Target aiming device

Abstract

The invention relates to a target (C) aiming device (10), which comprises: - a set of lasers (12) comprising: • a continuous or quasi-continuous power laser (20), and • a pulsed beacon laser (22), having a common line of sight; -a tracking assembly (14) comprising: • a tracking camera (30) able to acquire images of the target (C) and of the spot of the beacon laser (22) on the target (C), having a line of sight different from the lines of sight of the power laser (20) and beacon laser (22); • a unit (32) for generating a control setpoint; and • an actuator (34) able to modify the orientation of the line of sight of the lasers according to the control setpoint, the power laser (20) being activated only when the spot of the beacon laser (22) on the target (C) is controlled.

Description

[0001] TITLE: Target pointing device

[0002] The present invention relates to a device for pointing a target.

[0003] In particular, the pointing is a fine pointing performed by a power laser. In particular, the power laser, as well as the associated display devices, are generally carried by a (motorized) structure allowing pre-pointing to be performed. The invention thus relates to the ability to ensure relative tracking between a target and a laser to point (fine pointing) a very high average power laser.

[0004] Conventionally, in the state of the art, the supporting structure of the power laser is also the supporting structure of the tracking camera. The two channels are then mechanically adjusted in the factory relative to each other and the tracking camera works in a spectral band different from that of the continuous or quasi-continuous power laser. This allows rejection of the power band to avoid glare.

[0005] Generally, to ensure tracking day and night, the tracking camera is a camera supplemented (especially at night) by a pulsed laser which illuminates the entire target to improve the signal-to-noise ratio.

[0006] The tracking camera is a fast camera to ensure a fast servo loop of the line of sight in order to compensate for atmospheric turbulence and the area targeted by the laser is the tracking center, or a part not far from the tracking center. Thermal effects are not compensated but the duration of the shot is limited to avoid excessive heating.

[0007] This has several limitations:

[0008] The effects due to turbulence are linked to the spectral band considered, so if the tracking camera does not work in the spectral band of the laser, their effects cannot be correctly corrected.

[0009] When the power laser fires, the temperature rises in the optical carrier structure and it is extremely difficult to ensure that heating will not cause the laser optical axis to deviate from the tracking optical axis.

[0010] The illumination zone and the tracking center are close since it is relative to the tracking center that the illuminated location is estimated.

[0011] The illuminated area is only observed through the effects induced on the materials (smoke, flames, temperature rise, etc.) by the tracking camera.

[0012] - If we want to superimpose several tracks, we need as many tracking cameras. There is therefore a need for a pointing device allowing energy to be deposited on a precise area of ​​a target during tracking ensured by a camera and this for a sufficient duration to allow the destruction of the target.

[0013] To this end, the invention relates to a device for pointing a target comprising:

[0014] - a set of lasers including:

[0015] • a continuous or quasi-continuous power laser,

[0016] • a pulsed beacon laser, the power laser and the beacon laser having a common line of sight,

[0017] - a tracking set including:

[0018] • a tracking camera capable of acquiring images of the target and the beacon laser task on the target, the tracking camera having a line of sight different from the line of sight of the power laser and the beacon laser,

[0019] • a main unit for generating a control instruction based on the images acquired by the tracking camera so as to control the task of the beacon laser on the target, and

[0020] • a main actuator capable of modifying the orientation of the line of sight of the power laser and the beacon laser according to the control instruction, the power laser being activated only when the control of the beacon laser task on the target is achieved.

