Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Gregor Bern

Peter Nitz

Anna Heimsath

Peter Schoettl

Thomas Schmidt

De Wet Van Rooyen

Moritz Bitterling

Peter Schöttl

A method for determining relative degrees of reflectance of a measurement surface, having the method steps of applying measurement radiation to the measurement surface, such that a measurement spot is produced on the management surface, moving the measurement spot along at least a first straight measurement spot path, over the measurement surface in accordance with a first path movement and along a second straight measurement spot path with a second path movement, recording a first and second image sets of a plurality of locally resolved images of the measurement surface during the first path movement and the second path movement. An evaluation is carried out at intersection points, whose location points on the management surface are defined by evaluation lines, wherein a first group of straight evaluation lines within the first measurement path region and a second group of straight evaluation lines within the second measurement path region are predefined and/or determined. The evaluation lines of the first group are parallel to the first measurement spot path and the evaluation lines of the second group are parallel to the second measurement spot path, and each first group evaluation line has an intersection point with each second group evaluation line. For each intersection point, a maximum greyscale value is determined, and relative degrees of reflectance of the measurements surface are determined at least on a subset of the intersection points, depending on these greyscale values.

Method for determining relative degrees of reflectance of a measurement surface

A method for the optical determination of an intensity distribution, includes a) producing a spatially inhomogeneous radiation field of electromagnetic radiation; b) producing a first relative movement between a position-resolving image sensor and the radiation source with the radiation field moving along a first measurement path over a sensor field of the image sensor, so it is scanned by a first measurement path region of the radiation field; c) recording a first image set with position-resolved images of the radiation field during the first movement; d) producing a similar second relative movement between the image sensor and the radiation source, along a second measurement path not parallel to the first movement path; d) similarly recording a second image set during the second relative movement; e) evaluating the position-resolved images of the first and second image sets at least at points of intersection, the locations of which are defined by evaluation lines; and f) determining a relative intensity distribution based on points of intersection of the evaluation lines to characterize the image sensor and/or the radiation field.

Method for the optical determination of an intensity distribution

The invention relates to a calibration method for a group of reflectors for concentrating solar radiation onto a radiation receiver, having the following steps: A) aligning the reflectors in order to at least partly expose a calibration surface to solar radiation reflected by the reflectors; B) modifying the intensity distribution of the radiation incident on the calibration surface by carrying out a pattern of movements by each reflector of the group, wherein at least one specified parameter for the pattern of movements of each reflector differs from the parameters of the other reflectors, said parameter being selected from the group: &#x2014;movement frequency,&#x2014;movement amplitude,&#x2014;movement phase angle, and&#x2014;trajectory of the solar radiation, reflected by the reflector, within the calibration surface; C) recording rows of pixels for a plurality of differently located location points of the calibration surface by at least one camera, each row of pixel having at least five temporally offset pixel recordings; D) ascertaining a spectrum for each row of pixels by transforming the row of pixels into the frequency domain; E) assigning a subset of spectra to the reflectors on the basis of the movement pattern parameter of the reflector; and F) determining at least one reflection target position for each reflector at least on the basis of the subset of spectra assigned to the reflector. The invention additionally relates to a calibration device for a group of reflectors for concentrating solar radiation onto a radiation receiver.

Calibration method and calibration device for a group of reflectors for concentrating solar radiation onto a radiation receiver

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Freiburg, Germany

Gregor Bern