Optical system for obstacle detection

Abstract

Optical System for Obstacle Detection The invention relates to an optical system for vehicles for obstacle detection, characterized in that light-receiving means (32) comprise, on the one hand, several groups of photonic receptors (48) and, on the other hand, a plurality of focusing devices (9), each focusing device (9) being configured to focus the light onto one of the groups of photonic receptors (48) and oriented differently from the other focusing devices (9). (Figure 2)

Description

Title of the invention: Optical system for detecting obstacles

[0001] The present invention relates to the fields of optics and electronics, and finds a particular application in the automotive field. It relates more precisely to an optical system integrating an obstacle detection function, which can be installed in a vehicle.

[0002] In recent vehicles, sets of light-emitting diodes are commonly used to produce external lighting devices such as dipped headlights or signaling lights. These sets of diodes allow energy savings while providing vehicles with light signatures specific to each brand, and are anticipated as future means of communication between vehicles or with road infrastructures, thanks to an optical communication technology such as VLC (for "Visible Light Communication") for example.

[0003] Indeed, the bandwidth of a white light-emitting diode with a side dimension of one millimeter is approximately 2 MHz (MegaHertz), and may therefore be sufficient to enable light communication between vehicles or between a vehicle and a road infrastructure. However, this bandwidth is not suitable for obstacle detection type applications. Such an application is generally carried out optically in certain vehicles using LiDAR (Light Detection And Ranging) technology based on infrared laser emitters allowing analysis of the reflected signal over a bandwidth of the order of several tens of MegaHertz, or even a few hundred MegaHertz. LiDAR systems embedded in vehicles are nevertheless very expensive.

[0004] The inventors have however discovered that such an obstacle detection application is possible by using light-emitting diodes that emit light in the visible spectrum, by increasing their bandwidth, either by equalization techniques, or by using diodes smaller than 300 micrometers, or by combining these techniques. This application may require the use of a specific type of light-emitting diode drive unit such as a high-speed control unit or a laser control unit. The light-emitting diodes used for this application are also blue light-emitting diodes adapted to emit white light.

[0005] Thanks to this discovery, the inventors have made it possible to replace the expensive means of LiDAR technology in a vehicle with specific optical systems based on light-emitting diodes, which perform an obstacle detection function. and also perform regulatory signaling or lighting functions.

[0006] However, the cost issue remains a current issue for the implementation of such an optical system, particularly since it is necessary to have a large number of photoreceptors to achieve high-resolution detection over a large, expanded overall detection field.

[0007] The present invention falls within this context and aims to remedy at least in part the aforementioned drawbacks by providing an optical system integrating an obstacle detection function, which allows a large detection field without it being necessary to oversize the photoreceptor means.

[0008] To this end, the invention proposes an optical system for a vehicle enabling the detection of obstacles, the optical system comprising:

[0009] - light emitting means comprising at least one photonic emitter capable to emit a high-frequency coded light signal towards the exterior of the vehicle, the light signal being at least within a predefined range of wavelengths,

[0010] - light receiving means comprising at least one photonic receiver capable of receiving a reflected light signal contained in light arriving from outside the vehicle and heading towards the photonic receiver, said light comprising the reflected light signal and uncoded light, the reflected light signal originating from a reflection on an obstacle, of the light signal emitted by the light emission means, and at least one device for focusing the light arriving from outside the vehicle to direct it towards the photonic receiver,

[0011] - means for demodulating the reflected light signal received by the receiver photonics, and - obstacle detection means comprising means for calculating a distance to the obstacle as a function of a demodulated signal supplied by the demodulation means and the light signal emitted by the photonic transmitter,

[0012] the optical system being characterized in that the light receiving means comprise on the one hand several groups of photonic receivers and on the other hand a plurality of focusing devices, each focusing device of said plurality of focusing devices being configured to focus the light on one of the groups of photonic receivers and oriented differently from the other focusing devices.

[0013] By "uncoded light" we of course mean the part of the light heading towards the photonic receiver which does not include the high-frequency coded reflected light signal.

[0014] The predefined wavelength range is a useful range in which the light signal is received for decoding and corresponds, for example, to wavelengths for which the signal-to-noise ratio is most favorable, the light signal may also be present outside the predefined wavelength range. In an exemplary embodiment, the wavelength range may be in the visible spectrum, preferably between 420 nanometers (nm) and 460 nanometers (nm).

