DE102021200679A1 - Opto-mechanical measuring system for spatial vibration analysis - Google Patents

Abstract

Opto-mechanical measuring system (110) for spatial vibration analysis of at least one test body (112). The opto-mechanical measuring system (110) includes a laser Doppler vibrometer (116). The laser Doppler vibrometer (116) is set up to generate at least one illuminating light beam (150) for illuminating the test body (112), to detect at least one light beam (160) scattered by the test body (112) and, by superimposing it with at least a reference light beam (154) to determine at least one measured variable. The opto-mechanical measuring system (110) also includes at least one beam splitter system (118). The beam splitter system (118) is set up to split the illuminating light beam (150) into a plurality of partial beams (156) and to direct the partial beams (156) to at least one common point (158) on the test body (112).

Description

technical field

The present invention relates to an opto-mechanical measuring system for spatial vibration analysis of at least one test body and a method for spatial vibration analysis of at least one test body. Such measuring systems are used, for example, in the non-destructive testing of workpieces, in mechanical engineering, in materials science or in medicine. Other areas of application are also possible.

Technical background

In the field of metrology, the use of laser Doppler vibrometers is known for measuring test specimens. Laser Doppler vibrometers can detect the vibration of surfaces in the direction of propagation of the laser beam emanating from them. Due to the Doppler effect, the frequency of the backscattered laser light shifts when the surface to be measured moves. This frequency shift can then be evaluated in the laser Doppler vibrometer using interferometry. For example, at least one reference light beam is superimposed on the backscattered laser light in an interferometer and at least one interference signal is generated, which can provide information about the vibration behavior of the test body. With a scanning laser Doppler vibrometer, several points on the surface of the test object can also be scanned one after the other in a two-dimensional vibration analysis.

Despite the advantages that could already be achieved by the known measuring systems with laser Doppler vibrometers, various technical challenges still remain. A single laser Doppler vibrometer can only detect the vibration of surfaces in the direction of propagation of the laser beam. Thus, only a one-dimensional vibration analysis is possible for each point to be measured on the surface of a test body. Accordingly, three separate laser Doppler vibrometers are currently used for a three-dimensional vibration analysis, the laser beams of which must be simultaneously focused on a common point. This in turn increases the material requirements and the manufacturing costs of such measuring systems enormously. Furthermore, in the case of a scanning laser Doppler vibrometer, a scanning unit is required for tracking the laser Doppler vibrometer.

object of the invention

It would therefore be desirable to provide an opto-mechanical measuring system and a method for spatial vibration analysis of a test body which at least largely avoid the disadvantages of known measuring systems and methods. In particular, an inexpensive measuring system is to be provided with which a spatial vibration analysis can be carried out. In particular, it would be desirable to be able to expand an individual laser Doppler vibrometer in such a way that a two-dimensional three-dimensional vibration analysis can be carried out, in particular without an additional scanning unit and in particular also independently of the manufacturer.

General Description of the Invention

This object is addressed by an opto-mechanical measuring system and a method for spatial vibration analysis of a test body with the features of the independent patent claims. Advantageous developments, which can be implemented individually or in any combination, are presented in the dependent claims.

In the following, the terms "have", "have", "comprise" or "include" or any grammatical deviations thereof are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, apart from the features introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the phrase "A has B," "A has B," "A includes B," or "A includes B" can both refer to the situation in which, apart from B, there is no other element in A ( i.e. to a situation in which A consists exclusively of B), as well as to the situation in which, in addition to B, there are one or more other elements in A, e.g. element C, elements C and D or even further elements.

Furthermore, it is pointed out that the terms "at least one" and "one or more" as well as grammatical variations of these terms, if they are used in connection with one or more elements or features and are intended to express that the element or feature is provided once or several times can generally only be used once, for example when the feature or element is introduced for the first time. If the feature or element is subsequently mentioned again, the corresponding term "at least one" or "one or more" in the Usually no longer used, without restricting the possibility that the feature or element can be provided once or more than once.

Furthermore, the terms “preferably”, “particularly”, “for example” or similar terms are used below in connection with optional features, without alternative embodiments being restricted thereby. Thus, features introduced by these terms are optional features and are not intended to limit the scope of the claims, and in particular the independent claims, by these features. Thus, as will be appreciated by those skilled in the art, the invention may be practiced using other configurations. Similarly, features introduced by "in an embodiment of the invention" or by "in an exemplary embodiment of the invention" are understood as optional features without intending to limit alternative configurations or the scope of the independent claims. Furthermore, through these introductory expressions, all possibilities to combine the features introduced here with other features, be they optional or non-optional features, remain untouched.

1. i. ein Laser-Doppler-Vibrometer, wobei das Laser-Doppler-Vibrometer eingerichtet ist, um mindestens einen Beleuchtungslichtstrahl zur Beleuchtung des Prüfkörpers zu erzeugen, mindestens einen von dem Prüfkörper gestreuten Lichtstrahl zu detektieren und daraus durch Überlagerung mit mindestens einem Referenzlichtstrahl mindestens eine Messgröße zu bestimmen; und
2. ii. mindestens ein Strahlteilersystem, wobei das Strahlteilersystem eingerichtet ist, um den Beleuchtungslichtstrahl in eine Mehrzahl an Teilstrahlen aufzuteilen und die Teilstrahlen auf mindestens einen gemeinsamen Punkt auf dem Prüfkörper zu lenken.

