Laser beam device and coherence generating method

Abstract

The present invention relates to a laser beam device 10 for irradiating an object and to a method of operating such a laser beam device 10. According to the invention, at least two laser beams are made coherent.

Description

[Technical Field]

[0001] The present invention relates to a laser light device for irradiating a target object with efficient laser radiation, e.g., a HEL effector, a high-energy laser effector. The main components of a HEL effector include at least one laser source and a beam guidance system. The beam guidance system may include functions and / or subassemblies such as a fine imaging system (FIS), a fine tracking system (FTS), a telescope, and adaptive optics. The laser source may be a gas laser or a solid-state laser, e.g., a fiber laser.

[0002] The invention further relates to a laser beam device with a plurality of, at least two, amplification paths, wherein the useful laser radiation generated by the useful laser source is at least partially directed into a first amplification path and / or at least partially split into a second amplification path by a beam distribution and / or beam splitting device. [Background technology]

[0003] The particular amplification path includes an amplifier device for amplifying the useful laser radiation, and a laser beam device designed to irradiate a target object at least temporarily simultaneously with the useful laser beam emitted from the first amplification path and the useful laser beam emitted from the second amplification path.

[0004] In order to illuminate the target object as efficiently as possible, a coherent superposition of the effective laser beams emitted by the amplification paths is to be achieved.

[0005] The phase relationship between the two effective laser beams required to generate coherence cannot be measured directly. Typically, indirect measurements are performed to determine the phase, from which the superposition intensity is evaluated. When using high-power fiber lasers, the output power can vary significantly. This can place very high demands on the evaluation dynamics. To improve the evaluation, it is also known to additionally modulate the laser power with amplitude. This modulation can only be transferred to high-power fiber lasers to a limited extent, since the modulation introduces nonlinear processes, which in turn limits the output power of high-power fiber lasers. Another problem arises when switching on high-power fiber lasers. Due to their design, phase fluctuations occur, especially during switch-on, leading to large fluctuations in performance. This places very high demands on the measurement, evaluation, and control dynamics.

[0006] When a laser beam device is used to irradiate a distant target, phase variations along the propagation path, caused for example by turbulence, are added to the phase variations in the device itself, which become a further influence on the control and can only be identified and corrected when the high-power fiber laser is switched on. Furthermore, when the high-power fiber laser is switched on, its high intensity can cause luminescence phenomena at the target, which in turn negatively impacts the intensity assessment at the target.

[0007] These drawbacks are to be overcome by the present invention. Summary of the Invention

[0008] Therefore, according to the present invention, it is proposed that the laser beam device comprises a calibration laser source for generating calibration laser radiation, the wavelength of the calibration laser radiation deviating from the wavelength of the useful laser radiation, the laser beam device is designed in such a way that at least a portion of the calibration laser radiation generated by the calibration laser radiation can be split and / or distributed in a beam distribution and / or beam splitting device into a first and a second amplification path, a particular amplification path comprises a wavelength-dependent coupling element for coupling at least a portion of the calibration laser light, the laser beam device comprises means for determining the phase of the calibration laser light of the first amplification path and / or the phase of the calibration laser light of the second amplification path, at least one amplification path comprises at least one means for shifting the phase of the laser radiation, the at least one means for shifting at least the phase of the laser radiation, and the at least one means for shifting the phase (28) can be controlled as a function of the phase of the calibration laser light of the first amplification path (16-1) and / or the phase of the calibration laser light of the second amplification path (16-2).

[0009] The wavelength of the calibration laser radiation is at least slightly different from the wavelength of the useful laser radiation. The wavelength of the calibration laser radiation is outside the bandwidth of the amplifier. The useful laser source and the calibration laser source are operated so that the calibration laser radiation has a significantly lower power than the useful laser radiation. For example, the power of the calibration laser source is between 1 watt and 100 watts. The power of the useful laser source is, for example, between 100 watts and several thousand watts. For example, the useful laser light and the calibration laser light have the same polarization. The useful laser light and the calibration laser light can also be polarized perpendicular to each other.

[0010] Both the useful laser light and the calibration laser light are directed and / or split into each amplification path by a beam directing and / or beam splitting device. An example of a beam directing device is a mirror. An example of a beam splitting device is a beam splitter.

[0011] In the amplification path, at least the useful laser radiation is amplified by the amplifier device. The amplifier device is designed with a specific amplification path such that the useful laser radiation is amplified while the calibration laser radiation is not amplified or is only amplified at a relatively low level. This can be achieved, for example, by wavelength-dependent amplification.

[0012] The wavelengths of the calibration laser light and the effective laser light are different. The wavelengths are advantageously close to each other. This ensures that the influence on the phase of the calibration laser light and the effective laser light of the two wavelengths, e.g., the phase error, is the same or nearly the same. The wavelength of the effective laser light is, for example, 1035 nm or 1090 nm (λ1), and the wavelength of the calibration laser light is, for example, <1035 nm or >1095 nm (λ2), in any case outside the amplifier bandwidth.