[0021] According to other advantageous aspects of the invention, the pointing device comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0022] - the tracking assembly includes an illumination laser capable of illuminating the target;

[0023] - the tracking camera includes a spectral filter centered on a wavelength band different from that of the power laser;

[0024] - the spectral filter of the tracking camera is centered on the wavelength band of the beacon laser;

[0025] - the power laser is capable of switching off periodically during the beacon laser emission period;

[0026] - the beacon laser and the illumination laser have the same emission rate and are synchronized;

[0027] - the tracking camera is a camera with an opening time allowing the visualization of the beacon laser task without saturation by the power laser;

[0028] - the tracking camera is an event detection camera capable of detecting emissions from the beacon laser;

[0029] - the device comprises a tracking initialization assembly comprising: - an initialization camera having a line of sight common to the power laser and the beacon laser, the initialization camera operating on a wavelength band different from that of the power laser and being capable of acquiring images of the target, and

[0030] - an initialization unit capable of generating a superposition instruction as a function of the images acquired by the initialization camera to bring the target into a predetermined position in the field of vision of the initialization camera so that the line of sight of the beacon laser is positioned on the target, the main actuator being capable of modifying the orientation of the line of sight of the power laser as a function of the superposition instruction;

[0031] - the laser beacon is capable of scanning around the target until the laser beacon signal is observed on the tracking camera.

[0032] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0033] [Fig. 1] Figure 1 is a schematic view of a pointing device comprising a power laser, a beacon laser having a line of sight common to the power laser, and a tracking camera independent of the line of sight of the power laser and the beacon laser,

[0034] [Fig. 2] Figure 2 is a schematic view of the field of view of an initialization camera having a common line of sight with that of the power laser and the beacon laser, the target being off-center with respect to the line of sight of the initialization camera, and

[0035] [Fig. 3] Figure 3 is another schematic view of the field of view of the initialization camera of Figure 2, with the line of sight of the power laser and the beacon laser having been modified so that the target is in the center of the field of view of the initialization camera (laser spot of the beacon laser brought back onto the target).

[0036] A device 10 for pointing a target C is illustrated in Figure 1.

[0037] Target C is, for example, a moving target moving in the air, on land, or at sea. Target C is, for example, an aircraft, a drone, a land vehicle or even a naval vessel.

[0038] As illustrated in Figure 1, the pointing device 10 comprises a set of lasers 12 and a tracking assembly 14. Optionally, the pointing device 10 also comprises an initialization assembly 16.

[0039] The pointing device 10 is typically oriented in elevation and bearing.

[0040] The laser assembly 12 includes a power laser 20 and a beacon laser 22. The power laser 20 is a continuous or quasi-continuous laser. The term "quasi-continuous" implies that the emission time is greater than or equal to the energy reduction (or absence) time and that the emission times are several hundred milliseconds.

[0041] The power laser 20 is suitable for being activated only when the task of the beacon laser 22 on the target C is controlled.

[0042] The 20 power laser has a high average power, typically greater than or equal to 1 kilowatt (kW).

[0043] The 20 power laser typically has a wavelength band between 0.5 micrometers (pm) and 2.5 pm.

[0044] The 22 beacon laser is a pulsed laser. The pulse rate of the 22 beacon laser is high, typically a few kilohertz (kHz).

[0045] The 22 beacon laser has a high peak power, but an average power much lower than the average power of the 20 power laser, its purpose being to visualize the point of impact of the power laser (superimposed on the beacon laser), in order to ensure relative tracking between the target C and the beacon laser while guaranteeing eye safety at the level of the target C. Typically, the average power of the 22 beacon laser is less than or equal to a few W (e.g. 10 Watts).

[0046] The beacon laser 22 preferably has a wavelength band identical or close to that of the power laser 20. By the term "close" is meant a wavelength difference less than or equal to typically 0.2 pm. For example, the power laser 20 is at 1 pm and the beacon laser 22 is at 0.9 pm.

[0047] The power laser 20 and the beacon laser 22 have a common line of sight. For example, the beacon laser 22 may be injected into the fiber of the power laser 20 or may be combined with the power laser 20 by means of a grating-type optical component. For example, the power laser 20 and the beacon laser 22 are carried by the same support structure 17.

[0048] The tracking assembly 14 is suitable for ensuring the relative tracking of the target C by the beacon laser 22 (and therefore the power laser 20).