In a first aspect of the present invention, an opto-mechanical measuring system for spatial vibration analysis of at least one test body is proposed. The opto-mechanical measuring system includes:

1. i. a laser Doppler vibrometer, wherein the laser Doppler vibrometer is set up to generate at least one illuminating light beam for illuminating the test body, to detect at least one light beam scattered by the test body and to determine at least one measured variable from this by superimposing it with at least one reference light beam ; and
2. ii. at least one beam splitter system, wherein the beam splitter system is set up to split the illuminating light beam into a plurality of partial beams and to direct the partial beams to at least one common point on the test body.

The term "system" as used herein is a broad term that should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. In particular, the term may refer, without limitation, to a device comprising a plurality of interacting or interdependent components or elements forming a whole. The components can cooperate at least in part to perform at least one common function. At least two components can be handled independently of each other or they can be connected or be connectable. The term "opto-mechanical" as used herein is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a combination of optical, mechanical and optionally also electrical properties. The term can refer in particular to the fact that optical devices, for example mirrors, are mechanically adjusted, as a result of which light beams can be deflected differently, for example. The mechanical adjustment of the optical devices can be controlled electrically, for example via actuators. The term can also relate in particular to the conversion of electronic signals into optical signals and/or vice versa, as is the case, for example, in lasers and photodetectors. Consequently, the term “optomechanical measuring system” can relate in particular to a system that is set up for measuring purposes and includes at least one optomechanical component such as a mechanically or else electromechanically adjustable mirror.

The term "vibration analysis" as used herein is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a measurement method by means of which at least one vibration property of at least one object is recorded. In particular, fluctuations in a physical variable over time can be characterized with the vibration analysis. The fluctuations or oscillations can in particular include mechanical oscillations such as vibrations which are associated with the deformation of a body. The fluctuations can also be periodic and/or excited and/or damped. Accordingly, as used herein, the term “spatial vibration analysis” may specifically refer to vibration analysis at a specific location and/or over specific spatial dimensions. For example, in a one-dimensional vibration analysis of a point, a movement of the point in one spatial dimension can be characterized. For example, in a three-dimensional vibration analysis of a point, a movement tion of the point can be characterized in all three spatial dimensions. For example, in a three-dimensional vibration analysis of a surface, also called a two-dimensional three-dimensional vibration analysis, the movement of the surface, in particular the individual movement of a plurality of points within the surface, can be characterized in all three spatial dimensions.

The term "specimen" as used herein is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. In particular, the term can, without limitation, refer to an arbitrarily shaped object to be measured. In particular, the test body can comprise a vibrating surface.

The opto-mechanical measuring system includes a laser Doppler vibrometer. The term "laser Doppler vibrometer", hereinafter also referred to as "vibrometer" for short, as used herein, is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a measuring device for characterizing mechanical vibrations, which is set up to detect at least one frequency shift that is experienced by at least one light beam that is reflected on a moving object, in particular the test body described above. In particular, the laser Doppler vibrometer can be set up to measure oscillation frequencies and/or oscillation amplitudes.

In particular, the laser Doppler vibrometer can comprise at least one light source, for example at least one laser and/or at least one other light source. The light source can generate at least one light beam, for example at least one laser beam. The laser Doppler vibrometer can be set up to use this at least one light beam or at least part of this light beam, directly or, for example, also after passing through at least one modulation, as an illuminating light beam and to use this illuminating light beam itself or after passing through additional optics such as the following to direct the beam splitter system described in more detail to at least one point on a surface to be examined, as will be explained in more detail below.

The laser Doppler vibrometer can also include at least one interferometer, for example a Michelson interferometer and/or Jamin interferometer. This at least one interferometer can generally be set up to superimpose at least one light beam scattered by the surface, which results from the illumination light beam after scattering on the surface, with at least one reference light beam, so that one or more superimposed light beams arise, each of which is light of the reference light beam and light of the scattered light beam. For the purpose of this superimposition, the interferometer can, for example, comprise at least one combining beam splitter, by means of which the at least one reference light beam and the at least one light beam scattered by the test body can be superimposed and fed directly or indirectly to at least one photodetector.

The reference light beam can also be generated, for example, by means of the at least one light source with which the illuminating light beam is generated, so that the reference light beam and the illuminating light beam are, for example, coherent. The reference light beam can be modulated, for example, by at least one Bragg cell, for example in order to modulate one or more sidebands onto this reference light beam. For example, the laser Doppler vibrometer can have at least one separating beam splitter, which splits at least one light beam generated by the light source into the at least one reference light beam and the at least one illuminating light beam. The reference light beam can be modulated, for example. The light beam scattered by the test body can, for example, in turn be superimposed by the above-described combining beam splitter with the reference light beam and fed directly or indirectly to the at least one photodetector.

As stated above, the laser Doppler vibrometer can also include at least one photodetector. For example, the at least one photodetector can include at least one photodiode and/or at least one other type of photosensitive semiconductor component. Other types of photodetectors can also be used. For example, a plurality of photodetectors can also be provided, each of which is supplied with a light beam which comprises a superimposition of the light beam scattered by the test body or a part thereof and the reference light beam or a part thereof. In this way, for example, differential signals can be formed, for example by means of at least one differential amplifier to which the signals from the photodetectors are supplied. In this way For example, noise reduction can take place.

