Method and apparatus for characterizing an incoming electromagnetic energy beam

Abstract

The present invention relates to a method and apparatus for characterizing an incoming electromagnetic energy beam. The method comprises the steps of: generating a beam of laser pulses (3); generating a beam of plasma filaments from the laser pulses (5); directing the plasma filaments so that they intersect with an incoming electromagnetic energy beam, thereby generating a diffused electromagnetic energy beam (7); and detecting a first portion of the diffused electromagnetic energy beam using a first detector (9).

Description

Technical Field

[0005]

[0001] The present disclosure relates to methods and apparatus for characterizing an incoming electromagnetic energy beam.

Background Art

[0002] An electromagnetic energy beam, such as a high-energy laser beam, can be directed towards a target and used as a probe to obtain information about the target. It is desirable to be able to characterize an incoming energy beam in order to determine a likely beam source and / or origin.

Summary of the Invention

[0003] A first aspect of the present disclosure provides a method for characterizing an incoming electromagnetic energy beam having the steps set forth in claim 1 below.

[0004] A second aspect of the present invention provides an apparatus for characterizing an incoming electromagnetic energy beam having the features set forth in claim 12 below.

[0005] A third aspect of the present disclosure provides a platform including an apparatus according to the second aspect of the present disclosure.

[0006] It will be recognized, of course, that features described in connection with one aspect of the present disclosure may be incorporated into any other aspect of the present disclosure. For example, the apparatus may incorporate any of the features described in reference to the method, and vice versa.

[0007] Exemplary embodiments of the present disclosure are described herein by way of example only, with reference to the accompanying drawings.

Brief Description of the Drawings

[0008] [Figure 1] A flowchart showing a method according to an exemplary embodiment of the present disclosure. [Figure 2]This flowchart shows a second exemplary method according to an exemplary embodiment of the present disclosure. [Figure 3] This flowchart illustrates an exemplary implementation of the method of this disclosure, using a device mounted on a vehicle. [Figure 4] This is a schematic diagram showing an implementation configuration of the method and apparatus according to an embodiment of the present invention, the apparatus being mounted on a platform. [Figure 5] This is a schematic diagram showing the connections between the control unit and other components that form part of the device shown in Figure 4. [Figure 6] This is a schematic diagram showing the connection between the detector and the processor, which form part of the device shown in Figure 4. [Modes for carrying out the invention]

[0009] A first aspect of the present disclosure provides a method for characterizing an incoming electromagnetic energy beam. The method comprises the steps of generating a beam of laser pulses, generating a beam of plasma filaments from the laser pulses, directing the plasma filaments so that they intersect with an incoming electromagnetic energy beam, thereby generating a diffused electromagnetic energy beam, and detecting a first portion of the diffused electromagnetic energy beam using a first detector.

[0010] In the prior art, it is known that laser pulses with sufficiently high peak power can self-focus through the Kerr effect. In most situations, a laser beam diverges as it propagates, but the self-focusing of a laser pulse can cancel out or even overcome the divergence, allowing the pulse to propagate without diverging and forming a so-called laser filament. At critical pulse power, a self-focusing pulse can ionize the air it propagates through, forming a plasma. The plasma then influences the pulse, and the pulse can be trapped within the plasma. The phase inhomogeneity of the pulse's wavefront typically results in each pulse forming an array of plasma filaments along its lateral profile. The generation of such filaments is a technique known in the prior art. As used herein, “filament” is an elongated region of ionized air (i.e., plasma) formed by a laser pulse.

[0011] The laser pulse will have a wavelength that ionizes air, for example, 700 nm to 900 nm, or for example, 800 nm.

[0012] A plasma filament is an elongated region of ionized air, i.e., plasma. Because pulses propagate through the filament with high peak power, the self-focusing of laser pulses within the plasma due to the Kerr effect can create long filaments. Filaments can be, for example, >2 cm, >25 cm, >50 cm, >1 m, >4 m, or even >10 m in length. However, shorter filaments may be useful due to their higher peak power; for example, filaments can be <1 m, for example, <50 cm, <25 cm, or even <5 cm in length. The beam of the filament can have a width of less than 100 microns.