[0015] When the optical system is on board a vehicle, the light signal is emitted by the emitting means towards the outside of the vehicle, and the receiving means are configured to receive such a light signal having been reflected and arriving from outside the vehicle.

[0016] The demodulation means have the function in particular of analyzing the received light and identifying the uncoded light, that is to say the part of the light heading towards the photonic receiver not comprising the high-frequency coded light signal, in order to keep only the coded light signal and to be able to determine where the obstacle is located having reflected and returned to the vehicle this coded signal previously emitted by the vehicle's transmitting means.

[0017] Having a plurality of focusing devices allows the optical system to cover a larger detection field than it would if a single focusing device were provided opposite the same reception surface. It is thus possible to detect a greater quantity of light information and to increase the obstacle detection performance of the system.

[0018] According to the invention, the receiving means are configured so that a beam of light rays, transmitted from one of the focusing devices to a separate set of one or more photonic receivers corresponding to this focusing device, is separate from a beam of light rays transmitted from another of the focusing devices. To this end, the optical system is particular in that focusing devices are specifically provided for each group of photonic receivers, which makes it possible in particular to provide for each focusing device an orientation which is specific to it and where appropriate separate from that of the other focusing devices.

[0019] The orientation of a focusing device is defined by the optical axis of this focusing device and it is thus notable that according to the invention the optical axes of at least two focusing devices intersect each other. In this way, these focusing devices are arranged opposite different zones of the road scene, and an assembly formed by a focusing device and a group of photonic receivers can be dedicated to the obstacle detection of a particular zone of the road scene.

[0020] According to an optional characteristic of the invention, the groups of photonic receivers are oriented in different directions.

[0021] The orientation of the photonic receiver groups is determined by the normal to the plane in which the photonic receivers mainly extend. Advantageously, for a given assembly formed by a group of photonic receivers and a focusing device, the optical axis of the latter and the normal to the plane in which the photonic receivers mainly extend are substantially parallel, and possibly coincident.

[0022] According to an optional characteristic of the invention, the groups of photonic receivers are arranged on a common electronic circuit support.

[0023] According to an optional characteristic of the invention, the contact zone of a first group of photonic receivers with the electronic circuit support extends mainly in a plane intersecting a plane in which the contact zone of a second group of photonic receivers with the electronic circuit support extends mainly. In particular, the electronic circuit support is curved.

[0024] According to an optional characteristic of the invention, the focusing devices have optical properties which differ from one focusing device to another.

[0025] The focusing devices may comprise one or more lenses and the thickness and / or shape of these lenses may vary from one focusing device to another. These different configurations may result in a wider detection field from one focusing device to another. In each of these configurations, an optical axis of the focusing device is identified around which the detection field extends, the rays passing through a focusing device being directed, towards the group of photonic receivers, substantially parallel to the optical axis.

[0026] According to an optional characteristic of the invention, the focusing devices respectively associated with a group of photonic receivers are produced separately and arranged at a distance from each other.

[0027] Alternatively, at least two focusing devices are produced in a single piece by forming an optical block within which zones of different orientation and / or dimensions and / or shapes are formed to produce distinct focusing devices.

[0028] According to an optional characteristic of the invention, the groups of photonic receivers have distinct resolutions from one group of photonic receivers to another.

[0029] In other words, some groups of photonic receivers have a ratio between the number of pixels, defined by the number of photonic receivers in the group for example, and the extent of the angular detection range, which varies from one group to another. More particularly, an assembly formed by a focusing device and a group of photonic receivers surrounded by other groups of photonic receivers, intended to detect obstacles in a central area of ​​the road scene, can be optimized with a small detection field and a high resolution, while the Sets intended to detect obstacles at the periphery of the road scene can be optimized to cover larger detection fields at low resolution.

[0030] According to an optional characteristic of the invention, two groups of adjacent photonic receivers are arranged at a distance from each other.

[0031] It is thus possible to interpose between two groups of photonic receivers electronic components of the receiving means and / or elements forming the means for detecting obstacles or demodulating the light signal.

[0032] The different orientation of the focusing devices respectively associated with the groups of adjacent photonic receivers makes it possible to ensure that the overall detection field of the optical system does not have shadow zones despite the spacing of the adjacent groups, and this thus makes it possible to optimize the arrangement of the electronic components and to place them as close as possible to the photonic receivers, which simplifies the electrical connection of the components to the receivers and allows an increase in the response performance of the device.

