METHOD AND SYSTEM FOR MEASURING THE INFLUENCE OF TURBULENT DISTURBANCES ON LASER IRRADIATION OF A NON-COOPERATIVE TARGET WHILE PASSING THROUGH A TURBULENT ATMOSPHERE

Abstract

A method for measuring the influence of turbulent disturbances on laser irradiation of a target as it passes through a turbulent atmosphere comprises focusing a measuring laser beam onto the target with an optical device; collimating a reflected laser beam, which is reflected back from the target due to irradiation with the measuring laser beam and received by the optical device, in a sensor plane of a sensor device; repeatedly measuring a spatially dependent gradient field of a wavefront of the collimated reflected laser beam in the sensor plane in a number of individual measurements, wherein the measuring laser beam is adjusted after each individual measurement such that the individual measurements are statistically independent of each other;and averaging the measured gradient field over the number of individual measurements to estimate a turbulence disturbance of the measuring laser beam, whereby a corresponding turbulence-disturbed wavefront is reconstructed from the averaged gradient field using digital signal processing.

Description

[0001] The present invention relates to a method and a system for measuring the influence of turbulent disturbances on laser irradiation of a target while passing through a turbulent atmosphere.

[0002] The effect of a high-energy laser weapon (HEL weapon) on a target is determined not only by the laser power but also significantly by the spot diameter and intensity of the laser beam on the target. Air turbulence can considerably increase the spot diameter of the laser beam on the target, which can fundamentally affect the laser beam's impact on the target. For example, in such a case, it may become necessary to increase the exposure time to achieve a comparable effect to that achieved with negligible turbulence.

[0003] The effects of turbulence on a laser beam can be broadly divided into two components: the so-called tip / tilt component, which describes a turbulence-induced movement of the laser spot's center of gravity, and the component of so-called higher-order turbulence (hereafter abbreviated as hO turbulence), which can lead to smearing and / or broadening of the laser spot. Measuring and compensating for the movement of the laser spot's center of gravity is typically manageable with suitable methods, so that movement of the laser spot's center of gravity on the target can usually be sufficiently prevented.

[0004] To further reduce the effects of turbulence hO on the spot diameter, adaptive optics could, in principle, be used, drawing on techniques from astronomy or optical telecommunications. For example, the turbulence could be determined directly or indirectly, and the output beam could then be pre-distorted with a conjugate (inverted) wavefront to compensate for the turbulent disturbances during beam propagation to the target as much as possible.

[0005] One approach would be to directly measure the turbulent wavefront. For example, if a point light source were placed on the target, this point light source could be imaged onto a suitable wavefront sensor, such as a Hartmann-Shack sensor. Subsequently, compensation could be implemented using a mechanically movable and deformable mirror.

[0006] On the other hand, a direct measurement could be avoided by determining a quality factor for the turbulence-disturbed spot, e.g., the spot's intensity, and adjusting the focused laser's wavefront until an optimum quality factor, and thus indirectly a compensating conjugate wavefront, is found. In this case, the technologically complex and potentially dynamically limited mirror approach could be dispensed with. However, for such a method, the target would need to be equipped with a retroreflector, for example, to obtain a clear quality factor.

[0007] For the methods described above, the targets therefore require either an actively radiating point source and / or an additional element for quality measurement, e.g., a retroreflector. Since targets engaged with a HEL weapon generally do not possess these elements, the application of these methods appears rather difficult. Such targets are therefore referred to below as non-cooperative targets.

[0008] A key difference in the application of turbulence compensation methods in HEL weapon systems, compared to known and implemented applications in astronomy and laser-based communication, lies in the fact that neither a natural measure of quality for the beam diameter on the target nor an ideal point source, as in astronomy, is available. If a spot is generated on the target using a measuring laser and / or the high-energy laser, the result is not a point source, but rather a spot with finite dimensions influenced by diffraction and turbulence, which is reflected by the generally rough surface of the target. Consequently, in addition to the turbulent wavefront disturbances to be measured, so-called speckle effects can occur during backpropagation, leading to additional non-turbulence-induced wavefront errors in a collimated receiving plane of the HEL weapon.The finite spot size and the speckle effects caused by the target roughness thus have an influence on wavefront measurement of the turbulence, which makes classical measurement methods, e.g. based on a Hartmann-Shack sensor, inaccurate.

