Sensor for detecting and localising laser beam sources

Abstract

A sensor for detecting and localizing laser beam sources, includes a beam-sensitive detector which is arranged in the image field of an imaging optic, an electric image processing device which is connected to the detector, and an optical diffraction element which is arranged in the beam path. The diffraction properties of the optical diffraction element are such that incident laser light on different wavelength bands produce diffraction patterns with different shapes, and the electronic image processing device is designed such that it can detect and evaluate the different forms of the diffraction pattern.

Claims

1. A sensor for detecting and localizing laser radiation sources, comprising: a radiation-sensitive detector arranged in an image field of an imaging optical unit; an electronic image processing device coupled to the radiation-sensitive detector; and an optical diffraction element arranged in a beam path, wherein diffraction properties of the optical diffraction element are designed such that incident laser light in different wavelength bands produces diffraction patterns of different forms, wherein the different forms of the diffraction patterns that are associated with individual wavelength bands differ by way of a rotation about a same axis of rotation, the electronic image processing device is configured to detect and evaluate the different forms of the diffraction patterns, and the diffraction properties of the optical diffraction element are configured such that: a size of the diffraction pattern at a maximum wavelength of a wavelength band is substantially the same for all wavelength bands, and a size of the diffraction pattern at a minimum wavelength of a wavelength band is substantially the same for all wavelength bands.

2. The sensor according to claim 1, wherein the axis of rotation is an axis of symmetry.

3. The sensor according to claim 1, wherein the optical diffraction element is a kinoform.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained with respect to concrete exemplary embodiments with reference to figures, in which:

(2) FIG. 1 illustrates the diffraction image of a conventional optical diffraction element at minimum and maximum wavelengths, as described in the introduction of the description;

(3) FIG. 2 illustrates two different diffraction images from different wavelength bands according to an embodiment of the invention; and

(4) FIG. 3 illustrates a cross section through an apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 2 shows an example of the production of two different diffraction patterns in two different wavelength bands (not to scale with FIG. 1). These are intended to be produced with the same diffraction element. The two diffraction patterns differ from one another in that they are rotated with respect to one another by 45° about the axis of symmetry. An image processing system recognizes this rotation and associates the diffraction patterns with the respective wavelength band. Moreover, it is possible to determine the laser wavelength by using the spacing of the diffraction orders within the diffraction pattern. What can also be seen is that, although the diffraction patterns were produced at different wavelengths, the extent of the diffraction patterns remains the same.

(6) The solution according to the invention is associated with a change in the geometry of the diffraction patterns, in delineation to a pure change in size. For example, different symbols, numbers, digits, etc. can be used for the different wavelength bands. It would also be possible to vary the number of image points in a point grid.

(7) FIG. 3 shows, by way of example, the construction of an apparatus according to an embodiment of the invention. It includes in the beam path an optical diffraction element 10 in front of a standard optical unit 20 and a detector 30 with an image field matrix 31. The detector 30 is connected to an image processing device 40 which detects the diffraction patterns produced by the diffraction element 10 on the image field matrix 31 and associates it with a specific wavelength band.

(8) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.