FR3052266A1 - DEVICE AND METHOD FOR PROJECTING A LIGHT PATTERN - Google Patents

Abstract

Apparatus (10) for projecting a light pattern comprising a supercontinuum laser (12) which generates a white laser beam (51), a selector (14) which drives the white laser beam (51) thus generated to selectively project the light pattern in a set of solid corner ranges, and a diffuser (16) installed in the path of the laser beam (51) upstream or downstream of the selector (14).

Description

Field of invention

The present invention relates to a device and a method for projecting a light pattern.

The device is in particular an adaptive projector or a part of such a projector or a rear light or a flashing light or a part of a rear light or flashing equipment including a vehicle.

State of the art

In current vehicle headlamp systems, there are adaptive headlamp systems that dynamically adapt the lighting direction or lighting profile of the headlamp system (s) to the traffic state. . For example, in the case of cornering lights, the vehicle headlamp is controlled so that its light lobe follows the curve traveled at that moment by the vehicle and does not illuminate the curve in the direction tan-gential.

Projector systems that project a light pattern adapted to the state of the traffic are for example controlled to remove targeted light cone of the projector system the vehicle coming in front.

US 2010/079 836 A1 discloses a scanning laser for projecting a light pattern. Supercontinuum lasers are used in the scientific field and rely on the supercontinuum. Supercontinuum is a process of converting laser light into light having a very large spectral bandwidth and the spatial tolerance usually remains very high. Spectral spreading is usually achieved by driving the original optical pulse with an optical element of high non-linearity. Such elements are, for example, optical fibers having a waveguide structure or photonic crystal fibers. The supercontinuum laser beam is called white laser beam because of its broad spectrum and its effect on the human eye.

Description and advantages of the invention

The present invention relates to a device for projecting a light pattern comprising: a supercontinuum laser which generates a white laser beam, a selector which drives the white laser beam thus generated to project the light pattern selectively in a set of ranges of solid angle, and a diffuser installed in the path of the laser beam upstream or downstream of the selector. The invention also provides a method of projecting a light pattern of controlling a supercontinuum laser to generate a white laser beam and selectively driving the white laser beam into a set of solid angle ranges to project the light pattern to have a diffuser in the path of the laser beam.

In other words, the invention relates to a device for projecting a light pattern and comprising a supercontinuum laser which generates a white laser beam and a selector for driving the white laser beam obtained and selectively projecting the light pattern. on a set of solid corner areas and a diffuser installed in the path of the laser beam upstream or downstream of the selector. The diffuser serves in particular to spread the laser beam to improve for example the protection of the eyes. The diffuser comprises in particular glass or plastic with a structure for expanding the coherent laser beam.

The device according to the invention develops a laser beam having a particularly broad spectrum with components, for example of all wavelengths or substantially all wavelengths between 400 nm and 1700 nm. The light of the visible spectrum of the laser beam makes it possible, for example, to illuminate a road. At the same time, non-visible components such as the infrared components of the projected laser beam can be used for illumination and detection, for example for Lidar applications. Laser light with near-infrared (NIR) wavelengths of, for example, 1064 nm is particularly suitable for Lidar systems.

The radius of the supercontinuum laser has a very high quality, which simplifies the optical path through the device. It is thus possible to reduce the dimensions of the selector and other optical components installed in the beam path, which advantageously reduces overall the size of the device.

According to another advantageous characteristic, the phosphorus converter is removed. Phosphor converters usually convert with losses, blue light into a mixture of blue light and yellow light to obtain overall white laser light. Compared with solutions using phosphor converters, the invention makes it possible to adapt the color temperature of the laser beam used to project the light pattern during operation.

Compared with solutions using high power laser diodes to generate laser beams for projecting light patterns, the solution according to the invention has a longer life.

According to an advantageous development, the selector is made in the form of a deflection installation for deflecting the white laser beam. The deflection installation comprises for example one or more micro-mirrors, which makes it possible to scan a space zone in the manner of a scanning laser to project the light pattern.

According to another advantageous development, the selector is formed of an array of selectively switched pixels for passing or blocking the laser beam. The device can thus be used advantageously as a DLP projector, for example as a beam projector, that is to say as an image projector. In this case, the light pattern to be projected is for example a photo, a video, a presentation film or similar means. The device can also be used advantageously to illuminate objects seized by external devices.