The laser Doppler vibrometer can comprise at least one data processing device, for example at least one computer or microcontroller. The data processing device can include one or more volatile and/or non-volatile data memories. The laser Doppler vibrometer may include at least one interface, for example an electronic interface and/or a human-machine interface such as an input/output device such as a display and/or a keyboard.

In particular, the laser Doppler vibrometer can have at least one housing. In particular, the at least one light source and the at least one interferometer and the at least one photodetector can be completely accommodated in the at least one housing, or parts thereof. The laser Doppler vibrometer can also include one or more optical fibers, for example in order to guide at least one light beam in whole or in part over at least one path, in which case the light beam can be selected in particular from the group consisting of the at least one light beam generated by the light source, the at least one illuminating light beam, the at least one reference light beam and the at least one light beam scattered by the test body.

The laser Doppler vibrometer is set up to generate at least one illuminating light beam for illuminating the test body. The term “light” as used here can refer in particular to electromagnetic radiation in at least one spectral range selected from the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The term "beam of light" as used herein is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, be understood in particular to mean an amount of light that is emitted and/or directed in a certain direction. In particular, the light beam can comprise at least one laser beam. Accordingly, the term “illuminating light beam” can refer in particular to any light beam that is radiated onto and/or directed onto an object, in particular onto the test specimen.

The laser Doppler vibrometer is also set up to detect at least one light beam scattered by the test body. The terms "scattered" or "scattering" as used herein are broad terms which should be given their ordinary and current meaning as understood by those skilled in the art. The terms are not limited to any specific or adapted meaning. The terms can, without limitation, relate in particular to a directed or also diffuse deflection of a beam, in particular a light beam, as a result of an interaction with an object, in particular with the at least one test body. The scattering can be elastic scattering, where the interaction occurs without energy transfer. The scattering may be inelastic scattering where the interaction occurs with energy transfer. The scattering can be coherent scattering, in which there is a fixed phase relationship between the incident wave and the scattered wave. The scattering can be incoherent scattering, where there is no fixed phase relationship between the incident wave and the scattered wave. The scattering can be selected from the group consisting of: a reflection; a refraction; a bend. Consequently, the term "scattered light beam" can relate in particular to a light beam which is produced after the at least one illuminating light beam has been scattered on an object, in particular on the at least one test specimen.

The term "detect" as used herein is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a qualitative and/or quantitative detection of a physical variable, in particular an optical signal.

The laser Doppler vibrometer is also set up to determine at least one measured variable by superimposing the at least one scattered light beam with at least one reference light beam. The term "reference light beam" as used herein is a broad term which should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. In particular, the term may refer, without limitation, to a beam of light with known properties, in particular with a known frequency, which is suitable for comparison purposes. The reference light beam can be generated in the laser Doppler vibrometer. In particular, the reference light beam can be in a fixed relationship with the at least one illumination light beam and/or the at least one scattered light beam, for example by the reference light beam are generated with the at least one illuminating light beam from the same light source or at least from light sources coupled to one another. For example, the at least one light source of the laser Doppler vibrometer, as explained above, can generate at least one light beam from which both the at least one illumination light beam and the at least one reference light beam are formed. For example, the reference light beam can be generated from the light beam generated by the light source, which can also be referred to as the primary light beam, for example with the aid of at least one beam splitter. As explained above, the reference light beam can, for example, also pass through at least one modulation device, so that at least one sideband can also be modulated onto the reference light beam, for example.

The term "metric" as used herein is a broad term that should be given its ordinary and current meaning as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to any physical quantity and/or information resulting from a measurement and/or an investigation and/or an observation. The measured variable can in particular include at least one electrical signal, for example at least one voltage and/or at least one current of the at least one photodetector and/or at least one signal formed or derived therefrom, for example at least one differential signal of the measurement signals of at least two photodetectors. The measured variable can also be processed so that one or more derived measured variables can be determined from the at least one measured variable, for example by at least one filter method. The measured variable can in particular include at least one variable or describe at least one variable selected from the group consisting of: a movement sequence of at least one part of the test body; a vibration frequency; an oscillation wavelength; a vibration amplitude; a vibration speed; a vibration path; a vibration direction; a vibration acceleration; a resonant frequency; a local defect resonance frequency.

The opto-mechanical measuring system also includes at least one beam splitter system. This beam splitter system can be arranged in particular outside of the optional housing of the laser Doppler vibrometer described above, for example in front of an exit opening of the illuminating light beam. The term “beam splitter” as used here can, without limitation, refer in particular to an optical component which can split a single incoming light beam into a plurality of partial beams. The beam splitter can include a partially reflecting surface, in particular a partially reflecting surface and/or a partially reflecting coating. For example, the beam splitter can reflect a percentage of the incoming light beam, measured by intensity, and let the remaining part through. Consequently, the term “beam splitter system” can relate in particular to a system which comprises at least one beam splitter.

The beam splitter system is also set up to direct the partial beams to at least one common point on the test body. The term “direct” as used herein may refer, without limitation, to guiding and/or directing at least one light beam. For this purpose, the illuminating light beam can, for example, be deflected once or multiple times, for example by one or more reflecting and/or refracting elements. By directing the light beam, a fixed or adjustable beam path can be specified for the light beam.