[0033] According to an optional characteristic of the invention, light absorption means are arranged between two groups of adjacent photonic receivers.

[0034] In other words, means can be implemented to avoid the crossing of the rays passing from a first assembly formed by a focusing device and a group of photonic receivers to a second assembly formed by a focusing device and a group of photonic receivers, these means thus making it possible to avoid interference of a beam of light ray transmitted by a focusing device by another beam of light ray transmitted by another focusing device.

[0035] These absorption means can be formed by an opaque wall integral with the focusing device or the support on which the groups of photonic receivers are arranged.

[0036] According to an optional characteristic of the invention, the receiving means further comprise means for filtering the light heading towards the groups of photonic receivers, these filtering means being arranged downstream and / or upstream of the focusing means. These filtering means are in particular capable of increasing the signal-to-noise ratio between the light signal contained in the light heading towards the photonic receivers and the uncoded light heading towards these photonic receivers. The filtering means are for example wavelength filtering means, such as for example a blue light filter. Here, the terms “upstream” and “downstream” are defined with respect to the direction of propagation of the light signals heading towards the photonic receiver.

[0037] By way of example, the filtering means comprise a high-pass filter, with a cut-off wavelength greater than or equal to the upper limit of the range predefined range of wavelengths, and a low-pass filter, with a cutoff wavelength less than or equal to the lower limit of the predefined range of wavelengths. The high-pass filter allows very little passage of light components with wavelengths shorter than its cutoff wavelength, and the low-pass filter allows very little passage of light components with wavelengths longer than its cutoff wavelength.

[0038] According to an optional feature of the invention, the photonic receivers are respectively formed of single-photon avalanche diodes. Alternatively, the photonic receivers may be PIN (positive-intrinsic-negative) photodiodes or simple PN (positive-negative) junction photodiodes.

[0039] According to an optional characteristic of the invention, the emitting means are capable of forming a lighting beam and / or of fulfilling a signaling function.

[0040] The invention also relates to a vehicle comprising an optical system according to the invention. The vehicle according to the invention has advantages similar to those of the optical system according to the invention.

[0041] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0042] [Fig-1] represents an optical system for a vehicle integrating an obstacle detection function on a road scene,

[0043] [Fig.2] schematically represents the receiving means of the optical system of [Fig.l], according to a first embodiment of the invention;

[0044] [Fig.3] schematically represents the receiving means of the optical system of [Fig.l], according to a second embodiment of the invention.

[0045] [Fig.l] now represents the operation of such an optical obstacle detection system 1. The obstacle detection uses, on the face of the vehicle integrating this function, emitting means 12 comprising a plurality of photonic emitters, for example in each optical unit of the vehicle when the optical system is intended to detect frontal obstacles, and receiving means 32 comprising a plurality of photonic receivers, also present in this example in each optical unit of the vehicle. The plurality of photonic emitters of the emitting means 12 comprises for example two blue light-emitting diodes 121, 122, adapted to emit white light.

[0046] The light-emitting diodes 121, 122 each comprise, for example, a layer of Galium-Indium Nitride (InGaN) on which is deposited a light color conversion layer generally called phosphor in the bi bibliography. Thus they are adapted to produce a light beam of a daytime running light.

[0047] The photonic receivers can in particular be constituted by photon avalanche photodiodes or SPAD photodiodes (from the English "Single-Photon Avalanche Diode") for increasing the reception gain, such as the SPAD photodiodes referenced 321, 322. Of course, [Fig.l] only comprises two light-emitting diodes and two photodiodes for simplicity. Many more photodiodes are preferably used, and the daytime running lights can use many more diodes.

[0048] The plurality of light-emitting diodes is capable of emitting a high-frequency coded light signal s2 towards the exterior of the vehicle, and the plurality of photodiodes is capable of receiving a corresponding reflected light signal s2, arriving from the exterior of the vehicle.

[0049] In order to form the high-frequency coded light signal s 1 , each optical block comprises a source 10 of electrical signals in voltage square waves and a control unit 3, connected upstream of the light-emitting diodes 121, 122. To send the light signal s 1 , the source 10 provides a square wave signal whose width 1 of the square waves is, in an exemplary embodiment, approximately 10ns (nanoseconds), the frequency of the signal being 50MHz. The duty cycle of the signal is, in this example, less than or equal to 50%.

