DEVICE AND METHOD FOR DETECTING AND/OR EVALUATING ARTICLES OR PRODUCTS

Abstract

A device for detecting or evaluating articles or products, irradiated by a laser beam, for generation of Raman or fluorescence radiation on surfaces of them, and generated radiation is directed to a detector array designed for locally resolved detection of the radiation. Monochromatic electromagnetic radiation with no influence on Raman or fluorescence radiation is directed at the articles or products. Detectors detect radiation reflected or scattered by articles or products in a locally resolved manner. An optical filter or beam splitter is arranged between articles or products and detector array. Irradiation and detection are carried out during relative movement between articles or products, focal range of the laser beam, diodes emitting electromagnetic radiation and detectors of the detector array. Detectors are connected to an electronic evaluation unit designed for locally and spectrally resolved evaluation of detected intensities of Raman or fluorescence radiation and for image analysis.

Claims

1. A device for detecting and/or evaluating articles or products, in which articles or products are irradiated by a laser beam emitted by a laser beam source so that Raman or fluorescence radiation is generated at surfaces of the articles or products, and the generated Raman or fluorescence radiation is directed towards a detector array designed for spatially resolved detection of this radiation, at least approximately monochromatic electromagnetic radiation, a central wavelength of which is selected such that there is no influence on the Raman or fluorescence radiation during detection, is directed towards the articles or products, over the surface or regions of the surface of the articles or products, and is emitted by a plurality of diodes emitting this electromagnetic radiation, and detectors of the detector array are designed for the spatially resolved detection of electromagnetic radiation reflected or scattered by the articles or products, an optical filter or a beam splitter is arranged between the articles or products and the detector array and is designed such that electromagnetic radiation with the wavelength of the laser beam does not impinge on the detectors of the detector array; wherein the irradiation and detection are performed during a relative movement between the articles or products, a focal range of the laser beam, diodes emitting the electromagnetic radiation, and the detectors of the detector array, and at least the detectors of the detector array are connected to an electronic evaluation unit, and the electronic evaluation unit is designed for spatially and spectrally resolved evaluation of intensities of the Raman or fluorescence radiation detected by the detectors of the detector array and for carrying out an image analysis for determining shape, color or surface recognition of individual articles or products.

2. The device according to claim 1, wherein the laser beam is directed with a reflective element, pivotable or rotatable about at least one axis, or by means of a linear optical lens across the width in which the articles or products are arranged.

3. The device according to claim 1, wherein the electronic evaluation unit is designed to recognize spectral intensity differences of intensities of at least one wavelength detected by detectors or is designed to extract parameters by means of a multivariate data analysis, by a principal component analysis, discriminant analysis, support vector method, a neural network, a cluster analysis, or random forest method.

4. The device according to claim 1, wherein a reflective element that is pivotable about at least one axis or that is rotatable about a rotation axis is designed or controllable such that the focus of the beam moves in the event of the generation of Raman or fluorescence radiation at a frequency that is greater than the frequency at which detection is performed.

5. A method for detecting or evaluating articles or products irradiated by a laser beam emitted by a laser beam source such that a generation of Raman or fluorescence radiation is achieved at surfaces or regions of a respective surface of the articles or products, directing the generated Raman or fluorescence radiation towards a detector array designed for the spatially and spectrally resolved detection of this radiation, and emitting at least approximately monochromatic electromagnetic radiation by a plurality of diodes directed towards the articles or products, a central wavelength of said radiation being selected such that there is no influence on the Raman or fluorescence radiation during detection, and arranging an optical filter or a beam splitter between the articles or products and the detector array to prevent electromagnetic radiation with the wavelength of the laser beam from impinging on detectors of the detector array; wherein irradiation and detection are performed during a relative movement between the articles or products, a focus range of the laser beam, the diodes emitting electromagnetic radiation, and detectors of the detector array, and connecting at least the detectors of the detector array which are designed for spatially and spectrally resolved detection of the articles or products, the Raman or fluorescence radiation and reflected and scattered electromagnetic radiation to an electronic evaluation unit, and the electronic evaluation unit, is designed for spatially and spectrally resolved evaluation of intensities detected by detectors of the detector array, to evaluate the Raman or fluorescence radiation detected in a spatially resolved manner and also to perform an image analysis for determining shape, color or position recognition of individual articles or products.

Description

DESCRIPTION OF THE DRAWING

[0053] In the drawing:

[0054] FIG. 1 shows an example of a device according to the invention in a schematic depiction.

DESCRIPTION OF THE INVENTION

[0055] In FIG. 1 merely the optical part of the device is shown and the depiction of the electronic evaluation unit has been omitted.

[0056] A laser beam 1 with a wavelength of 532 nm is directed by means of a laser radiation source 2 over a stream comprising products 3 via an element 6 which is pivotable about an axis and which reflects the laser beam 1. The focus of the laser beam 1 is directed here over the entire width of the stream, which is formed by the products 3 and moves in one direction. The focus moves here perpendicularly to the direction of movement of the stream. As a result of this irradiation, Raman scattering is generated and/or fluorescence radiation is excited.

[0057] At the same time, the stream is irradiated linearly by electromagnetic radiation, which is emitted by an arrangement of diodes 7 in a row. This electromagnetic radiation has a central wavelength of 850 nm and a scattering around this wavelength of ±10%. This irradiation is preferably performed in the region of the surfaces of the products 3 in which Raman scattering or fluorescence radiation is no longer detected.

[0058] Above the irradiation region, there is arranged a detector array 4, which is formed with a plurality of detectors arranged in rows or in rows and columns. The detectors are designed such that they enable a spatially and spectrally resolved detection of intensities.

[0059] A spectral, spatially resolved analysis and a spatially resolved image analysis are thus possible.

[0060] The measurement signals of the individual detectors are supplied to an electronic evaluation unit (not shown), by means of which an assessment of products 3, for example made of specific materials or having specific shapes or colors/color combinations, may be performed.

[0061] In order to enable a practically undisturbed detection of the measurement signals, an optical filter 5 is arranged between the region irradiated by the laser beam 1 and the detector array 4, by means of which filter it is possible to prevent reflected and scattered laser radiation from impinging on the detectors of the detector array 4 and possibly negatively influencing the actual measurement signals. The optical filter 5 in this example is an edge filter which is practically fully transparent only for electromagnetic radiation with wavelengths greater than 532 nm.

[0062] The evaluation may be performed by means of a PC. The data detected by the detector must be transmitted via a sufficiently fast data connection. The software must be capable of evaluating the data with the speed of the detection. The approach for evaluation may be fixedly defined as a “formula” or will have been freely defined beforehand. Ideally, only the results of the evaluation are stored; the original data are discarded. Besides the results of the recognition, further data such as location information and timestamp may also be detected and forwarded.