Detection and / or communication system for a motor vehicle comprising a module for receiving a light beam

Abstract

The invention relates to a system (1) for a motor vehicle, the system comprising a receiving module (3) capable of receiving a light beam (F2), wherein the receiving module comprises an elementary acquisition module (32) comprising a photodetector (32a) capable of converting a light signal that it receives into an electrical signal, characterised in that the receiving module comprises an optical unit (31) arranged in front of the elementary acquisition module, the optical unit comprising a lens (52) made of an absorbent material to form a first bandpass optical filter (I1) capable of transmitting a first range of wavelengths (BP1) and an optical element (53) arranged to form a second interference optical filter (I2) capable of transmitting a second range of wavelengths (BP2) at least partially within the first range and substantially narrower than the first range.

Description

Motor vehicle detection and / or communication system comprising a module for receiving a light beam

[0001] The invention relates to the field of automotive lighting and data transmission functions using light emitted by an automotive lighting system. More specifically, the invention relates to a system of a motor vehicle for receiving data transmitted by a light beam.

[0002] It is known in the automotive field to use a light beam emitted by a light module to perform a given photometric function, and also to transmit data.

[0003] Conventionally, the light source enabling the emission of this light beam is controlled by a pulse width modulated electrical signal, or PWM (from the English "Pulse Width Modulation"). The light source is thus periodically activated and deactivated by this PWM signal, so that the emitted light beam is composed of light pulses succeeding one another with a frequency high enough that the human eye can no longer distinguish them. The intensity of the emitted light beam is a function of the duty cycle of this PWM signal, so that it is possible to control it by adjusting this duty cycle. It is then possible to modulate this PWM signal using a data sequence so that this data sequence is transported by the light beam. In this way, the light beam can retain its original function, namely to perform a photometric function, while allowing the transport of the data sequence.This type of technology is known for example as VLC (Visible Light Communication) or even LiFi (Light Fidelity).

[0004] Thus, beyond the realization of one or more photometric functions, such as a daytime running light or dipped beam type lighting, various functions can be implemented by this type of light module. For example, the light module can thus be integrated into a transmission module capable of carrying out functions of communication of a data sequence with another vehicle or with an infrastructure which is equipped with a reception module capable of demodulating the light beam that it receives to extract the data sequence. In another example, the headlight comprising the transmission module can be equipped with a reception module in order to receive the emitted light beam, after reflection on an object in the vicinity of the vehicle. It is then possible, by demodulation and extraction of the emitted data sequence, to determine the time of flight of the emitted light beam and therefore evaluate the distance separating the vehicle from the object.

[0005] However, this type of system based on the use of a transmission module capable of both performing a photometric light function and data transmission has a drawback. Indeed, the reception module intended to receive the light beam carrying the data, whether it is arranged in the same vehicle or in another vehicle, must include at least one photodetector to convert this light beam into an electrical signal in order to demodulate this signal and extract a data sequence from it.

[0006] However, under certain conditions, this photodetector may see its signal-to-noise ratio significantly degraded. This is particularly the case under significant sunlight conditions. Indeed, under such conditions, the illumination of the sun, in the visible spectrum in which the light source of the emission module operates, may be significantly greater than that of the received light beam, so as to cause saturation of the photodetector. In this state, the photodetector enters a non-linear operating state and is unable to properly convert the light beam into an electrical signal that can be demodulated without loss of information.

[0007] In order to avoid this saturation of the photodetector, it could be considered to filter the received light beam in a very narrow wavelength band, for example between 420 nm and 470 nm, so as to limit the impact of sunlight. However, given the extent of the solar irradiance spectrum, the production of a bandpass filter capable of filtering the light beam over a narrow band is particularly complex. For example, it would be necessary to superimpose more than fifty thin layers to form an interference filter capable of reflecting, in a sufficient way, the entire solar irradiance spectrum outside this narrow band. In addition, beyond the manufacturing complexity, the cost of such a filter to obtain zero or sufficiently low gain outside the narrow band and to obtain a high slope of the gain at the limits of this narrow band becomes prohibitive.

