DE102007024051B4 - Device and method for the detection and localization of laser radiation sources - Google Patents

Abstract

Device (1) for detecting, locating and tracking laser radiation sources (8) with a radiation-sensitive detector (4) arranged in the image field of an imaging optical system (3) and an electronic signal evaluation device connected to the detector (4), between the laser radiation source (8) and the optic (3) is arranged a diffraction grating, such that the diffractive grating diffraction patterns are imaged on the detector in the focal plane of the optics, and that the electronic signal evaluation means detecting means for recognizing the punctiform images and for locating the direction; the laser radiation source of the diffraction pattern, characterized in that the diffraction grating is a grating formed as a surface relief or volume phase grating for point-like imaging of coherent laser radiation, wherein the height structure of the surface relief grating or the refractive index of the Volume phase grating is formed such that - the +/- 1-th and +/- 2-th diffraction order is formed in the grid and the remaining diffraction orders are suppressed, or - the + 1-th and + 2-th diffraction order in the Grating is created and the remaining diffraction orders are suppressed, or - the +/- 1-th diffraction order is created in the grating and the remaining diffraction orders are suppressed, or - the + 1-th diffraction order is formed in the grating and the remaining diffraction orders are suppressed.

Description

The invention relates to a device for detecting, locating and tracking of laser radiation sources in the image field of a camera with superior optical coherence filter and associated with the camera signal processing and a method for detecting, locating and tracking of laser radiation sources with such a device.

Since laser devices are used in the military field for a variety of purposes, to protect and initiate countermeasures against laser threats sensors are required that can detect and locate such laser sources. Such devices are z. B. from the applications DE 33 23 828 C2 or DE 35 25 518 C2 used for the detection and localization of pulse laser sources as z. B. for rangefinder, target illuminator or glare laser used, as well as EP 0283538 A1 , in addition to the radiation of modulated continuous wave lasers z. B. can detect the laser beam rider weapons known.

The publication WO 97/45751 A1 discloses a method for determining direction to an object which emits optical radiation.

The localization of laser radiation sources is described in FR 2888333 A1 ,

Next discloses the US 6118119 A a device for spectral analysis with simultaneous determination of the direction and wavelength of the light beam.

From the DE 198 51 010 A1 For example, a device for detecting and locating laser radiation sources using a cross grating is known.

In civil applications z. As in land surveying, speed measurement of vehicles or optical data transmission and the display of the presence and position of laser sources is increasingly required.

The laser radiation of both military and civil systems of this kind is mostly in the near infrared range and thus can not be perceived by the human eye. Since the laser wavelength of a threat is usually unknown, a laser warning sensor designed for reception in this range must have a sufficient spectral reception bandwidth.

This then makes it difficult to identify the narrowband laser radiation among the broadband natural and technical sources of the environment. Therefore, laser sources with most laser warning sensors are detected by the difference in the timing of their emission from the incoherent sources. Thus, because of the emission duration of their individual pulses of nanoseconds, rangefinders, target illuminators and glare lasers can even be distinguished from the fastest incoherent sources, such as flash units with a duration in microseconds. On the other hand, the modulated CW radiation from laser beam riders can be detected due to their fixed modulation frequencies by frequency sampling over time.

However, the recognition of laser sources within the radiation background of the environment using the principle of time analysis is today made difficult by the fact that with the progress of the development of the primary laser sources laser threats with complex time course z. B. in pulse packets with high repetition frequency and low laser power increasingly in the military area in appearance. The detection of modulated CW radiation is also much more difficult because of the variety of modulation frequencies and the potential confusion with modulated incoherent radiation sources.

In addition to detecting the presence of a laser threat within a larger viewing angle of a laser warning sensor, the angle of incidence of the laser beam or the position of the beam source in the vicinity must be determined with sufficient accuracy by the sensor for initiating a passive or active countermeasure. However, since very fast individual photodetectors are needed for time analyzes, different directions of incidence can first be determined with an array of photodetectors and shadow masks, which determine their viewing direction individually, as in FIG U.S. Patent 5,428,215 Digital High Angular Resolution Laser Irradiation Detector (HARLID), or by the time-of-flight encoding of incident short laser pulses over glass fibers of different lengths as in the German patent DE 3525518 C2 Device for detecting and detecting the direction of laser radiation described, be performed. With a very high technical effort manages here the modest angular resolution of a few degrees. With the early availability of active optical countermeasures against laser threats, eg. As by glare and noise lasers, but soon grow the requirements for the angular resolution of laser warning sensors to fractions of degrees.