[0013] The useful and calibration laser radiations travel the same optical path in each amplification path and experience the same runtime effects during operation, such as changes in length due to thermal expansion and changes in refractive index. As a result, they are subject to approximately the same phase error. Therefore, the wavelengths of the useful and calibration laser radiations are in phase relation.

[0014] The wavelength-dependent coupling-out element couples part of the calibration laser radiation or the entire calibration laser radiation out of the specific amplification path, for example a beam splitter, for example, by transmitting the useful laser light and reflecting, thus directing and coupling, the calibration laser light.

[0015] The coupled-out calibration laser light is in each case supplied to means for determining the phase of the calibration laser light, and if a common means for phase determination, e.g. a central processing unit, is used, the ratio of the phases of the calibration laser radiation coupled-out from the first amplification path and the calibration laser radiation coupled-out from the second amplification path can be determined.

[0016] If the calibration laser radiation combined from the first and second amplification paths is fed to specific means for phase determination, it is possible to ascertain a specific phase in particular relative to a reference value.

[0017] Various intensity-based methods, such as power-in-the-bucket (PiB) or coherence pattern evaluation, can be used to determine the phase.

[0018] Unlike useful laser radiation, the calibration laser radiation is a power-independent input variable for intensity measurements and the resulting phase determinations.

[0019] According to the present invention, the phase relationship of the calibration laser radiation of the first and second beam paths is determined. This phase relationship is used to adjust the laser radiation of the first and second amplification paths. According to the present invention, it is not necessary to determine the phase relationship of the effective laser radiation. Since the effective laser radiation and the calibration laser radiation pass through the same optical path in each amplification path and are therefore subject to the same phase error, the phase relationship of the effective laser radiation can be inferred from the phase relationship of the calibration laser radiation. An advantage of using the calibration laser radiation to determine the phase relationship and not the effective laser radiation is that the calibration laser radiation contains a significantly lower power than the effective laser radiation. Due to its lower power, the calibration laser source can be operated continuously, for example, even if the effective laser radiation has not yet irradiated the target object. The use of the calibration laser radiation to determine the phase relationship reduces the demands on the control loop regarding measurement dynamics and control dynamics.

[0020] Furthermore, due to the use of calibration laser radiation, the verification of the phase relationship and in particular the generation of the phase coupling can be carried out even before the active laser source is switched on.

[0021] It is further provided that the laser beam device comprises at least one means for shifting the phase, also called phase shifter, of the laser radiation, which can be controlled as a function of the phase of the calibration laser light of the first amplification path and / or the phase of the calibration laser light of the second amplification path, in particular as a function of the ratio of the two phases.

[0022] The phase shifter may be designed, for example, with one or two stages. The phase shifter may be designed, for example, as a piezo phase shifter and / or an EOM phase shifter. For example, piezo phase shifters are used for large phase changes. For example, EOM phase shifters are used for small, rapid phase changes.

[0023] For example, a control signal for a phase shifter can be determined based on the phase or phase ratio, particularly by an electronic computing device, and the phase shifter can be controlled accordingly based on the control signal.

[0024] Due to the phase shift of the laser radiation by the phase shifter, the phase relationship between the laser radiation of the first amplification path and the laser radiation of the second amplification path can be adjusted relative to each other so that coherent superposition of the laser radiation can be achieved, which may also be called phase combining.

[0025] It may be advantageous if a particular amplification path comprises at least one means for shifting the phase of the laser radiation, the particular means being controllable as a function of the phase of the calibration laser light of the first amplification path and / or the phase of the calibration laser light of the second amplification path.

[0026] Adjusting the phase relationship between the laser radiation of the first amplification path and the laser radiation of the second amplification path to achieve coherent superposition can in this case be achieved by shifting the phase of the laser radiation of the first amplification path and the laser radiation of the second amplification path.

[0027] According to one embodiment, it is provided that the coupling-out element is arranged and designed to be able to couple at least a portion of the calibration laser radiation out of the amplification path before it leaves the amplification path in the direction of the target object. This may also be called near-field coupling-out or near-field coupling-out in the near field, or phase determination. Due to appropriate control of the phase shifter(s) as a function of the phase of the calibration laser light of the first amplification path and / or the calibration laser light of the second amplification path, coherent superposition at a nearby target object can be achieved by means of near-field phase determination.

[0028] According to one embodiment, it is provided that the coupling-out element is designed so that the calibration laser radiation reflected from the target object can be coupled out of the amplification path. This can also be called far-field coupling-out, or far-field coupling-out, or phase determination. Due to appropriate control of the phase shifter(s) as a function of the phase of the calibration laser light of the first amplification path and / or the calibration laser light of the second amplification path reflected from the target, coherent superposition at the distant target can be achieved by means of far-field phase determination.

[0029] At least a portion of the calibration laser radiation is directed by a specific amplification path, in particular via suitable optical means, for example a telescope, towards the target object, whereby due to reflection from the target object at least a portion of the calibration laser radiation returns to the amplification path, in particular via the telescope.