[0008] There is therefore a need for a system capable of transmitting a sequence of data, from a transmission module integrating a light module participating in the realization of a photometric function to an acquisition module, whose signal to noise ratio is optimal in all weather conditions, including in the case of strong sunshine, and whose production complexity and cost are reasonable.

[0009] The present invention is placed in this context, and aims to meet this need.

[0010] For these purposes, the subject of the invention is a system of a motor vehicle, comprising a reception module capable of receiving a light beam, the reception module comprising an elementary acquisition module comprising a photodetector capable of converting a light signal that it receives into an electrical signal, characterized in that the reception module comprises an optical unit arranged in front of the elementary acquisition module, the optical unit comprising a lens made of an absorbent material to form a first optical filter of the bandpass type capable of transmitting a first range of wavelengths and an optical element arranged to form a second optical filter of the interference type capable of transmitting a second range of wavelengths at least partially included in the first range and substantially narrower than the first range.

[0011] It is thus understood that the invention proposes to filter the received light beam in two stages. A first filter makes it possible to refine this light beam by eliminating a significant part of the spectrum of this beam, without however the bandwidth of this filter being particularly narrow. This type of filter can be easily produced using a lens made of an absorbent material, for example by being tinted in the mass. A second filter, of the interference or dichroic type, then refines the received light beam, by selecting a narrow band in the bandwidth of the first filter. Given the fact that a major part of the spectrum has been eliminated by the first filter, the number of layers of the second filter can be greatly reduced, without the performance of this second filter being affected. Therefore, the complexity of production and the cost of this second filter can be reduced.Furthermore, in conditions of strong sunlight, when sunlight is added to the light emitted by an emission module, these filters can significantly reduce the impact of sunlight and therefore avoid saturation of the photodetector.

[0012] It should be noted that it is possible to provide for the first filter to be arranged upstream of the second filter or vice versa, without departing from the scope of the present invention. It is also possible to provide for the addition of other optical elements forming other interference filters which further narrow the band of the received light beam. It is also possible to provide for the second range to be partially or totally included in the first range.

[0013] Preferably, the optical unit has a focal plane passing through the photodetector of the elementary acquisition module.

[0014] In the present invention, the absorbent material of said lens may be selected so that the first optical filter has a transmission coefficient of at least 80% in the first range, or bandwidth, and a transmission coefficient of less than 80% outside the first range. The lens may be made of a single material, such as glass or a thermoplastic material, tinted or colored, to form said first filter, or it may be made of a plurality of materials, organized for example in layers, at least one of which forms said first filter.

[0015] Advantageously, the absorbent material of the lens is selected so that the first range is centered on a wavelength of the visible spectrum, i.e. a wavelength between 380 nm and 780 nm. For example, the first optical filter may have a transmission peak, i.e. a peak whose transmission coefficient is greater than 95%, in the violet or in the blue, in particular between 380 nm and 500 nm, in particular at substantially 390 nm or at substantially 450 nm. Where appropriate, the first range, i.e. the range of wavelengths for which the transmission coefficient of the first filter is greater than or equal to 80%, extends partially or totally into the visible spectrum, and may for example be the range 420 nm to 490 nm, the transmission coefficient of the first filter being less than 80% outside this range and in particular less than 40% in green, yellow, red and infrared.

[0016] For example, the absorbent material of the lens may be a glass composition as described in patent EP0481165.

[0017] In the present invention, the optical element may be arranged so that the second optical filter has a transmission coefficient of at least 80% in the second range, or bandwidth, and a transmission coefficient of less than 80% in the first range outside the second range. The optical element may be arranged so that the second optical filter has a transmission coefficient of less than and / or greater than 80% outside the first range. It may in particular be envisaged that the second optical filter has other bandwidths provided outside the first range, without departing from the scope of the present invention. This second filter, of the interference type, makes it possible to improve the signal-to-noise ratio of the system, by reflecting what has not been absorbed or what should not be absorbed by the first filter.

[0018] Advantageously, the optical element is arranged so that the width of the second range is less than 30 nm. For example, the second range may be centered on a wavelength included in the first range, for example between 445 nm and 450 nm.