A prerequisite for the usability of laser warning sensors is a high probability of detection of laser threats at the same time low false alarm rate by other optical and electronic interference, which a possible large receiving aperture of the sensor required. In contrast, the receiving surface of the photodiodes should be as small as possible in order to resolve fast light signals and at the same time to achieve a high directional resolution. A compromise between these contradictory requirements can be found in time-resolved laser warning sensors only by a very complex signal processing.

It is therefore an object of the present invention to avoid the disadvantages of the prior art and to provide a device and a method for the detection and localization of laser beam sources, the / a laser source regardless of their time characteristic, d. H. irrespective of whether it is pulsed, continuous-wave or modulated, detects at very low radiant power and at the same time can detect its exact angular position within an extended angle of view of the sensor with high probability of detection and low false alarm rate.

This object is achieved by a device having the features of claim 1 and by a method having the features of claim 7. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

This avoids the disadvantages of the prior art and provides a device and method for detecting and locating laser beam sources which detects a laser source almost independently of its time characteristic at very low power and at the same time maintains its accurate angular position within an extended viewing angle of the sensor high detection probability and low false alarm rate.

The device according to the invention provides for this instead of the use of individual detectors or detector arrays with shadow masks as entrance pupil and in previous warning sensors a camera system with lens and image sensor (Focal Plane Array) before. This has the fundamental advantage that the direction of incidence of a laser threat is directly determined by mapping the environment onto the image sensor, and that the size of the entrance pupil can be set variably by the objective diameter together with the objective diaphragm. The entrance pupils of a camera system used in this case are far larger than the previous laser warning sensors.

However, this measure alone is not sufficient to differentiate laser sources from other sources in the environment. Therefore, the invention makes use of the two fundamental properties of a laser source, namely its spatial and temporal coherence, and uses a camera system with a superior coherence filter for its evaluation, which leads to different imaging of coherent and incoherent sources in the image plane of the camera. A laser threat is a radiation source with a high spatial coherence, because the image size of a laser source at a great distance from a camera is a point with an extent that corresponds to the limit of the imaging resolution of the camera.

However, since many incoherent sources of environment such. As sun reflections, stars, street lamps, vehicle lights, etc. appear at a greater distance even at a very small angle of view, and thus have a comparable with the laser source spatial coherence, the spatial coherence is not enough alone as a distinguishing feature. Therefore, in addition, temporal coherence is used to safely distinguish lasers from other sources.

The distinction of the temporal coherence, which is equivalent to the spectral bandwidth of the radiation, now takes place in the sense of the invention in that a spectrum analyzer arranged in front of the camera objective is provided which can be used as a linear holographic transmission grating, i. H. a grating is designed, which splits the images of the camera from point sources in line spectra whose length corresponds to the bandwidth of the source. With this additional device incoherent point sources are then displayed as a bar pattern, the temporally coherent laser point sources of the threats on the other hand still due to their low spectral bandwidth as a dot pattern. Areal incoherent or coherent sources continue to be rendered as diffuse images. To detect the image of the laser threat, a subsequent image processing, which is designed for the distinction of point and line or point in the diffuse background, then used.

The use of a linear grid (bar or strip grid), d. H. a 1-dimensional grid, facing a holographic cross lattice, d. H. a 2-dimensional grid, the decisive advantages of easier manufacturability, the higher by about a factor of 3 light intensity in the individual orders, the same hologram, the same lattice constant and the same atomic number and the considerably simpler image processing of the diffraction pattern. Apart from the fundamentally different interpretation of the linear grating, it brings a significant progress in comparison to the cross grid.

