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

Abstract

The invention relates to a system (1) comprising an emission module (2) comprising a light module (21) capable of emitting a light beam (F1) whose spectrum has at least one portion in the visible spectrum and a linear polarizing device (25) arranged to polarize said emitted light beam according to a given polarization direction (P), a reception module (3) capable of receiving a light beam (F2), in which the reception module comprises an elementary acquisition module (32) comprising a photodetector (32a) capable of converting a light signal that it receives into an electrical signal, characterized in that the reception module comprises a linear polarizing filter (34) arranged to transmit only to the elementary acquisition module the component of said received light beam polarized according to said given polarization direction. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: System for detecting and / or communicating a motor vehicle comprising a transmission module and 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 to also 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 under the name VLC (from the English “Visible Light Communication”), or even under the name LiFi (from the English Light Fidelity).

[0004] Thus, beyond the realization of one or more photometric functions, such as a daytime running light or dipped-beam 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 communicating 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 therefrom. 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 data sequence emitted, determine the flight time of the emitted light beam and therefore assess 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 comprise at least one photodetector to convert this light beam into an electrical signal in order to demodulate this signal and extract a data sequence therefrom.

[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 finds itself incapable of suitably converting the light beam into an electrical signal that can be demodulated without loss of information.

[0007] There is thus a need for a system capable of transmitting a data sequence, from a transmission module integrating a light module participating in the realization of a photometric function to an acquisition module, and whose signal to noise ratio is optimal in all weather conditions, including in the event of significant sunshine.

[0008] The present invention is placed in this context, and aims to meet this need.

[0009] For these purposes, the invention relates to a system of a motor vehicle, comprising: a. an emission module comprising a light module capable of emitting a light beam whose spectrum has at least one portion in the visible spectrum and a linear polarizing device arranged to polarize said emitted light beam according to a given polarization direction, b. a reception module capable of receiving a light beam, in which the reception module comprises 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 a linear polarizing filter arranged to transmit only to the elementary acquisition module the component of said received light beam polarized according to said given polarization direction.

[0010] As indicated above, under conditions of high sunlight, the light sunlight is added to the light emitted by a transmitting module, which can cause saturation of the photodetector(s) of the receiving module. However, sunlight is generally not or only slightly polarized. In other words, half of this light is polarized according to one polarization direction P while the other half of this light is polarized according to the other polarization direction S.

[0011] Furthermore, linearly polarized light retains its polarization after reflection, specular, on a surface. However, the different use cases considered by the invention aim either at transmission without reflection of light, for the case of communication functions, or at specular reflections on surfaces of objects to be detected.

[0012] It is therefore understood that the light beam received by the receiving module is composed of light polarized according to said polarization direction given by the linear polarizer device and, in the case of strong sunlight, of unpolarized light. The linear polarizer filter then makes it possible to eliminate the component of the sunlight polarized according to the other polarization direction, so that the quantity of sunlight arriving at the photodetector is divided by two. This prevents saturation of the photodetector(s) of the receiving module in the case of strong sunlight and the signal-to-noise ratio is thus multiplied by two.

[0013] In one embodiment of the invention, the light module is capable of emitting a light beam whose spectrum has a peak at a wavelength in the visible, in particular between 400 nm and 500 nm. Advantageously, the light module comprises a light source comprising a semiconductor generator capable of emitting an elementary light beam, in particular whose spectrum has a peak at a wavelength in the visible, and a photoluminescent element capable of converting said elementary light beam to obtain said light beam.

[0014] The semiconductor may, for example, be a gallium nitride, or GaN, capable of emitting, by electroluminescence and in response to an electric current passing through it, rays of blue light. The photoluminescent element may, for example, be in the form of a resin comprising a cerium-doped yttrium and aluminum garnet, or CE:YAG, capable of absorbing blue light and, by photoluminescence and in response to the excitation carried out by this light, of emitting rays of yellow light. 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, rays of yellow light. The other portion of the blue light rays passes through this element. Thus, the light source simultaneously emits, when it is electrically powered, rays of blue and yellow light, the light thus formed appearing white to the human eye.

[0015] The light source may thus 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”).

[0016] Advantageously, the light module may comprise an optical unit arranged to project the light rays emitted by the light source to form said light beam. It may be provided that the linear polarizing device is arranged between the light source and the optical unit or that it is arranged downstream of said optical unit.