[0019] In the case where the light beam is emitted from a semiconductor light source, such as a light-emitting diode, the white light used to obtain the light beam is generally obtained from a blue light generator, and a photoluminescent material, or phosphor, absorbing part of this blue light to emit yellow light in response, the rest of the blue light and this yellow light forming, by additive synthesis, a white light. However, due to this absorption-re-emission, a yellow photon is therefore necessarily emitted more slowly than a blue photon. Therefore, in the context of obstacle detection by analyzing a time of flight of a light beam, the resolution of evaluating the time of flight will necessarily be higher if the evaluation is done using only blue light rather than using another wavelength range, or even using the entire visible spectrum.The fact that the second range is centered on a wavelength between 445 nm and 450 nm thus makes it possible to reduce the uncertainty in detecting the distance of an obstacle to the vehicle. Symmetrically, this second range makes it possible to increase the data communication rate between a transmitting module and the receiving module.

[0020] In an exemplary embodiment of the invention, the optical element comprises a stack of thin layers each having, alternately, a high refractive index or a low refractive index. The low refractive index will be substantially lower than the high refractive index. Such a configuration is also called a Bragg mirror. The thickness of each layer may, for example, be determined as a function of the central wavelength of the second range and the high and / or low refractive indices. It will be noted that the thickness of each layer will be substantially lower than the central wavelength of the second range.

[0021] For example, for thin films with a high refractive index, one of the following materials can be used: niobium pentoxide (Nb2O5), titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), zirconium dioxide (ZrO2) or hafnium dioxide (HfO2). For thin films with a low refractive index, silicon dioxide (SiO2) can be used.

[0022] The number of layers in the optical element will advantageously be less than 20 layers. In other words, the design of the optical element is simpler and its cost is lower, thanks to the presence of the first filter.

[0023] In one embodiment of the invention, the lens is a plano-convex lens and the optical element is a coating formed on the flat face of the lens. Where appropriate, said flat face of the lens may be the face of the lens facing the elementary acquisition module.

[0024] In an alternative or cumulative embodiment, the optical element is a flat blade interposed between the lens and the elementary acquisition module.

[0025] Advantageously, the optical unit comprises a plurality of lenses comprising said lens forming the first optical filter and at least one other lens made of a transparent material.

[0026] In one embodiment of the invention, the reception module comprises a plurality of elementary acquisition modules each comprising a photodetector capable of converting a light signal that it receives into an electrical signal. Where appropriate, it may be provided that the optical unit has a focal plane passing through each of the photodetectors.

[0027] For example, all photodetectors can form a sensor, for example a single electronic component.

[0028] Advantageously, the photodetector of the or each elementary acquisition module is an avalanche photodiode. This type of photodetector is also known as SPAD, from the English "Single-Photon Avalanche Diode". The set of avalanche photodiodes can thus form a silicon photomultiplier or SiPM (from the English "Silicon PhotoMultiplier"). This type of photodetector makes it possible to detect the incidence of a single photon with a significant gain, for example of the order of 10 6 , and therefore to compensate for the degradation of the signal-to-noise ratio due to external conditions or even to filter absorptions.

[0029] Advantageously, the reception module comprises a demodulation unit connected to the or each photodetector and arranged to extract a data sequence from an electrical signal converted by this photodetector.

[0030] In one embodiment of the invention, the system comprises an emission module comprising a light module capable of emitting a light beam whose spectrum has at least one portion in the second wavelength range and a modulation unit capable of receiving a data sequence and arranged to modulate said emitted light beam from the received data sequence.

[0031] For example, the light module may be arranged such that the spectrum of the emitted light beam has a first peak in the visible spectrum, for example in a range of 440 nm to 500 nm, in particular at 450 nm.

[0032] In one embodiment of the invention, the light module comprises a light source capable of emitting light rays of which at least one or at least some wavelengths are located in the second wavelength range and an optical unit arranged to project the light rays emitted by the light source to form said light beam. The light source may be a laser type source, a light-emitting diode, a vertical-cavity surface-emitting laser diode, also called VCSEL (from the English "Vertical-Cavity Surface-Emitting Laser") or even a superluminescent diode or SLED (from the English "Superluminescent diode"). Where appropriate, the modulation unit may be arranged to control the light source, and in particular a power supply supplied to this light source, to modulate the light beam.

