceiling layer has a thickness of less than 15% of the height of the room, directly under the ceiling.
• sensors operating in the infrared domain can be used to manufacture sensors operating in the infrared domain.
• pyroelectric sensors and thermopiles are widely used for very low resolution detectors conventionally comprising only a few sensitive elements.
• Sensors incorporating micro-bolometers are used in medium and high resolution sensors that can be used as imagers.
• sensors of moderate resolution which allow the implementation of basic imaging functions, such as the location of an infrared source.
• Such sensors can have a resolution between 16x16 pixels and 80x80 pixels and can operate on the basis of one of the aforementioned technologies.
• An anti-intrusion alarm system typically relies on a pyroelectric sensor comprising two or four sensitive elements associated with a simple and inexpensive optical device defining the detector's field of vision.
• This optical device can in particular be a Fresnel lens matrix made of polyethylene or a set of mirrors each made from a plastic substrate, such as polymethyl methacrylate (PMMA) or polycarbonate (PC), at least metallized on its functional surface.
• PMMA polymethyl methacrylate
• PC polycarbonate
• An anti-intrusion detector of this type is qualified as a passive detector because it emits no radiation.
• an intrusion detector is based on the observation of a simultaneous variation in the ambient infrared flux received by all the sensitive elements of the sensor.
• anti-intrusion detector installation on the ceiling, in which case the field of vision is 360 ° in azimuth and typically of the order of about 45 ° in elevation, on either side of the vertical , or a wall installation, in which case the detector's field of vision can be determined according to the configuration of the walls of the room in which it is installed.
• Occupancy sensors which usually control the automatic switching on of lighting, are similar to anti-intrusion sensors in their operation. There are also, for fire alarms, so-called thermo-velocimetric detectors, sensitive to an abnormal increase in the temperature of the walls of a room which characterizes the presence of a heat source.
• a pyroelectric sensor with a resolution of 16x16 pixels.
• This sensor which can for example be installed above a store queue, is associated with a germanium or chalcogenide glass lens which makes it possible to obtain a field of vision having a limited angle, on the order of 50 ° to 60 °.
• the resolution of the sensor although relatively low, is nevertheless sufficient to obtain a good approximation of the number of people and their location in the queue.
• FIG. 1 schematically represents an infrared detector 1 comprising an imager of moderate resolution intended to be arranged on a ceiling.
• Infrared radiation enters the detector through the optical system 2, which in particular comprises an input lens and an infrared sensor.
• the layer under the ceiling plays a key role for the comfort of a living place.
• These include the boundary layer of convection, where heat buildup can take place, especially in summer.
• monitoring the ceiling layer produces important information for managing the thermal comfort of a room.
• monitoring the layer under the ceiling improves safety in the context of preventing or detecting the start of a fire. It makes it possible to observe the thermo-velocimetry of the walls, that is to say the speed of temperature change of the walls, and therefore to detect an abnormal rise in their temperature characteristic of a pre-fire situation.
• the accumulation of hot smoke in the ceiling layer in the event of a fire can also be detected.
• a fire detector observing the layer under the ceiling has the advantage of not being able to trigger an alarm on the basis of a false signal, for example from the occupants of the room or hot objects that they are likely to handle.
• the object of the invention is to meet this need at least in part.
• the invention relates to an optical device, intended to be arranged on a detector provided with an infrared sensor to modify the field of vision of the detector, comprising:
• the primary and secondary mirrors being adapted to reflect radiation in the infrared; and the primary and secondary mirrors being configured to define the field of vision of the device, to form an afocal system and to form a continuous image of the periphery of the device, the center of the image being masked by the secondary mirror.
• peripheral of the device means all the directions substantially perpendicular to the axis of symmetry of the cone of the primary mirror, delimiting a panoramic view.