[0030] The reflected part of the calibration laser radiation is fed to the phase determination via a coupling element, in particular a wavelength-dependent coupling element.

[0031] When determining the phase in the far field, in addition to the phase changes already described in the device itself, there are also phase changes along the propagation path, especially in certain amplification paths, which are caused, for example, by turbulence. Along the optical axis, the calibration laser radiation is subject to the same, or at least nearly as, effects, especially turbulence-induced phase changes, refraction, etc., as the effective laser radiation. Therefore, the calibration laser radiation can also be used to determine phase relationships in the far field.

[0032] The determination of the phase relationship according to the present invention can be used to determine control parameters for achieving coherent superposition even before the effective laser source is switched on. In methods and apparatuses known from the prior art, the phase relationship, and therefore the control parameters, can only be determined when the effective laser is switched on and can then be corrected. When the effective laser is switched on, a luminous phenomenon may appear at the target due to the high intensity of the effective laser. This may also have a negative impact on the determination of the phase relationship and control parameters in methods and apparatuses known from the prior art. According to the present invention, far-field phase determination can be used to compensate for the effects on phase caused by turbulence, despite the luminous phenomenon at the target generated by the effective laser.

[0033] According to one embodiment, it is further provided that the particular beam path comprises at least one optical element, in particular a telescope and / or a tip / tilt mirror, for aligning the laser radiation on the target object.

[0034] In addition to or instead of the phase shifter, it is provided that the optical elements, in particular the telescope and / or the tip / tilt mirror, can be controlled as a function of the phase of the calibration laser light of the first amplification path and / or the calibration laser light of the second amplification path, in particular as a function of the ratio of the two phases, in particular to achieve coherent superposition of the effective laser radiation of the target object. In this connection, control signals for the telescope and / or the tip / tilt mirror can be determined, in particular by an electronic computing device, and the telescope and / or the tip / tilt mirror can be controlled accordingly based on the control signals.

[0035] The control signals for the telescope and / or tip / tilt mirror can additionally be determined as a function of the evaluation of the visual capture of the laser radiation of the target object. In this case, for example, a corresponding optical sensor, for example, a camera, is provided for capturing the laser radiation of the target object. The telescope and / or tip / tilt mirror of a particular amplification path can then be controlled, for example, so that the laser radiation is superimposed on a point on the target.

[0036] It is also possible that the or at least one amplification path comprises a coupling output element for near-field coupled output and a coupling output element for far-field coupled output.

[0037] It can also be provided that the coupling-out element is designed for both near-field and far-field coupling, e.g., such a coupling-out element can be switched between near-world and far-field coupling.

[0038] The laser beam device is advantageously designed to perform a calibration of the phase relationship between the wavelength λ1 of the useful laser light and the wavelength λ2 of the calibration laser light.

[0039] According to one embodiment, it is provided that the laser beam device comprises at least one beam combining device for combining the calibration laser radiation with the useful laser radiation, the beam combining device being arranged such that the combination takes place before the splitting and / or distribution of the active laser radiation and / or the calibration laser radiation into the at least two amplification paths.

[0040] According to one embodiment, it is provided that the laser beam device includes a modulation device for modulating the calibration laser radiation, in particular for modulating the amplitude. The amplitude modulation is performed, for example, in the form of a cw modulation or in the form of a pulse. Furthermore, the type of modulation can be changed, for example, as a function of the operating mode of the laser beam device. The modulation device is, for example, arranged in front of the beam combining device. The modulation device is, for example, controllable. The calibration laser radiation can be modulated without affecting the dynamics of the effective laser radiation.

[0041] The modulation device can be used, for example, in combination with a specific receiver, in particular a receiving method that can be used for phase determination and / or is part of the means for phase determination. Typical means, in particular receiving methods, are lock-in amplifiers, homodyne receivers or heterodyne receivers. In combination with modulation of the calibration laser radiation, the signal-to-noise ratio (SNR) can be improved and therefore the phase determination can be improved, for example, accelerated and / or made more precise.

[0042] Due to modulation of the calibration laser radiation, the signal to noise ratio can also be improved when determining phase relationships in the far field, for example by appropriately modulating the calibration laser radiation to reduce the effect of luminescence phenomena on the target object generated by the effective laser radiation on the calibration laser radiation.

[0043] A further embodiment relates to a method for operating a laser beam device according to the above embodiments, the method comprising at least the steps of generating calibration laser radiation, directing and / or splitting at least a portion of the generated calibration laser radiation into at least a first amplification path and at least a second amplification path, wherein in a specific amplification path at least a portion of the calibration laser radiation is coupled out by a wavelength-dependent output coupling element, determining a phase of the calibration laser light of the first amplification path and / or a phase of the calibration laser light of the second amplification path, and controlling at least one means for shifting the phase of the laser radiation as a function of the phase of the calibration laser light of the first amplification path and / or the phase of the calibration laser light of the second amplification path.