The basic function of a transmission bar screen is known to those skilled in the art. Is α ₀ the angle of incidence of a light beam in the plane of incidence perpendicular to the grating, then the light is diffracted by an angle α when passing through the grid. The diffracted light wave is focused with a lens and there are in the focal plane at the angles α _n in the orders n = 0, +/- 1, +/- 2, .... etc intensity maxima for the wavelength of the incident light λ with : sin α _n -sin α _o = nλ / g where g represents the lattice constant of the transmission grating. With α _o = 0 °, g = 4 microns, n = 1, z. B. α _n = 15.4 ° at λ = 1.06 microns and α _n = 12.3 ° at λ = 0.85 microns

• • Monochromatische Punktquellen werden als Punkte entlang einer Linie senkrecht zu den Streifen des Gitters als scharfe Intensitätsmaxima in der Bildebene, z. B. einer Kamera abgebildet, breitbandige Punktquellen hingegen als ausgedehnte Striche und können somit von einander unterschieden werden.
• • Flächenhafte breitbandige Lichtquellen erzeugen ein verschmiertes Mosaik über die ganze Bildfläche; die Hintergrundstrahlung wird dadurch über die ganze Bildfläche homogenisiert, was die Erkennung von punktförmigen Abbildungen von Laserquellen erleichtert. Flächenhafte schmalbandige Quellen, wie z. B. Reflexe in der unmittelbaren Umgebung des Sensors werden in ihrer Form als mehrfaches direktes Abbild in den verschiedenen Ordnungen in ihrer Intensität auf sie verteilt.
• • Die nullte Ordnung des Beugungsmusters liegt auf der Hauptachse der einfallenden Lichtwelle, geht also ohne Beugung durch das Gitter. Diese Richtung ist auch die Symmetrierichtung des Beugungsmusters höherer Ordnungen. Die Richtung zur Strahlungsquelle kann damit eindeutig aus dem Beugungsmuster ermittelt werden.
• • Der Beugungswinkel verschiebt sich mit der Wellenlänge nach der Formel Δα = n/g·Δλ/cosα, d. h. die zentrale Wellenlänge der Lichtquelle kann aus der Winkellage der Beugungsmaxima und die spektrale Bandbreite der Quelle aus der Winkelbreite der Spektrallinie bestimmt werden.
• • Bei höheren Ordnungen vervielfacht sich der Beugungswinkel. Bei kürzeren Gitterabständen vergrößert sich die Wellenlängenauflösung, gleichzeitig auch der Beugungswinkel.

When using a bar grating, the following properties are important:

• Monochromatic point sources are represented as points along a line perpendicular to the stripes of the grating as sharp intensity maxima in the image plane, e.g. B. a camera, broadband point sources, however, as extended dashes and thus can be distinguished from each other.
• • Area-wide broadband light sources create a smeared mosaic over the entire image area; The background radiation is thus homogenized over the entire image area, which facilitates the recognition of punctiform images of laser sources. Areal narrowband sources, such. B. Reflexes in the immediate vicinity of the sensor are distributed in their form as a multiple direct image in the various orders in their intensity on them.
• • The zeroth order of the diffraction pattern lies on the main axis of the incident light wave, thus passes through the grating without diffraction. This direction is also the symmetry direction of the diffraction pattern of higher orders. The direction to the radiation source can thus be determined clearly from the diffraction pattern.
• • The diffraction angle shifts with the wavelength according to the formula Δα = n / g · Δλ / cosα, ie the central wavelength of the light source can be determined from the angular position of the diffraction maxima and the spectral bandwidth of the source from the angular width of the spectral line.
• • At higher orders, the diffraction angle multiplies. With shorter lattice spacings, the wavelength resolution increases, as does the diffraction angle.

The following calculation examples show by way of example the effectiveness of the laser with Δλ = 1 nm Δα = 0.24 millirad. With a focal length of the camera lens of f = 8 mm, this corresponds to a linear extension of the image by Δx = 2 μm. Since the pixel size of a CCD camera is typically 5-7 μm, this bandwidth corresponds to one third of the diameter of an image pixel. An image of a reflection of the sun or a distant light bulb with Δλ = 250 nm in the near infrared between 850 nm to 1100 nm is then extended correspondingly over about 100 pixels in the focal plane of the camera. A technical source with a bandwidth of 25 nm or a point source with spectral lines of fluorescent tubes or light emitting diodes will cover as an image about 10 pixels in the first order and 20 pixels in the second order.