[0050] To enable the transmission of this signal having such a high frequency level, the control unit 3 comprises for example a pre-equalization stage, possibly associated with an amplifier stage. It is therefore an electronic device. Instead of or in addition, the light-emitting diodes 121, 122 are chosen to be smaller than 300 micrometers so as to naturally have a cut-off frequency greater than 50 MHz.

[0051] The light signal si sent by the diodes 121, 122 encodes a specific sequence of "slots" or light peaks of width 1 of 10ns, this sequence repeating cyclically. In other words, the light signal si is modulated according to a specific data sequence, called modulating. The sequence of slots is defined so as to easily evaluate a time shift between its transmission and its reception as explained below.

[0052] The reflection of the light signal s on an obstacle 6 gives rise to the reflected light signal s2 of sufficient light power to be captured by the photodiodes 321, 322.

[0053] The receiving means 32 comprise, in addition to the photodiodes 321, 322, at least one focusing device 9 configured to focus the light onto the photodiodes 321, 322. As illustrated, the receiving means 32 may comprise means of filtering 8 for filtering the light from the reflected light signal s2, in particular so as to only allow the blue component of this light to pass through, and a focusing device 9 focusing the component resulting from the filtering of the light towards the photodiodes 321, 322. The blue light emitted by the diodes 121, 122 generally has a light intensity lower than that of the illumination of the sun, but approaches it for wavelengths close to 460nm (nanometers). The modulation of the reflected signal s2 makes it possible to distinguish it from external light pollution in the process of demodulation of this reflected light signal s2.

[0054] More precisely, the photodiodes 321, 322 capture the blue components of the reflected light signal s2 and of the ambient light, for example sunlight, and provide an electrical signal to an electronic control device 13 which amplifies it and provides it to demodulation means 38. The electronic control device 13 optionally comprises, in addition to an amplifier stage, a post-equalization stage. The photodiodes 321 and 322 being SPAD photodiodes, the electrical signal that they provide is equivalent to a count Nb of the photons received as a function of time t by each of the photodiodes 321, 322. Thresholding means 34 adjust the detection level of these photodiodes so as to separate in the intensity of the light signal received by the photodiodes 321, 322, the portion of light intensity due to sunlight.This thresholding corresponds to keeping in the counting signal Nb as a function of time t, only the values ​​extending beyond a number of photons corresponding to the luminous intensity of the blue component of sunlight, which gives rise to a thresholded light signal s3. Such thresholding makes it possible to remove the component due to sunlight from the received electrical signal. Of course, here we call a thresholded light signal in reality an electrical or digital signal corresponding to the thresholding of the received reflected light signal s2.

[0055] The demodulation means 38 also comprise means 36 for correlating the thresholded light signal s3 once demodulated, with the light signal s1 sent by the diodes 121, 122. These correlation means 36 determine a time shift r between the demodulated thresholded light signal s3 and the light signal s1 sent, and transmit this time shift r to obstacle detection means 40 of the vehicle. The obstacle detection means 40 convert this time shift r into a distance relative to the obstacle 6, and therefore make it possible to detect this obstacle. Described otherwise, the demodulation means 38, from the reflected light signal 2 received by the photodiodes 321, 322, are capable of providing the obstacle detection means 40 with at least one value representative of a time shift r between, on the one hand, the reflected light signal s2 and, on the other hand, the light signal s1 emitted by the photonics 121, 122.

[0056] We will now describe in more detail, in particular with reference to figures 2 and 3, the receiving means 32.

[0057] The receiving means 32 comprise in particular a printed circuit board 42, photonic receivers 321, 322 and electronic components 44 associated with these photonic receivers, and optical elements 46 forming focusing devices 9.

[0058] The photonic receivers consist of photodiodes, here of the SPAD type for Single Photon Avalanche Diode. These photonic receivers are all fixed on the printed circuit board 42, it being noted that the printed circuit board here produced in one piece could be segmented without departing from the context of the invention.

[0059] The photonic receivers are arranged in groups of photonic receivers 48. In the example illustrated, the receiver means 32 comprise three groups of photonic receivers 48, each group being able to be formed from a matrix of around ten or hundreds of photodiodes.

[0060] The electronic components 44 associated with the photonic receivers form part of the electronic control device 13 previously mentioned and their function is in particular to recover the electrical output signals from the photonic receivers 321, 322, when light is focused on these photonic receivers, in order to then transmit them to the demodulation means 38. The electronic components 44 can, if necessary, amplify the electrical signals before supplying them to the demodulation means 38.