[0044] According to one embodiment, the method comprises emitting useful laser radiation, and provides that at least one means for shifting the phase of the laser radiation is controlled such that when emitting the useful laser radiation, coherent superposition of the useful laser radiation is achieved.

[0045] According to one embodiment, the laser beam device is at least temporarily operated so that only the calibration laser radiation is emitted. This is, for example, a configuration operation. In the configuration operation, no useful laser radiation is emitted, but only the calibration laser radiation is emitted. However, the means for shifting the phase of the laser radiation can already be controlled so that, when the useful laser source is switched on, a coherent superposition of the useful laser beams emitted by the amplification paths can be immediately achieved.

[0046] According to one embodiment, it is provided that the laser beam device is at least temporarily operated such that the calibration laser radiation and the useful laser radiation are emitted simultaneously, for example in normal operation as specifically intended, for example following the configuration operation.

[0047] According to one embodiment, the method includes modulating the calibration laser light. This is performed, for example, by a controllable modulation device. The calibration laser radiation can be advantageously modulated without affecting the dynamics of the effective laser radiation. The amplitude modulation is performed, for example, in the form of a cw modulation or in a pulsed form. The type of modulation can also be changed, for example, as a function of the operating mode. For example, the modulation is performed in pulses for length adjustment at the start of operation, for example during a configuration operation. For example, this modulation is then performed in the form of a cw modulation during operation, for example during normal operation.

[0048] Modulating the calibration laser light can be used in combination with a receiving method that can be used for phase determination, for example. Typical receiving methods are lock-in amplification, homodyne reception, or heterodyne reception. By combining with modulation of the calibration laser radiation, the signal-to-noise ratio (SNR) can be improved, and therefore the phase determination can be improved, for example, accelerated, and / or made more precise.

[0049] According to one embodiment, it is provided that the method comprises a step of calibrating the phase relationship between the wavelength λ1 of the effective laser light and the wavelength λ2 of the calibration laser light. Calibration, also called a calibration process, comprises checking and, if necessary, setting the phase relationship. This can be performed, for example, by a means or set of means for phase determination, for example, separately for a specific amplification path or jointly for two or more amplification paths.

[0050] To calibrate the phase relationship, a portion of the calibration laser radiation and a portion of the useful laser radiation are coupled out of the amplification path by a coupling output element.

[0051] The coupling-out element is, for example, a switchable wavelength-dependent coupling-out element, for example a beam splitter, which is switchable between a switching state in which only the calibration laser light is coupled out and a switching state in which the calibration laser light and the useful laser light are coupled out.

[0052] The combined output calibration and useful laser light are provided to a means for determining a phase relationship.

[0053] As a function of the ascertained phase relationship, a control signal for the particular phase shifter can be determined, particularly by an electronic computing device, and the particular phase shifter can be controlled accordingly based on the control signal. As a result, the phase relationship between the wavelengths λ1 and λ2 of the effective laser light can be appropriately set for the particular amplification path. Advantageously, the phase relationship is set so that the wavelengths λ1 of the effective laser light of all amplification paths are coherently superimposed.

[0054] It can be provided that the calibration is performed at the start of the method of operating the laser beam device.

[0055] Advantageously, it is provided that the calibration is performed repeatedly during the execution of the method for operating a laser beam device. The calibration can be repeated, for example, at specified time intervals. It is also possible to provide for the calibration to be repeated after a certain number of wavelength shifts have been performed.

[0056] An acceptable phase error can be specified, for example <λ1 / 10. The phase difference Δ is determined by Δ=|n*λ1-n*λ2| depending on the functions λ1 and λ2, so that the acceptable number of wavelength shifts n depending on the direction can be determined. If the acceptable number of wavelength shifts n is reached or exceeded, the calibration is performed again.

[0057] During the calibration process, it may be advantageous to reduce the effective laser light power.

[0058] Further advantages can be seen in the description and the accompanying drawings. Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description, where the same reference signs in different drawings indicate the same or at least functionally equivalent elements. In the description of an individual drawing, reference can also be made to elements from other drawings. [Brief explanation of the drawings]

[0059] [Figure 1] FIG. 1 shows a laser beam device according to the first embodiment. [Figure 2] FIG. 2 shows a laser beam device according to a further embodiment. [Figure 3] FIG. 3 illustrates a method of operating the laser beam device described in FIGS. [Figure 4] FIG. 4 shows a laser beam device according to a further embodiment. [Figure 5] FIG. 5 shows a laser beam device according to a further embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0060] 1 shows a laser beam device, generally designated by the reference numeral 10. The laser beam device 10 is designed and operable to project laser radiation, particularly effective laser radiation, onto a target object (not shown), particularly a distant target object, for example at a distance of between 10 m, particularly 50 m, to 1000 m or more. The laser beam device may be, for example, a laser weapon or laser weapon system.

[0061] Laser weapons or laser weapon systems are used, for example, to protect objects, whether moving or stationary. A laser weapon or laser weapon system can include one or more HEL (High Energy Laser) effectors. Multiple HEL effectors can be aligned with a target object or with multiple target objects simultaneously.