[0013] Directioning the plasma filament beam so that it intersects with the incoming energy beam may include, for example, steering the pulse beam by steering a gimbal mount.

[0014] Directioning the filament beam so that it intersects with an incoming energy beam may include the steps of receiving a radar or electro-optical signal indicating a potential light source for the incoming beam, and directional the pulsed beam toward that potential light source.

[0015] This suggests that the laser pulse beam can be generated before the incoming energy beam is detected.

[0016] Directing the plasma filament beam to intersect with the incoming energy beam may include the step of sensing that the incoming energy beam is incident on the target.

[0017] A plasma filament beam, directed to intersect with an incoming electromagnetic energy beam, will alter the optical properties of the air through which the incoming beam passes. This alteration of the air's optical properties will disrupt the incoming beam.

[0018] Such interaction between the incoming energy beam and the plasma filament results in the energy of the incoming electromagnetic beam spreading over a wider range of propagation angles. The incoming electromagnetic energy beam will therefore be detectable by one or more detectors. Rather than being concentrated on a small spot on the target, the incoming electromagnetic energy beam spreads out into a larger, more diffused pattern, and the beam's energy spreads over a wider area. Hereinafter, the incoming electromagnetic energy beam may be called a diffused electromagnetic energy beam or diffused energy beam after interacting with the filament's beam. The diffused energy beam may have a lower lateral peak power than the incoming beam.

[0019] The incoming electromagnetic energy beam may be a focused energy beam. The incoming electromagnetic energy beam may be a laser beam. The incoming energy beam may originate from an active sensor. The incoming energy beam may originate from a communication device. The incoming electromagnetic energy beam may be an infrared electromagnetic energy beam.

[0020] The intersection point between the filament beam and the incoming energy beam should ideally be as close as possible to the source of the incoming beam in order to maximize the spread of energy from the incoming beam. For example, the intersection point may be at least 50 m, at least 100 m, at least 500 m, or at least 1 km away from the location where the laser pulse beam is generated.

[0021] This method comprises detecting a first portion of a diffusing energy beam using a first detector.

[0022] The diffusing energy beam will extend over a range of propagation angles greater than the range of propagation angles experienced by the beam arriving before it interacts with the plasma filament. The first detector can detect a first portion of the diffusing electromagnetic energy beam that extends over a subset of the range of propagation angles experienced by the diffusing energy beam.

[0023] The first detector can be an area detector. The first detector can be configured to detect from 0.1% to 100% of the total area of the diffusing beam.

[0024] Alternatively, the first detector can be a point detector.

[0025] The first detector can be configured to detect an energy beam that diffuses over a fixed time period. This time period can be from 0.1 milliseconds to 10 seconds.

[0026] The first detector can be a CCD detector, a photodiode detector, a CMOS detector, or a thermal detector. The first detector can be a wavelength detector, a frequency detector, a pulse length or pulse frequency detector, or an intensity detector.

[0027] This method can include measuring a first characteristic of a first portion of the diffusing energy beam.

[0028] The first characteristic can be measured using the first detector. The first characteristic can be the wavelength or frequency of the first portion of the diffusing energy beam. The first portion can include a range of wavelengths and frequencies. The first characteristic can be the average wavelength or frequency of the first portion. The first detector can be configured to detect a range of wavelengths and frequencies. The first detector can be configured to detect a range of wavelengths from 10 nm to 10 mm. The first detector can measure the spread or range of the wavelength of the first portion of the energy beam.

[0029] The first characteristic can be the energy of the first portion of the diffusing energy beam. The first detector can be configured to detect a range of energies. The first portion of the diffusing energy beam can include a range of energies. The detector can measure the average energy of the first portion of the diffusing energy beam. The first detector can measure the spread or range or energy of the first portion of the electromagnetic energy beam.

[0030] The first characteristic may be the power of a first portion of the diffusing energy beam. The first detector may be configured to detect a range of power.