[0009] It should be noted that luminescence phenomena, referred to below as process luminescence, can occur due to the interaction of the laser beam with the target material. The intensity of this luminescence can influence wavefront sensor measurements and the determination of quality factors to a greater or lesser degree. Furthermore, the surface of the target can be altered by the high-energy laser beam, which in turn can affect its reflectivity for wavefront sensor measurements and quality factor determination. These aspects must be considered when comparing different wavefront measurement methods.

[0010] German patent application DE 10 2021 001 067 B4 describes a method for precisely measuring and correcting turbulence hO and its amplitude distribution in a receiving plane, even when wavefront errors are present due to a finite spot size combined with a rough target surface. To achieve this, a spatially dependent phase and, if applicable, a spatially dependent amplitude of a measuring laser beam reflected from the target are repeatedly measured in a number of individual measurements. After each measurement, the measuring laser beam is adjusted to ensure statistical independence. The measured spatially dependent phases and, if applicable, spatially dependent amplitudes are then averaged over the number of individual measurements to estimate the turbulence disturbance of the measuring laser beam.The effects of the rough target surface average out because the reflection of the extended spot off the rough target surface causes a stochastic change in the wavefront of the reflected beam. The resulting estimate of the turbulence disturbance can then be used for turbulence suppression methods.

[0011] Against this background, the present invention aims to find solutions for the precise measurement and, if necessary, correction of turbulence in laser weapons, which can be implemented with the simplest possible measurement setup.

[0012] According to the invention, this problem is solved by a method having the features of claim 1 and by a system having the features of claim 7.

[0013] Accordingly, a method is provided for measuring the influence of turbulent disturbances on laser irradiation of a target as it passes through a turbulent atmosphere.The method comprises focusing a measuring laser beam onto the target with an optical device; collimating a reflected laser beam, which is reflected back from the target due to irradiation with the measuring laser beam and received by the optical device, in a sensor plane of a sensor device; repeatedly measuring a spatially dependent gradient field of a wavefront of the collimated reflected laser beam in the sensor plane in a number of individual measurements, wherein the measuring laser beam is adjusted after each individual measurement such that the individual measurements are statistically independent of each other; and averaging the measured gradient field over the number of individual measurements to estimate a turbulence disturbance of the measuring laser beam, wherein an associated turbulence-disturbed wavefront is reconstructed from the averaged gradient field by means of digital signal processing.

[0014] Furthermore, a system for measuring the influence of turbulent disturbances on laser irradiation of a target as it passes through a turbulent atmosphere is provided. The system comprises a laser device configured to generate a measurement laser beam; an optical device configured to focus the measurement laser beam onto the target, to receive a laser beam reflected back from the target due to irradiation with the measurement laser beam, and to collimate the reflected laser beam in a sensor plane; a sensor device configured to repeatedly measure a spatially dependent gradient field of a wavefront of the collimated reflected laser beam in the sensor plane in a number of individual measurements, wherein the measurement laser beam is adjusted after each individual measurement such that the individual measurements are statistically independent of one another.and a computational device which is designed to average the measured gradient field over the number of individual measurements and, based on this, to estimate a turbulence disturbance of the measuring laser beam, whereby a corresponding turbulence-disturbed wavefront is reconstructed from the averaged gradient field by means of digital signal processing.

[0015] One of the underlying ideas of the present invention is to precisely measure and, if necessary, correct the turbulence hO in the receiving plane despite wavefront errors caused by the rough target surface, by eliminating possible influences of the target surface through suitable averaging of a number N of measurement results. In particular, the invention provides an approach whose measurement result is not influenced by turbulence-induced spot broadening and the rough target surface.

[0016] The conceptual starting point here is the phase and amplitude / intensity averaging method of DE 10 2021 001 067 B4 (hereinafter referred to as PIMV). In the method described therein, a wavefront of the turbulently disturbed beam reflected from the target is measured directly in each of N individual measurements based on the associated spatially dependent phases and, if applicable, amplitudes. In contrast, the present method measures the gradient field of the wavefront, i.e., the spatial derivative of the wavefronts, and thus the differential wavefront, N times. Subsequently, an averaged gradient field is determined from which the corresponding, turbulence-disturbed wavefront can be reconstructed using known digital signal processing techniques (therefore, the present method is abbreviated as dPIMV in the following).Just as in the method of DE 10 2021 001 067 B4, the influence of the rough surface of the target becomes apparent during averaging. The reconstructed wavefront can be used as a measurement of turbulence and passed on to a turbulence compensation system.