Since the linear magnification of incoherent point sources in the direction perpendicular to the grating strips is proportional to their bandwidth, their intensity in the first order is attenuated to the same extent. This also improves the intensity ratio between the laser source and the incoherent source in the same ratio in favor of the laser detection. With the calculation example from above this factor is in the first order, in the case of incandescent lamps already 1: 100 in the sun about 1:50 and with light diodes 1:10.

In some applications, a grating with a fixed grating pitch g and regular arrangement of the diffraction orders may be preferred. The use of a grating with two different grating constants g and g 'in the same grating, d. H. A bimodal lattice with only slightly different values for g and g 'leads to the formation of pairs of points in the orders +/- 1, +/- 2, .... etc. in coherent sources. But not in the zeroth order, in which no spectral decomposition takes place. Thus, such a grid is particularly advantageous for a clear distinction between the zeroth and higher orders and beyond to distinguish from electronic interference that may appear as points in the image. Using an even larger number of lattice constants may also be beneficial.

The pairs of points whose angular spacing in the various orders can be calculated by the above formula are e.g. B. preferably adjusted so that the points z. For example, in the first order, there may be only a few pixels (eg, a few nanometers) apart.

The grating gratings provided for the coherence detector are preferably so-called holographic gratings which can be written as master holograms by optical exposure or by electron beam lithography, from which hologram copies can then be made in high numbers at low cost using etching techniques, embossing technique or reexposure. Here there are two classes of holograms, first so-called surface relief holograms and second volume-phase holograms, with an incident wave at the first is diffracted by the differently long paths in the relief structure, and the second diffracted by structured variations of the refractive index.

Holograms of the first type can be incorporated in a variety of optical material carriers, such as glasses, plastics, photoresist or the like. Reflection gratings can be produced by additional metallization of the surface. By contrast, volume phase holograms can only be included in materials suitable for volume hologram exposure, such as silver halides, dichromated gelatin, or photopolymer as both transmission and reflection holograms.

It is understood that depending on the application of the invention different hologram types may be preferred.

For a coherence sensor according to the invention commercial lenses, standard lenses and wide-angle lenses can be used. In a standard lens with a viewing angle of 40 ° × 30 °, the grating hologram is preferably mounted directly in front of the lens. Parallel beams from a point source will then hit the lens after passing through the grating as a series of parallel beams of different angles, each parallel bundle being imaged by a coherent source as the point in the focal plane of the camera.

Depending on the angular position of the source, the entire diffraction pattern shifts with a parallel offset across the focal plane. The common axis of the orders is perpendicular to the grating and can be rotated arbitrarily with the grid against the main directions of the focal plane array. If the source lies on the edge of the field of view of the camera, then orders are still far within the field. If the source lies outside the field of view, then orders are bent into the field of view of the camera over a certain angular range and are imaged, i. H. the grid enlarges the field of view of the camera for point sources.

In many applications it is required that a laser warning sensor cover a complete half-space around military vehicles (180 ° × 360 °). For helicopters and airplanes even the whole hemisphere is required (360 ° × 360 °). So that a not too large number of sensors is needed for this wide coverage, the invention provides that with a wide-angle attachment optics (fisheye attachment), the angular range of a standard lens can be extended to 180 ° × 360 °. In this case, the grille is preferably mounted between the header and the standard lens. The inevitable image distortion of the intent then has no effect on the imaging of the diffraction orders by the standard lens, only the diffraction pattern as a whole then follows the distortion of the image field. Alternatively, another embodiment of a fisheye optic may be used which is not designed as a face optic of a standard lens but as a unitary optic of the camera. In this case, the grating can be integrated either before or between lenses of this optics.

The invention provides a further variant for increasing the angle of view, which dispenses with a wide-angle optics but has a redesign of the Strichgittervorsatzes. This may, for example, be a cylindrical grating with circular stripes mounted coaxially with the axis of a standard lens in front of it. This grid diffracts a portion of orders of rays outside the field of view into the field of view and thus they can be evaluated.