[0031] The first characteristic may be the intensity of a first portion of a diffusing energy beam. The intensity of a first portion of an electromagnetic energy beam may exhibit spatial variations in a direction transverse to the beam propagation direction. A first detector can measure the spatial variations in the intensity of the first portion of the beam. A first detector and / or measuring device can measure the average intensity of a first portion of a diffusing electromagnetic energy beam. A first detector can measure variations in the intensity of a first portion of a diffusing energy beam over a period of time.

[0032] The diffusing energy beam may be a pulsed beam, and the first characteristic may be the pulse frequency of a first portion of the diffusing electromagnetic energy beam. The first characteristic may also be the pulse length of the first portion of the electromagnetic energy beam. The first detector may detect or measure the average pulse length or pulse frequency of the first portion of the diffusing energy beam.

[0033] This method may include recording data related to a first characteristic. This method may include displaying data related to a first characteristic using display means. This method may include transmitting data related to a first characteristic to a processor.

[0034] The method may include measuring a second characteristic associated with a first portion of a diffusing electromagnetic energy beam. The second characteristic may be measured using a first detector or a second different detector. The second characteristic may be different from the first characteristic. The second characteristic may be the wavelength, frequency, pulse length, intensity, or energy of the first portion of the electromagnetic energy beam. For example, the first characteristic may be the wavelength of the first portion of the diffusing electromagnetic energy beam, and the second characteristic may be the intensity of the first portion of the diffusing electromagnetic energy beam. The first characteristic may be measured using a wavelength detector, and the second characteristic may be measured using an intensity detector.

[0035] The method may include recording data relating to both a first and a second characteristic. The method may include transmitting data relating to the first and second characteristics to a processor and / or display means. The method may include using data relating to the first and second characteristics and using data combined to determine the characteristics of an incident electromagnetic energy beam. The characteristics may be the size, shape, or beam profile of the incoming energy beam. The characteristics may be the direction from which the beam is coming. The characteristics may be information relating to the light source or origin of the beam. For example, the method may include measuring the wavelength of a first portion of a diffusing energy beam and the intensity of a first portion of a diffusing energy beam and using this information to determine the light source and / or location of the incident energy beam.

[0036] The method may comprise measuring several different properties of a first portion of a diffusing energy beam. Each of the several different properties may be measured using a different detector. The method may comprise recording and / or storing data associated with the several different properties. The method may comprise transmitting the data associated with the several different properties to a processor and / or display means. The method may comprise combining the data associated with several different properties of a first portion of a diffusing energy beam and using that data to determine one or more properties of an incident energy beam. The properties may be used to determine the source origin, direction of arrival, size, or beam shape / profile of the incident energy beam.

[0037] The method may include detecting a second portion of a diffusing energy beam. The second portion of the diffusing energy beam may be measured using a second different detector. Alternatively, for example, if the first detector is movable or configured to detect the beam over different time periods, the second portion of the diffusing energy beam may be measured using the first detector. The second portion of the diffusing energy beam may be different spatial areas of the diffusing beam, spanning different ranges of propagation angles. The second portion may be detected using a second detector located at a different position from the first detector. The second portion may be detected using the first detector by moving the first detector to a second location. Alternatively, the first portion of the diffusing energy beam may be measured over a first time period, and the second portion of the diffusing electromagnetic energy beam may be measured over a second different time period. In this case, the second portion may be measured using the first detector.

[0038] The method may include measuring a first characteristic of a second portion of a diffusing energy beam. The first characteristic of the second portion may be the same first characteristic measured for the first portion. The first characteristic may be wavelength, frequency, pulse length, pulse frequency intensity, or energy. Alternatively, the first characteristic of the second portion may be different from the first characteristic measured for the first portion. The characteristics measured for the second portion may have different values ​​from those measured for the first portion; for example, the second portion may include a different range of wavelength, frequency, energy, or intensity than the first portion.