[0062] These can include static target objects such as landmines, IEDs (improvised explosive devices), etc., but can also include dynamic targets such as rockets, artillery shells, or RAM rounds. These targets are then blown up and / or destroyed as part of countering the threat. Small targets in particular (low speed, slow & small = LSS targets) are easily destroyed or blown away by such weapon systems. LSS targets also include so-called UAVs (unmanned aerial vehicles), such as drones, which are often mistakenly used to deliver explosives.

[0063] The main components of a HEL effector include a laser source and a beam guidance system. The beam guidance system can house subassemblies such as a fine imaging system (FIS), a fine tracking system (FTS), a telescope, and, if necessary, at least one adaptive optics system (AO). Known laser sources are gas lasers, such as CO2 lasers, and solid-state lasers, such as diode lasers and fiber lasers.

[0064] HEL effectors, like other weapon systems, can be mounted on fixed or mobile platforms. In this regard, weapon stations are also called platforms. These platforms, in turn, can be attached to stationary objects (e.g., houses, bunkers, containers, etc.) or mobile objects (e.g., land, air, and sea vehicles, containers, etc.).

[0065] Aiming a high-energy laser beam at a target in a military environment is a major technical challenge. This involves the transmission of high laser power (high laser density) through optical systems such as mirrors and lenses. Also, focusing on a moving target, for example with a telescope, places high demands on tracking accuracy or target tracking. A further problem is compensating for atmospheric turbulence. Furthermore, high environmental stresses, such as shock, vibration, temperature, and EMC, on the entire transmission system, along with tracking the impact on the target in real time, present a variety of complex tasks to those skilled in the art.

[0066] The present invention addresses the problem of achieving coherent superposition of useful laser beams emitted by different amplification paths.

[0067] The laser beam device 10 includes an effective laser source 12 for generating effective laser radiation. The effective laser radiation is indicated in Figure 1 by a dotted line and λ1. The effective laser radiation has a wavelength of, for example, λ1 = 1040 nm. The effective laser source 12 is a high-power laser.

[0068] According to the embodiment shown, the useful laser radiation generated by the useful laser source 12 is directed and / or split by the beam distribution and / or beam splitting device 14 at least partially into a first amplification path 16-1 and at least partially into a second amplification path 16-2. The representation in the figure is merely exemplary. For example, it may be advantageous to use more than two amplification paths, for example between 2 and 10, or even 20 or more amplification paths.

[0069] The particular amplification path 16-1, 16-2 includes an amplifier 18 for amplifying the useful laser radiation, the amplifier 18 providing wavelength-dependent amplification, for example, depending on the wavelength λ1.

[0070] Advantageously, the laser beam device 10 is designed and operable so that the target object is at least temporarily irradiated simultaneously with the effective laser beam emerging from the first amplification path 16-1 and the effective laser beam emerging from the second amplification path 16-2.

[0071] Also, the laser beam device 10 may include more than two amplification paths 16-1, 16-2.

[0072] In order to illuminate the target object as efficiently as possible, a coherent superposition of the effective laser beams emitted by the amplification paths 16-1, 16-2 is to be achieved, as will be explained below.

[0073] According to this embodiment, a laser light device 10 is provided that includes a calibration laser source 20 for generating calibration laser radiation. The calibration laser source 20 and the effective laser source 12 are designed so that the wavelength λ2 of the calibration laser radiation is different from the wavelength λ1 of the effective laser radiation. The calibration laser radiation is shown in FIG. 1 as a solid line and is designated λ2. The wavelength of the calibration laser radiation λ2 can be greater or less than λ1. λ2 is preferably outside the amplifier bandwidth of the particular laser system, e.g., λ1 1040 nm amplifier, λ2 < 1030 nm, or λ1 1085 nm amplifier, λ2 > 1090 nm.

[0074] According to this embodiment, it is provided that the laser beam arrangement 10 comprises at least one beam combining device 22 for combining the calibration laser radiation and the useful laser radiation, the beam combining device 22 being arranged such that the combining is performed before the splitting and / or distribution of the combined active and / or calibration laser radiation into the at least two amplification paths 16-1, 16-2.

[0075] The combination of active laser and / or calibration laser radiation is shown in FIG. 1 by the dotted line and λ1+λ2.

[0076] Finally, the beam distribution and / or beam splitting device 14 distributes the combined active and / or calibration laser radiation, and thus at least a portion of the calibration laser radiation generated by the calibration laser source, in each case into the first amplification path 16-1 and the second amplification path 16-2.

[0077] This calibration laser radiation experiences no or relatively low amplification by the amplifier device 18, since it is amplified on a wavelength-dependent basis, for example as a function of wavelength λ 1 .

[0078] According to an embodiment, it is provided that the particular amplification path 16-1, 16-2 comprises a wavelength-dependent coupling-out element 24 for coupling out at least a portion of the calibration laser light.

[0079] According to the embodiment shown in FIG. 1, the coupling output element 24, also designated 24-1, is positioned and designed so that at least a portion of the calibration laser radiation can be coupled out of a particular amplification path 16-1, 16-2 before exiting the amplification path in the direction of the target object.