Advantageously, commercially available Si (silicon) CCD and CMOS cameras can be used for today's most important threats in the wavelength range 0.8 μm-1.1 μm. Because of the possible strong intensity of solar radiation in this wavelength interval, but the intensity of the threat can be very weak (10 ⁴ W / m ² ), it is necessary to provide cameras that have a very high optical dynamics of over 5 Leistungsdekaden. The task is made easier by the fact that the grid attenuates the intensity of the sun by a factor of 50 compared to a laser source alone. Commercially available CCD cameras with anti-blooming characteristics and highly dynamic CMOS cameras with stepwise adjustable integration time or a logarithmic characteristic curve are suitable for this purpose.

In the 1.1 μm-1.7 μm wavelength range, threats at 1.5 μm-1.6 μm are most prevalent, which can be covered with a commercially available InGaAs camera with the sensitivity range of 0.85 μm-1.7 μm ,

For the wavelength range 3-5 μm, infrared cameras with platinum silicide (Pt: Si) or indium antimonide (In: Sb) detectors and in the wavelength range 8-12 μm mercury cadmium telluride (HgCdTe) or microbolometer cameras based on amorphous silicon available in the market. Some of these detectors require additional cooling or temperature stabilization.

To evaluate the diffraction images, a suitable fast electronics (ASIC or FPGA) is advantageously provided, which is connected to the camera and which obtained Evaluates individual images in real time with an image processing algorithm implemented thereon.

The invention provides that the proposed sensor can be used both for continuous wave laser threats and pulsed laser threats, because in addition to the large receiving aperture, a camera has a long integration time of 10-50 ms and with the distribution of light reception to only a few orders z. B. 3-5 distributed a proportion of 20-33% remains in each pixel, which allows the detection of particularly faint modulated continuous wave sources.

The large receiving pupil additionally enables the detection of pulsed laser threat. Each pulse is recorded by the camera within its exposure time, because in modern cameras so-called dead times, which can arise during reading of the image sensor, are avoided. Thus, a continuous reception of the camera for short pulses is guaranteed. Because of the charge integration of the camera details such. For example, if the refresh rate is lost, but with a typical refresh rate of 20-60 Hz, the camera can distinguish between single-pulse threats (laser rangefinders) and threats with low pulse rates of 10-20 Hz (target illuminator) and determine the pulse rate. For recording higher frequencies in the kilohertz range, a higher refresh rate is required, which is also made possible by some cameras.

The invention provides that the refresh rate of the camera is sufficiently high to the movement of the threat within the viewing angle of the laser warning sensor, whether by the movement of the threat itself or by the movement of the platform on which the laser warning sensor is mounted. to track for a warning or countermeasures.

The invention further provides that either the laser warning sensor alone provides the necessary image information, or that the coordinates of the laser threat in the field of view based on other camera images of the same environment, eg. B. an identical camera without grid attachment, an IR camera or a night vision camera, are mirrored.

• – Suchen von Einzelpunkten im Gesamtbild gemäß lokaler Kriterien. Derartige Kriterien können sein: lokaler Kontrast, Rundheit des Punktes, Größe, etc. Bei den gefundenen Punkten wird das Zentrum mit Subpixel Genauigkeit bestimmt.
• – Suchen von möglichen Partnerpunkten im Bild, die zu einem gemeinsamen Beugungsmuster gehören könnten. Die Punkte eines solchen Beugungsmusters liegen relativ zueinander an exakt definierbaren Stellen im Bild. Bei einer gut vermessenen Kamera (d. h. Ausrichtung des Beugungsgitters und Verzeichnung des Kameraobjektivs werden exakt berücksichtigt) sind diese Stellen auf einige 1/10 Pixel genau bestimmbar. Durch die Subpixel genaue Bestimmung der Punktzentren können Fehlzuordnungen verhindert/vermindert werden.
• – Lokales Unterscheiden von Punkten 1. Ordnung von Punkten 0. Ordnung. Bei einem bimodalem Gitter bestehen die „Punkte” der 1. Ordnung (und höhere Ordnungen) aus Doppelpunkten. Das ergibt ein sehr wesentliches lokales Kriterium.