[0049] The tracking assembly 14 comprises a tracking camera 30, a main unit 32 for generating a servo-control instruction and a main actuator 34. Optionally, the tracking assembly 14 also comprises an illumination laser 36.

[0050] The tracking camera 30 is capable of acquiring images of the target C and of the task of the beacon laser 22 on the target C (illuminated or not by the illumination laser 36).

[0051] The tracking camera 30 has a line of sight different from the line of sight of the power laser 20 and the beacon laser 22. The tracking camera 30 is notably positioned outside the supporting structure 17 of the power laser 20 and the beacon laser 22. The tracking camera 30 being positioned outside, it is no longer hindered by the backscattering of the power laser 20, nor by the obligation to be at a wavelength other than that of the power laser 20.

[0052] The tracking camera 30 is preferably a camera allowing at least an output rate of certain pixels at more than 5 kHz.

[0053] The tracking camera 30 is capable of imaging the task of the beacon laser 22 on the target C. For this, several means of implementation, listed below and combinable with each other, are possible:

[0054] In an exemplary implementation, the tracking camera 30 includes a spectral filter centered on a spectral band of the camera different from that of the power laser 20. This allows the tracking camera 30 not to be dazzled by the power laser 20. Preferably, the spectral filter of the tracking camera 30 is centered on the spectral band of the beacon laser 22 (e.g., beacon laser 22 and spectral filter at 0.9 pm, and power laser 20 at 1 pm).

[0055] In an exemplary implementation, the power laser 20 is capable of turning off periodically during the emission period of the beacon laser 22. This makes it possible not to saturate the tracking camera 30. This phenomenon is called “blanking”. The extinction duration is, for example, a few tens of nanoseconds.

[0056] In an exemplary implementation, the tracking camera 30 is a camera having an opening time allowing the visualization of the task of the beacon laser 22 without saturation by the power laser 20. The opening time is therefore sufficiently short to avoid saturation. In one example, telemetry is used to open the tracking camera 30 synchronously with the pulses of the retrodiff illumination laser 36 worn by the target C and the visualization of the task of the beacon laser 22 without saturation. o the opening duration is, for example, determined by means of a telemeter present on the structure supporting the carrier camera 30, and which measures the distance from the tracking camera 30 to the target C.

[0057] In an exemplary implementation, the tracking camera 30 is an event-based camera capable of detecting the emissions of the beacon laser 22. This makes it possible to limit the latency for tracking and to have a strong dynamic range so as not to saturate the tracking camera 30.

[0058] The main unit 32 is capable of generating a control instruction based on the images acquired by the tracking camera 30 so as to carry out control of the task of the beacon laser 22 on the chosen area of ​​the target C. The main unit 32 is, for example, a computer.

[0059] The main actuator 34 is capable of modifying the orientation of the line of sight of the power laser 20 and the beacon laser 22 as a function of the servo-control instruction. The main actuator 34 is typically carried by the supporting structure 17 and is at the output of the power laser 20. The main actuator 34 comprises, for example, one or more opto-mechanical components.

[0060] The illumination laser 36 is suitable for illuminating the target C.

[0061] The illumination laser 36 is a pulsed laser. The illumination laser 36 and the beacon laser 22 have wavelengths compatible with observation by the tracking camera 30 (i.e., within the wavelength band of the tracking camera 30).

[0062] The optional initialization assembly 16 is suitable for initializing the relative tracking of the task of the beacon laser 22 on the target C. In particular, the initialization assembly 16 is particularly useful in the case of small targets, to facilitate the superposition of the task of the beacon laser 22 on the target C at start-up. The initialization assembly 16 is typically carried by the supporting structure 17.

[0063] The initialization assembly 16 comprises an initialization camera 40, an initialization unit 42.

[0064] The initialization camera 40 operates in a spectral band different from that of the power laser 20 and is capable of acquiring images of the target C.

