The invention relates to a method for calibrating an optical measurement set-up having a measuring volume (10) and a plurality of cameras (141, 142, 143) by means of which object points (12) in the measuring volume (10) can be imaged onto image points (201, 202, 203) of corresponding camera images (161, 162, 163). Such imaging can be described mathematically by a base imaging function known from a pre-calibration. The method comprises: a) simultaneously imaging the measuring volume (10) by means of the cameras (141, 142, 143); b) identifying the image points (201, 202, 203) which are assigned to an object point (12) imaged on each camera image (161, 162, 163); c) determining an approximated object point (24) which best corresponds to the imaged object point (12) at the imaging time; d) calculating a difference vector (28) which is representative of an error of the base imaging function with respect to the imaged object point (12); and e) providing an extended imaging function comprising the base imaging function and a correction vector field, wherein the correction vector field consists of a grid of support points (32) to which correction vectors (30) are assigned by which points which correspond to the support points (32) and to which the imaging function can be applied in the context of measurement data evaluation are to be shifted locally in addition to applying the base imaging function.
The invention relates to a method for detecting primary gas flows (18) in flow chambers (10), wherein the primary gas (18) flowing in a flow chamber (10) is locally seeded with a seed, and its movement representative of the flow of the primary gas (18) is imagingly detected by means of an image detector (28) comprising imaging optics (30) connected upstream. The invention is characterised in that a gas mixture (34) that moves together with the primary gas (18) in a manner free of relative movement is used as the seed, which gas mixture has a refractive index that is distinguishable from the primary gas (18), and the imaging detection is carried out by means of a background schlieren measurement method.
B08B 15/02 - Précautions prises pour empêcher les crasses ou les fumées de s'échapper de la zone où elles sont produites; Ramassage ou enlèvement des crasses ou fumées de cette zone par utilisation de chambres ou de hottes recouvrant cette zone
F24F 3/163 - Postes de travail en air pur, c. à d. zones sélectionnées à l'intérieur d'une enceinte dans lesquelles de l’air filtré est acheminé
G01P 5/00 - Mesure de la vitesse des fluides, p.ex. d'un courant atmosphérique; Mesure de la vitesse de corps, p.ex. navires, aéronefs, par rapport à des fluides
G01P 5/26 - Mesure de la vitesse des fluides, p.ex. d'un courant atmosphérique; Mesure de la vitesse de corps, p.ex. navires, aéronefs, par rapport à des fluides en mesurant l'influence directe du courant de fluide sur les propriétés d'une onde optique de détection
G01N 21/15 - Prévention de la souillure des éléments du système optique ou de l'obstruction du chemin lumineux
3.
METHOD FOR CALIBRATING AN OPTICAL MEASUREMENT SET-UP
The invention relates to a method for calibrating an optical measurement set-up with a measurement volume (V) inoculated with particles and with at least two cameras (K1, K2, K3), by means of which the measurement volume (V) can be photographed from different observation angles, in each case with an imaging function known from a pre-calibration, said method comprising the following step: a) simultaneously photographing the measurement volume (V) by means of the cameras (K1, K2, K3) in order to produce a camera image (1, l2, l3) for each camera (K1, K2, K3). The invention is distinguished by the further following steps: b) rectifying each camera image (l1, l2, l3) in relation to a common reference plane in the measurement volume (V) with use of the associated, pre-calibrated imaging function, c) performing a two-dimensional correlation for at least one pair of rectified camera images (lr1, lr2, lr3) in order to produce a corresponding number of correlation fields (C12), wherein each correlation field (C12) presents an elongate correlation maxima band, d) for each correlation field (C12): d1) reducing the correlation maxima band to a straight line representative of it (g12), d2) determining the distance (d12) of these representative straight lines (g12) from the coordinate origin of the correlation field (C12) as correction value, e) using the determined correction values to correct the imaging functions of those cameras (K1, K2, K3) for which rectified camera images (lr1, lr2, lr3) were included in the correlation in step c.