[0033] Advantageously, the modulation unit is arranged to generate a pulse width modulated control signal, to modulate said control signal from the received data sequence and to control the emission of said light beam by the light module from the modulated control signal. For example, the modulation unit may be arranged to convert said received data sequence into a modulating signal and to modulate, for example in amplitude, frequency or phase, the control signal with this modulating signal.

[0034] Advantageously, the system comprises a calculation unit arranged to detect, in a data sequence extracted by the demodulation unit from an electrical signal converted by the photodetector from a light beam received by the reception module, the presence of a data sequence modulating the light beam emitted by the transmission module and to determine a time of flight separating the emission of said emitted light beam from the reception of said received light beam.

[0035] Advantageously, the emission module is arranged so that the light beam participates, totally or partially, in the realization of a predetermined regulatory photometric function. It could for example be a daytime running light or DRL (from the English "Daytime Running Lamp"), which has the advantage of being emitted in a wide field with a low intensity.

[0036] Advantageously, the reception module, and where appropriate the transmission module, is arranged in a front headlight of the motor vehicle.

[0037] The invention also relates to a reception module for a system of a motor vehicle according to the invention.

[0038] The invention also relates to a front headlight of a motor vehicle comprising a reception module, and optionally a transmission module, according to the invention.

[0039] The present invention is now described using examples which are purely illustrative and in no way limitative of the scope of the invention, and from the appended drawings, drawings in which the various figures represent:

[0040] represents, schematically and partially, a view of a system of a motor vehicle according to an exemplary embodiment of the invention;

[0041] represents, schematically and partially, an example of the embodiment of a reception module of the system of the; and

[0042] represents, schematically and partially, a transmission spectrum of the optical unit of the receiving module of the.

[0043] In the following description, elements which are identical, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references.

[0044] A system 1 of a motor vehicle according to an exemplary embodiment of the invention is shown.

[0045] The system 1 comprises an emission module 2 arranged to emit a light beam F1 and a reception module 3 intended to receive a light beam F2.

[0046] In the example described, the transmission module 2 and the reception module 3 are arranged in the same front headlight of the motor vehicle. It may be provided that the modules 2 and 3 are arranged in different locations of the motor vehicle, without departing from the scope of the present invention.

[0047] The emission module 2 comprises a light module 21 and a modulation unit 22.

[0048] The light module 2 is arranged so that the light beam F1, which it emits, has an electromagnetic spectrum S of which at least a portion is located in the visible spectrum. As shown in, the spectrum S has a first intensity peak P1, or line, in the blue, for example at 450 nm. It will be noted that it is possible for the spectrum S to have other intensity peaks, and in particular intensity peaks in the infrared.

[0049] In order to emit this light beam F1, the light module 21 comprises a light source 23 capable of emitting light rays and an optical unit 24 arranged to project these light rays to form the light beam F1. In the invention, the optical unit 24 may indifferently comprise one or more reflectors, one or more lenses, one or more diaphragms or one or more collimators or even a combination of several of these optical elements.

[0050] The light source 23 comprises, for example, a semiconductor generator (not shown), for example a gallium nitride or GaN, capable of emitting, by electroluminescence and in response to an electric current passing through it, rays of blue light with an emission peak at 450 nm. The light source also comprises a photoluminescent element, in the form of a resin comprising a cerium-doped yttrium aluminum garnet, or CE:YAG, capable of absorbing blue light and, by photoluminescence and in response to the excitation produced by this light, of emitting rays of yellow light, with a peak at 550 nm.

[0051] The photoluminescent element is arranged on the generator so that a portion of the blue light rays excites this element so that it emits, by photoluminescence, yellow light rays. The other portion of the blue light rays passes through this element. Thus, the light source 23 simultaneously emits, when electrically powered, blue and yellow light rays, the light thus formed appearing white to the human eye.