According to another advantageous development, the network is constituted by a network of micro-optics. According to another advantageous development, the network is a GLV valve. Such devices allow to have a very bright projected light pattern and a good contrast. These devices offer a high resolution and are realized with relatively small technical means.

According to another advantageous development, the white laser beam is transmitted by the optical fiber of the supercontinuum laser to the selector. This makes it possible to separate the location where the laser beam is generated from that of the selection (i.e. the deflection), offering additional design freedom and better cooling possibilities.

According to another advantageous development, the path of the white laser beam comprises a filter for modifying the color temperature and / or the composition of the laser beam. It is thus possible to adapt the laser beam to a multiplicity of applications.

According to another advantageous development, the device is a portable or fixed projector. According to another advantageous development, the device is a projector, especially a vehicle, or a projector installed in a construction. According to another development, the device is a rear light or a turn signal.

drawings

The present invention will be described in more detail below with the aid of examples of devices and methods for projecting a light pattern, shown in the accompanying drawings in which: FIG. 1 is a block diagram of FIG. a first embodiment of a device for projecting a light pattern according to the invention, FIG. 2 shows graphs representing an advantageous distribution of the optical transmission coefficient as a function of the scanning angle, FIG. block diagram of another embodiment of a device for projecting a light pattern according to the invention, FIG. 4 is a block diagram of another embodiment of a projection device of a FIG. 5 is a block diagram of another embodiment of a device for projecting a light pattern according to the invention, FIG. 6 is a sc flow chart. method describing a method of projecting a light pattern according to another embodiment of the invention.

In all the figures, elements and devices of the same function or identical functions bear the same references unless otherwise indicated. The numbering of the process steps is for the description but is not required and implicitly contains another chronological order. In particular, several process steps can be executed simultaneously.

Description of embodiments

Fig. 1 is a block diagram of a device 10 for projecting a light pattern 70 corresponding to a first embodiment of the present invention.

The device 10 comprises a supercontinuum laser 12 for generating a white laser beam 51 by supercontinuum generation, that is to say a supercontinuum laser beam 51.

A selector 14 of the device 10 guides the white laser beam 51 generated by the supercontinuum laser 12 selectively to project the light pattern 70 into a set of ranges (set of solid angle ranges). The supercontinuum laser 12 is controlled for example according to an internal programming or a control signal of external origin as a function of each solid angle range to which the white laser beam 51 is driven at each instant by the selector 14 such as for example a control installation that generates or not the white laser beam 51, current.

The laser beam 51 forms a white pixel in the corresponding solid angle range. In the absence of laser beam 51 in the corresponding solid angle range, there will thus be a dark or black pixel. The use of color filters makes it possible to transform a white pixel into a color pixel, for example red, green or blue.

The projected light pattern 70 thus makes it possible in its entirety between white and black, to develop color pixels and white pixels and to represent, for example, a photo or the luminous cone with spatial resolution of a projector. The device 10 can thus serve as a projector of a vehicle or be integrated in such a projector and serve to develop the adaptive light cone of the projector, for example for curved lighting. Reversing light and turn signal applications are also beneficial.

Between the supercontinuum laser 12 and the selector 14 of a portion of the supercontinuum laser 12, an optional shutter can be provided to cut the laser beam 51 generated by the supercontinuum laser 12. A black pixel can thus be obtained in the luminous pattern 70. by actuating the shutter to cut the laser beam 51.

In the case of the device 10, a diffuser 16 is provided in the path of the laser beam 51 generated, downstream of the selector 14. The diffuser 16 is an optical component used to diffract the light by using in particular the effects of the diffuse reflection for refraction of the light. the light.

The diffuser 16 is for example made as will be described below with reference to Figure 2.

FIG. 2 shows an advantageous coefficient of transmission curve 81, that is to say a distribution of the transmission coefficient produced for example by the diffuser 16 and obtained by producing a polymer structure on glass. (polymer technique on glass); in other words, it is a polymer structure on glass or a polymer structure applied to glass. Depending on the intended application, the polymer structure will have a predefined roughness to have the appropriate diffraction characteristics. The curve of the transmission coefficient 81 of the diffuser makes it possible in particular to adjust the intensity and the spot size of the combined laser beam 54 coming out of the device 10.

The transmission coefficient curves 81 with the flatter maximum are preferably chosen because they have a low energy density for the laser beam 54 for a deflection angle 71 of 0 °.