[0017] In one embodiment of the invention, the linear polarizer device comprises a semi-reflecting plate arranged downstream of the light module and inclined according to the Brewster angle with respect to the emission axis of said light module.

[0018] In another embodiment of the invention, the linear polarizer device comprises a grid polarizer.

[0019] If desired, the linear polarizer device may comprise a linear polarizer arranged to transmit a portion of the emitted light beam by polarizing it along said given polarization direction and to reflect another portion of the emitted light beam by polarizing it along the other polarization direction and a delay optical element arranged to receive said other portion and to polarize it along said given polarization direction. A delay optical element is understood to mean an optical element capable of introducing a phase delay between the P and S components of the light, and in this case a phase delay of 180°, which thus makes it possible to modify the polarization direction of linearly polarized light. It is thus possible to polarize, along the same component, substantially all of the light emitted by the light module and therefore maximize the efficiency of the linear polarizer device.

[0020] In this example, the linear polarizer may be a semi-reflecting plate inclined at the Brewster angle relative to the emission axis of the light module or a grid polarizer. The optical delay element may, for example, be a half-wave plate or a pair of diamond-shaped Fresnel prisms. Where appropriate, the linear polarizer device may comprise at least one optical deflection element, such as a plane mirror, arranged downstream of the linear polarizer or between the linear polarizer and the optical delay element or downstream of the optical delay element, so that said part of the light beam transmitted by the linear polarizer and said part polarized by the optical delay element are emitted in the same direction.

[0021] Preferably, the first linear polarizing device is arranged to polarize said emitted light beam according to the polarization direction P.

[0022] It has indeed been found that, under certain conditions, sunlight can be polarized according to a polarization direction S. This is for example the case when the sun is low, at dawn or at dusk, and its light is reflected by a reflective surface inclined according to the Brewster angle, such as a puddle of water. Under these conditions, it is therefore advantageous to favor a polarization of the emitted light beam according to the polarization direction P in order to avoid saturation of the photodetector.

[0023] Advantageously, it may be provided that the linear polarizing filter comprises a linear polarizer such as a semi-reflecting plate inclined according to the Brewster angle with respect to the optical axis of the reception module or a grid polarizer, said linear polarizer being arranged upstream of the elementary acquisition module.

[0024] 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.

[0025] For example, the set of photodetectors can form a sensor, for example a single electronic component.

[0026] 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 106, and therefore to compensate for the degradations of the signal-to-noise ratio due to external conditions or even to the absorptions of the filters.

[0027] According to an exemplary embodiment of the invention, the reception module may comprise an optical unit arranged in front of the elementary acquisition module. It may be provided that the linear polarizing filter is arranged between the elementary acquisition module and the optical unit or that it is arranged upstream of said optical unit.

[0028] In one embodiment of the invention, the transmission module comprises a modulation unit capable of receiving a data sequence and arranged to modulate said light beam emitted from the received data sequence and the reception module comprises a demodulation unit connected to the photodetector and arranged to extract a data sequence from an electrical signal converted by this photodetector.

[0029] 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.

[0030] Where appropriate, the modulation unit may be arranged to control the light source of the light module, and in particular an electrical power supply supplied to this light source, to modulate the light beam.

[0031] 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.

[0032] 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.

[0033] Advantageously, the reception module and the transmission module are arranged in a front headlight of the motor vehicle.

[0034] The invention also relates to a front headlight of a motor vehicle comprising a reception module and a transmission module of a system according to the invention.

[0035] The present invention is now described with the aid of 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:

[0036] [Fig-1] represents, schematically and partially, a view of a system of a motor vehicle according to an exemplary embodiment of the invention;

[0037] [Fig.2] represents, schematically and partially, an example of the realization of a linear polarizing device of the system of [Fig.l].

[0038] In the following description, elements which are identical, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references.

[0039] [Fig.l] shows a system 1 of a motor vehicle according to an exemplary embodiment of the invention.

[0040] 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.

[0041] 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 outside the scope of the present invention.

[0042] The emission module 2 comprises a light module 21 and a modulation unit 22.

[0043] 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 [Fig.l], the spectrum S has an intensity peak P1, or line, in the blue at 450 nm. It will be noted that it is possible for the spectrum S to have other intensity peaks, in the visible and / or in the infrared.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] To the extent that the light beam Fl is composed, partially or totally, of white light, it is possible to use this light beam Fl 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 Fl so that its photometric distribution satisfies the requirements of said function. It may, for example, be provided that the light beam Fl participates in the realization of a function of the daytime running light, or DRL, type.

