WO2009152930A1 - Procédé de mesure stroboscopique et dispositif correspondant - Google Patents

Procédé de mesure stroboscopique et dispositif correspondant Download PDF

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Publication number
WO2009152930A1
WO2009152930A1 PCT/EP2009/003723 EP2009003723W WO2009152930A1 WO 2009152930 A1 WO2009152930 A1 WO 2009152930A1 EP 2009003723 W EP2009003723 W EP 2009003723W WO 2009152930 A1 WO2009152930 A1 WO 2009152930A1
Authority
WO
WIPO (PCT)
Prior art keywords
radiation
stroboscopic
measuring method
reflected
wavelength
Prior art date
Application number
PCT/EP2009/003723
Other languages
German (de)
English (en)
Inventor
Peter Peuser
Klaus Schertler
Original Assignee
Eads Deutschland Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eads Deutschland Gmbh filed Critical Eads Deutschland Gmbh
Publication of WO2009152930A1 publication Critical patent/WO2009152930A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/245—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using a plurality of fixed, simultaneously operating transducers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/50—Systems of measurement based on relative movement of target

Definitions

  • the present invention relates to a stroboscopic measuring method for measuring changes in shape and / or position of an object in space.
  • a radiation source is provided, with which the pulsed radiation is provided and directed at the object, wherein the radiation reflected by the object is detected by detecting means for determining the changes in shape and / or position.
  • Stroboscopic measuring methods are suitable for measuring changes in the shape and / or position of an object in space, wherein the changes in shape and / or position of the object take place very quickly and comprise very small path distances that can not be detected with conventional imaging measurement methods. Consequently, both very small changes in position of the object in the room must be detected by measurement, whereby a change in shape of the object itself must be detected by stroboscopic measurement.
  • Such changes in shape result, for example, in vibration-excited objects, as can be observed in jet engines of aircraft in operation.
  • the vibration behavior of blade elements of aircraft engines may be mentioned, which may have natural oscillations during operation and which must be detected by measurement.
  • the Scherlick can be called, whose method is based on the measurement of mechanical deformation of the object surface. From this defects can be detected in the material, which also allows a quantitative assessment of the defects and their monitoring, since the deformations of the object in connection with mechanical, strength-relevant properties such as stiffness and damping of the object stand.
  • the present method utilizes a radiation source to provide pulsed radiation, the radiation source being mostly a laser beam source.
  • the laser beam source emits pulsed radiation with a high repetition rate, which describes the number of laser pulses emitted per unit of time.
  • the pulsed radiation is directed at the object whose surface reflects it.
  • the reflected radiation can be detected with recording means, wherein the changes in shape and / or position of the object are reflected in the behavior of the reflected radiation.
  • the reflected radiation is recorded by a camera, these image sequences of the object reflecting the spatial changes of the object.
  • images of an object can be virtually frozen.
  • the disadvantage is that the temporal resolution of the spatial changes is limited by the repetition rate of the laser and the image processing time of the optical camera. Consequently, not only the minimum detectable pulse duration of the individual pulse is to be mentioned as a limiting factor, since the repetition rate of the laser is limited and the required image processing time of the optical camera limits the number of detectable images per unit time.
  • the object of the present invention to further develop a stroboscopic measuring method for measuring changes in shape and / or position of an object in space in such a way that it is possible to measure changes in shape and / or position of an object in space with high temporal resolution.
  • the present invention relates to a stroboscopic measuring device for measuring the changes in shape and / or position of the object in space.
  • a radiation source is provided which provides pulsed radiation and which is directed onto the object, wherein radiation reflected from the object for detecting the changes in shape and / or position via recording means are detectable.
  • first means are provided which provide the radiation directed at the object in terms of length and time, wherein second means are provided with which the reflected radiation can be allocated to a plurality of recording means in a wavelength-discrete and time-discrete manner.
  • the first means are formed by beam splitters, with which the radiation can be divided into a plurality of partial beams, which pass through different path lengths, wherein the first means further comprise optically non-linear materials with which the partial beams are wavelength-transformable. Due to the different path lengths, the individual pulses can be converted into a pulse sequence, which have the same distances from each other by a suitable choice of the extension of the path lengths. The emitted individual pulses can be in the picosecond range or in the Femtosecond range, so that the required difference in the path length of the individual pulses within the pulse sequence is technically feasible, for example, with an optical table in a limited space.