The diffuser 16 will be described hereinafter with the advantageous characteristics concerning its normalized optical transmission coefficient 72 for given exit angles 71 of the deviated laser beam 51 after passing through the diffuser 16. The normalized optical transmission coefficient is the optical transmission coefficient normalized so that the maximum of the optical transmission coefficient corresponds to the value 1.0 and the minimum to the value 0.0.

Preferably, the diffuser 16 has an output angle 71 of the combined laser beam 51 deviated, after passing through the diffuser 16 having a value between 0 ° and a first output angle value with a normalized optical transmission coefficient of more 0.5 and in particular more than 0.6 and particularly preferably more than 0.7. The first exit angle is greater than or equal to 5 ° and preferably greater than or equal to 10 ° and in particular greater than or equal to 15 °.

For output angles 71 of the laser beam 51 after passing through the diffuser 16 of an amplitude greater than the second exit angle corresponds to a normalized optical transmission coefficient for the diffuser 16 of less than 0.5 and in particular of less than 0, 3 and particularly preferably less than 0.2.

The second exit angle is equal to the first exit angle, or preferentially, it is greater than the first exit angle. The second exit angle is preferably greater than or equal to 5 ° and in particular greater than or equal to 10 ° and in particular greater than or equal to 15 ° or greater than or equal to 20 °. The second exit angle is further preferably less than or equal to 30 ° and particularly preferably less than or equal to 25 ° and in particular less than or equal to 20 °.

The first and / or second exit angle is preferably between 10 ° and 20 ° and in particular between 15 ° and 20 °. Alternatively or additionally, the first and / or second exit angle is (are) preferably separated by less than 10 ° and especially less than 5 °. In principle, such configurations are particularly preferred when they have a particularly steep drop in the normalized optical transmission coefficient.

Preferably, there is a symmetrical rotation distribution of the normalized optical transmission coefficient, that is to say a distribution on which depends the amplitude of the exit angle 71 but not the orientation of this angle 71 around from normal to the surface of the diffuser 16. For other applications, the diffuser 16 may also be configured to have a rectangular distribution, including square of the optical transmission coefficient.

The described properties of the diffuser 16 with respect to the standardized optical transmission coefficient are advantageous for developing an advantageous radius profile through the diffuser 16. On the one hand, there will be a particularly narrow output profile, that is to say a standardized optical transmission coefficient which drops very rapidly around 0 ° with a high resolution of the light pattern to be projected. On the other hand, for such narrow profiles of the radius, it will have a high light intensity, undesirable, especially at 0 °. These output characteristics of the diffuser make it possible to have an advantageous balance between these two interesting objectives. In a particularly advantageous manner, the diffuser 16 has the characteristics represented by the curve 81 or by the ideal curve 85 in FIG.

Thus, the particularly preferred diffuser 16 will have an exit angle 71 for the combined laser beam 54 deviated from the direction normal to the surface of the diffuser 16 after passing through it: for an exit angle 71 of a value between 0 ° and a first output angle value, a normalized optical transmission coefficient of more than 0.5, in particular of more than 0.6 and particularly preferably of more than 0.7 and for the output angle 71 with an amplitude greater than or equal to a second output angle value with a normalized optical transmission coefficient of less than 0.5 and in particular of less than 0.3 and particularly preferably less than 0.2.

Figure 3 is a block diagram of another embodiment of a device 110 for projecting a light pattern 70 according to the invention. The device 110 is a variant of the device 10 and differs therefrom in that the device 110 comprises a selector 114 in place of the selector 14 of the device 10.

The selector 114 is specially designed as a deflection device 114 for deflecting the white laser beam 51 according to the current embodiment of the deflection installation 114. The deflection installation 114 comprises, for example, a controlled micromirror or a certain number of micromirrors installed one after the other in the path of the laser beam 51; the one or more micro-mirrors are controlled for example by an actuator of the deflection installation 114 so that the laser beam 51 can be deflected and scan a certain solid angle and / or to be decoupled from the device 110. The deflection installation 114 allows to deflect the laser beam 51 in one dimension and preferably in two dimensions.

A decoupling installation 118 of the device 110, provided as an option, makes it possible to decouple the projected light pattern 70 from the device 110, for example in the case of a vehicle headlight to guide it in the vehicle environment. The decoupling installation 118 comprises for example a secondary optics or is constituted by a secondary optic, a cover glass or is made with such means.