[0061] The groups of photonic receivers 48 and the electronic components 44 are arranged alternately on the printed circuit board 42. More particularly, the groups of photonic receivers 48 are spaced apart from each other in sufficient proportions to form blank areas 50 in which electronic components 44 can be housed between two adjacent groups of photonic receivers 48. As will be described in more detail below, the arrangement of the focusing devices 9 in the optical system 1 according to the invention makes it possible to space the groups of photonic receivers 48 apart from each other without creating shadow areas in the overall detection field 100 of the optical system 1.

[0062] In the first embodiment illustrated in [Fig. 2], the printed circuit board 42, on which the photonic receiver groups 48 and the electronic components 44 are fixed, is flexible and curved so that each of the photonic receiver groups 48 has an orientation different from the orientations of the other receiver groups.

[0063] More particularly, the printed circuit board 42 is of the flex-PCB type, and it advantageously follows the curvature of a support 52 allowing the assembly to be fixed in a housing of the optical system 1.

[0064] This results in an orientation specific to each group of photonic receivers 48. The orientation of a group of photonic receivers 48 is here defined by the average elongation plane of the area of ​​the printed circuit board 42 in contact with the receivers of this group. This different orientation from one group of photonic receivers 48 to another implies that the groups of photonic receivers are able to detect obstacles in different areas of the road scene.

[0065] The focusing devices 9 are arranged between the road scene and the photonic receivers. According to the invention, each focusing device 9 is configured to focus the light onto one of the groups of photonic receivers 48 and oriented differently from the other focusing devices 9.

[0066] The orientation of a focusing device is defined by its optical axis 54 and it is notable in [Fig. 2] that the optical axes 54 of the focusing devices 9 are not parallel to each other but intersecting two by two. Each focusing device 9 is configured to focus the light coming from outside the vehicle onto a particular group of photonic receivers 48, or where appropriate, in an alternative not shown here, onto a particular area of ​​a group of photonic receivers.

[0067] In other words, according to the invention, one or more photonic receivers of the same group of photonic receivers 48 are specifically associated with a single focusing device 9. The light received by this or these photonic receivers comes only from the focusing device dedicated to them. More particularly, each of the groups of photonic receivers 48 is arranged opposite a focusing device 9.

[0068] In the example illustrated in [Fig. 2], the arrangement of the groups of photonic receivers and the focusing devices is such that a first group of photonic receivers 481 is opposite a first focusing device 91 and receives only the light having passed through this first focusing device 91, that a second group of photonic receivers 482 is opposite a second focusing device 92 and receives only the light having passed through this second focusing device 92 and that a third group of photonic receivers 483 is opposite a third focusing device 93 and receives only the light having passed through this third focusing device 93.

[0069] Of course, it is understood that the optical system according to the invention is such that an n-th group of photonic receivers is opposite an n-th focusing device and only receives the light having passed through this n-th focusing device.

[0070] Each focusing device 9 is here represented in the form of a converging lens, capable of directing the external rays towards a focal zone corresponding to the zone of the printed circuit board on which one of the groups of photonic receivers is arranged. It should be understood that this focusing device 9 could, without departing from the context of the invention, be formed from a plurality of lenses or a matrix of microlenses, and where appropriate additionally include mirrors, provided that these optical elements are configured to give the focusing device the convergent properties mentioned above.

[0071] In this way, a singular detection field 90 specific to each assembly formed by a focusing device 9 and a group of photonic receivers is defined. 2 and 3 show the singular detection fields 90 of each subassembly formed by a focusing device and a group of photonic receivers in dotted lines.

[0072] The detection field 100 of the optical system 1 according to the invention is defined by the addition of the singular detection fields 90 of each of these sets. It is notable according to the invention that the singular detection fields 90 are oriented differently, which makes it possible to achieve a wide detection field of the optical system with narrower singular detection fields, and therefore easier and less expensive to implement for a given detection resolution.

[0073] For this purpose, and as mentioned previously, the focusing devices 9 are configured to respectively focus the light on one of the groups of photonic receivers 48 and are oriented differently from each other. Additionally, the focusing devices may have optical properties that are different from each other, and for example a particular shape that ensures focusing on the dedicated group of photonic receivers but with an angular aperture specific to each focusing device.