  • the second means are formed by a filter arrangement which distributes the radiation reflected by the object wavelength-discretely to a plurality of associated cameras.
  • an image processing unit which compares the color-coded images of the cameras with each other and generates an image sequence thereof.
  • the invention includes the technical teaching that the radiation directed to the object is provided wavelength-and time-coded, and means are provided with which the reflected radiation is allocated to a plurality of recording means in a time- and wavelength-dependent manner.
  • the wavelength- and time-coded provision of the pulsed radiation affords the possibility of providing an image sequence of the object which has more images per unit of time than corresponds to the repetition rate of the pulsed radiation.
  • the wavelength encoding effects different wavelengths into which the single pulse emitted by the radiation source is transferred. Consequently, the individual pulse comprises a plurality of colors, the time coding describing a succession of the color-separated pulses of a pulse sequence.
  • the radiation source is preferably a single laser beam source, which initially emits single pulses of a discrete wavelength.
  • the individual pulses are converted into pulse trains, with successive pulse sequences describing the repetition rate of the laser beam source.
  • the number of available frames per Time unit increased by the factor resulting from the number of pulses into which the individual pulses emitted by the laser are transferred.
  • the wavelength and time coding of the radiation directed to the object also results for the reflected radiation. Therefore, according to the invention, means are provided by which the pulses can be allocated to a plurality of recording means in a wavelength-dependent manner.
  • the means for the wavelength and time coding of the radiation directed to the object can be arranged either in the radiation source itself or in the beam path between the radiation source and the object.
  • the means which are provided to allocate the reflected radiation to a plurality of receiving means are arranged in the region of the beam path which extends between the object and the receiving means. Consequently, both a conventional radiation source and conventional recording means, for example in the form of cameras can be used, wherein not a camera but a plurality of cameras are provided, the wavelength-dependent to detect the reflected radiation.
  • both the first means for wavelength and time coding of the radiation directed at the object and the second means for wavelength-dependent and time-dependent allocation of the radiation to a plurality of recording means are shown in greater detail.
  • the radiation emitted by the radiation source is split by means of beam splitters into a plurality of partial beams, resulting in different path lengths for the partial beams.
  • Beam splitters are generally optical components, through which a light beam in two
  • Partial beams can be divided. These usually comprise substrates with a surface coating, which cause a partial reflection of the radiation, so that as a result two partial beams are formed with a beam splitter. at Arrangement of multiple beam splitters, a single beam can be divided into several sub-beams, in the present case three sub-beams are provided. In the context of the present invention, however, two sub-beams or more than three sub-beams can be provided, with a higher number of sub-beams, the accuracy of the measurement can be further increased. The of the
  • Laser pulses provided individual pulses have pulse lengths of a few picoseconds or femtoseconds. If the individual beam is divided into several sub-beams, different path lengths for the sub-beams result. For pulses with such short pulse durations result in different path lengths consecutive wave trains that impinge on the object and are reflected on this again.
  • the partial beams provided by the beam splitters pass through optically non-linear materials, thereby transforming them wavelength-wise.
  • the wavelength transformation is effected by interaction between the radiation and the matter of the optically non-linear materials, whereby a shift of the wavelength can take place.
  • the partial beams are combined before striking the object by means of edge filter again on an optical axis and passed through a telescope to create a collimation of the partial beams before they hit the object.
  • the partial beams form the pulse sequence, with three partial beams three wave trains of different wavelengths follow each other and form the pulse train.
  • the pulse sequence is repeated at the repetition rate of the laser beam source, so that a continuous sequence of partial beams of different wavelengths impinges on the object.
  • the stroboscopic measuring method is based on the principle of reflection of the radiation directed to the object, in which the changes in shape and / or position of the object are reflected.
  • the reflected radiation is therefore first detected with another telescope, wherein all wave trains are collimated with the respective wavelengths on an optical axis. After passing through the telescope, the reflected radiation is split back into the individual wave trains by means of a filter arrangement.