At least one component of the beam splitter system can be adjustable, in particular electromechanically and/or automatically, for example computer-controlled, for example by a controller of the opto-mechanical measuring system. The term "adjustable" can refer in particular to the fact that a change in a position and/or an orientation of an object is possible. The change in position can involve moving the object in any direction and by any distance. The change in orientation can include a rotation of the object through any angle and around any spatial axis. By adjusting at least one component of the beam splitter system, at least one partial beam can be deflected, for example, to different points on a test body. The term "electromechanical" may refer specifically, without limitation, to converting an electrical signal into a mechanical movement and/or a change in pressure. The electrical signal can be converted, for example, via an actuator into a displacement and/or rotation of an object, in particular a component of the beam splitter system.

At least two components of the beam splitter system can be adjusted independently of one another, in particular electromechanically and/or automatically, for example by computer controls, for example by controlling the opto-mechanical measuring system.

At least one component of the beam splitter system can be integrated into at least one upstream component. The term "upstream" as used herein may, without limitation, refer in particular to the fact that a first element is arranged spatially in front of a second element in such a way that a signal, for example an optical and/or an electrical signal, first element passes before the second element in time. The term “upstream component” as used here can consequently, without limitation, relate in particular to a first component which is upstream of a second component or a system, in particular the beam splitter system. The at least one upstream component can comprise the laser Doppler vibrometer, i.e. at least one component of the beam splitter system can be integrated into the laser Doppler vibrometer.

The beamsplitter system may include at least one component selected from the group consisting of: a beamsplitter cube; a beam splitter prism; a mirror.

The beam splitter system can be designed in such a way that the optical path lengths covered by the partial beams are the same. The term "optical path length" can refer in particular, without limitation, to a distance that a light ray travels, for example between two points and/or between its emission and its detection. The optical path length can include a weighting of the geometric distance covered with an optical density of a medium passed through.

The beam splitter system can be set up in such a way that the partial beams are offset symmetrically to one another, in particular are rotationally symmetrical about an axis of symmetry. The beam splitter system can split the illuminating light beam into exactly three partial beams, which can run rotationally symmetrically about an axis of symmetry, so that they can impinge on the test body from three different spatial directions, for example. With a total of three light beams that meet at one point, a light beam can be arranged every 120°, for example, on an imaginary circle that intersects all three light beams.

The opto-mechanical measuring system can also include a camera aimed at the test body for viewing the test body. The beam splitter system, in particular all components of the beam splitter system, can be arranged outside of a line of sight between the camera and the test object. For example, the components of the beam splitter system can be spatially arranged around the line of sight without blocking it. As an example, the camera may include at least one camera chip, such as at least one CCD chip and/or at least one CMOS chip configured to capture images. For example, the camera can take at least one photo and/or at least one video film of the test body during a spatial vibration analysis.

1. I. Bereitstellen mindestens eines optomechanischen Messsystems nach einer der vorhergehenden Ausführungsformen und/oder nach einer der nachfolgenden ein optomechanisches Messsystem betreffenden Ausführungsformen;
2. II. Erzeugen mindestens eines Beleuchtungslichtstrahls zur Beleuchtung des Prüfkörpers mittels des Laser-Doppler-Vibrometers;
3. III. Aufteilen und optional auch Ablenken des Beleuchtungslichtstrahls in eine Mehrzahl an Teilstrahlen und Lenken der Teilstrahlen, insbesondere in ihren jeweiligen Strahlengängen, auf mindestens einen gemeinsamen Punkt auf dem Prüfkörper mit dem Strahlteilersystem; und
4. IV. Detektieren mindestens eines von dem Prüfkörper gestreuten Lichtstrahls und Bestimmen mindestens einer Messgröße durch Überlagerung des gestreuten Lichtstrahls mit mindestens einem Referenzlichtstrahl mittels des Laser-Doppler-Vibrometers.

In a second aspect, a method for spatial vibration analysis of at least one test body is proposed within the scope of the present invention. The procedure comprises the following procedural steps:

1. I. Providing at least one optomechanical measuring system according to one of the preceding embodiments and/or according to one of the following embodiments relating to an optomechanical measuring system;
2. II. Generating at least one illuminating light beam for illuminating the test body by means of the laser Doppler vibrometer;
3. III. Splitting and optionally also deflecting the illuminating light beam into a plurality of partial beams and directing the partial beams, in particular in their respective beam paths, to at least one common point on the test body with the beam splitter system; and
4. IV. Detecting at least one light beam scattered by the test body and determining at least one measured variable by superimposing the scattered light beam with at least one reference light beam using the laser Doppler vibrometer.

The method steps can be carried out in the order given, with one or more of the method steps being able to be carried out at least in part simultaneously, and with one or more of the method steps being able to be repeated several times. In addition, other process steps, whether or not mentioned here, can additionally be carried out.

The spatial vibration analysis of the at least one test body can include a three-dimensional vibration analysis of at least one point of the test body. The three-dimensional vibration analysis of the at least one test body can also include a two-dimensional vibration analysis of at least one part of the test body. For example, a vibration analysis can be carried out one after the other for several points on a surface Analysis, in particular a three-dimensional vibration analysis, are carried out. For further definitions and configurations of the method for spatial vibration analysis of at least one test body, reference can be made to definitions and configurations of the opto-mechanical measuring system. For example, the fact that at least one component of the beam splitter system, such as a mirror, can be adjusted electromechanically can be used for the two-dimensional vibration analysis, whereby at least one partial beam can be directed step by step to different points on a surface. This can be done automatically, for example, under computer control, for example by controlling the opto-mechanical measuring system.