[0080] This is sometimes called coupling out in the near field or near-field coupling out, especially for phase determination in the near field.

[0081] The laser beam device 10 includes a means 26 for determining the phase of the calibration laser light of the first amplification path 16-1 and / or the phase of the calibration laser light of the second amplification path 16-2. According to the illustrated embodiment, both calibration laser radiations coupled from the first amplification paths 16-1, 16-2 are supplied to the means 26 for phase determination. For example, the phase is checked against a reference value. As the reference value, for example, a reference signal from the output of the element labeled 14 or 30 is supplied to the means 26 for phase determination.

[0082] Alternatively, a common means 26' for comparing the dotted boundaries of Figures 1 and 2 can be used for phase determination, and accordingly, for example, the ratio between the phase of the calibration laser radiation coupled from the first amplification path 16-1 and the phase of the calibration laser radiation coupled from the second amplification path 16-2 can be determined.

[0083] According to the embodiment shown, the particular amplification path 16-1, 16-2 is provided with means 28 for shifting the phase of the laser radiation. The means 28 for shifting the phase of the laser radiation is a phase shifter.

[0084] The phase shifter 28 can be controlled as a function of the phase of the calibration laser light in the first amplification path 16-1 and / or as a function of the phase of the calibration laser light in the second amplification path 16-2. For example, the phase shifter 28 in the first amplification path 16-1 can be controlled as a function of the phase of the calibration laser light in the first amplification path 16-1, and the phase shifter 28 in the second amplification path 16-2 can be controlled as a function of the phase of the calibration laser light in the second amplification path 16-2.

[0085] For example, a control signal for a particular phase shifter can be determined, particularly by an electronic computing device, based on the phase or phase ratio, and the particular phase shifter can be controlled accordingly based on the control signal. The computing device for determining the control signal is not explicitly shown in FIG.

[0086] By modulating the phase of the laser radiation by the phase shifter 28, the phase relationship between the laser radiation of the first amplification path 16-1 and the laser radiation of the second amplification path 16-2 can be adjusted relative to each other so that coherent superposition of the laser radiation can be achieved. This can also be referred to as phase combining. According to the embodiment shown in FIG. 1, coherent superposition at a nearby target can be achieved by near-field phase determination.

[0087] According to this embodiment, it is provided that the laser light device 10 comprises a modulator 30 for modulating the calibration laser light, in particular for modulating the amplitude of the calibration laser light. The modulator 30 is, for example, arranged before the beam combining device. The modulator 30 is, for example, controllable. The calibration laser radiation can be modulated without affecting the dynamics of the effective laser radiation. In combination with modulation of the calibration laser radiation, the signal-to-noise ratio (SNR) can be improved and therefore the phase determination can be improved, for example, accelerated and / or made more precise.

[0088] FIG. 2 shows a further embodiment of the laser beam device 10 .

[0089] According to the embodiment shown, it is provided that a coupling-out element 24, also indicated as 24-2, is designed so that the calibration laser radiation reflected by the target object can be coupled out of the specific amplification path 16-1, 16-2, which may also be called far-field coupling-out or far-field coupling-out, in particular for phase determination in the far field.

[0090] At least a portion of the calibration laser radiation is directed towards the target object by a particular amplification path 16-1, 16-2, in particular via suitable optical means, such as a telescope 32 and / or a tip / tilt mirror 34. Due to reflection from the target object, at least a portion of the calibration laser radiation returns to the particular amplification path 16-1, 16-2, in particular via the telescope 32.

[0091] The reflected portion of the calibration laser radiation is fed to a phase determination 26 via a coupling output element 24, 24-2, in particular via a wavelength-dependent coupling output element 24, 24-2.

[0092] Along the optical axis, the calibration laser radiation experiences the same, or at least approximately the same, effects, e.g., phase changes, refraction, as the useful laser radiation, and therefore can also be used to determine phase relationships in the far field.

[0093] Due to appropriate control of the phase shifter 28 as a function of the phase of the calibration laser light of the first amplification path 16-1 and / or the calibration laser light of the second amplification path 16-2, coherent superposition at the distant target can be achieved by means of phase determination in the far field.

[0094] In addition to or as an alternative to the phase shifter 28, optical elements, in particular the telescope 32 and / or the tip / tilt mirror 34, can be controlled as a function of the phase of the calibration laser light in the first amplification path 16-1 and / or the calibration laser light in the second amplification path 16-2, in particular as a function of the ratio of the two phases, in particular to achieve coherent superposition of the effective laser radiation of the target object.

[0095] An exemplary method 300 of operating the laser beam device 10 will now be described with reference to FIG.