[0052] To the extent that the light beam F1 is composed, partially or totally, of white light, it is possible to use this light beam F1 to participate, partially or totally, in the realization of a predetermined photometric function, in particular regulatory. In this case, the optical unit 24 is arranged to shape this light beam F1 so that its photometric distribution satisfies the requirements of said function. For example, it may be provided that the light beam F1 participates in the realization of a function of the daytime running light type, or DRL.

[0053] In addition to this photometric function, the light beam F1 allows the system 1 to perform functions of detecting and evaluating the position of an obstacle on the road and / or communicating with another vehicle or with road infrastructure.

[0054] The modulation unit 22 is capable of receiving a data sequence, for example predetermined in the context of a use for detecting and evaluating the position of an obstacle, the sequence being in this case stored in a memory of the system 1 (not shown) or, as a variant, generated by a computer of the system 1 (not shown) to communicate with a system identical to that provided in another vehicle or in a road infrastructure.

[0055] The modulation unit 22 is arranged to modulate the light beam F1 emitted by the light module 21, from this data sequence, for example by controlling the electrical power supplied to the light source 23.

[0056] For these purposes, the modulation unit 22 comprises a generator of a pulse-width modulated control signal. This control signal makes it possible to control a switching power supply (not shown) of the light source 23. Conventionally, the duty cycle of this control signal, set by the modulation unit 22, thus makes it possible to control the average electrical power supplied to the light source 23, and therefore to control the light intensity of the light beam F1, so as to satisfy the requirements of the photometric function that it performs.

[0057] In the example described, the modulation unit 22 is arranged to convert the data sequence into a modulating signal and to modulate the initial control signal using this modulating signal. It will be noted that several types of modulation can be used indifferently within the framework of the present invention, and in particular an on-off keying modulation (OOK), a pulse code modulation (PCM), a pulse amplitude modulation (PAM), a pulse width modulation (PWM) or a pulse position modulation (PPM).

[0058] The light beam F1 thus emitted is composed of a train of light pulses succeeding one another with a sufficiently high frequency, for example greater than 30 MHz, in particular between 70 MHz and 100 MHz, so that the human eye can no longer distinguish them. Furthermore, the amplitude, width and / or position of each pulse with respect to the period allows the light beam F1 to transport the data sequence to the reception module 3.

[0059] The reception module 3 comprises an optical unit 31, downstream of which a plurality of elementary acquisition modules 32 are provided. The reception module 3 also comprises a demodulation unit 33.

[0060] Each of the elementary acquisition modules 32 comprises a photodetector 32a. The light beam F2 received by the reception module 3 is thus concentrated by the optical unit 31 onto one or more of the photodetectors 32a.

[0061] The light beam F2 may indifferently be the light beam F1 emitted by the transmission module 2 and reflected by an obstacle or an object, located in the environment of the vehicle, towards the reception module 3, or a light beam emitted by a transmission module of a system of another vehicle or of a road infrastructure equipped with a transmission module similar to module 2.

[0062] The photodetectors 32a are identical and are each formed by an avalanche photodiode of a silicon photomultiplier. These photodiodes are distributed in a matrix manner. It will be noted that the dimensions of the photodetectors 32a are of the order of a micrometer. The assembly thus forms a sensor whose spatial reception resolution is of the order of 0.1°, and whose detection capabilities, due to the use of avalanche photodiodes, are particularly high, even in the case of degraded acquisition conditions.

[0063] Each of the photodetectors converts the portion of the light beam F2 that it receives into an electrical signal that it transmits to the demodulation unit 33, which can then extract a data sequence from it.

[0064] In the event that system 1 implements a communication function, this data sequence can then be transmitted to a vehicle computer to be interpreted, decoded and / or transmitted to equipment or to a user of the vehicle.

[0065] In the case where the system 1 implements a function for detecting and evaluating the position of an object or obstacle, this data sequence can be transmitted to a computing unit 4 of the system 1. This computing unit 4 can thus detect the presence of a predetermined data sequence with which the modulation unit 22 modulates the light beam F1 emitted by the light module 21. In this case, the computing unit can determine a flight time separating the emission of the light beam F1 from the reception of the light beam F2.

[0066] In connection with the and with the, we will now describe an embodiment of the optical unit 31.