G06T 7/80 - Analyse des images capturées pour déterminer les paramètres de caméra intrinsèques ou extrinsèques, c. à d. étalonnage de caméra
G01P 5/20 - Mesure de la vitesse des fluides, p.ex. d'un courant atmosphérique; Mesure de la vitesse de corps, p.ex. navires, aéronefs, par rapport à des fluides en mesurant le temps mis par le fluide à parcourir une distance déterminée en utilisant des particules entraînées par un courant de fluide
4.
DEVICE FOR GENERATING TEMPORALLY OFFSET, SPATIALLY MODULATED ILLUMINATION REGIONS
The invention relates to a device for generating temporally offset, spatially modulated illumination regions (22, 22') having periodic modulation patterns that are phase-shifted with respect to one another, comprising – two pulsed laser sources (121, 122), which are triggerable in a manner temporally offset with respect to one another and serve for generating two laser beams pulsed in a temporally offset manner, – intensity modulation means (16) for the spatially periodic intensity modulation of the laser beams perpendicular to the direction of propagation thereof, – beam superimposing means (126) for combining the beam paths of the laser beams in a common beam path section and – beam shaping means (20, 20') for illumination region shaping. The invention is distinguished by the fact that in the common beam path section – the laser beams combined by the beam superimposing means (126) are differently polarized and – the intensity modulation means are arranged upstream of an optically anisotropic beam splitter (18).
The invention relates to a method for ascertaining a spatial displacement vector field ((dx, dy, dz)) of a test object. At least one projection pattern image, which is captured by illuminating the test object with a spatially modulated projection pattern projected onto the test object, is captured from the test object and compared with a reference. The invention is characterized in that a) a combination of a first mathematical function (P(x-dxp, y-dyp)) and a second mathematical function (S(x-dxs, y-dys)) of surface variables (x, y) is generated as a mathematical model of the projection pattern image, wherein a1) the first mathematical function (P(x-dxp, y-dyp)) is a mathematical model of the projection pattern distorted about a first planar displacement vector field ((dxp, dyp)) and a2) the second mathematical function (S(x-dxs, y-dys)) is a mathematical model of a reference image distorted about a second planar displacement vector field ((dxs, dys)), said reference image being captured as a pattern image which is particular to the test object at a reference time (tref), b) the planar displacement vector fields ((dxp, dyp), (dxs, dys)) are varied using a mathematical error minimization method until the mathematical model of the projection pattern image matches the captured projection pattern image, and c) the spatial displacement vector field ((dx, dy, dz)) is calculated from the varied planar displacement vector fields ((dxp, dyp), (dxs, dys)) resulting in the match in step b.
G01B 11/16 - Dispositions pour la mesure caractérisées par l'utilisation de techniques optiques pour mesurer la déformation dans un solide, p.ex. indicateur optique de déformation
Determination of a spatial displacement vector field (300) of a test object (10), in which images of two types are recorded from the test object (10), specifically - at least one inherent pattern image (100, 100F), during the recording of which the test object (10) is illuminated with uniform illumination light, and - at least one projection pattern image (200, 200F), during the recording of which the test object (10) is illuminated with a spatially modulated projection pattern projected onto the test object, wherein - a planar displacement vector field (110, 110F) of the test object (10) is calculated from the inherent pattern image (100, 100F) at the time of recording the inherent pattern image (100, 100F) as a representation of the test object (10) assigned to the inherent pattern image (100, 100F) and - a form (210, 210F) of the test object is calculated from the projection pattern image (200, 200F) at the time of recording the projection pattern image (200, 200F) as a representation of the test object (10) assigned to the projection pattern image (200, 200F), and wherein the spatial displacement vector field (300) is determined from the representations of the test object (10) which are assigned to the recorded images (100, 100F; 200, 200F).
G01B 11/16 - Dispositions pour la mesure caractérisées par l'utilisation de techniques optiques pour mesurer la déformation dans un solide, p.ex. indicateur optique de déformation
G01B 11/25 - Dispositions pour la mesure caractérisées par l'utilisation de techniques optiques pour mesurer des contours ou des courbes en projetant un motif, p.ex. des franges de moiré, sur l'objet
7.