[0048] In addition to this photometric function, the light beam Fl 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 an infrastructure. road.

[0049] 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 of [Fig.l] provided in another vehicle or in a road infrastructure.

[0050] The modulation unit 22 is arranged to modulate the light beam Fl emitted by the light module 21, from this data sequence, for example by controlling the electrical power supplied to the light source 23.

[0051] 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.

[0052] 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 all-or-nothing modulation (OOK for "On Off Keying"), a pulse code modulation (PCM for "Puise Code Modulation"), a pulse amplitude modulation (PAM for "Puise Amplitude Modulation"), a pulse width modulation (PWM for "Puise Width Modulation") or a pulse position modulation (PPM for "Puise Position Modulation").

[0053] In the case of use for detecting and evaluating the position of an obstacle, it may be provided that the data sequence is a binary signal having different predetermined characteristics, such as in particular an autocorrelation peak for a zero time shift and / or low autocorrelation values ​​for a non-zero time shift and / or a significant length, these characteristics making it possible to improve the signal-to-noise ratio of the system, and / or a Hamming weight such that the average light intensity level of the emitted light beam remains substantially unchanged during its modulation with the data sequence. Such a sequence may for example be generated by means of a random code or pseudo-random code generation algorithm.

[0054] The light beam Fl thus emitted is composed of a train of light pulses succeeding each other with a sufficiently high frequency, for example greater than 30 MHz, in particular between 50 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 Fl to transport the data sequence to the reception module 3.

[0055] 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.

[0056] 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.

[0057] The light beam F2 may indifferently be the light beam Fl emitted by the emission 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 emission module of a system of another vehicle or of a road infrastructure equipped with an emission module similar to the module 2.

[0058] 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.

[0059] 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.

[0060] In the case where the system 1 implements a communication function, this data sequence can then be transmitted to a computer of the vehicle to be interpreted, decoded and / or transmitted to equipment or to a user of the vehicle.

[0061] 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 calculation unit 4 of the system 1. This calculation unit 4 can thus detect therein 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 calculation unit can determine a flight time separating the emission of the light beam F1 from the reception of the light beam F2.

[0062] 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.

[0063] Therefore, the light beam F2 received by the receiving module 3 consists of a part of the light beam Fl emitted by the transmitting module 2, or by another similar transmitting module, and of the sunlight. The intensity levels of this beam F2 greatly exceed those of the beam Fl for the wavelength ranges of the visible domain.

[0064] In order to avoid saturation of the photodetectors 32a, the emission module 2 comprises a linear polarizing device 25.

[0065] In the example described, the linear polarizer device 25 is arranged between the light source 23 and the optical unit 24. It may be possible to arrange this device 25 in other locations of the emission module, such as downstream of the optical unit 24, without departing from the scope of the present invention.

[0066] This linear polarizing device 25 is arranged to polarize the light of the beam Fl according to a preferred polarization direction, namely the direction P.

[0067] [Fig.2] shows a linear polarizer device 25, according to an exemplary embodiment of the invention.

[0068] The device 25 comprises a linear polarizer 25a, produced in the form of a semi-reflecting plate arranged upstream of the light source 23 and inclined according to the Brewster angle with respect to the emission axis of this light source 23. The linear polarizer 25a is thus capable of transmitting a portion of the light emitted by the light source 23, by polarizing it according to the polarization direction P, and of reflecting the other portion of this light by polarizing it according to the polarization direction S.

[0069] A plane mirror 25b is arranged downstream of the light reflected by the blade 25a to reflect this light in the same direction as the light transmitted by the blade 25a.

[0070] A half-wave plate 25c is arranged downstream of the plane mirror 25b. This half-wave plate 25c is capable of introducing a phase delay of 180° between the P and S components of the light. The light reflected by the plane mirror 25b being polarized globally in the direction S, it is thus polarized, at the output of the half-wave plate 25c, in the direction P.

[0071] It is thus understood that the device 25 described in [Fig.2] makes it possible to polarize substantially all of the light emitted by the light source 23 in the direction P.

[0072] Other embodiments of the device 25 may be designed, for example by using other optical components, such as grid polarizers or diamond-shaped Fresnel prisms. The design of the device 25 may also be simplified by using a single linear polarizer. It may also be possible to design the device 25 for polarizing the light from the source 25 in the direction S rather than the direction P.