[0065] The initialization camera 40 has a common line of sight to the power laser 20 and the beacon laser 22 (factory setting). Thus, the task formed by the beacon laser 22 (and also by the power laser 20) is approximately (subject to turbulence effects) in the center of the field of vision of the initialization camera 40. The use of the initialization camera 40 aims to bring the target C back to a predetermined position in the field of vision of the initialization camera 40 before starting the high-speed servo-control of the fine pointing.

[0066] For example, the line of sight of the initialization camera 40 is brought back to that of the power laser 20 and the beacon laser 22 via a hole mirror 46, a beam splitter or a spectral filter.

[0067] The initialization unit 42 is capable of generating a superposition instruction as a function of the images acquired by the initialization camera 40 to bring the target C into a predetermined position in the field of vision of the initialization camera 40 so that the line of sight of the beacon laser 22 is positioned on the target C. The predetermined position is typically the center or an area close to the center of the field of vision of the initialization camera 40. The initialization unit 42 is, for example, a computer. The main actuator 34 is capable of modifying the orientation of the line of sight of the power laser 20 and of the beacon laser 22 (and where appropriate of the initialization camera 40) as a function of the superposition instruction.

[0068] Alternatively, the pointing device 10 does not include an initialization assembly 16 and the positioning of the task of the beacon laser 22 on the target C is done at startup via a scan carried out by the beacon laser 22 around the target C until the signal is observed on the tracking camera 30. For example, the site-bearing orientation of the device 10 could be used to produce the scan pattern.

[0069] An example of operation of the pointing device 10 will now be described.

[0070] At startup, only the 22 beacon laser is activated and the 20 power laser is switched off.

[0071] When the device 10 comprises an initialization assembly 16, the target C, possibly illuminated by the illumination laser 36, is imaged by the initialization camera 40. The initialization unit 42 generates a superposition instruction sent to the main actuator 34 aimed at bringing the target C back to the center of the field of vision of the initialization camera 40 so that the line of sight of the beacon laser 22 is positioned on the target C.

[0072] By way of example, Figures 2 and 3 illustrate the field of view of the initialization camera 40, the beacon laser 22 being emitted in the center of the field of view (common line of sight with the initialization camera 40). The transition from Figure 2 to Figure 3 is carried out by a modification of the orientation of the line of sight of the beacon laser 22 (and therefore of the initialization camera 40) making it possible to bring the target C back to the center of the field of view of the initialization camera 40.

[0073] Alternatively, the beacon laser 22 scans around the target C until the signal from the beacon laser 22 on the target C is observed on the tracking camera 30.

[0074] Once the task of the beacon laser 22 is visible on the target C by the tracking camera 30, images of the target C and of the task of the beacon laser 22 are successively acquired by the tracking camera 30. The main unit 32 generates a servo instruction, sent to the main actuator 34, aimed at carrying out a servo control of the task of the beacon laser 22 on the target C (so that the task of the beacon laser 22 remains concentrated in the same place).

[0075] The power laser 20 is then activated once the task of the beacon laser 22 on the target C has been controlled.

[0076] Thus, the pointing device 10 described allows the replacement of a monostatic system comprising a tracking camera 30 and a continuous or quasi-continuous power laser adjusted in the factory by a bistatic system between these two elements, the absence of adjustment between the two being compensated by the knowledge of the line of sight position of the power laser 20 via the visualization of a beacon laser 22 collinear and superimposed with this power laser 20.

[0077] The position of the beacon laser 22 seen on the target C by the tracking camera 30 allows the control of the beacon laser task 22 on the target C, then the start-up of the power laser 20 allows the effect to be had on the target C. This relative tracking of the target C and the laser task makes it possible to avoid monostatism and precise harmonization between the camera and the laser.

[0078] Such a pointing device 10 allows much more flexibility (orientation of the line of sight, multiple beams, etc.) and better correction of the pointing (correction by seeing the beacon laser 22). Thus, it makes it possible to overcome the problems of heating in the structure carrying the power laser 20, the problems of glare of the camera linked to the monostatic system and better tilt correction linked to turbulence.