[0074] Furthermore, this configuration of the optical system, with focusing devices dedicated to one of the groups of photonic receivers and with a specific orientation of the singular detection fields 90, makes it possible to have different resolutions within the same detection field of the optical system, with different resolutions and different angular apertures from one singular detection field to another.

[0075] In the example illustrated, and without this configuration being limiting, the three groups of photonic receivers have the same technical characteristics, with in particular the same number of pixels, and the focusing devices differ according to their position. The focusing device arranged in the center, that is to say surrounded by the other focusing devices and oriented facing the road scene, here the second focusing device 92, is configured to have a narrower angular aperture than that of the neighboring focusing devices 91, 93 arranged on the periphery. In this way, the group of photonic receivers associated with this focusing device, here the second group of photonic receivers 482, can detect obstacles in the given angular range with better resolution. In this example a central detection zone, materialized by the second focusing device 92, with a narrow singular detection field, and therefore a high detection resolution, and two peripheral detection zones, materialized by the first and third focusing devices 91, 93, with a wide singular detection field, and therefore with a lower resolution, it being understood that the extent of the detection field changes while the surface of the receiving means and therefore the density of the detection elements remains the same. This is particularly advantageous because it makes it possible to combine both a high detection resolution for the road scene directly in front of the vehicle, where the risk of collision with an obstacle is the highest, and a wide detection field of the optical system, without having to multiply the number of photonic receivers.

[0076] [Fig. 2] illustrates another advantage of the different orientation of the focusing devices, mentioned previously. A blank area 50 is formed between the groups of photonic receivers, without having dark areas in the overall detection field 100, formed by the juxtaposition of the singular detection fields 90 associated with each focusing device 9. The different orientation of the focusing devices 9, and where appropriate their different optical properties varying the angular aperture from one to the other of the focusing devices, makes it possible, at a given detection distance, to make the boundaries of the neighboring singular detection fields coincide, while allowing the presence of blank areas. These blank areas 50 are occupied here by the electronic components 44 associated with the processing of the electrical data at the output of the photodiodes.

[0077] In order to avoid crossings of light rays between the different light channels formed between a focusing device 9 and its dedicated group of photonic receivers 48, light absorption means, and for example opaque partitions, not shown here, can delimit these channels. More particularly, these partitions can protrude from the support and / or the printed circuit board to surround the groups of photonic receivers over a given height.

[0078] [Fig. 2] shows more particularly receiving means of an optical system 1 intended to detect frontal obstacles, with a detection field which extends in front of the vehicle in a longitudinal direction, considering this longitudinal direction as the main direction of elongation and circulation of the vehicle. Of course, what will be described below can be applied to optical devices arranged in other areas of the vehicle, and for example to an optical system intended to detect lateral obstacles, with the longitudinal direction replaced by the transverse direction.

[0079] [Fig. 3] illustrates a second embodiment which differs in particular from the first embodiment in the orientation of the groups of photonic receivers. arranged on the printed circuit board.

[0080] In this second embodiment, the printed circuit board 42 is planar, and the support 52 on which it is fixed is also planar. In this way, the groups of photonic receivers 48 are all oriented in the same way, extending substantially in the same plane. In accordance with what has been previously described, blank areas 50 are left between the groups of photonic receivers 48 to allow the presence between them of electronic components 44 and the focusing devices 9 are configured to prevent shadow areas from being present in the detection field.

[0081] The focusing devices 9, however, differ structurally from what was described in the first embodiment, insofar as they are produced here in a single piece, forming a single optical body 94 which can facilitate the assembly of the optical system 1, since the manufacturing tolerances of the focusing devices are tightened.

[0082] The optical body 94 is thus formed from a plurality of optical zones 96 respectively forming one of the focusing devices 9, each of the optical zones being connected to a neighboring optical zone by a neutral zone 98 having the sole function of mechanical strength of the assembly.

[0083] These neutral zones 98 may be covered, on one or other of the faces of the optical body 94, with an opaque coating preventing the passage of light rays towards the groups of photonic receivers, this opaque coating having the same function as the light absorption means previously mentioned. Alternatively, these neutral zones may be formed from an opaque material.

[0084] In accordance with what has been described previously for the first embodiment, the focusing devices 9 are oriented differently from one focusing device to another so that the optical detection field 100 of the optical system is formed by the juxtaposition of singular detection fields 90, each singular detection field being specific to an assembly formed by a group of photonic receivers and a focusing device specifically dedicated to this group of photonic receivers.