[0017] This modified approach offers the significant advantage that the system can be implemented with a considerably simpler setup. Direct measurement of the disturbed turbulent wavefront for PIMV requires heterodyne or interferometric receiving sensors. These necessitate a very complex optical setup, place high demands on the measuring laser, and hardening them for military applications is technically very challenging. In contrast, the optical setup for the present dPIMV is significantly simpler to implement, for example, using a standard Hartmann-Shack sensor as the sensor device in combination with a fast tip-tilt mirror to adapt the measuring laser beam. While the reconstruction of the turbulent wavefront from the averaged gradient field is complex, it can be performed using digital signal processing and is readily achievable in real time with known methods from the state of the art.Examples of such procedures include: - C. Schulze et al., “Wavefront reconstruction by modal decomposition,” - G. Dai, “Modal wave-front reconstruction with Zernike polynomials and Karhunen-Loève functions,” - RC Cannon, “Global wave-front reconstruction using Shack-Hartmann sensors,” - KL Baker, “Least-squares wave-front reconstruction of Shack-Hartmann sensors and shearing interferometers using multigrid techniques”.

[0018] It is also worth noting that the Doppler effect must be taken into account when implementing PIMV with heterodyne methods. This effect is not relevant for the dPIMV used here. Further advantages of dPIMV include its ease of integration into null-controlling turbulence suppression methods and the absence of the "unwrapping problems" encountered with PIMV.

[0019] The present method, like PIMV, is based on the premise that the spot of the measuring laser on the target (without turbulence compensation) is generally significantly larger compared to a diffraction-limited image. If this broadened spot is reflected from the rough target surface, a stochastic change in the wavefront of the back-reflected beam occurs. In the receiver, the back-reflected beam is re-collimated. Using a suitable method, the gradient field of the wavefront, i.e., the differential wavefront, of the back-reflected collimated beam can be measured in the sensor plane or the collimated receiver plane. This wavefront no longer corresponds to the desired turbulence distribution as it would be generated by a point light source, but is superimposed with a disturbance caused by the rough surface.

[0020] To determine the turbulence pattern, the present approach involves performing N consecutive measurements. For each measurement, the spatial derivative of the wavefront of the collimated receiving field is determined. It is assumed that the turbulence is approximately constant during the measurement time of the N sub-measurements, and that the reflection from the rough surface of the target is approximately constant during a single measurement. Furthermore, it is assumed that the reflection of the measuring laser occurs on a surface whose roughness is greater than the wavelength of the measuring laser, and that the N sub-measurements are statistically independent. The latter can be achieved, for example, by appropriately modifying the measuring laser spot on the target after each measurement, e.g., by shifting it within the isoplanatic angle N such that the statistical distribution of the surface roughness results in statistically independent measurements.If the N measurements are averaged, the wavefront reconstructed from the averaged gradient field converges to the desired wavefront hO.

[0021] In this context, the term wavefront refers to the position-dependent phase distribution of the optical field that a point source would generate on the target as it passes through a turbulent atmosphere in the collimated receiving plane. The higher-order wavefront (hO wavefront) thus describes the portion of the wavefront excluding the linear phase component (i.e., the tip-tilt component). It is further assumed that the tip-tilt component of the turbulence is already compensated for by other factors, meaning the laser spot on the target no longer exhibits any center-of-mass migration.

[0022] To measure the time-varying wavefront hO, the following measurement sequence can be repeated periodically, whereby the period is significantly shorter than the time of change of the wavefront: Within one period, N individual measurements are performed. The number N is chosen such that a desired measurement accuracy for the wavefront hO is achieved. An individual measurement can proceed approximately as follows: ▪ The measuring laser is focused onto the target surface using an optical element (e.g. a lens and / or a telescope). ▪ The laser beam reflected from the rough target surface is received and collimated by the same optical element. ▪ The reflected collimated receiving beam is separated from the transmitting beam by a suitable optical element (e.g. a beam splitter or a polarization beam splitter). ▪ The gradient field of the wavefront of the collimated receiving beam is determined with a suitable evaluation sensor, whereby the measured gradient field can be stored for further processing. After a single measurement is completed, the emitted beam of the measuring laser is modified by an optical device to allow for a further statistically independent measurement. This can be achieved, for example, by a tip / tilt shift, which moves the laser spot of the measuring laser on the target. However, other methods, such as distortion of the emitted beam, are also conceivable. New individual measurements will be taken until N measurements have been reached. To estimate the wavefront hO, the measured, location-dependent gradient fields from N individual measurements are averaged, and the turbulent wavefront is reconstructed from the averaged profile using suitable digital methods. The result is an estimate of the wavefront hO. - The estimation of the wavefront hO can then be used for turbulence suppression methods. - After the period has elapsed, the measurement process can begin again.