A plurality of partial beams, for example three partial beams, can be generated in succession from the at least one illuminating light beam. The partial beams can be directed to a common point on the test body. A three-dimensional vibration analysis of the point can be carried out with the same vibration excitation of the test body during a measurement with a partial beam, for example in sweep measurements, chirp measurements or CW measurements. If the vibration excitation is not the same in each case, a one-dimensional vibration analysis of the point can be carried out.

The device according to the invention and the method according to the invention have numerous advantages over known devices and methods. In particular, they offer a cost-effective way to carry out three-dimensional vibration analyses. A single laser Doppler vibrometer that is potentially already available can be flexibly expanded with a cost-effective mirror system, independently of the manufacturer, instead of using two more expensive laser Doppler vibrometers. In addition, no additional scanning unit is generally required for a two-dimensional vibration analysis, in particular a two-dimensional three-dimensional vibration analysis, especially if a scanning unit is integrated directly into the mirror apparatus.

• Ausführungsform 1: Optomechanisches Messsystem zur räumlichen Schwingungsanalyse mindestens eines Prüfkörpers, umfassend:
  1. i. ein Laser-Doppler-Vibrometer, wobei das Laser-Doppler-Vibrometer eingerichtet ist, um mindestens einen Beleuchtungslichtstrahl zur Beleuchtung des Prüfkörpers zu erzeugen, mindestens einen von dem Prüfkörper gestreuten Lichtstrahl zu detektieren und daraus durch Überlagerung mit mindestens einem Referenzlichtstrahl mindestens eine Messgröße zu bestimmen; und
  2. ii. mindestens ein Strahlteilersystem, wobei das Strahlteilersystem eingerichtet ist, um den Beleuchtungslichtstrahl in eine Mehrzahl an Teilstrahlen aufzuteilen und die Teilstrahlen auf mindestens einen gemeinsamen Punkt auf dem Prüfkörper zu lenken.
• Ausführungsform 2: Optomechanisches Messsystem nach der vorhergehenden Ausführungsform, wobei mindestens eine Komponente des Strahlteilersystems verstellbar ist, insbesondere elektromechanisch.
• Ausführungsform 3: Optomechanisches Messsystem nach der vorhergehenden Ausführungsform, wobei mindestens zwei Komponenten des Strahlteilersystems unabhängig voneinander verstellbar sind, insbesondere elektromechanisch.
• Ausführungsform 4: Optomechanisches Messsystem nach einer der vorhergehenden Ausführungsformen, wobei mindestens eine Komponente des Strahlteilersystems in eine vorgeschaltete Komponente integriert ist.
• Ausführungsform 5: Optomechanisches Messsystem nach der vorhergehenden Ausführungsform, wobei die mindestens eine vorgeschaltete Komponente das Laser-Doppler-Vibrometer umfasst.
• Ausführungsform 6: Optomechanisches Messsystem nach einer der vorhergehenden Ausführungsformen, wobei das Strahlteilersystem mindestens eine Komponente aufweist, ausgewählt aus der Gruppe bestehend aus: einem Strahlteilerwürfel; einem Strahlteilerprisma; einem Spiegel.
• Ausführungsform 7: Optomechanisches Messsystem nach einer der vorhergehenden Ausführungsformen, wobei das Strahlteilersystem derart ausgestaltet ist, dass von den Teilstrahlen zurückgelegte optische Weglängen gleich sind.
• Ausführungsform 8: Optomechanisches Messsystem nach einer der vorhergehenden Ausführungsformen, wobei das Strahlteilersystem derart eingerichtet ist, dass die Teilstrahlen zueinander symmetrisch versetzt sind, insbesondere rotationssymmetrisch um eine Symmetrieachse.
• Ausführungsform 9: Optomechanisches Messsystem nach einer der vorhergehenden Ausführungsformen, wobei das Strahlteilersystem den Beleuchtungslichtstrahl in drei Teilstrahlen aufteilt.
• Ausführungsform 10: Optomechanisches Messsystem nach einer der vorhergehenden Ausführungsformen, weiterhin umfassend eine auf den Prüfkörper ausgerichtete optische Kamera zur Betrachtung des Prüfkörpers.
• Ausführungsform 11: Optomechanisches Messsystem nach der vorhergehenden Ausführungsform, wobei das Strahlteilersystem, insbesondere alle Komponenten des Strahlteilersystems, außerhalb einer Sichtlinie zwischen der Kamera und dem Prüfkörper angeordnet ist.
• Ausführungsform 12: Verfahren zur räumlichen Schwingungsanalyse mindestens eines Prüfkörpers, umfassend die folgenden Verfahrensschritte:
  1. I. Bereitstellen mindestens eines optomechanischen Messsystems nach einem der vorhergehenden Ansprüche;
  2. II. Erzeugen mindestens eines Beleuchtungslichtstrahls zur Beleuchtung des Prüfkörpers mittels des Laser-Doppler-Vibrometers;
  3. III. Aufteilen des Beleuchtungslichtstrahls in eine Mehrzahl an Teilstrahlen und Lenken der Teilstrahlen auf mindestens einen gemeinsamen Punkt auf dem Prüfkörper mit dem Strahlteilersystem; und
  4. IV. Detektieren mindestens eines von dem Prüfkörper gestreuten Lichtstrahls und Bestimmen mindestens einer Messgröße durch Überlagerung des gestreuten Lichtstrahls mit mindestens einem Referenzlichtstrahl mittels des Laser-Doppler-Vibrometers.
• Ausführungsform 13: Verfahren nach der vorhergehenden Ausführungsform, wobei die räumliche Schwingungsanalyse des mindestens einen Prüfkörpers eine dreidimensionale Schwingungsanalyse mindestens eines Punkts des Prüfkörpers umfasst.
• Ausführungsform 14: Verfahren nach einer der vorhergehenden ein Verfahren betreffenden Ausführungsformen, wobei die räumliche Schwingungsanalyse des mindestens einen Prüfkörpers eine flächige Schwingungsanalyse mindestens eines Teils des Prüfkörpers umfasst.