[0073] As shown in [Fig.l], the light of the light beam Fl is thus substantially polarized according to the polarization direction P. Therefore, when this light beam Fl is reflected by an obstacle with a specular reflection, it retains its polarization. In other words, the component of the light beam F2 received by the reception module 3, which corresponds to the light beam Fl emitted by the emission module 2, or by another similar emission module, is polarized according to the direction P.

[0074] On the other hand, sunlight is generally not or only slightly polarized. In other words, the component of the light beam F2 corresponding to sunlight is polarized, for half, according to the polarization direction P, and for the other half, according to the other polarization direction S.

[0075] The reception module 3 thus comprises a linear polarizing filter 34. In the example described, the linear polarizing filter 34 is arranged between the optical unit 31 and the elementary acquisition modules 32. It will be possible to arrange this device 25 in other locations of the reception module, such as upstream of the optical unit 31, without departing from the scope of the present invention.

[0076] The filter 34 is arranged to transmit only to the elementary acquisition modules 32 the component of said light beam F2 which is polarized according to the same polarization direction as that of the light beam FL.

[0077] It may be provided that the linear polarizing filter 34 comprises a linear polarizer such as a semi-reflecting plate inclined according to the Brewster angle with respect to the optical axis of the optical unit 31 or a grid polarizer.

[0078] It is thus understood that the filter 34 makes it possible to eliminate the component of the light beam F2 which is polarized in the direction S, which is solely due to the sun. In this way, only half of the sunlight is received by the photodetectors, so that saturation of these photodetectors 32a is thus avoided.

[0079] The preceding description clearly explains how the invention makes it possible to achieve the objectives it has set itself, namely to provide a system of a motor vehicle capable of carrying out communication or detection functions from visible light and whose signal-to-noise ratio is optimal regardless of the weather conditions, including in the case of strong sunlight. These objectives are achieved in particular using a transmission module and a reception module each equipped with polarizing devices. These devices make it possible to significantly reduce the signal-to-noise ratio linked to the sun, taking into account the fact that sunlight is not polarized.

[0080] In any event, the invention cannot be limited to the embodiments specifically described in this document, and extends in particular to all equivalent means and any technically operative 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 linear polarizer device and / or the linear polarizer filter.

Claims

Claims

1. System (1) of a motor vehicle, comprising: a. an emission module (2) comprising a light module (21) capable of emitting a light beam (Fl) whose spectrum has at least one portion in the visible spectrum and a linear polarizing device (25) arranged to polarize said emitted light beam according to a given polarization direction (P), b.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 that it receives into an electrical signal, characterized in that the receiving module comprises a linear polarizing filter (34) arranged to transmit only to the elementary acquisition module the component of said received light beam polarized according to said given polarization direction characterized in that the linear polarizing device (25) comprises a semi-reflecting plate (25a) arranged downstream of the light module (21) and inclined according to the Brewster angle with respect to the emission axis of said light module and in that the linear polarizing device (25) is arranged to polarize said emitted light beam (F1) according to the polarization direction P.

2. System (1) according to one of the preceding claims, characterized in that the linear polarizer device (25) comprises a grid polarizer.

3. System (1) according to one of the preceding claims, characterized in that the linear polarizer device (25) comprises a linear polarizer (25a) arranged to transmit a part of the emitted light beam (Fl) by polarizing it according to said given polarization direction (P) and to reflect another part of the emitted light beam by polarizing it according to the other polarization direction (S) and a delay optical element (25c) arranged to receive said other part and to polarize it according to said given polarization direction.

4. System (1) according to one of the preceding claims, characterized in that the transmission module (21) comprises a modulation unit (22) capable of receiving a data sequence and arranged to modulate said emitted light beam (Fl) from the received data sequence and in that the reception 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.

5. 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 (Fl) by the light module (21) from the modulated control signal.

6. System (1) according to one of claims 4 or 5, characterized in that it comprises a calculation unit (4) arranged to detect, in a data sequence extracted by the demodulation unit (33) from an electrical signal converted by the photodetector (32a) from a light beam (F2) received by the reception module (3), the presence of a data sequence modulating the light beam (F1) emitted by the transmission 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.

7. System (1) according to one of the preceding claims, in which the emission module (2) is arranged so that the light beam (Fl) participates, totally or partially, in the realization of a predetermined regulatory photometric function.

8. Lighting system (1) according to one of the preceding claims, characterized in that the transmission module (2) and the reception module (3) are arranged in a front headlight of the motor vehicle.

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