[0039] The second detector may be of the same type as the first detector. The second detector may be of a different type than the first detector. The second detector may be a CCD detector, a photodiode detector, a CMOS detector, or a thermal detector. The first detector may be a wavelength detector, a frequency detector, a pulse length or pulse frequency detector, or an intensity detector. The first and second detectors may be of the same type and be located in different spatial locations. For example, both the first and second detectors may be intensity detectors and may be positioned to measure different ranges of propagation angles for the first and second portions of a diffusing energy beam.

[0040] The method may include measuring a second characteristic associated with a second portion of a diffusing energy beam. The second characteristic measured for the second portion may be different from the first characteristic measured for the first portion. The second characteristic may be the wavelength, frequency, pulse length, intensity, or energy of the first portion of the electromagnetic energy beam.

[0041] The method may comprise detecting multiple distinct portions of a diffusing electromagnetic energy beam. These distinct portions may be measured using multiple different detectors. For example, the distinct portions may extend to different areas of the diffusing energy beam or to different propagation angles. The multiple different detectors may be positioned at different locations to detect different portions of the beam. Alternatively, for example, if the detectors are mobile or configured to detect the beam over different time periods, the multiple distinct portions may be measured using the same detector. The method may comprise measuring a first characteristic of a first portion of a diffusing electromagnetic energy beam using a first detector, and measuring the same characteristic for multiple distinct portions of the electromagnetic energy beam.

[0042] The method may include using data relating to the characteristics of a first portion of a diffusing energy beam and data relating to the characteristics of a second portion of a diffusing electromagnetic energy beam to determine the characteristics of an incident electromagnetic energy beam. The method may include recording the data relating to the characteristics of the first portion and the data relating to the characteristics of the second portion. The method may include transmitting the data relating to the first and second portions to a processor and / or display means. The method may include processing the data associated with the first portion of the beam and the data associated with the second portion of the beam, and combining the processed data to determine the characteristics of the beam. For example, the method may include measuring the intensity of a first area of ​​the beam, measuring the intensity of a second different area of ​​the beam, and using the first and second intensities to determine the beam shape and / or size and / or direction of the incident energy beam.

[0043] According to a second aspect, the disclosure provides an apparatus for characterizing an incoming energy beam. The apparatus includes a filament generator comprising a laser configured to generate a beam of laser pulses. The filament generator includes a beam manipulation optical system configured to manipulate the beam of laser pulses into a beam of plasma filament. The apparatus includes a steerable mount. The apparatus includes a sensor for detecting the incoming energy beam. The apparatus includes a first detector for detecting a first portion of an electromagnetic energy beam. The apparatus includes a control unit. At least a portion of the filament generator is mounted on the mount. The sensor is configured to send a detection signal to the control unit when an incoming energy beam is detected. The control unit is configured to send a steering signal to the mount in response to the detection signal to steer the mount so that the mount directs the beam of the filament to intersect with the incoming energy beam, thereby generating a diffused energy beam. The apparatus includes a first detector configured to detect a first portion of the diffused energy beam.

[0044] The filament generation apparatus may include, for example, a waveguide connecting the laser to the beam manipulation optical system, such as an optical fiber.

[0045] The filament generation apparatus may include a beam steering optical system. The beam steering optical system may be mounted on a mount.

[0046] The laser could be a solid-state laser, such as a Ti:sapphire laser. Alternatively, the laser could be a gas laser, such as a CO2 laser.

[0047] The beam manipulation optical system may include a beam expander and / or a beam reducer. The beam manipulation optical system may include diverging or converging lenses for diverging or converging the pulsed beam.

[0048] (As used herein, "lens" may mean either a transmitting lens or a reflective lens, i.e., a spherical mirror.)

[0049] The sensor may be or may include a monopulse sensor. The sensor may be or may include a quadrant sensor.

[0050] The sensor may be, or include, a radar receiver or an electro-optic detector. The radar receiver or electro-optic detector may be on the same platform as the filament generator or may be separate from it. The radar receiver or electro-optic detector may be configured to track the source of an incoming energy beam.