METHOD FOR ASCERTAINING A CHANGING SPATIAL DISTRIBUTION OF PARTICLES AT MULTIPLE POINTS IN TIME
DEUTSCHES ZENTRUM FÜR LUFT- UND RAUMFAHRT E.V. (Allemagne)
LAVISION GMBH (Allemagne)
Inventeur(s)
Schröder, Andreas
Schanz, Daniel
Wieneke, Bernhard
Abrégé
The invention relates to a method for ascertaining a changing spatial distribution of particles (1) at multiple points in time (tn-2, tn-1, tn) which follow one another at intervals, said method having the following steps for each point in time (tn-2, tn-1, tn): (i) capturing real two-dimensional images of the particles (1) at the point in time (tn-2, tn-1, tn) with differently effective imaging functions; (ii) specifying an estimated spatial distribution of the particles (1); (iii) calculating virtual two-dimensional images of the estimated spatial distribution with the different imaging functions; (iv) detecting differences (5) between the virtual two-dimensional images and the real two-dimensional images with the same imaging functions; and (v) changing the estimated spatial distribution of the particles (1) to reduce the differences (5) in order to obtain a spatial distribution which approximates the actual spatial distribution of the particles (1) at the point in time (tn-2, tn-1, tn). The estimated spatial distribution of the particles (1) is specified for at least one point in time (tn) in which the positions of the individual particles (1) in an approximated spatial distribution obtained for an earlier point in time (tn-1) are moved depending on how the particle positions have been moved between spatial distributions approximated for at least two earlier points in time (tn-2, tn-1).
G01P 5/00 - Mesure de la vitesse des fluides, p.ex. d'un courant atmosphérique; Mesure de la vitesse de corps, p.ex. navires, aéronefs, par rapport à des fluides
G01P 5/20 - Mesure de la vitesse des fluides, p.ex. d'un courant atmosphérique; Mesure de la vitesse de corps, p.ex. navires, aéronefs, par rapport à des fluides en mesurant le temps mis par le fluide à parcourir une distance déterminée en utilisant des particules entraînées par un courant de fluide
8.
METHOD FOR DETERMINING A SET OF OPTICAL IMAGING FUNCTIONS FOR THREE-DIMENSIONAL FLOW MEASUREMENT
The invention relates to a method for determining a set of optical imaging functions, which describe the imaging of a measuring volume onto each of a plurality of detector surfaces on which the measuring volume can be imaged at in each case a different observation angle by means of detector optics. In addition to assigning an image position (x, y) to each volume position (X, Y, Z), according to the inventive method the shape of the imaging of a punctiform particle in the measuring volume is described by a shape parameter (a, b, φ, I) and for each detector surface the corresponding set of shape parameter values is assigned to each volume position (X, Y, Z).
The invention relates to a method for determining flow conditions in a measured volume permeated by a fluid spiked with optically detectable particles. A plurality of two-dimensional images of the particle distribution is thereby created at each of a plurality of times, an estimated particle distribution is determined therefrom, and a three-dimensional displacement vector field is calculated. According to the invention, a transfer function for the image detectors used is first determined, by means of which the real distribution is mapped by the image detector. Starting from a roughly estimated initial distribution, and by means of the transfer function, virtual images of the estimated distribution are then calculated and compared to the associated real images. The estimated distribution is modified in an iterative method until sufficient matching of the virtual and real images has been achieved.
G01P 5/00 - Mesure de la vitesse des fluides, p.ex. d'un courant atmosphérique; Mesure de la vitesse de corps, p.ex. navires, aéronefs, par rapport à des fluides
10.
METHOD FOR THE CONTACT-FREE MEASUREMENT OF DEFORMATIONS OF A SURFACE OF A MEASURED OBJECT
The invention relates to a method for the contact-free measurement of deformations of a surface of a measured object in which a series of individual images is captured in each of two time windows (T1, T2), wherein the image detector is displaced relative to the measured object and parallel to the detector surface thereof by an optical offset of the size of a fraction of a pixel up to a few pixels between every two individual image captures, the individual images of the first time window (T1) are processed in pairs with the individual images of the second time window (T2) to produce a set of individual deformation fields (18) and an average of the individual deformation fields (18) is calculated as an output deformation field (20).
G01B 11/16 - Dispositions pour la mesure caractérisées par l'utilisation de techniques optiques pour mesurer la déformation dans un solide, p.ex. indicateur optique de déformation
brevets