Between the supercontinuum laser 12 and the deflection facility 114, there is an optional fiberglass installation 120 for driving the laser beam 51 generated by the supercontinuum laser 12 through optical fibers. The laser beam 51 thus generated will be conducted without loss while achieving a separation of construction and space between the supercontinuum laser 12 and the selector 114. This separation in space is particularly advantageous for cooling and allows greater freedom of movement. design.

The device 110 may be modified and developed in particular from the point of view of the diffuser 16 according to the modifications and developments described in connection with the device 10 and vice versa.

Fig. 4 is a block diagram of another embodiment of a device 210 for projecting a light pattern 70 according to another embodiment of the present invention. The device 210 is a variant of the device 10 and is distinguished in that the device 210 comprises the diffuser 16 in the path of the laser beam 51 between the supercontinuum laser 12 and the selector 14. For the rest, the various elements of the device 210 may also be made as described with reference to the devices 10, 110, especially with regard to the diffuser 16. The device 210 may comprise an optical decoupling installation 118 as described above with reference to FIG. device 110.

A glass fiber installation 220 may be optionally provided between the supercontinuum laser 12 and the diffuser 16 to drive the laser beam 51 generated by the supercontinuum laser 12 with glass fibers. Thus, the laser beam 51 can be transmitted in a particularly low loss manner while having a constructive and spatial separation between the supercontinuum laser 12 and the diffuser 16. This gap in space is particularly advantageous for reasons of cooling and it allows a greater freedom of design.

Figure 5 is a block diagram of another embodiment of a device 310 for projecting a light pattern 70 according to the invention. The device 310 is a variant of the device 210 and can be adapted to all the modifications and developments described in connection with the device 210 and vice versa.

The device 310 differs from the device 210 by its selector 314 in place of the selector 14 of the device 210.

The selector 314 of the device 310 is an array of pixels controlled to selectively transmit or not the laser beam 51. The supercontinuum laser 12 and the diffuser 16 of the device 310 are preferably made and installed so that the laser beam 51 fully illuminates the laser beam. network 314.

For this purpose, for example, the diffuser 16 is provided for spreading the laser beam 51 which, initially, is narrow. The selective transmission or non-transmission of the array pixels 314, thus controlled, gives the luminous pattern to be projected 70 in the path of the beam downstream of the array 314. The device 310 may also include an optional decoupling device 118 for uncoupling the pattern projected light 70 of the device 310, to continue to be projected in the environment of the device 310 as described with respect to the device 110 as indicated above.

The network 314 is for example a microoptical array, that is to say in particular a regular arrangement, in particular in two dimensions, of separate micro-mirrors, the position of each of which can be modified separately. For each of the micro-mirrors of the array 314, there is a first position of the respective micro-mirror which transmits the laser beam 51 through the pixels forming the micro-mirror. For each of the micro-mirrors, there is also a second representation of the micro-mirror which corresponds to the non-crossing of the pixels of the micro-mirror.

The device 310 may for example comprise an optical trap and an optical receiver and the micromirrors of the array 314 are arranged so that in the respective second position of the micromirror they guide the incident light component of the laser beam 51 each time in the trap. to light. The light trap makes it possible to absorb the incident light beam 51 as completely as possible, which can also be called a "beam stop".

It is further provided that the micromirrors of the array 314 in the respective first position of the micromirrors conduct the laser beam component 41 to project the light pattern 70 onto the optional decoupling apparatus 118 of the apparatus 310.

The entirety of the transmission pixels that have not yet been switched in the blocking direction results in a corresponding set of white and black pixels representing the light pattern 70 to be projected.

As a variant, in the production of a microoptic array, the selector 314 of the device 310 can be made in the form of a GLV valve. In the case of such a GLV valve, each selector pixel 314 is formed of a number of separately controlled metal strips. The control of the metal strips is such that the different metal strips can pass selectively through electrostatic fields and deflect differently to each respective pixel.

For example, if none of the metal strips of a pixel are deflected, the portion of the laser beam 51 arriving at the pixel is reflected back to the skylight as described above so that pixel has the effect of a black pixel in the projected light pattern 70. The bending, for example of each second metal strip, causes the portion of the laser beam 51 arriving on the pixel to be diffracted so that a new light wave develops in another direction than that of the light well, which corresponds to a white pixel of 70 projected light pattern. The light wave may, for example, be deployed in the direction of the optional decoupling device 118 of the device 310.