[0023] In order to implement the present dPlMV approach in practice, the expert can ensure the following assumptions or prerequisites, depending on the application: - A laser with good beam quality could be considered as a measuring laser, for example. - The time constant for the change of the wavefront hO to be measured should be significantly larger than the measurement time for the N individual measurements, i.e. the measurement rate should be significantly larger than the change frequency of the turbulence (Greenwood frequency). - The roughness of the target surface should be greater than the wavelength used. - During a single measurement, the reflections on the rough target surface should be approximately constant. - The travel time of the light should be taken into account when timing the process. - The distance between the described device and the target should be known, e.g. by separate measurement. - The generated measurement laser spots should remain within the isoplanatic angle of the wavefront to be measured hO.

[0024] Estimating the wavefront hO can be used, in particular, to implement turbulence-suppressing methods for one or more laser beams. For example, turbulence can be compensated for in a measurement laser beam. This can reduce measurement inaccuracies due to scintillation effects, for instance, by adjusting the amplitude profile accordingly. It is also possible to compensate for turbulence in a projectile beam, such as that of a laser weapon or in other applications. The described approach could also be applied in other technical fields, such as ophthalmic measurement, optical telecommunications, and imaging techniques under strong turbulence.

[0025] Advantageous designs and further developments result from the additional sub-claims as well as from the description with reference to the figures.

[0026] According to further training, the measuring laser beam can be moved and / or distorted after each individual measurement on the target in order to make the individual measurements statistically independent of each other.

[0027] For example, a tip-tilt device can be used to shift the beam(s) within the isoplanatic angle N times on the target surface. Alternatively or additionally, further modifications of the measuring laser beam are possible, leading to statistically independent measurements. For instance, the measuring laser beam can be suitably distorted by phase changes.

[0028] According to further training, a Hartmann-Shack sensor can be used as a sensor device.

[0029] The sensor system can therefore be implemented cost-effectively using known, simple standard solutions.

[0030] According to further training, the measuring laser beam can be operated in pulsed mode.

[0031] Specifically in this advanced training, the present method avoids difficulties with backscattering and process luminescence. Since the optical transmit and receive channels are preferably identical for both PIMV and dPIMV for reasons of implementation and accuracy, they result in small backscatters in the optical setup for the measuring laser, which are fed back into the receive channel and can interfere with the received signal. This can be easily circumvented by using pulsed measuring lasers and gating the receiving sensor. Another advantage of a gated sensor, e.g., a Hartmann-Shack sensor, is the ability to suppress process luminescence, which can occur due to laser-material interaction of a high-energy laser. Although pulsed operation to suppress backscattering and process luminescence also seems conceivable for PIMV, the necessary optical setup and the requirements for the measuring laser are significantly higher than for dPIMV.In contrast, established components can be used for the implementation of dPIMV.

[0032] According to further training, a location-dependent intensity of the collimated reflected laser beam can be repeatedly measured together with the gradient field and subsequently averaged over the number of individual measurements to estimate a turbulence disturbance of the measuring laser beam.

[0033] This approach takes into account not only the phase profiles but also the intensity profiles, thereby fully exploiting the improvement potential of the present approach (e.g., in the case of strong turbulence). This enables, among other things, full-field compensation.

[0034] According to further training, the target can be irradiated with a laser beam from a laser weapon. The procedure can then further include adjusting the irradiation of the target with the laser beam depending on the estimated turbulence disturbance in order to compensate for the influence of turbulence.

[0035] This advanced training course focuses on adapting the laser beam(s) of a high-energy laser (HEL) weapon system to suppress turbulence effects. The described measurement setup can thus be used to compensate for turbulence hO in an HEL weapon system. In particular, the method allows for the precise measurement of the turbulence-disturbed wavefront in uncooperative targets (i.e., military, non-instrumented targets), where the targets generally have a rough surface. Physically, the bandwidth of the method is limited only by the travel time of the light, and no fundamental technical limitations are expected. Therefore, this method is also suitable for measuring and suppressing turbulence in very fast-moving targets, such as flying targets in airborne laser applications. In general, the method can be used with both coherent and conventional high-energy laser sources.