[0079] In summary, the 10 pointing device has many advantages:

[0080] The use of a 22 beacon laser to achieve the control allows the 20 power laser to be switched on only once the control has been achieved, in complete eye safety.

[0081] - As we see the beacon laser 22 on the tracking camera 30, it is possible to correct the effects linked to turbulence, in particular with a measurement at the same wavelength or close to that of the power laser.

[0082] - If the structure moves in temperature, the direction of the beacon laser 22 will be corrected in real time and therefore will always illuminate the same target point.

[0083] It is possible to directly address any location of the target C, especially the most vulnerable areas.

[0084] The illuminated area is observed directly and it is possible to directly see the effects of the laser on target C.

[0085] It is possible to manage several lasers simultaneously at the same wavelength or at close wavelengths.

[0086] The glare problems of monostatic solutions are eliminated.

[0087] Those skilled in the art will understand that the described embodiments can be combined with each other provided that they are technically compatible.

Claims

CLAIMS 1. Device (10) for pointing a target (C) comprising: - a set of lasers (12) comprising: • a continuous or quasi-continuous power laser (20), • a pulsed beacon laser (22), the power laser (20) and the beacon laser (22) having a common line of sight, - a tracking assembly (14) comprising: • a tracking camera (30) capable of acquiring images of the target (C) and of the task of the beacon laser (22) on the target (C), the tracking camera (30) having a line of sight different from the line of sight of the power laser (20) and the beacon laser (22), • a main unit (32) for generating a control instruction based on the images acquired by the tracking camera (30) so as to control the task of the beacon laser (22) on the target (C), and • a main actuator (34) capable of modifying the orientation of the line of sight of the power laser (20) and the beacon laser (22) as a function of the control instruction, the power laser (20) being activated only when the control of the task of the beacon laser (22) on the target (C) is achieved.

2. Device (10) according to claim 1, in which the tracking assembly (14) comprises an illumination laser (36) capable of illuminating the target (C).

3. Device (10) according to claim 1 or 2, in which the tracking camera (30) comprises a spectral filter centered on a wavelength band different from that of the power laser (20).

4. Device (10) according to claim 3, wherein the spectral filter of the tracking camera (30) is centered on the wavelength band of the beacon laser (22).

5. Device (10) according to any one of claims 1 to 4, in which the power laser (20) is capable of switching off periodically during the emission period of the beacon laser (22).

6. Device (10) according to claim 2 optionally combined with any one of claims 3 to 5, in which the beacon laser (22) and the illumination laser (36) have the same emission rate and are synchronized.

7. Device (10) according to any one of claims 1 to 6, in which the tracking camera (30) is a camera having an opening time allowing the visualization of the task of the beacon laser (22) without saturation by the power laser (20).

8. Device (10) according to any one of claims 1 to 6, in which the tracking camera (30) is an event detection camera capable of detecting the emissions of the beacon laser (22).

9. Device (10) according to any one of claims 1 to 8, wherein the device (10) comprises a tracking initialization assembly (16) comprising: - an initialization camera (40) having a line of sight common to the power laser (20) and to the beacon laser (22), the initialization camera (40) operating on a wavelength band different from that of the power laser (20) and being capable of acquiring images of the target (C), and - an initialization unit (42) capable of generating a superposition instruction as a function of the images acquired by the initialization camera (40) to bring the target (C) into a predetermined position in the field of vision of the initialization camera (40) so that the line of sight of the beacon laser (22) is positioned on the target (C), the main actuator (34) being capable of modifying the orientation of the line of sight of the power laser (12) as a function of the superposition instruction.

10. Device according to any one of claims 1 to 8, in which the beacon laser (22) is capable of performing a scan around the target (C). until the signal from the beacon laser (22) is observed on the tracking camera (30).

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