[0051] The sensor may include a wavelength detector that, for example, utilizes a bandpass filter or a spectral analyzer to detect one or more wavelengths of the incoming energy beam. Identifying the incoming energy beam may allow for the identification of which part of the target is being targeted, for example, a specific sensor.

[0052] A steerable mount could be a gimbal mount.

[0053] The control unit may be a microprocessor or, for example, implemented in a field-programmable gate array (FPGA).

[0054] The first detector may be configured such that a first portion of a diffusing energy beam is incident on the first detector. The first detector may be an area detector. The first detector may be a point detector. The first detector may be a CCD detector, a photodiode detector, a CMOS detector, or a thermal / IR detector. The first detector may be a wavelength detector, a frequency detector, a pulse length or pulse frequency detector, or an intensity detector. The first detector may be in a fixed position. Alternatively, the first detector may be movable to detect different portions of the diffusing energy beam. The first detector may be positioned in close proximity to the sensor and / or in close proximity to the filament generator. The first detector may be positioned on a steerable mount.

[0055] The apparatus may include a second detector configured to detect a second portion of a diffusing energy beam. The second detector may be spatially separated from the first detector. The first detector may be configured to measure a first area of ​​the diffusing energy beam, and the second detector may be configured to measure a second, different area of ​​the diffusing energy beam. The second detector may be of the same type as the first detector, and the first and second detectors may be used to measure the same characteristics of two different portions of the beam. Alternatively, the second detector may be of a different type than the first detector. The first detector may be used to measure a first characteristic of the first portion of the beam, and the second detector may be used to measure a different characteristic of the first or second portion of the beam.

[0056] The apparatus may include multiple detectors. The detectors may be positioned at different locations and configured to detect different portions of a diffusing energy beam. The detectors may be of the same type. The detectors may be of different types for measuring different characteristics of the diffusing beam.

[0057] The device may include a processor for processing data from the first detector and any additional detectors. The device may also include display means for displaying data from the first detector and any additional detectors.

[0058] In a third aspect, the Disclosure provides a platform including a device having any of the features described above. The platform may be ground-based. The platform may be mounted on a vehicle. The platform may be mounted on a ship or aircraft. The platform may be mounted on a building. The first detector and any additional detectors may be fixed in place on the platform or may be movable relative to the platform.

[0059] Figure 1 is a flowchart illustrating an exemplary method 1 according to an embodiment of the present disclosure. In a first step 3, a beam of laser pulses is generated, and in a second step 5, a beam of plasma filament is generated from the laser pulses. In a third step 7, the beam of plasma filament is directed to intersect with an incoming energy beam. The beam is directed in response to a signal received from a sensor indicating that a beam source has been detected. The beam is directed by steering the beam toward its source. When the filament beam intersects with the incoming energy beam, the energy of the incoming beam is dispersed over a wider range of propagation angles, thereby generating a diffused energy beam. In a fourth step, the method comprises detecting a first portion of the diffused energy beam using a detector. Optionally, in step 11, the method may comprise detecting a second portion of the diffused energy beam using a second different detector. Optionally, in step 13, data from the first detector and data from the second detector may be combined and used to determine the characteristics of the incoming energy beam.

[0060] Figure 2 is a flowchart illustrating an exemplary method 1 according to an embodiment of the present disclosure. In a first step 103, a beam of laser pulses is generated, and in a second step 105, a beam of plasma filament is generated from the laser pulses. In a third step 107, the plasma filament is directed to intersect with the incoming energy beam. Directionalizing the filament beam requires receiving a signal indicating a potential light source for the beam and steering the beam toward that light source. When the filament beam intersects with the incoming energy beam, the energy of the incoming beam spreads over a wider range of propagation angles, thereby generating a diffused energy beam. In a fourth step 109, the method comprises detecting a first portion of the diffused energy beam using a first detector. Optionally, in a fifth step 111, data from the first detector may be used to measure a first characteristic of the first portion of the diffused energy beam. Optionally, in the sixth step 113, data from the first detector may be used to measure a second distinct characteristic of the first portion of the diffusing energy beam, and the method may comprise detecting the second characteristic of the first portion of the diffusing energy beam. Optionally, in step 115, the first and second characteristics may be used to determine the characteristics of the incoming energy beam.