[0067] As shown in, the optical unit 31 comprises a plurality of lenses including three lenses 51 made of a transparent or translucent material as well as a lens 52 made of an absorbent material to form a first optical filter I1 of the bandpass type capable of transmitting a first range of wavelengths BP1.

[0068] It will be noted that the number of lenses, the profile of the lenses and the respective positions of the lenses illustrated constitute a non-limiting example of the invention and that this number, these profiles and these positions may be varied without departing from the scope of the present invention.

[0069] In the example described, this set of lenses 51 and 52 has a focal plane passing through the photodetectors 32a of the elementary acquisition modules 32.

[0070] The absorbent material of the lens 52 is a tinted glass which has been selected so that the first optical filter I1 has a transmission coefficient of at least 80% in the first wavelength range BP1 and a transmission coefficient of less than 80% outside this first range BP1.

[0071] Lamontre shows the transmission spectrum of this first optical filter I1 formed by the lens 52 (shown in dotted lines). We can thus see that the bandwidth BP1 of the first filter I1, for which the transmission coefficient is greater than or equal to 80%, is a range 420 nm to 490 nm with a transmission peak at 450 nm. Outside this range, the transmission coefficient is less than 80%, or even less than 50%.

[0072] The optical unit 31 also comprises an optical element 53 arranged to form a second optical filter I2 capable of transmitting a second range of wavelengths BP2 at least partially included in the first range BP1 and substantially narrower than the first range BP1.

[0073] In the example shown, the optical element 53 is an interference filter comprising a stack of thin layers each having, alternately, a high refractive index or a low refractive index. The high refractive index layers are made of titanium dioxide (TiO2) and the low refractive index thin layers are made of silicon dioxide (SiO2).

[0074] The lens 52 is a plano-convex lens and the optical element 53 is a coating formed on the flat face of this lens facing the photodetectors 32a.

[0075] The number of layers and the thickness of the layers were determined so that the second optical filter I2 has a transmission coefficient of at least 80% in the second range BP2.

[0076] La also shows the transmission spectrum of this second optical filter I2 formed by the optical element 53 (represented in mixed dotted lines). It can thus be seen that the bandwidth BP2 of the second filter I2, for which the transmission coefficient is greater than or equal to 80%, is a range 430 nm to 460 nm with a transmission peak at 445 nm. It will be noted that the second optical filter I2 has other bandwidths outside the first range BP1, without this impacting the performance of the system, as will be described later. In the non-limiting example of la, the optical element 53 is formed of 11 superimposed layers.

[0077] The set of filters I1 and I2 thus forms a filter I whose transmission spectrum has been superimposed on the other transmission spectra of filters I1 and I2. We can thus see that the spectrum of filter I thus presents only a single wavelength range, corresponding to the BP2 range, for which the transmission coefficient is greater than 80%.

[0078] When the sunlight conditions in the vicinity of the vehicle are particularly strong, sunlight is thus added to the light beam F2 received by the receiving module 3. The illumination of the sun, in the visible spectrum, is significantly greater than that of a photometric function such as a daytime running light. Therefore, the light beam F2 received by the receiving module 3 consists of a part of the light beam F1 emitted by the transmitting module 2, or by another similar transmitting module, and sunlight. The intensity levels of this beam F2 greatly exceed those of the beam F1 for the wavelength ranges in the visible domain.

[0079] However, the combination of filters I1 and I2 makes it possible to minimize the influence of the sun on beam F2, by eliminating all wavelengths of beam F2 except those of the second range BP2. In this way, saturation of the photodetectors 32a which will receive this beam F2 is avoided, without filter I being particularly complex or expensive.

[0080] It will also be noted that the filter I makes it possible to preserve only the blue component of the beam F2, that is to say the component corresponding to the light rays emitted first by the light source 23, the yellow light rays being emitted with a longer response time taking into account the delay introduced by the photoluminescence. Therefore, to the extent that the detection is carried out solely from the blue light received by the reception module 3, the resolution for evaluating the time of flight of the light beam F2 and / or the data transmission rate between a transmission module and the reception module 3 is thus improved.