In summary, the following embodiments are proposed without restricting further possible configurations:

• Embodiment 1: optomechanical measuring system for spatial vibration analysis of at least one test body, comprising:
  1. i. a laser Doppler vibrometer, wherein the laser Doppler vibrometer is set up to generate at least one illuminating light beam for illuminating the test body, to detect at least one light beam scattered by the test body and to determine at least one measured variable from this by superimposing it with at least one reference light beam ; and
  2. ii. at least one beam splitter system, wherein the beam splitter system is set up to split the illuminating light beam into a plurality of partial beams and to direct the partial beams to at least one common point on the test body.
• Embodiment 2: optomechanical measuring system according to the previous embodiment, wherein at least one component of the beam splitter system is adjustable, in particular electromechanically.
• Embodiment 3: optomechanical measuring system according to the previous embodiment, wherein at least two components of the beam splitter system can be adjusted independently of one another, in particular electromechanically.
• Embodiment 4 Optomechanical measuring system according to one of the preceding embodiments, wherein at least one component of the beam splitter system is integrated in an upstream component.
• Embodiment 5: Optomechanical measuring system according to the previous embodiment, wherein the at least one upstream component comprises the laser Doppler vibrometer.
• Embodiment 6: Optomechanical measurement system according to one of the preceding embodiments, wherein the beam splitter system has at least one component selected from the group consisting of: a beam splitter cube; a beam splitter prism; a mirror.
• Embodiment 7 Opto-mechanical measuring system according to one of the preceding embodiments, wherein the beam splitter system is designed in such a way that the optical path lengths covered by the partial beams are the same.
• Embodiment 8 Optomechanical measuring system according to one of the preceding embodiments, wherein the beam splitter system is set up in such a way that the partial beams are offset symmetrically to one another, in particular rotationally symmetrically about an axis of symmetry.
• Embodiment 9 Opto-mechanical measuring system according to one of the preceding embodiments, wherein the beam splitter system splits the illuminating light beam into three partial beams.
• Embodiment 10: Opto-mechanical measuring system according to one of the preceding embodiments, further comprising an optical camera aligned to the test body for viewing the test body.
• Embodiment 11: Opto-mechanical measuring system according to the previous embodiment, wherein the beam splitter system, in particular all components of the beam splitter system, is arranged outside of a line of sight between the camera and the test body.
• Embodiment 12: Method for spatial vibration analysis of at least one test body, comprising the following method steps:
  1. I. Providing at least one opto-mechanical measuring system according to one of the preceding claims;
  2. II. Generating at least one illuminating light beam for illuminating the test body by means of the laser Doppler vibrometer;
  3. III. splitting the illuminating light beam into a plurality of partial beams and directing the partial beams to at least one common point on the test body with the beam splitter system; and
  4. IV. Detecting at least one light beam scattered by the test body and determining at least one measured variable by superimposing the scattered light beam with at least one reference light beam using the laser Doppler vibrometer.
• Embodiment 13 Method according to the previous embodiment, wherein the spatial vibration analysis of the at least one test body comprises a three-dimensional vibration analysis of at least one point of the test body.
• Embodiment 14 Method according to one of the preceding embodiments relating to a method, wherein the spatial vibration analysis of the at least one test body comprises a two-dimensional vibration analysis of at least one part of the test body.

character list

Further details and features emerge from the following description of exemplary embodiments, in particular in connection with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. The same reference numerals in the individual figures designate elements that are the same or have the same function or that correspond to one another in terms of their functions.

• 1 eine schematische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen optomechanischen Messsystems; und
• 2 ein Flussdiagramm eines Ausführungsbeispiels eines erfindungsgemäßen Verfahrens zur räumlichen Schwingungsanalyse mindestens eines Prüfkörpers.

Show in detail:

• 1 a schematic representation of an embodiment of an opto-mechanical measuring system according to the invention; and
• 2 a flowchart of an embodiment of a method according to the invention for spatial vibration analysis of at least one test body.

Description of the exemplary embodiments

1 shows a schematic representation of an embodiment of an optomechanical measuring system 110 according to the invention for the spatial vibration analysis of at least one test body 112. The test body 112 can include an arbitrarily shaped object to be measured and in particular at least one vibrating surface 114.

The opto-mechanical measuring system 110 comprises a laser Doppler vibrometer 116 and at least one beam splitter system 118. The beam splitter system 118 can in particular be arranged outside of an optional housing 120 of the laser Doppler vibrometer 116, for example in front of an exit opening 122 of the housing 120 of the laser Doppler -Vibrometers 116. An interior of the laser Doppler vibrometer 116 can thus be completely protected, for example, whereas the beam splitter system 118 can be easily accessible, for example for an adjustment and/or an adaptation to the test body 112.