Furthermore, according to the invention, a method for image processing of the images obtained with the device according to claim 1 is provided, wherein the diffraction orders of the strip grid are imaged on the formed as areal matrix detector detector in the focal plane of the optics and connected to the detector electronic signal evaluation is designed such that distinction can be made between point-like and line-shaped luminous points of the diffraction order, the method comprising the following steps:

• - Search for individual points in the overall picture according to local criteria. Such criteria may be: local contrast, roundness of the point, size, etc. For the points found, the center is determined with subpixel accuracy.
• - Search for possible partner points in the image, which could belong to a common diffraction pattern. The points of such a diffraction pattern lie relative to each other at exactly definable points in the image. With a well-measured camera (ie alignment of the diffraction grating and distortion of the camera lens are considered exactly), these bodies can be determined to a few 1/10 pixels exactly. By subpixel accurate determination of the point centers misallocations can be prevented / reduced.
• - Locally distinguishing 1st order points from 1st order points. In a bimodal lattice, the "1st order" (and higher order) points consist of colons. This results in a very important local criterion.

Further measures improving the invention will be described in more detail below together with the description of preferred embodiments of the invention with reference to the figures. Show it:

1 The 0th, +/- 1st and 2nd order of a stripe lattice with a fixed lattice constant of a coherent laser source as points;

2 The 0th, +/- 1st and 2nd order of a stripe lattice with a fixed lattice constant of an incoherent source as a stripe;

3 The 0th, +/- 1st and 2nd order of a stripe lattice with two different fixed lattice constants of a coherent source as colons;

4 The 0th, +/- 1st, and 2nd order of a stripe lattice with two different fixed lattice constants of an incoherent source as a double stripe;

5a Cross-section of a sensor with a strip grid in front of standard optics;

5b Cross section of a sensor with a wide angle attachment in front of the strip grid and the standard optics;

6 Illustration of the 0th, +/- 1st, and 2nd order of a strip grid using a standard lens on the image sensor matrix;

7 The mapping of 0th, +/- 1st, and +/- 2nd order of a stripe grid using a panoramic look;

8a Cross-section of the beam path in the illustration of the + 1st, 0th and -1st orders through the standard objective strip grid;

8b Cross section of the beam path in the illustration of the + 1st, 0th and -1st orders through the strip grid with fisheye lens; and

8c Cross-section of the beam path when imaging the + 1th, 0th and -1st orders through the strip grid with a cylindrical strip grid attachment in front of the standard objective.

1 shows a device 1 for detecting, locating and tracking laser radiation sources, where the 0th, +/- 1st, and 2nd order of a strip grating 2 with a fixed lattice constant of a coherent laser source 8th as points with a camera lens as optics 3 on the focal plane detector array of the camera as a detector 4 are shown. In addition, the angle of incidence α _o and the diffraction angles α _{n of} the +/- 1-th and +/- 2-th order are plotted in the image.

2 shows a device 1 similar to the one in 1 shown at the 0th, +/- 1st and 2nd order of a strip grid 2 with a fixed lattice constant of an incoherent source as stripes with a camera lens on the focal plane detector array of the camera. In addition, the angle of incidence α ₀ and the diffraction angle α _n of +/- 1 th and +/- 2 nd order are plotted in the image.

3 shows a device 1 similar to the one in 1 shown at the 0th, +/- 1st and 2nd order of a strip grid 2 are formed with two different solid lattice constants of a coherent source as colons a and b in every order down to the 0th order.

4 shows a device 1 similar to the one in 3 shown at the 0th, +/- 1st and 2nd order of a strip grid 2 are formed with two different solid lattice constants of an incoherent source as double stripes a and b in each order except for the 0th order.

5a shows a cross section of a sensor with a strip grid 2 in front of a standard look 3 and 5b a cross section of a sensor with a front of the strip grid 2 and the standard optics 3 advanced wide angle attachment (fisheye attachment) 6 with the marginal rays of the image drawn up to the matrix sensor.