[0081] The preceding description clearly explains how the invention makes it possible to achieve the objectives it has set itself, namely to provide a system for a motor vehicle capable of performing communication or detection functions using visible light and whose signal-to-noise ratio is optimal regardless of the weather conditions, including in the case of strong sunlight, and whose production complexity and cost are reasonable. These objectives are achieved in particular using a reception module equipped with two filters, including a first filter made using a lens made of an absorbent material and which makes it possible to eliminate a significant part of the spectrum of this beam, and a second interference filter which selects a narrow band in the bandwidth of the first filter.

[0082] In any event, the invention cannot be limited to the embodiments specifically described in this document, and extends in particular to any equivalent means and to any technically effective combination of these means. In particular, it may be possible to use other types of light source than that described, such as a laser diode, a VCSEL or a SLED. It may also be possible to provide other photometric functions than that described, and in particular dipped beam type lighting functions or position light type signaling functions. It may also be possible to provide other configurations of the optical element forming the second optical filter, such as a flat plate. It may also be possible to provide other materials for producing the lens or the optical element making it possible to obtain the same wavelength ranges or other wavelength ranges, or to arrange the first filter upstream of the second filter.

Claims

System (1) of a motor vehicle, comprising a receiving module (3) capable of receiving a light beam (F2), in which the receiving module comprises an elementary acquisition module (32) comprising a photodetector (32a) capable of converting a light signal which it receives into an electrical signal, characterized in that the receiving module comprises an optical unit (31) arranged in front of the elementary acquisition module, the optical unit comprising a lens (52) made of an absorbing material to form a first optical filter (I1) of the bandpass type capable of transmitting a first range of wavelengths (BP1) and an optical element (53) arranged to form a second optical filter (I2) of the interference type capable of transmitting a second range of wavelengths (BP2) at least partially included in the first range and substantially narrower than the first range. System (1) according to the preceding claim, wherein the absorbing material of the lens (52) is selected so that the first area (BP1) is centered on a wavelength of the visible spectrum. System (1) according to the preceding claim, wherein the optical element (53) is arranged so that the width of the second range (BP2) is less than 30 nm. System (1) according to the preceding claim, wherein the optical element (53) comprises a stack of thin films each having alternately a high refractive index or a low refractive index. System (1) according to any one of the preceding claims, wherein the lens (52) is a plano-convex lens and the optical element (53) is a coating formed on the flat face of the lens. System (1) according to any one of the preceding claims, wherein the optical element (53) is a flat plate interposed between the lens (52) and the elementary acquisition module (32). System (1) according to any one of the preceding claims, wherein the optical unit (31) comprises a plurality of lenses (51, 52) comprising said lens (52) forming the first optical filter (I1) and at least one other lens (51) made of a transparent material. System (1) according to any one of the preceding claims, characterized in that the receiving module (3) comprises a demodulation unit (33) connected to the photodetector (32a) and arranged to extract a data sequence from an electrical signal converted by this photodetector. System (1) according to the preceding claim, characterized in that it comprises an emission module (2) comprising a light module (21) capable of emitting a light beam (F1) whose spectrum has at least a portion in the second wavelength range (BP2) and a modulation unit (22) capable of receiving a data sequence and arranged to modulate said light beam emitted from the received data sequence. System (1) according to the preceding claim, wherein the modulation unit (22) is arranged to generate a pulse-width modulated control signal, to modulate said control signal from the received data sequence and to control the emission of said light beam (F1) by the light module (21) from the modulated control signal. System (1) according to any one of claims 9 or 10, characterized in that it comprises a computing unit (4) arranged to detect, in a data sequence extracted by the demodulation unit (33) from an electrical signal converted by a photodetector (32a) from a light beam (F2) received by the receiving module (3), the presence of a data sequence modulating the light beam (F1) emitted by the transmitting module (2) and to determine a time of flight separating the emission of said emitted light beam from the reception of said received light beam. System (1) according to any one of claims 9 to 11, wherein the emission module (2) is arranged so that the light beam (F1) participates, totally or partially, in the realization of a predetermined regulatory photometric function Lighting system (1) according to any one of the preceding claims, characterized in that the receiving module (3) is arranged in a front headlight of the motor vehicle.

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