[0061] Figure 3 is a flowchart illustrating an exemplary implementation of Method 201 according to an embodiment of the present disclosure. In the first step 202, sensors on the vehicle detect the incoming laser beam. In the second step 204, the detection signal is sent to a control unit. In the third step 206, a filament generator and beam maneuvering optics are used to generate a beam of laser pulses and a beam of plasma filament from the laser pulses. In the fourth step 208, the control unit steers the plasma filament beam to intersect with the incoming laser beam. The plasma filament beam causes the incoming laser beam to diverge at the filament, so that the beam spreads over a wider range of propagation angles. In the fifth step 209, a first intensity detector detects the intensity of a first portion of the diffusing energy beam. In the sixth step 210, a second intensity detector, spatially separated from the first detector, detects the intensity of a second different location of the diffusing energy beam. In the seventh step 212, data from the first and second detectors are sent to the processor. In the eighth step 214, the data from the first and second detectors are combined to determine the direction of the incoming energy beam.

[0062] Figures 4, 5, and 6 are schematic diagrams illustrating exemplary implementations of the method and apparatus according to embodiments of the present disclosure. Figure 4 shows a platform 320 on which the apparatus according to embodiments of the present disclosure can be mounted. Figures 5 and 6 are schematic diagrams showing connections between components of the apparatus. As shown in Figure 4, the platform 320 includes a sensor 324 for detection of a laser beam. In response to the sensor 324 detecting an incoming laser beam 326 from a laser light source 327, the sensor 324 transmits a detection signal to a control unit 328 (illustrated in Figure 5, not shown in Figure 4). The platform 320 also includes a steerable mount 330 connected to the control unit 328. As shown in Figure 5, a filament generating apparatus 332, comprising a pulsed laser light source 334 and a beam manipulation optical system 336, is mounted on the mount 330. When the control unit 328 receives a detection signal from the sensor 324, the control unit 328 directs the filament generator to generate a filament beam 338 using the pulsed laser light source 334 and the beam manipulation optical system 336. The control unit 328 directs the maneuverable mount 330 to direct the filament beam 338 toward the incoming laser beam 326. As shown in Figure 4, when the filament beam 338 intersects with the incoming laser beam 326, the incoming laser beam 326 diverges, and thus the energy of the laser beam spreads over a wider range of propagation angles, generating a diffused energy beam 340. A first intensity detector 342 mounted on the platform 320 detects a first portion of the diffused energy beam 340. As shown in Figure 6, data related to the first portion of the diffused energy beam is transmitted to the data processor 344, where a first characteristic, in this case the intensity of the first portion of the diffused energy beam 340, is measured and recorded. A second intensity detector 346 mounted on platform 320 detects a second portion of the diffusing energy beam 340. Data related to the second portion of the diffusing energy beam is transmitted to a data processor, where the intensity of the second portion of beam 340 is measured and recorded.The intensities of the first and second portions of the diffusing beam 340 are used to determine the direction of the incoming energy beam 326.

[0063] In embodiments of this disclosure, the platform shown in Figure 4 is mounted on a vehicle, such as an aircraft or a ship. In other embodiments of this disclosure, the platform is ground-based or mounted on a building.

[0064] Although the present invention has been described and illustrated with reference to specific embodiments, it will be recognized by those skilled in the art that the present invention is suitable for many different modifications not specifically illustrated herein.

[0065] Where, in the foregoing description, integers or elements having known, obvious, or predictable equivalents are referred to, such equivalents are incorporated herein as if they were individually described. References to the claims should be made to determine the true scope of the invention, and should be interpreted to encompass any such equivalents. It will also be recognized by the reader that integers or features of the invention described as preferred, advantageous, convenient, or similar are optional and do not limit the scope of the independent claims. Furthermore, it should be understood that such optional integers or features may be beneficial in some embodiments of the invention but undesirable and therefore may not be present in other embodiments.