• the invention essentially consists in the use of two conical mirrors, the primary mirror collecting the infrared radiation coming from the layer under the ceiling around the device to return it to the secondary mirror, which in turn reflects it to the sensor of the infrared detector.
• the reflecting surfaces of the mirrors are configured to fulfill this function.
• the image obtained by the optical device according to the invention comprises central masking: in fact, the presence of the secondary mirror facing the central opening of the primary mirror has the effect of blocking the infrared radiation coming from the floor, when the device is arranged on a detector installed on the ceiling of a room.
• the sensor therefore only receives signals from the ceiling layer: the floor and any occupants of the room are completely hidden.
• mirrors make it possible, on the one hand, to avoid the use of expensive infrared lenses, and on the other hand to obtain afocal reflective optics thereby avoiding focus adjustments.
• a simple infrared optical device is thus obtained, inexpensive and making it possible to modify the field of vision of a detector and to provide a clear image of the periphery of the device (which may be a layer under the ceiling), corrected and with masking of the ground.
• the angle of the field of vision is between 5 ° and 10 °.
• the field of vision opens onto the ceiling layer: it is only the infrared radiation coming from the ceiling layer which is transmitted to the detector, and this over the entire periphery of the device, that is to say say 360 ° in azimuth.
• the device consists of a single piece of injection molded plastic, such as polymethyl methacrylate (PMMA) or polycarbonate (PC), at least the surfaces of the primary mirror and of the secondary mirror being metallic.
• PMMA polymethyl methacrylate
• PC polycarbonate
• the maximum diameter of the primary mirror is less than 1010 mm, preferably less than 70 mm, and the height of the device in the direction of the axis of the cone defining the reflecting surface is less than 40 mm, preferably less at 30 mm.
• the invention also relates to an infrared detector comprising an optical device as described above, the device being arranged so as to form the image on the infrared sensor of the detector.
• the invention relates to the use of this infrared detector to detect an accumulation of heat or a cold spot in the ceiling layer of a room. It also relates to the use of this infrared detector to detect an accumulation of hot smoke in the ceiling layer or an abnormal change in the temperature of the walls of a room at the level of the ceiling layer.
• the invention finally relates to an optical accessory intended to be arranged on an infrared detector, comprising an optical device as described above and a mechanism for hanging the optical device on the infrared detector.
• Figure 1 is a schematic profile view of an infrared detector according to the state of the art
• Figure 2 is a schematic view of an optical device according to the invention.
• Figure 3 is a longitudinal sectional view of an optical device according to the invention in a sectional view
• Figure 4 is a schematic view of an optical device according to the invention arranged on an infrared detector according to the state of the art;
• Figure 5 is a side view of an optical device according to the invention arranged on an infrared detector according to the state of the art;
• Figure 6 is an image obtained by an infrared detector according to the state of the art
• FIG. 7 is a simulation of the image obtained by an infrared detector according to the state of the art on which an optical device according to the invention is arranged.
• the optical device 10 comprises a primary mirror 11, a secondary mirror 12 and connecting means 13 for linking the primary mirror and the mirror.
• connection means 13 are rigid connection means, constituted by four elongated supports, distributed equiangularly, each attached by one of their ends to the primary mirror and by the other end to the mirror secondary.
• the height of the optical device that is to say its dimension in the vertical direction, can typically be of the order of 25 mm.
• the primary mirror has a central opening 14 as well as a reflecting surface 15.
• the diameter of the primary mirror can be of the order of 60 mm.
• the secondary mirror has a reflecting surface 16.
• the reflecting surface 16 of the secondary mirror is arranged opposite the central opening 14 of the primary mirror.
• the secondary mirror 12 masks the ground, and only the radiation reflected by the secondary mirror penetrates into the central opening 14 to reach the optical system 2 of the detector 1.
