System and non-contact method for measuring vibrations on the surface of an object - Patents.com

Abstract

A non-contact method for measuring vibrations on a surface of an object is presented. The method includes projecting light from three light sources toward a point of interest on the surface of the object and detecting light reflected from the point of interest on the surface with three detectors, each detector of the three detectors capturing light from a corresponding one of the three light sources. From the captured light, triangulation is used to calculate a vertical displacement of the surface at the point of interest, triangulation is used to calculate a rotational displacement of the surface at the point of interest about an x-axis, and triangulation is used to calculate a rotational displacement of the surface at the point of interest about a y-axis, where the x-axis and y-axis define a plane parallel to the surface of the object.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to the benefit of U.S. Patent Application No. 18 / 087,190, filed December 22, 2022, and U.S. Provisional Patent Application No. 63 / 361,455, filed December 27, 2021, the disclosures of which are incorporated herein by reference in their entireties.

[0002] Technical Field The present disclosure relates to a non-contact and minimally invasive method for measuring vibration or oscillation on the surface of an object, such as in the frequency range of 0 to 50 kilohertz. [Background technology]

[0003] Conventional methods for measuring surface vibrations on the surface of an object or structure under test rely on physically attaching piezoelectric sensors to the surface of the object. The physical attachment of these sensors on the surface of the object introduces several undesirable effects and dependencies, which affect the physical and acoustic behavior of the surface, and can lead to inaccurate and unreliable observations of surface vibrations. Therefore, it is desirable to develop a non-contact technique for measuring vibrations or vibrations on the surface of an object.

[0004] This section provides background information related to the present disclosure that is not necessarily prior art. Summary of the Invention [Means for solving the problem]

[0005] This section provides a general overview of the disclosure and is not an exhaustive disclosure of the entire scope or every feature of the disclosure.

[0006] In one aspect, a non-contact method for measuring vibrations on a surface of an object is presented, the method including projecting light by a light source along a projection axis toward a point of interest on the surface of the object, detecting light reflected from the point of interest on the surface by a detector, determining a change in position over time of the reflected light detected by the detector by a processor, the processor being interfaced with the detector, and calculating at least three measurements of vertical displacement of the surface from the change in position using triangulation by the processor.

[0007] In one embodiment, if the change in position of the reflected light on the detector is dz1 and the angle between the projection axis and the base plane is Θ, the vertical displacement is dz=dz1 / (2*sin(Θ)) where the line between the source and the detector lies in the base plane, and the base plane is parallel to the surface of the object.

[0008] A detector detects light reflected from points of interest on a surface at speeds greater than 40,000 frames per second, for example 160,000 frames per second.

[0009] In another aspect, a non-contact method for measuring vibrations on a surface of an object along three degrees of freedom includes projecting light from three light sources toward a point of interest on the surface of the object, the light projected from the three light sources being coherent, and detecting light reflected from the point of interest on the surface with three detectors, each detector of the three detectors capturing light from a corresponding one of the three light sources. From the light captured by the three detectors, a processor calculates three displacement values ​​associated with the point of interest, the processor being interfaced with each of the three detectors. Specifically, the processor calculates a vertical displacement of the surface at the point of interest using triangulation, calculates a rotational displacement of the surface at the point of interest about an x-axis using triangulation, and calculates a rotational displacement of the surface at the point of interest about a y-axis using triangulation, the x-axis and the y-axis defining a plane parallel to the surface of the object.

[0010] In one example embodiment, three light sources and three detectors are arranged in a base plane parallel to the surface of the object. The three light sources and three detectors are positioned relative to the surface of the object such that each pair of light sources and detectors forms an isosceles triangle with the point of interest, and the point of interest is a common vertex for each isosceles triangle. The three light sources and three detectors may be integrated into one observation device.

[0011] In one embodiment, a first light source and detector pair and a second light source and detector pair are positioned on the x-axis, while a third light source and detector pair is positioned on the y-axis, such that the first light source is adjacent to the second detector and the second light source is adjacent to the first detector.

[0012] In this embodiment, if the change in position of the reflected light due to a change in the vertical displacement of the surface is denoted as dz1, and the angle between the projection axis of the light toward the object and the base surface is denoted as Θ, then the vertical displacement (dz) is given by: dz=dz1 / (2*sin(Θ)) where the line between the source and the detector lies in the base plane, and the base plane is parallel to the surface of the object.

[0013] If the change in position of the reflected light due to a change in rotational displacement about the x-axis is dz, the length of the base of the triangle formed by the light source, the detector corresponding to that light source, and the point of interest is b, and the height of the triangle relative to the base is L, then the rotational displacement about the x-axis (Δ) is given by Δ=arctan(dz / sqrt(L*2+b*2)) / 2 It is calculated according to:

[0014] If the change in position of the reflected light due to a change in rotational displacement about the y-axis is dy, the length of the base of the triangle formed by the light source, the detector corresponding to that light source, and the point of interest is b, and the height of the triangle relative to the base is L, then the rotational displacement about the y-axis (ρ) is given by: ρ=arctan(dy / sqrt(L*2+b*2)) / 2 It is calculated according to:

[0015] In another embodiment, a first light source and detector pair is positioned on the x-axis, a second light source and detector pair is positioned directly above the point of interest, and a third light source and detector pair is positioned on the y-axis.

[0016] Additionally, three displacement values ​​may be calculated over time so that at least one of the direction and frequency of waves propagating along the surface at the point of interest may be determined.