[0036] Specific implementations for such turbulence corrections of a laser weapon system based on an estimation of the turbulence disturbance can be found, for example, in DE 10 2021 001 067 B4.

[0037] According to further training, the active laser beam can be used as a measuring laser beam.

[0038] One advantage of this variant is that, in addition to the active laser, e.g., a coherently coupled high-energy laser with a tiled aperture, no additional measuring laser is required. However, it should be noted that the beam reflection from the target can be influenced by the interaction of the HEL with the target material. Beam splitting and the suppression of scattered radiation, particularly within the optics, can also pose technological challenges. Furthermore, it should be ensured that the total measurement time is short compared to the beam time to act on the target, because otherwise the time required to destroy the target would increase, and turbulence compensation would no longer be justified.

[0039] According to further training, the working laser beam can have a different wavelength than the measuring laser beam.

[0040] In this case, the active laser and the measuring laser could thus be implemented separately, whereby they could be focused and detected with the same optical device despite the different wavelengths.

[0041] According to further training, the effective laser beam can be focused within the isoplanatic angle next to the measuring laser beam onto a spatially separate area of ​​the target.

[0042] In this case, the turbulence measurement is not affected by the interaction of the HEL with the target material. Due to the wavelength separation of the HEL and the measurement laser, the dPlMV measurement channel can be significantly better protected against HEL scatter radiation.

[0043] The above embodiments and further developments can be combined with one another as appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

[0044] The present invention will be explained in more detail below with reference to the exemplary embodiments shown in the schematic figures. These figures show: Fig. 1 Schematic view of a system for measuring the influence of turbulent disturbances on the laser irradiation of a target according to an embodiment of the invention; and Fig. 2. Schematic flowchart of a procedure for measuring the influence of turbulent disturbances with the system consisting of Fig. 1.

[0045] The accompanying figures are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention. Other embodiments and many of the advantages mentioned will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale.

[0046] In the figures of the drawing, identical, functionally equivalent and similarly acting elements, features and components - unless otherwise stated - are each provided with the same reference symbols.

[0047] Fig. Figure 1 shows a schematic view of a system 10 for measuring the influence of turbulent disturbances on laser irradiation of a target 2 as it passes through a turbulent atmosphere according to an embodiment of the invention. A corresponding method M is shown as a flowchart in Figure 1. Fig. 2 to be seen. This follows the in Fig. The variant shown in Figure 1 is a generic basic structure of the system 10, which is suitable for both measuring and correcting turbulence-induced wavefront errors.

[0048] System 10 fundamentally comprises a laser device 1, which is configured to generate a (pulsed) measuring laser beam 4. Furthermore, in this configuration, System 10 includes an effective laser device 17 for generating an effective laser beam 3. System 10 is thus configured as a laser weapon.

[0049] The measuring laser beam 4 enters a first correction device 7 and is then directed by an optical device 6 onto the target 2. The optical device 6 may include, among other things, a first beam splitter 9, a deflecting mirror 13 (tip-tilt unit) for moving the measuring laser beam 4 over a target surface of the target 2, a second beam splitter 19 (e.g., a dicroic mirror or the like) for coupling in the active laser beam 3, and a telescope 11, through which the measuring laser beam 7 is focused onto the target 2. The measuring laser beam 4 is reflected back from the target 2 and re-enters the optical device 6, which receives this reflected laser beam 5, deflects it via the beam splitter, and collimates it in a sensor plane of a sensor device 8.

[0050] The sensor device 8 is configured as a Hartmann-Shack sensor for repeatedly measuring a position-dependent gradient field of a wavefront of the collimated reflected laser beam 5 in the sensor plane in a number N of individual measurements. In other words, the differential wavefront of the reflected beam 5 in the sensor plane is measured. The measuring laser beam 4 is adjusted after each individual measurement such that the individual measurements are statistically independent of one another. For this purpose, the measuring laser beam 4 is shifted by the deflecting mirror 13 on the target 2 within the isoplanatic angle (i.e., the deflecting mirror 13 assumes a slightly different position for each individual measurement). In addition to the gradient field, the position-dependent intensity can optionally also be determined to improve the accuracy of the turbulence measurement.