Laser Doppler vibrometer 116 may include at least one light source 124, such as at least one laser and/or at least one other light source 124. Laser Doppler vibrometer 116 may further include at least one interferometer 126. As in 1 As shown, interferometer 126 may include, for example, a separating beamsplitter cube 128, a combining beamsplitter cube 130, and at least one interferometer mirror 132. The laser Doppler vibrometer 116 may further include at least one photodetector 134 . For example, the at least one photodetector 134 may include at least one photodiode and/or at least one other type of photosensitive semiconductor device. Other types of photodetectors 134 can also be used. The interferometer 126 may also include other components not shown, such as a or multiple modulators. Furthermore, one or more of the arms of the interferometer can also be implemented entirely or partially as an optical waveguide. The laser Doppler vibrometer 116 can further comprise at least one data processing device 136, for example at least one computer or microcontroller. Data processing device 136 may include one or more volatile and/or non-volatile data stores. The laser Doppler vibrometer 116 may further include at least one interface 138, such as an electronic interface and/or a human-machine interface, such as an input/output device such as a display and/or a keyboard. In particular, the at least one light source 120, the at least one interferometer 130 and the at least one photodetector 138, or parts thereof, can be completely accommodated in the housing 120.

As 1 1, the beam splitter system 118 can in particular comprise at least one beam splitter 140. Furthermore, the beam splitter system can include at least one mirror 142 . At least one component of the beam splitter system 118 can be adjustable, in particular electromechanically and/or automatically, for example computer-controlled, for example by a controller 144 of the opto-mechanical measuring system 110. Furthermore, at least two components of the beam splitter system 118 can be adjustable independently of one another, in particular electromechanically and/or automatically, computer-controlled, for example, by the controller 144 of the opto-mechanical measuring system 110.

As 1 shows, the opto-mechanical measurement system 110 can further comprise a camera 146 aligned to the test body 112 for viewing the test body 112 . Camera 146 may be attached to laser Doppler vibrometer 116, for example. The beam splitter system 118, in particular all components of the beam splitter system 118, can be arranged outside of a line of sight 148 between the camera 146 and the test body 112. For example, the components of the beamsplitter system 118 can be spatially arranged around the line of sight 148 without blocking it. As an example, the camera 146 may include at least one camera chip, such as at least one CCD chip and/or at least one CMOS chip configured to capture images. The camera 146 can, for example, record at least one photo and/or at least one video of the test body 112 during a spatial vibration analysis.

The laser Doppler vibrometer 116 is set up to generate at least one illuminating light beam 150 for illuminating the test body 112 . As 1 1, light source 124 may initially produce at least one light beam 152, such as at least one laser beam. The light beam 152 can then be split into the at least one illumination light beam 150 and at least one reference light beam 154 in the interferometer 126 with the aid of the separating beam splitter cube 128 . The at least one illumination light beam 152 and the at least one reference light beam 154 can be coherent. The at least one reference light beam 154 can then be directed to the merging beam splitter cube 130, for example via the interferometer mirror 132, on a different path than the at least one illumination light beam 150. The at least one illumination light beam 150 can at least partially pass through the merging beam splitter cube 130 and the laser Doppler -Vibrometer 116 leave through the outlet opening 122 of the housing 120.

The at least one beam splitter system 118 is set up to split the illuminating light beam 150 into a plurality of partial beams 156 . As 1 shows, the illuminating light beam 150 can be divided at the beam splitter 140 into a plurality of partial beams 156, in particular into three partial beams 156. The at least one beam splitter system 118 is also set up to direct the partial beams 156 to at least one common point 158 on the test body 112. The beam splitter system 118 can be designed in such a way that the optical path lengths covered by the partial beams 156 are the same. The beam splitter system 118 can also be set up in such a way that the partial beams 156 are offset symmetrically with respect to one another, in particular rotationally symmetrically about an axis of symmetry. As 1 shows, the partial beams 156 can be directed to the point 158 on the surface 114 of the test body 112, for example with the aid of the mirror 142. At the point 158, the partial beams 156 can then be scattered and, in particular, reflected back. In the beam splitter system 118 , the scattered light beams 160 can return to the laser Doppler vibrometer 116 again, for example via the mirrors 142 and/or the beam splitter 140 .

The laser Doppler vibrometer 116 is set up to detect at least one light beam 160 scattered by the test body 112 and to determine at least one measured variable from this by superimposition with at least one reference light beam 154 . As 1 1, the scattered light beam 160 can enter the laser Doppler vibrometer 116 through the exit opening 122 of the housing 120. FIG. The reference light beam 154 can be superimposed on the scattered light beam 160 with the aid of the combining beam splitter cube 130 . The superimposed light beam 162 can then be detected by the photodetector 134. Finally, the at least one measured variable can be determined with the aid of the data processing device 136, for example.

1. I. (gekennzeichnet durch Bezugszeichen 164) Bereitstellen mindestens eines optomechanischen Messsystems 110 nach einem der vorhergehenden Ansprüche;
2. II. (gekennzeichnet durch Bezugszeichen 166) Erzeugen mindestens eines Beleuchtungslichtstrahls 150 zur Beleuchtung des Prüfkörpers 112 mittels des Laser-Doppler-Vibrometers 116;
3. III. (gekennzeichnet durch Bezugszeichen 168) Aufteilen des Beleuchtungslichtstrahls 150 in eine Mehrzahl an Teilstrahlen 156 und Lenken der Teilstrahlen 156 auf mindestens einen gemeinsamen Punkt 158 auf dem Prüfkörper 112 mit dem Strahlteilersystem 118; und
4. IV. (gekennzeichnet durch Bezugszeichen 170) Detektieren mindestens eines von dem Prüfkörper 112 gestreuten Lichtstrahls 160 und Bestimmen mindestens einer Messgröße durch Überlagerung des gestreuten Lichtstrahls 160 mit mindestens einem Referenzlichtstrahl 154 mittels des Laser-Doppler-Vibrometers 116.