[0096] In the method 300, the step 310 of generating and emitting calibration laser radiation comprises a step 320 of directing and / or splitting at least a portion of the calibration laser radiation generated, in particular by the calibration laser source 20, into at least one first amplification path 16-1 and at least one second amplification path 16-2, in particular by a beam directing and / or beam splitting device 14, and coupling at least a portion of the calibration laser radiation from a particular amplification path 16-1, 16-2, in particular by a wavelength-dependent output coupling element; a step 330 of determining the phase of the calibration laser light in said first amplification path 16-1 and / or said second amplification path 16-2; and a step 340 of controlling at least one means 28 for shifting the phase of the laser radiation in dependence on the phase of the calibration laser light in the first amplification path 16-1 and / or the phase of the calibration laser light in the second amplification path 16-2. Step 340 may alternatively or additionally include control of optical elements, particularly telescope 32 and / or tip / tilt mirror 34, particularly alignment of these elements in addition to or instead of phase shifter 28. In this connection, control signals for phase shifter 28 and / or telescope 32 and / or tip / tilt mirror 34 are determined, particularly by an electronic computing device, and phase shifter 28 and / or telescope 32 and / or tip / tilt mirror 34 are controlled accordingly based on the control signals.

[0097] The method 300 may further comprise a step 350 of emitting useful laser radiation, in particular by the effective laser source 12. In step 340, the at least one means 28 for shifting the phase of the laser radiation is advantageously controlled such that, when emitting the useful laser radiation 350, a coherent superposition of the useful laser beams emitted by the at least two amplification paths 16-1, 16-2 is achieved.

[0098] According to one embodiment, it is provided that the laser beam device 10 is at least temporarily operated so that only calibration laser radiation is emitted. This is, for example, configuration operation 300a. In configuration operation 300a, no useful laser radiation is emitted and only calibration laser radiation is emitted. Configuration operation 300a includes, for example, steps 310, 320, 330, and 340.

[0099] However, according to step 340, the means 28 for shifting the phase of the laser radiation can already be controlled so that subsequent switching on of the effective laser source 12 immediately achieves coherent superposition of the effective laser beams emitted by the at least two amplification paths 16-1, 16-2.

[0100] According to one embodiment, the laser beam device 10 is at least temporarily operated such that the calibration laser radiation and the useful laser radiation are emitted simultaneously. This is particularly intended, for example, during normal operation 300b. For example, normal operation 300b follows configuration operation 300a. During normal operation 300b, for example, steps 310, 320, 330, 340, and 350 are performed.

[0101] According to one embodiment, the method includes modulating the calibration laser light 360. For example, step 360 may be performed during both configuration operation 300a and normal operation 300b.

[0102] The order of steps shown is exemplary, and steps may be performed in a different order and / or at least partially in parallel.

[0103] According to one embodiment, it is provided that the laser device 10 is designed to perform a calibration process.

[0104] Thus, the method 300 may include performing a calibration process, which is illustrated in the example as step 370.

[0105] The calibration process can be performed repeatedly at start-up and during operation of the laser device.

[0106] The calibration will be explained with reference to, for example, FIGS.

[0107] The calibration process involves calibrating the phase relationship between the wavelength λ1 of the effective laser light and the wavelength λ2 of the calibration laser light. Calibration involves checking and, if necessary, setting the phase relationship.

[0108] To calibrate the phase relationship, a portion of the calibration laser radiation and a portion of the useful laser radiation are coupled out of the amplification path by a coupling-out element, e.g., wavelength-dependent coupling-out elements 24, 24-1, 24-2. The coupling-out elements 24, 24-1, 24-2 are, e.g., switchable wavelength-dependent coupling-out elements. For example, the coupling-out elements are switchable between a switching state in which only the calibration laser light is coupled out and a switching state in which the calibration laser light and the useful laser light are coupled out.

[0109] To ascertain the phase relationship, the calibration laser light and the useful laser light are combined from a particular amplification path and fed to a means 26, 26' or set of means for phase determination 26. Ascertaining the phase relationship between the calibration laser light and the useful laser light can be performed, for example, separately for a particular amplification path or jointly for two or more amplification paths.

[0110] As a function of the ascertained phase relationship, a control signal for the particular phase shifter 28 can be determined, particularly by an electronic computing device, and the particular phase shifter 28 can be controlled accordingly based on the control signal. As a result, the phase relationship between the wavelengths λ1 and λ2 of the useful laser light can be appropriately set for a particular amplification path. Advantageously, the phase relationship is set so that the wavelengths λ1 of the useful laser light of all amplification paths are coherently superimposed.

[0111] It can be provided that the calibration is performed at the start of the method of operating the laser beam device.

[0112] Advantageously, it is provided that the calibration is performed repeatedly during the execution of the method for operating a laser beam device. The calibration can be repeated, for example, at specified time intervals. It can also be provided that the calibration is repeated after a certain number of wavelength shifts have been performed.

[0113] An acceptable phase error can be specified, for example <λ1 / 10. The phase difference Δ is determined by Δ=|n*λ1-n*λ2| depending on the functions λ1 and λ2, so that the acceptable number of wavelength shifts n depending on the direction can be determined. If the acceptable number of wavelength shifts n is reached or exceeded, the calibration can be performed again.

[0114] During the calibration process, it may be advantageous to reduce the effective laser light power.