• the reflecting surfaces 15, 16 of the primary and secondary mirrors are of frustoconical and conical shape. respectively, and are configured to transmit to the optical system 2 of the detector the rays coming from the layer under the ceiling.
• the frustoconical profile of the primary mirror is such that the incident rays from the ceiling layer are returned to the secondary mirror, the profile of which is adapted to reflect the rays on the optical system 2 of the detector 1.
• the field of vision of the device extends continuously over 360 ° around the vertical and has an angle of field a on the layer under the ceiling of between 5 ° and 10 °, as more particularly visible in FIG. 5.
• the mirrors are configured so that the image formed on the sensor is clear, with aspherical corrections.
• the two mirrors form an afocal device.
• the optical device 10 is preferably made in a single piece of injection molded plastic, such as polymethyl methacrylate (PMMA) or polycarbonate (PC). The whole part, or at least the reflecting surfaces of the mirrors, are then metallized, in order to be able to reflect incident infrared radiation.
• PMMA polymethyl methacrylate
• PC polycarbonate
• Figures 4 and 5 schematically represent an optical device 10 according to the invention arranged on an infrared detector 1.
• the optical system 2 of the detector does not require any modification and no electrical connection is necessary to arrange the optical device 10 on the detector 1.
• a hanging mechanism can be provided.
• This mechanism may for example include a semi-transparent semi-spherical polyethylene (PE) dome of small thickness, typically close to 0.5 mm, to efficiently transmit infrared radiation.
• PE semi-transparent semi-spherical polyethylene
• the secondary mirror is integral with the internal face of the dome and the latter is attached to the base of the detector, thus covering the device.
• Figure 6 is an image obtained by an infrared detector according to the state of the art.
• the detector's field of vision is directed towards the floor of the room, and its angle a does not exceed 90 °.
• FIG. 7 shows for comparison the result of a computer simulation reproducing the effect obtained by the installation of an optical device according to the invention on the infrared detector used for obtaining the image of FIG. 6. It is noted that the field of vision of the detector is modified and allows the observation of the layer under the ceiling. A total masking of the ground in the center of the image is obtained, because the secondary mirror blocks the field of vision of the detector in the direction of the ground.
• this central masking makes it possible to avoid any risk of inadvertent triggering of the alarm by a false signal caused for example by an occupant of the room or an object that he manipulates (cup coffee for example).
• a simple, compact and lensless optical device can be used to modify the field of vision of an infrared detector in order to observe the layer under the ceiling.
• the invention can be implemented to fulfill a fire alarm function. Indeed, infrared monitoring of the ceiling layer allows the detection of hot smoke. It also makes it possible to observe the thermo-velocimetry of the walls of a room, that is to say the speed of rise in their temperature, likely to indicate a pre-fire situation.
• the invention can also be implemented with the aim of improving the thermal comfort of a room: infrared monitoring of the layer under the ceiling can indicate an accumulation of heat or makes it possible to detect a window that has remained open when the weather conditions outside are winter.
• the invention is also applicable to any field in which it is advantageous to modify the field of vision of an infrared vision device with a simple and inexpensive optical device for obtaining a periscopic field of vision.
• the optical device described can also be used in the automotive and transport fields.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Optics & Photonics (AREA)
• Photometry And Measurement Of Optical Pulse Characteristics (AREA)
• Radiation Pyrometers (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=67001942

Family Applications (1)

Country Status (7)

Families Citing this family (3)

Family Cites Families (17)

• 2019
  • 2019-01-08 FR FR1900160A patent/FR3091594B1/fr active Active
• 2020
  • 2020-01-08 WO PCT/EP2020/050312 patent/WO2020144231A1/fr unknown
  • 2020-01-08 EP EP20701259.2A patent/EP3908872A1/fr active Pending
  • 2020-01-08 KR KR1020217024552A patent/KR20210136984A/ko unknown
  • 2020-01-08 JP JP2021539463A patent/JP2022516364A/ja not_active Ceased
  • 2020-01-08 US US17/419,975 patent/US20220074792A1/en not_active Abandoned
  • 2020-01-08 CA CA3125842A patent/CA3125842A1/fr active Pending

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