2 shows a flowchart of an embodiment of a method according to the invention for spatial vibration analysis of at least one test body 112. The method comprises the following method steps:

1. I. (identified by reference numeral 164) providing at least one opto-mechanical measuring system 110 according to one of the preceding claims;
2. II. (identified by reference numeral 166) generating at least one illuminating light beam 150 for illuminating the test body 112 by means of the laser Doppler vibrometer 116;
3. III. (identified by reference numeral 168) splitting the illuminating light beam 150 into a plurality of sub-beams 156 and directing the sub-beams 156 to at least one common point 158 on the specimen 112 with the beam splitter system 118; and
4. IV. (identified by reference numeral 170) Detecting at least one light beam 160 scattered by test body 112 and determining at least one measured variable by superimposing scattered light beam 160 with at least one reference light beam 154 using laser Doppler vibrometer 116.

The method steps can be carried out in the order given, with one or more of the method steps being able to be carried out at least in part simultaneously, and with one or more of the method steps being able to be repeated several times. In addition, other process steps, whether or not mentioned here, can additionally be carried out.

The spatial vibration analysis of the at least one test body 112 can include a three-dimensional vibration analysis of at least one point of the test body 112. The spatial vibration analysis of the at least one test body 112 can also include a two-dimensional vibration analysis of at least one part of the test body 112. For example, a vibration analysis, in particular a three-dimensional vibration analysis in each case, can be carried out one after the other for a plurality of points 158 on a surface. For example, the fact that at least one component of the beam splitter system 124, such as a mirror 142, can be adjusted electromechanically can be used for the two-dimensional vibration analysis, whereby at least one partial beam 156 can be directed step by step to different points 158 on a surface. This can be done automatically, for example, computer-controlled, for example by a controller 144 of the opto-mechanical measuring system 110.

Reference List

110

Optomechanical measuring system

112

specimen

114

surface

116

Laser Doppler Vibrometer

118

beam splitter system

120

Housing

122

exit port

124

light source

126

interferometer

128

Separating Beamsplitter Cube

130

Merging Beamsplitter Cube

132

interferometer mirror

134

photodetector

136

data processing device

138

interface

140

beam splitter

142

mirror

144

steering

146

camera

148

line of sight

150

illumination light beam

152

beam of light

154

reference light beam

156

partial beam

158

Point

160

Scattered beam of light

162

Superimposed beam of light

164

Process step I

166

Process step II

168

Process step III

170

Process step IV

Claims (11)

Opto-mechanical measuring system (110) for spatial vibration analysis of at least one test body (112), comprising: i. a laser Doppler vibrometer (116), the laser Doppler vibrometer (116) being set up to generate at least one illuminating light beam (150) for illuminating the test body (112), at least one light beam scattered by the test body (112). (160) and to determine at least one measured variable therefrom by superimposition with at least one reference light beam (154); and ii. at least one beam splitter system (118), wherein the beam splitter system (118) is set up to split the illuminating light beam (150) into a plurality of partial beams (156) and direct the partial beams (156) to at least one common point (158) on the test body (112 ) to steer. Optomechanical measurement system (110) according to the preceding claim, wherein at least one component of the beam splitter system (118) is adjustable. Opto-mechanical measuring system (110) according to the preceding claim, wherein at least two components of the beam splitter system (118) can be adjusted independently of one another. Opto-mechanical measuring system (110) according to one of the preceding claims, wherein at least one component of the beam splitter system (118) is integrated into at least one upstream component. An opto-mechanical measurement system (110) according to any one of the preceding claims, wherein the beam splitter system (118) comprises at least one component selected from the group consisting of: a beam splitter cube; a beam splitter prism; a mirror (142). Optomechanical measuring system (110) according to one of the preceding claims, wherein the beam splitter system (118) is designed in such a way that the optical path lengths covered by the partial beams (156) are the same. Optomechanical measuring system (110) according to one of the preceding claims, wherein the beam splitter system (118) is set up in such a way that the partial beams (156) are symmetrically offset from one another. Opto-mechanical measuring system (110) according to any one of the preceding claims, wherein the beam splitter system (118) splits the illuminating light beam (150) into three partial beams (156). Opto-mechanical measuring system (110) according to one of the preceding claims, further comprising a camera (146) aimed at the test body (112) for viewing the test body (112). Method for spatial vibration analysis of at least one test body (112), comprising the following method steps: I. Providing at least one opto-mechanical measuring system (110) according to one of the preceding claims; II. Generating at least one illuminating light beam (150) for illuminating the test body (112) by means of the laser Doppler vibrometer (116); III. splitting the illuminating light beam (150) into a plurality of partial beams (156) and directing the partial beams (156) to at least one common point (158) on the test specimen (112) with the beam splitter system (118); and IV. Detecting at least one light beam (160) scattered by the test body (112) and determining at least one measured variable by superimposing the scattered light beam (160) with at least one reference light beam (154) using the laser Doppler vibrometer (116). Method according to the preceding claim, wherein the spatial vibration analysis of the at least one test body (112) comprises a three-dimensional vibration analysis of at least one point (158) of the test body (112).

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