Claims

1. A method for characterizing an incoming electromagnetic energy beam, the method is The steps include generating a laser pulse beam and The steps include generating a plasma filament beam from the laser pulse, The steps include: directing the plasma filament so that it intersects with the incoming electromagnetic energy beam, thereby generating a diffusing electromagnetic energy beam; A step of detecting a first portion of the diffusing electromagnetic energy beam using a first detector. A method that includes [a certain feature].

2. The method according to claim 1, further comprising measuring the first characteristics of the first portion of the diffusing electromagnetic energy beam.

3. The method according to claim 2, wherein the first characteristic is the wavelength, frequency, pulse length, pulse frequency, intensity, or energy of the first portion of the diffusing electromagnetic energy beam.

4. The method according to claim 2 or 3, further comprising measuring a second characteristic associated with the first portion of the diffusing electromagnetic energy beam.

5. The method according to claim 4 or 5, further comprising using data relating to the first characteristic and data relating to the second characteristic to determine the characteristics of the incident electromagnetic energy beam.

6. The method according to any one of claims 1 to 5, further comprising detecting a second portion of the diffusing electromagnetic energy beam.

7. The method according to claim 6, further comprising measuring the first characteristics of the second portion of the diffusing electromagnetic energy beam.

8. The method according to claim 7, wherein the first characteristic of the second portion is the wavelength, frequency, pulse length, pulse frequency, intensity, or energy of the second portion of the electromagnetic energy beam.

9. The method according to any one of claims 2 to 8, comprising measuring a first characteristic of the first portion of the diffusing electromagnetic energy beam and measuring the same characteristic for a plurality of different portions of the electromagnetic energy beam.

10. The method according to any one of claims 7 to 9, further comprising using data relating to the characteristics of the first portion of the diffusing electromagnetic energy beam and data relating to the characteristics of the second portion of the diffusing electromagnetic energy beam to determine the characteristics of the diffusing electromagnetic energy beam.

11. The method according to claim 10, further comprising using intensity data for a first portion of the diffusing energy beam and intensity data for a second portion of the diffusing energy beam, and combining this data to determine the size and / or shape and / or direction of the incident electromagnetic energy beam.

12. A device for characterizing an incoming energy beam, the device is A filament generation apparatus comprising a laser configured to generate a beam of laser pulses and a beam manipulation optical system configured to manipulate the beam of laser pulses to generate a beam of plasma filament, A steerable mount, A sensor for detecting the incoming energy beam, A control unit, wherein at least a portion of the filament generating apparatus is mounted on the mount, the sensor is configured to send a detection signal to the control unit when it detects the incoming energy beam, and the control unit is configured to send a steering signal to the mount in response to the detection signal to steer the mount so that the mount intersects the incoming energy beam, thereby generating a diffusing energy beam. A first detector for detecting a first portion of a diffusing electromagnetic energy beam, wherein the first detector is configured to detect the first portion of the diffusing energy beam. A device equipped with the following features.

13. The apparatus according to claim 12, wherein the first detector is a CCD detector, a photodiode detector, a CMOS detector, or a thermal detector, a wavelength detector, a frequency detector, a pulse length or pulse frequency detector, or an intensity detector.

14. The apparatus according to claim 12 or 13, further comprising a second detector configured to detect different portions of the diffusing energy beam.

15. The apparatus according to any one of claims 12 to 14, comprising a plurality of detectors configured to detect different portions of the diffusing energy beam.

16. A platform comprising the apparatus according to any one of claims 12 to 15.

17. The platform according to claim 16, wherein the platform is ground-based.

18. The platform according to claim 16, wherein the platform is installed on a building.

19. The platform according to claim 16, wherein the platform is mounted on a vehicle.

20. The platform according to claim 16, wherein the platform is installed on a ship.

21. The platform according to claim 16, wherein the platform is installed on an aircraft.

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