Fig. 6 is a schematic flow chart for describing a method of projecting the light pattern 70 according to another embodiment of the invention. The method of FIG. 6 can be applied by all the devices 10, 110, 210, 310 of the invention and adapts to the modifications and developments of the devices and vice versa.

In the SOI step, the supercontinuum laser 12 is commanded to generate a white laser beam 51. In the step S02, the white laser beam 51 is selectively directed to a set of solid angle ranges to project the light pattern 70 with a diffuser 16 in the path of the laser beam 51.

As described above, the SOI command of the supercontinuum laser 12 can in particular be a command for generating the white laser beam 51 as a function of time and decide whether or not the white laser beam 51 should be generated at the instant, for example by the state of the selector 14, 114, 314. Alternatively or additionally, the SOI command may also consist of controlling a shutter which cuts the laser beam 51 generated by the supercontinuum laser 12. According to the state of the selector 14, 114, 314, as described above, it is for example the current position of a deflection micro-mirror or of several micro-mirrors on which the laser beam 51 would arrive if it were generated at this time. The breaking of the generation of the laser beam 51 or its shutter failure results in particular in the development of black pixels if the selector is the deflection installation 114. If the selector 314 is a network, the intensity of each pixel is determined, preferably by the modulation of the different elements of the network.

At least one filter element is provided between the supercontinuum laser 12 and the selector 14, 114, 314 upstream or downstream of the diffuser 16 to modify the color temperature or the composition of the spectrum of the laser beam 51. The filter element is for example an acousto-optical modulator AOM or an acousto-optical filter tuned AOTF. Such an acousto-optic modulator consists of an anisotropic optical crystal made of telurium dioxide, lithium niobate or quartz, to which is coupled a piezoelectric crystal, also called an acoustic transducer.

By applying a radio frequency, for example between 150 and 350 MHz to the piezoelectric crystal, it generates an ultrasonic wave deployed in the anisotropic optical crystal. The ultrasonic wave generates in the crystal an array of refractive indices so that the laser beam 51 will be diffracted as a function of this network of refractive indices. The wavelength of the diffracted light varies according to the frequency of the sound wave. The intensity of the diffracted laser beam is for example regulated by the intensity of the sound waves.

NOMENCLATURE DBS MAIN ELEMENTS

For sets of similar reference elements, only the first reference will be taken over 10 Luminous pattern projection device 12 Supercontinuum laser 14 Selector switch 16 Diffuser 51 White laser beam 54 Combined laser beam 70 Projected light pattern 71 Output angle 72 Coefficient Standardized optical transmittance 81 Transmission coefficient curve 118 Decoupling installation 120 Glass fiber installation 314 Network-shaped selector

Claims (10)

1 °) Device (10, 110, 210, 310) for projecting a light pattern (70) comprising: a supercontinuum laser (12) which generates a white laser beam (51), a selector (14, 114, 314) which conducts the white laser beam (51) thus generated to selectively project the light pattern (70) into a set of solid angle ranges, and a diffuser (16) installed in the path of the laser beam (51) upstream or downstream of the selector (14, 114, 314). 2) Device (110) according to claim 1, characterized in that the selector is formed as a deflection facility (114) for deflecting the white laser beam (51). 3) Device (310) according to claim 1, characterized in that the selector is a network (314) of switched pixels which transmit or not the laser beam (51). 4) Device (310) according to claim 3, characterized in that the network (314) is a network of micro-optics. 5 °) Device (310) according to claim 3, characterized in that the network (314) is a GLV valve. 6 °) Device (10, 110) according to one of claims 1 or 2, characterized in that the white laser beam (51) is driven from the supercontinuum laser (12) in the selector (14, 114) by an optical fiber . Device (10, 110, 210, 310) according to one of Claims 1 to 6, characterized in that a filter is placed in the path of the white laser beam (51) to change the color temperature and / or to modify the spectral composition of the laser beam (51). 8 °) Device (10, 110, 210, 310) according to one of claims 1 to 7, characterized in that it is designed as a projector. 9 °) Device (10, 110, 210, 310) according to one of claims 1 to 7, characterized in that the device is a projector as a rear light or as a blinker. A method of projecting a light pattern (70) comprising: controlling (SOI) a supercontinuum laser (12) to generate a white laser beam (51), and selectively driving (S02) the white laser beam (51) in a set of solid angle ranges for projecting the light pattern (70) to have a diffuser (16) in the path of the laser beam (51).