Apparatus and method for optically characterizing materials

Patent metadata

Field	Value
Publication number	US-2016054217-A1
Application number	US-201514837012-A
Country	US
Kind code	A1
Filing date	Aug 27, 2015
Priority date	Sep 24, 2010
Publication date	Feb 25, 2016
Grant date	—

Abstract

The present invention relates to a device for optical characterisation of a sample and/or of the material(s) of the same having an illumination unit that can be orientated to illuminate with incident light a sample spatial portion into which the sample can be introduced, a detection unit which is orientated or can be orientated to image the sample introduced into the sample spatial portion by receiving light reflected by the sample, and which is configured to detect at least two different, preferably orthogonal, polarization components in the reflected light, and an evaluation unit with which, in the imaging data recorded by the detection unit, those imaged surface elements (reflection elements) of the sample can be identified, and with which the detected different polarization components for these reflection elements can be evaluated for optical characterisation.

First claim

What is claimed is:

1 . A device for optical characterisation of a sample and/or of the material/materials of the sample, the device comprising:
an illumination unit which is capable of being orientated to illuminate with incident light a sample spatial portion into which the sample can be introduced, a detection unit which is capable of being orientated to image the sample introduced into the sample spatial portion by receiving light reflected by the sample, and which is configured to detect at least two different polarisation components in the reflected light, and an evaluation unit with which, in the imaging data recorded by the detection unit, those imaged surface elements being reflection elements of the sample can be identified, the reflected, received light of which is based on a reflection of the incident light on the sample, and with which the detected different polarisation components for these reflection elements is evaluated for optical characterisation.

2 . The device according to claim 1 , wherein the reflection elements can be identified with the evaluation unit, before the detected different polarisation components are evaluated and/or on the basis of the identified reflection elements, or in that polarisation components of imaged surface elements, which are detected with the evaluation unit are evaluated in order to determine the reflection elements of the sample before the detected different polarisation components for the thus determined reflection elements are evaluated for optical characterisation.

3 . The device according to claim 1 , wherein differentiation, for identifying the reflection elements, of reflection elements and of imaged surface elements being scattered elements of the sample, the reflected, received light of which is based other than on a reflection of the incident light on the sample, is effected on the basis of intensity of imaging data of one, of a plurality, or of all of the detected polarisation components, is effected using intensity differences and/or intensity ratios of the different detected polarisation components and/or on the basis of the total intensity of the detected polarisation components,
and/or is effected on the basis of the position of the image of surface elements of the sample in one or in a plurality of image(s) of the sample, produced by the detection unit, relative to each other and/or relative to one or more reference point(s) of the image/images of the sample.

4 . The device according to claim 1 , wherein the detected different polarisation components for one or more of the reflection elements is evaluated for optical characterisation by forming one or more ratio(s) of two of the different polarisation components which are detected for the respective reflection element.

5 . The device according to claim 1 , wherein the angle between the detection unit and/or the optical axis thereof, on the one hand, and the illumination unit and/or the optical axis thereof, on the other hand, in the triangle which is spanned by firstly the detection unit, secondly the illumination unit and thirdly the sample spatial portion, in particular the centre and/or centroid thereof, and/or the sample, is less than 180°, and/or
in that there can be identified as reflection elements, those surface elements, the normal of which bisects the above-mentioned angle.

6 . The device according to claim 5 , wherein the device for optical characterisation of a defined material of the sample is capable of being configured by adjustment of the angle to twice the Brewster angle of this material.

7 . The device according to claim 1 , wherein the illumination unit comprises an individual illumination element
or wherein the illumination unit comprises a plurality of individual illumination elements which are capable of being orientated to illuminate the sample spatial portion with incident light from different directions, in addition preferably at least one of the following features, being produced in combination with each other:
the angle between the detection unit and/or the optical axis thereof, on the one hand, and the illumination element and/or the optical axis thereof, on the other hand, in the triangle which is spanned by firstly the detection unit, secondly the illumination element and thirdly the sample spatial portion, in particular the centre and/or centroid thereof, and/or the sample (P), is identical in all the illumination elements;
the illumination unit comprises two or four individual illumination elements;
the illumination elements are disposed on the side of the sample spatial portion and/or of the sample, situated opposite the detection unit, and also in a plane orientated perpendicular to the optical axis of the detection unit; the illumination unit comprises a plurality of individual illumination elements which are disposed at equidistant angle spacings, wherein, in the case of four illumination elements at angle spacings of 90°, on a circle about the optical axis of the detection unit; or at least one of the illumination elements, viewed relative to the detection unit and/or the optical axis thereof, are disposed such that, for the illumination element(s) and/or the optical axis(axes) thereof, angle ratios apply as are described in claim 5 for the illumination unit.

8 . The device according to claim 1 , wherein the device is configured for surface testing of a sample, in that the device is configured for characterisation, differentiation, and/or separation of individual elements of a sample comprising a large number of elements or in the form of a bulk material flow,
and/or in that the device is configured for identifying and sorting of samples and/or of elements of the same which deviate from an established value(s) in one or more predefined material parameter(s).

9 . The device according to claim 8 , wherein the sample spatial portion is configured as a free flight- or falling stretch part or as a conveyer belt portion of a bulk material sorting plant comprising the device.

10 . The device according to claim 1 , wherein the device is configured as laser scanner having one or more laser(s), in particular with (a) laser(s) emitting in the wavelength range between 380 nm and 780 nm, as illumination unit and/or illumination element(s) scanning the sample spatial portion and/or the sample, and having a receiver as detection unit which is suitable for receiving the laser light reflected by the sample
or in that the device comprises as illumination unit or as illumination element(s), one or more monochromatic light source(s) and as detection unit, at least one camera.

11 . The device according to claim 1 , wherein the detection unit and/or the illumination unit is/are constructed according to one of the following features:
the detection unit comprises two individual cameras and a polarising optical element, in particular a polarising prism or a polarising beam splitter, which is disposed in the beam path in front of the individual cameras, with which polarising optical element the light reflected by the sample is split into two different polarisation components and with which respectively the light of one of the two polarisation components is directed towards one of the two individual cameras; the detection unit comprises a multiline camera and a number of polarisers which correspond to the number of lines of the camera and are disposed in the beam path in front of the camera, respectively alternately differently orientated polarisers being disposed in front of successive lines of the camera and directing the light reflected by the sample towards the camera line assigned respectively to them; the detection unit comprise

Assignees

• Fraunhofer Ges Forschung

Inventors

• Hartrumpf Matthias

Classifications

• G01N2201/06113

  Coherent sources; lasers · CPC title

• G01N2201/0438

  Linear motion, sequential · CPC title

• G01N21/84

  Systems specially adapted for particular applications · CPC title

• G01N2021/845

  Objects on a conveyor · CPC title

• G01N21/21 Primary

  Polarisation-affecting properties (G01N21/19 takes precedence) · CPC title