6 shows the mapping of 0 th, +/- 1 th and +/- 2 nd order of a strip grid using a standard objective onto the image sensor matrix (Focal Plane Array). Shown are some possible cases of mapping the orders, top twice in the image where all orders are mapped within the sensor matrix, the third case where the 0th order is just mapped to the edge of the matrix and only the -1th and -2 -th order lie within the sensor. The fourth case shows the limiting case where the second order hits the sensor. These borderline cases are still marked with a dashed line.

7 shows the mapping of 0th, +/- 1st, and +/- 2nd order of a stripe lattice using a panoramic optic consisting of a fisheye optics header placed on the lattice grating and a standard lens on the image sensor matrix. Plotted (gray) is the image field of the optics on the image sensor matrix with different angles of view to the optical axis of the optics and the mapping of the different orders of the stripe grid between the standard optics and the optics of coherent source for different cases of image position, with all or only some orders within the image field.

8a shows a cross section of the beam path in the mapping of the + 1, 0 and -1 orders by a strip grid 2 with standard lens 3 . 8b when pictured by a fisheye lens 6 and 8c when pictured by a cylindrical strip grid attachment 7 in front of the standard lens 3 ,

LIST OF REFERENCE NUMBERS

1

Device for detecting, locating and tracking laser radiation sources

2

strip grid

3

optics

4

detector

5

Image sensor matrix

6

Wide-angle attachment (fisheye lens)

7

Cylindrical strip grid header

8th

Laser radiation source

Claims (7)

Contraption ( 1 ) for the detection, localization and tracking of laser radiation sources ( 8th ) with an image field of an imaging optic ( 3 ) arranged radiation-sensitive detector ( 4 ) and one with the detector ( 4 ) electronic signal evaluation device, wherein between the laser radiation source ( 8th ) and the optics ( 3 ) a diffraction grating is arranged, such that the diffraction grating diffraction patterns are imaged on the detector in the focal plane of the optics, and in that the electronic signal evaluation means comprises recognition means for recognizing the punctiform images and for locating the direction; the laser radiation source of the diffraction pattern, characterized in that the diffraction grating is a grating formed as a surface relief or volume phase grating for point-like imaging of coherent laser radiation, wherein the height structure of the surface relief grating or the refractive index of the Volume phase grating is formed such that - the +/- 1-th and +/- 2-th diffraction order is formed in the grid and the remaining diffraction orders are suppressed, or - the + 1-th and + 2-th diffraction order in the Grating is created and the remaining diffraction orders are suppressed, or - the +/- 1-th diffraction order is created in the grating and the remaining diffraction orders are suppressed, or - the + 1-th diffraction order is formed in the grating and the remaining diffraction orders are suppressed. Contraption ( 1 ) according to claim 1, characterized in that in front of the grating ( 2 ) a wide-angle attachment or fisheye lens ( 6 ) is arranged. Contraption ( 1 ) according to claim 1, characterized in that the grating ( 2 ) as a cylindrical strip grid intent ( 7 ) is trained. Contraption ( 1 ) according to one of the preceding claims, characterized in that the grating ( 2 ) is designed as a transmission or reflection grating. Contraption ( 1 ) according to one of the preceding claims, characterized in that a grating ( 2 ) is provided only with a lattice constant, a lattice with two different lattice constants or a lattice with more than two different lattice constants. Contraption ( 1 ) according to one of the preceding claims, characterized in that a camera with standard objective as optics ( 3 ) and detector ( 4 ) is provided. Method for detecting, locating and tracking laser radiation sources with a device ( 1 ) according to one of claims 1 to 6, wherein the method comprises the following steps: - imaging of the diffraction orders of the strip grid ( 2 ) on the detector designed as a planar matrix detector ( 4 ) in the focal plane of the optics ( 3 ); - Detecting luminous points by the detector ( 4 ); - Distinguish between point-shaped luminous points, which image laser radiation sources, and line-shaped luminous points, which mimic other radiation sources, in the signal evaluation device; - Locating the direction of the laser radiation source from the diffraction pattern on the detector.

Images