  • the filter arrangement may consist of color filters which are tuned to the previously split wavelengths of the partial beams.
  • the recording means are such that they can individually record the wave trains reflected by the object, whereby these are discretely further processed by the recording means.
  • the recording means can preferably be formed by cameras which can record color-coded pictures. It is also conceivable to use a camera which, separated by color, associates with the sub-beams at a discrete point in time an image of the object with regard to the change in shape and / or position.
  • the color-coded pictures are subsequently fed to an image processing unit, which compares them with each other and generates a picture sequence.
  • the present measuring method therefore makes use of the possibility of subdividing a monochromatic single pulse of short pulse duration into a color-coded partial beam by means of a wavelength transformation.
  • the pulse durations of the partial beams are arranged in the picosecond range or in the femtosecond range.
  • three partial beams with three different wavelengths are generated. If more than three sub-beams are generated, an image sequence with more than three successive snapshots of the object can be generated. Consequently, the increase in the measurement accuracy increases with the number of generated and color different sub-beams.
  • Figure 1 shows an embodiment of a beam path between a
  • Figure 2 is an exemplary illustration of the course of the through
  • FIG. 3 shows a schematic representation of the beam path of the radiation reflected by the object in the direction of a plurality of recording means, which are formed by cameras and which detect the partial beams in color separated from each other.
  • FIG. 1 shows an exemplary embodiment of a beam path between a radiation source 2 and an object 1 with which a stroboscopic measuring method according to the present invention can be carried out.
  • the radiation is provided by the radiation source 2 as pulsed radiation 3 and directed to the object 1.
  • the pulsed radiation 3 consists of a sequence of individual pulses, wherein the radiation source 2 is designed as a laser beam source.
  • the individual pulses are monochromatic, coherent and parallel to the optical axis of the pulsed radiation 3.
  • the individual pulses impinge on beam splitters, by means of which the pulsed radiation 3 is split up into a plurality of partial beams 3a, 3b and 3c.
  • a total of three beam splitters 4a, 4b and 4c are provided, wherein the first beam splitter 4a, for example, transmits one third of the radiation and deflects two-thirds of the radiation to the adjacent beam splitters 4b and 4c. Consequently, the beam splitter 4b is designed such that it reflects 50% of the radiation and 50% of the radiation can pass through the beam splitter.
  • the beam splitter 4c is designed as a pure beam deflection and has a reflection of 100%. As a result, three partial beams 3a, 3b and 3c are formed, all of which have a substantially equal intensity.
  • the partial beams 3a, 3b and 3c pass through respectively associated optically non-linear materials 5a, 5b and 5c which cause a wavelength transformation of the partial beams 3a, 3b and 3c. Consequently, at least the partial beams 3b and 3c are wavelength-transformed, so that all three partial beams 3a, 3b and 3c have a different wavelength.
  • the sub-beams are reunited by edge filters 6a, 6b and 6c on the optical axis, so that all three sub-beams 3a, 3b and 3c can pass through a telescope 7 to a
  • FIG. 2 shows three consecutive color pulses which are represented by the pulse sequences with the separated wave trains ⁇ 1, A2, and A3.
  • the individual pulses are represented by the respective pulse sequences, three individual pulses each having three color pulses being shown.
  • FIG. 3 shows the beam path of the radiation reflected by the object 1. This first meets again on a telescope 8, which causes a collimation of the radiation. Subsequently, the radiation impinges on a filter arrangement 9, which divides the radiation into the individual wave trains ⁇ 1, A2, and A3 as already described above. Consequently, the filter assembly 9 is implemented as an array of three color filters so that multiple cameras 10a, 10b and 10c can be illuminated. Therefore, the camera 10a is illuminated with the pulse of the wavelength A1, the camera 10b with the pulse of the wavelength ⁇ 2, and the camera 10c with the pulse of the wavelength A3.
  • an image processing unit to which the color-coded images are passed through the cameras, which compares them with each other and, as a result, generates an image sequence.
  • the temporal distance from image to image within the image sequence generated by the wave trains A1, A2, and A3 corresponds to the time interval between the wave trains A1, A2, and A3, which is characterized by the path length difference of the partial beams 3a, 3b and 3c results. Consequently, with the stroboscopic measuring method according to the invention, a considerable increase in the temporal resolution of the measurement of changes in shape and / or position of an object in space is made possible, wherein a further increase in the temporal resolution of the measurement is possible by transferring the individual pulses into more than three pulses of a pulse sequence is.
  • the invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