Claims

1. A laser beam device (10) for irradiating useful laser radiation, said laser beam device (10) comprising a beam directing and / or beam splitting device (14) for directing and / or splitting at least a portion of useful laser radiation generated by an useful laser source (12) into at least one first amplification path (16-1) and at least one second amplification path (16-2), each of said amplification paths (16-1, 16-2) comprising an amplification device (18) for amplifying the useful laser radiation, said laser beam device (10) being designed to irradiate a target object at least temporarily simultaneously with the useful laser beam emerging from the first amplification path (16-1) and the useful laser beam emerging from the second amplification path (16-2), said laser beam device (10) comprising a calibration laser source for generating calibration laser radiation, said calibration laser radiation having a wavelength (λ ２ ) is the wavelength of the effective laser radiation (λ １ ), and the laser beam device (10) is designed so that at least a portion of the calibration laser radiation generated by the calibration laser source (20) can be split and / or distributed into a first amplification path and a second amplification path (16-1, 16-2) by a beam distribution and / or beam splitting device (14), and certain amplification paths (16-1, 16-2) include wavelength-dependent coupling output elements (24, 24-1, 24-2) for coupling at least a portion of the calibration laser light, and the laser beam device (10) 1. A laser beam device (10) comprising means (26) for determining the phase of calibration laser light of the first amplification path (16-1) and / or the phase of calibration laser light of the second amplification path (16-2), wherein at least one amplification path (16-1) comprises at least one means (28) for shifting the phase of the laser radiation, said at least one means (28) for shifting the phase being controllable as a function of the phase of the calibration laser light of the first amplification path (16-1) and / or the phase of the calibration laser light of the second amplification path (16-2).

2. 2. The laser beam device (10) according to claim 1, wherein a particular amplification path (16-1, 16-2) comprises at least one means (28) for shifting the phase of the laser radiation, the particular means (28) being controllable as a function of the phase of the calibration laser light of the first amplification path (16-1) and / or the phase of the calibration laser light of the second amplification path (16-2).

3. 3. The laser beam device (10) according to claim 1 or 2, wherein the at least one means (28) for shifting the phase of the laser radiation is or comprises a modulation device, in particular an electro-optical modulation device for modulating a phase, in particular an EOM for modulating a phase.

4. 4. The laser beam device (10) according to claim 1, wherein the coupling output element (24, 24-1) is designed and arranged such that at least a portion of the calibration laser radiation can be coupled out of the amplification path (16-1, 16-2) before it exits the amplification path (16-1, 16-2) in the direction of the target object.

5. 5. The laser beam device (10) according to claim 1, wherein the coupling output element (24, 24-2) is designed so that calibration laser radiation reflected by a target object can be coupled out of the amplification path (16-1, 16-2).

6. 6. The laser beam device (10) according to claim 1, wherein a particular amplification path (16-1, 16-2) comprises at least one optical element, in particular a telescope (32) and / or a tip / tilt mirror (34), for aligning the laser radiation on a target object.

7. 7. The laser beam device (10) according to claim 1, further comprising at least one beam combining device (22) for combining the calibration laser radiation with the useful laser radiation, the beam combining device (22) being arranged such that the combining takes place before the splitting and / or distribution of the active and / or calibration laser radiation into the at least two amplification paths (16-1, 16-2).

8. 8. The laser beam device (10) according to any one of claims 1 to 7, wherein the laser beam device (10) comprises a modulation device (30) for modulating, in particular amplitude modulating, the calibration laser light.

9. A method (300) of operating a laser beam device (10) according to any one of claims 1 to 8, comprising the steps of: In a particular amplification path, at least a portion of the calibration laser radiation is coupled out (320) by a wavelength-dependent coupling element, generating, distributing, and / or splitting (310) at least a portion of the generated calibration laser radiation into at least a first amplification path and at least a second amplification path; determining (330) a phase of the calibration laser light of the first amplification path and / or a phase of the calibration laser light of the second amplification path and controlling (340) at least one means for modulating laser radiation in response to the phase of the calibration laser light of the first amplification path and / or the phase of the calibration laser light of the second amplification path; A method (300) comprising at least:

10. 10. The method (300) of claim 9, wherein the method (300) includes emitting effective laser radiation, and wherein at least one means (28) for shifting the phase of the effective laser radiation is controlled such that coherent superposition of the effective laser radiation is achieved when emitting the effective laser radiation.

11. 10. The method (300) according to claim 8 or 9, wherein the laser beam device (10) is at least temporarily in operation so that only calibration laser radiation is emitted (300a).

12. 12. The method (300) of any one of claims 8 to 11, wherein the laser beam device (10) is at least temporarily operated (300b) such that calibration laser radiation and useful laser radiation are emitted simultaneously.

13. 13. The method (300) of any one of claims 8 to 12, comprising modulating (360) the calibration laser light.

14. 14. The method (300) of claim 13, wherein modulating comprises modulating amplitude, said modulation being performed by cw modulation and / or pulse forming.

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