[0051] The measured signals, in particular the currently measured gradient field, are forwarded to a processing unit 11 (e.g., a computer system), which is designed to average the measured spatially dependent gradient field over the number of individual measurements (possibly supplemented by a corresponding average of the measured intensities) and, based on this, to estimate any turbulence disturbance of the measuring laser beam 4. For this purpose, an averaged differential wavefront is determined from the partial measurements of the differential wavefront, i.e., the individual measurements of the gradient field, from which a corresponding measured wavefront is then reconstructed using known methods from the literature. This reconstructed (turbulence-disturbed) wavefront is forwarded as a measured value for the turbulence to the correction unit 7 for turbulence compensation.

[0052] The calculation device 11 is controlled by a control device 15 of the system 10, which can also control the measurement process of the system 10, i.e., according to the described algorithm, the laser device 1, if applicable the first correction device 7, the sensor device 8 and the optical device 6, in particular the deflecting mirror 13.

[0053] The optional first correction device 7 can be configured to adjust the laser irradiation of the target 2 by the measuring laser beam 4 as a function of the estimated turbulence disturbance (e.g., by phase adjustment and, if necessary, amplitude adjustment). This can lead to an improvement in the measurement of the turbulence disturbance.

[0054] A second correction device 16 can be configured to adjust the laser irradiation of the target 2 by the active laser beam 3 in relation to the estimated turbulence disturbance (e.g., by phase adjustment and, if necessary, amplitude adjustment). This can be used, for example, to adjust the active laser beam 3 of the laser weapon in relation to the estimated turbulence disturbance in order to improve the irradiation quality of the target 2 and thus the effective power of the laser weapon. Likewise, the influence of turbulence on a measuring laser beam can be minimized.

[0055] The corrected laser beam 18 can be coupled into the beam path of the optical device 6 via the second beam splitter 19 and focused on the target 2 by the telescope 14.

[0056] The laser device 1 is operated in pulsed mode, allowing the sensor device 8 to be controlled by suitable gating to suppress backscattering in the optical setup. This backscattering could otherwise be fed back into the receiving channel due to the identical transmit and receive channels, thus interfering with the received signal. The gating can also be used to suppress any process luminescence that may occur when the target 2 is irradiated with the laser beam 3.

[0057] That with reference to Fig.Method M, as schematically shown, comprises, as M1, focusing the measuring laser beam 4 onto the target 2 with the optical device 6. Method M further comprises, as M2, collimating the reflected laser beam 5, which is reflected back from the target 2 due to irradiation with the measuring laser beam 4 and received by the optical device 6, in the sensor plane of the sensor device 8. Method M further comprises, as M3, repeatedly measuring the spatially dependent gradient field of a wavefront of the collimated reflected laser beam 5 in the sensor plane in a number of statistically independent individual measurements. Method M further comprises, as M4, averaging the measured gradient field over the number of individual measurements to estimate the turbulence disturbance of the measuring laser beam 4, wherein a corresponding turbulence-disturbed wavefront is reconstructed from the averaged gradient field by means of digital signal processing.Finally, the procedure M under M5 can include adjusting the laser irradiation of target 2 depending on the estimated turbulence disturbance in order to compensate for the influence of turbulence.

[0058] In the preceding detailed description, various features have been summarized in one or more examples to improve the clarity of the presentation. However, it should be clear that the above description is merely illustrative and in no way limiting. It serves to cover all alternatives, modifications, and equivalents of the various features and embodiments. Many other examples will be immediately and directly clear to the person skilled in the art based on their technical knowledge, given the above description.

[0059] The exemplary embodiments were selected and described to best illustrate the principles underlying the invention and its practical applications. This enables those skilled in the art to optimally modify and utilize the invention and its various exemplary embodiments with regard to the intended purpose. In the claims and the description, the terms "including" and "comprising" are used as neutral language terms for the corresponding terms "comprehensive".