[0085] Of course, the focusing devices 9 illustrated in [Fig.3] could also be implemented in the first embodiment.

[0086] Furthermore, in this second embodiment, filtering means 8 are shown capable of increasing the signal-to-noise ratio between the reflected light signal s2 contained in the light heading towards the SPAD photodiodes, and the uncoded light contained in this light.

[0087] These filtering means 8 shown schematically in [Fig.3] downstream of each of the focusing devices 9, considering the direction of propagation of the light towards the receiving means, could be arranged upstream of the focusing devices in accordance with what has been shown in [Fig.l]. Similarly, these filtering means 8 are here shown in the form of a single plate common to each focusing device 9 but they could alternatively be formed in several separate pieces respectively arranged between a focusing device and a group of photonic receivers. Of course, the filtering means illustrated in [Fig.3] could be implemented in the first embodiment.

[0088] These filtering means 8 have the function of obtaining a light representative of the reflected light signal s2 despite the sunlight which interferes with this reflected light signal s2. They may consist of a high-pass filter and / or a low-pass filter. The high-pass filter may for example have a cut-off wavelength of the order of 420 nm and be made for example of a layer of tinted resin. This high-pass filter has the function in particular of preventing ultraviolet rays from passing towards the groups of photonic receivers. The low-pass filter may for example have a cut-off wavelength of the order of 430 nm and its function in particular of reducing the quantity of light received by the photonic receivers of the receiving means.

[0089] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. By way of example, the invention is not limited to the use of light-emitting diodes capable of emitting blue light, the high-frequency coded light signal being able to be emitted in another wavelength range.

[0090] Finally, the characteristics of the different variant embodiments of the invention envisaged in this application can be combined to achieve the invention, to the extent that these variants are not incompatible with each other.

Claims

Claims

1. Optical system (1) for a vehicle enabling the detection of obstacles, the optical system (1) comprising: - light emitting means (12) comprising at least one photonic emitter capable of emitting a high-frequency coded light signal (si) towards the outside of the vehicle, said light signal being included at least in a predefined range of wavelengths, - light receiving means (32) comprising at least one photonic receiver capable of receiving a reflected light signal (s2) contained in light arriving from outside the vehicle and heading towards the photonic receiver, said light comprising the reflected light signal (s2) and an uncoded light, the reflected light signal (s2) coming from a reflection on an obstacle (6), of the light signal (si) emitted by the light emitting means,and at least one focusing device (9) for the light arriving from outside the vehicle to direct it towards the photonic receiver, - means for demodulating (38) the reflected light signal (s2) received by the photonic receiver, and - obstacle detection means (40) comprising means for calculating a distance to the obstacle as a function of a demodulated signal supplied by the demodulation means (39) and the light signal (si) emitted by the photonic transmitter, the optical system (1) being characterized in that the light receiving means (32) comprise on the one hand several groups of photonic receivers (48) and on the other hand a plurality of focusing devices (9), each focusing device (9) of said plurality of focusing devices being configured to focus the light on one of the groups of photonic receivers (48) and oriented differently from the other focusing devices (9).,

2. An optical system (1) according to claim 1, wherein the groups of photonic receivers (48) are oriented in different directions.

3. Optical system (1) according to claim 1 or 2, wherein the groups of photonic receivers (48) are arranged on a common electronic circuit support (42).

4. Optical system (1) according to one of the preceding claims, wherein the focusing devices (9) have dif- optical properties differ from one focusing device to another.

5. Optical system (1) according to one of the preceding claims, in which the groups of photonic receivers (48) have distinct resolutions from one group of photonic receivers to another.

6. Optical system (1) according to one of the preceding claims, in which two groups of adjacent photonic receivers (48) are arranged at a distance from each other.

7. Optical system according to the preceding claim, in which light absorption means are arranged between two groups of adjacent photonic receivers (48).

8. Optical system according to any one of the preceding claims, in which the receiving means (32) further comprise means (8) for filtering the light heading towards the groups of photonic receivers (48), these filtering means (8) being arranged downstream and / or upstream of the focusing means.

9. An optical system according to any preceding claim, wherein the photonic receivers (48) are respectively formed from single-photon avalanche diodes.

10. Optical system (1) according to any one of the preceding claims, in which the emitting means (12) are capable of forming an illumination beam and / or of fulfilling a signaling function.

11. Vehicle comprising an optical system (1) according to any one of claims 1 to 10.

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