La présente invention concerne un dispositif de mesure et un procédé de mesure stroboscopique, destinés à mesurer les variations de forme et/ou de position d'un objet (1) dans l'espace, avec une source de rayonnement (2) à l'aide de laquelle est fourni un rayonnement pulsé (3) qui est dirigé vers l'objet (1). Le rayonnement réfléchi par l'objet (1) est détecté par des moyens de réception afin de déterminer des variations de forme et/ou de position. Selon l'invention, le rayonnement (3) dirigé vers l'objet (1) est fourni sous une forme codée en longueur d'onde et dans le temps. Il est prévu des moyens pour partager le rayonnement réfléchi entre plusieurs moyens de réception, en fonction de la longueur d'onde et du temps.
PCT/EP2009/003723 2008-05-26 2009-05-26 Procédé de mesure stroboscopique et dispositif correspondant WO2009152930A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008025062.7 2008-05-26
DE102008025062.7A DE102008025062B4 (de) 2008-05-26 2008-05-26 Stroboskopisches Messvorrichtung und Verfahren hierzu

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WO2009152930A1 true WO2009152930A1 (fr) 2009-12-23

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DE102014110226B4 (de) * 2014-07-21 2021-01-14 LDV Laser- und Lichtsysteme GmbH Verfahren und Vorrichtung zur Ausleuchtung von visuell zu inspizierenden Oberflächen bewegter Bauteile

Citations (5)

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DE3244286A1 (de) * 1982-11-26 1984-05-30 Kollmorgen Technologies Corp., Dallas, Tex. Elektro-optische vorrichtung zum erkennen von farben
EP0557558A1 (fr) * 1992-02-26 1993-09-01 Mitsui Mining & Smelting Co., Ltd. Appareil pour inspecter la surface de matériaux
DE4447117C1 (de) * 1994-12-29 1996-03-28 Erwin Dr Rer Nat Rojewski Farbcodiertes 3D-Bilderkennungsverfahren
EP1030173A1 (fr) * 1999-02-18 2000-08-23 Spectra-Physics VisionTech Oy Dispositif et méthode d'inspection de la qualité d'une surface
EP1439385A1 (fr) * 2003-01-15 2004-07-21 Negevtech Ltd. Procédé et appareil pour la détection électro-optique rapide et en ligne de défauts de tranches de semi-conducteur

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DE4432029C2 (de) * 1994-09-08 1997-08-21 Ldt Gmbh & Co Lasergestützte Farbbildanzeige- und Projektionsvorrichtung
DE19926494C2 (de) * 1999-06-10 2001-07-26 Max Planck Gesellschaft Verfahren und Vorrichtung zur Abbildung von mikroskopisch kleinen Teilchen
DE10004412A1 (de) * 2000-02-02 2001-10-31 Schneider Laser Technologies R-G-B Laserstrahlungsquelle
TW466346B (en) * 2001-03-05 2001-12-01 Nat Science Council A low-cost continuous-wave-laser (CW laser) digital particle image velocimetry
US7777199B2 (en) * 2004-09-17 2010-08-17 Wichita State University System and method for capturing image sequences at ultra-high framing rates

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3244286A1 (de) * 1982-11-26 1984-05-30 Kollmorgen Technologies Corp., Dallas, Tex. Elektro-optische vorrichtung zum erkennen von farben
EP0557558A1 (fr) * 1992-02-26 1993-09-01 Mitsui Mining & Smelting Co., Ltd. Appareil pour inspecter la surface de matériaux
DE4447117C1 (de) * 1994-12-29 1996-03-28 Erwin Dr Rer Nat Rojewski Farbcodiertes 3D-Bilderkennungsverfahren
EP1030173A1 (fr) * 1999-02-18 2000-08-23 Spectra-Physics VisionTech Oy Dispositif et méthode d'inspection de la qualité d'une surface
EP1439385A1 (fr) * 2003-01-15 2004-07-21 Negevtech Ltd. Procédé et appareil pour la détection électro-optique rapide et en ligne de défauts de tranches de semi-conducteur

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DE102008025062B4 (de) 2016-07-28
DE102008025062A1 (de) 2009-12-17

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