[0060] Furthermore, the use of the terms "ein", "einer" and "eine" should not fundamentally exclude a plurality of such described features and components. Reference symbol list 1 laser device 2 Goal 3 active laser beam 4 measuring laser beam 5 collimated reflected laser beam 6 optical device 7 Correction device measuring laser 8 Sensor device 9 first beam splitter 10 System 11 Calculation device 12 turbulent atmosphere 13 deflecting mirrors 14 Telescope 15 Control unit 16 Correction device Working laser 17 Working class equipment 18 corrected effective laser beam 19 second beam splitter M procedure M1-M5 process steps QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 001 067 B4 [0010, 0016, 0036]

Claims

[1] Method (M) for measuring the influence of turbulent disturbances on a laser irradiation of a target (2) as it passes through a turbulent atmosphere, with: Focusing (M1) a measuring laser beam (4) onto the target (2) using an optical device (6); Collimation (M2) of a reflected laser beam (5) from the target (2) due to irradiation with the measuring laser beam (4) and received by the optical device (6) in a sensor plane of a sensor device (8); repeated measurement (M3) of a position-dependent gradient field of a wavefront of the collimated reflected laser beam (5) in the sensor plane in a number of individual measurements, wherein the measuring laser beam (4) is adjusted after each individual measurement such that the individual measurements are statistically independent of each other; and Averaging (M4) of the measured gradient field over the number of individual measurements to estimate a turbulence disturbance of the measuring laser beam (4), wherein an associated turbulence-disturbed wavefront is reconstructed from the gradient field using digital signal processing. [2] Method (M) according to claim 1, wherein the measuring laser beam (4) is shifted and / or distorted after each individual measurement on the target (2) in order to make the individual measurements statistically independent of each other. [3] Method (M) according to claim 1 or 2, wherein a Hartmann-Shack sensor is used as the sensor device (8). [4] Method (M) according to one of claims 1 to 3, wherein the measuring laser beam (4) is operated in pulsed mode. [5] Method (M) according to one of claims 1 to 4, wherein together with the gradient field of the wavefront a location-dependent intensity of the collimated reflected laser beam (5) is repeatedly measured and subsequently averaged over the number of individual measurements to estimate a turbulence disturbance of the measuring laser beam (4). [6] Method (M) according to any one of claims 1 to 5, wherein the target (2) is irradiated with an effective laser beam (3, 18) of a laser weapon, the method further comprising: Adjusting (M5) the irradiation of the target (2) with the effective laser beam (3, 18) depending on the estimated turbulence disturbance in order to compensate for the influence of turbulence. [7] System (10) for measuring the influence of turbulent disturbances when passing through a turbulent atmosphere using a method (M) according to one of claims 1 to 6, comprising: a laser device (1) which is designed to generate a measuring laser beam (4); an optical device (6) which is designed to focus the measuring laser beam (4) onto the target (2), to receive a laser beam (5) reflected back from the target (2) due to irradiation with the measuring laser beam (4) and to collimate the reflected laser beam (5) in a sensor plane; a sensor device (8) which is configured for repeatedly measuring a position-dependent gradient field of a wavefront of the collimated reflected laser beam (5) in the sensor plane in a number of individual measurements, wherein the measuring laser beam (4) is adjusted after each individual measurement such that the individual measurements are statistically independent of each other; and a computational device (11) which is designed to average the measured gradient field over the number of individual measurements and Based on this, a turbulence disturbance of the measuring laser beam (4) is estimated, whereby a corresponding turbulence-disturbed wavefront is reconstructed from the averaged gradient field using digital signal processing. [8] System (10) according to claim 7, wherein the optical device (6) is configured to shift and / or distort the measuring laser beam (4) after each individual measurement on the target (12) in order to make the individual measurements statistically independent of each other. [9] System (10) according to claim 7 or 8, wherein the sensor device (8) is designed as a Hartmann-Shack sensor. [10] System (10) according to one of claims 7 to 9, wherein the laser device (1) is configured to operate the measuring laser beam (4) in a pulsed manner. [11] System (10) according to one of claims 7 to 10, wherein the sensor device (8) is configured to repeatedly measure a location-dependent intensity of the collimated reflected laser beam (5) together with the gradient field, wherein the computation device (11) is configured to subsequently average the measured intensities over the number of individual measurements to estimate the turbulence disturbance of the measuring laser beam (4). [12] System (10) according to one of claims 7 to 11, wherein the system (10) is configured as a laser weapon for generating an effective laser beam (3, 18) for irradiating the target (2), wherein the system further comprises: a correction device (16) which is designed to adjust the irradiation of the target (2) with the active laser beam (3, 18) depending on the estimated turbulence disturbance in order to compensate for the influence of turbulence.

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