[0017] In yet another aspect, a system for measuring vibrations on a surface of an object is presented. The system includes a first light source configured to project light along a first projection axis toward a point of interest on the surface of the object, a first photodetector configured to detect light from the first light source primarily, where the light is reflected from the point of interest on the surface, a second light source configured to project light along a second projection axis toward the point of interest on the surface of the object, a second photodetector configured to detect light from the second light source primarily, where the light is reflected from the point of interest on the surface, a third light source configured to project light along a projection axis toward the point of interest on the surface of the object, and a third photodetector configured to detect light from the third light source primarily, where the light is reflected from the point of interest on the surface. A processor is in data communication with the first photodetector, the second photodetector, and the third photodetector. The processor determines a change in position of the reflected light detected by at least one of the first photodetector, the second photodetector, or the third photodetector, and calculates a vertical displacement of the surface at the point of interest from the change in position using triangulation.

[0018] The processor further calculates a rotational displacement of the surface at the point of interest about an x-axis using triangulation and calculates a rotational displacement of the surface at the point of interest about a y-axis using triangulation, the x-axis and y-axis defining a plane parallel to the surface of the object.

[0019] In one example embodiment, three light sources and three detectors are arranged in a base plane that is parallel to the surface of the object. The three light sources and three detectors are positioned relative to the surface of the object such that each pair of light sources and detectors forms an isosceles triangle with the point of interest, and the point of interest is a common vertex for each isosceles triangle. The three light sources and three detectors may be integrated into one observation device.

[0020] In one embodiment, a first light source and detector pair and a second light source and detector pair are positioned on the x-axis, while a third light source and detector pair is positioned on the y-axis, such that the first light source is adjacent to the second detector and the second light source is adjacent to the first detector.

[0021] In another embodiment, a first light source and detector pair is positioned on the x-axis, a second light source and detector pair is positioned directly above the point of interest, and a third light source and detector pair is positioned on the y-axis.

[0022] Further scope of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0023] The drawings described herein are for purposes of illustrating only selected embodiments rather than all possible implementations and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 illustrates a non-contact technique for measuring vibrations on the surface of an object. [Diagram 2] FIG. 1 illustrates a non-contact technique for measuring vibrations on the surface of an object using three emitter / detector pairs. [Figure 3A] FIG. 3A illustrates the geometric relationships for determining the vertical displacement of a surface. [Figure 3B]FIG. 3B illustrates the geometric relationships for determining the rotational displacement of a surface about the x-axis when the surface lies in the xy plane. [Figure 3C] FIG. 3C illustrates the geometric relationships for determining the rotational displacement of a surface about the y-axis when the surface lies in the xy-plane. [Figure 4] FIG. 1 is a top view showing an example arrangement of three emitter / detector pairs of the system. [Diagram 5] FIG. 13 is a top view showing another example of an arrangement of three emitter / detector pairs of the system. [Figure 6] 1 illustrates the use of an interference device to split light projected from a light source. [Figure 7] FIG. 13 is a diagram illustrating an implementation example for an observation device. [Figure 8] 1A-1C show examples of cube elements that may be embedded in an observation device. [Figure 9] FIG. 1 illustrates waves propagating along a surface for an array of observation devices. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0026] Example embodiments will now be described in more detail with reference to the accompanying drawings.

[0027] 1 illustrates a non-contact technique for measuring vibrations (or oscillations) on an object's surface 10. Light is projected by a light source 12 along a projection axis 8 toward a point of interest on the object's surface. Light reflected from the surface is then detected by a photodetector 14. In one example, the light source is further defined as a laser and the photodetector is further defined as a charge-coupled device (CCD). It is readily understood that other types of photodetectors are within the scope of this disclosure.

[0028] To calculate the vertical displacement of the surface at the point of interest, the light detector 14 is interfaced with a processor 16. The processor 16 determines the change in position of the reflected light detected by the detector. From that change in position, the vertical displacement of the surface can be calculated using triangulation. More specifically, the vertical displacement can be calculated as: dz=dz1 / (2*sin(Θ)) where dz1 is the change in position of the reflected light on the detector, and Θ is the angle between the projection axis 8 and the base plane 6, where the line between the light source and the detector is in the base plane, which is parallel to the surface of the object. To report the surface oscillations, the photodetector 14 is configured to capture the change in light position at a rate faster than 40,000 frames per second. In an example embodiment, the photodetector is clocked at 160,000 frames per second. In addition, at least three measurements are required to define a waveform indicative of the oscillations. This non-contact approach does not affect the physical and acoustic behavior of the object's surface. Furthermore, it is insensitive to exposure to high temperatures, high temperature gradients, and extreme electrostatic and electromagnetic interference.

[0029] In one example, the processor 16 is implemented as a microcontroller. It should be understood that the functions performed by the processor may be implemented in hardware logic, software logic, or a combination of hardware and software logic. In this regard, the processor 16 may be or include any of a digital signal processor (DSP), a microprocessor, a microcontroller, or other programmable device programmed by software to perform the above-described methods. Alternatively, it should be understood that the processor is or includes other logic devices, such as, for example, a field programmable gate array (FPGA), a complex programmable logic device (CPLD), or an application specific integrated circuit (ASIC). When the processor 16 is described as performing or configured to perform a function, it should be understood that the processor 16 is configured to do so by appropriate logic (e.g., in software, a logic device, or a combination thereof).

[0030] To observe dynamic changes in the topography of a surface in three degrees of freedom, the non-contact measurement technique preferably includes three emitter / detector pairs as seen in FIG. 2. Light is projected from three light sources towards a point of interest 21 on the surface of the object. The projected light is preferably coherent. Light reflected from the surface is detected using three different photodetectors. Each photodetector captures light from a corresponding one of the three light sources. More specifically, the position of the reflected light incident on the detector is captured by the photodetectors such that the change in the position of the reflected light incident on the detector over time can be measured. The measurements by each photodetector may be triggered simultaneously, for example by a reference clock signal. For synchronization, each measurement is tagged or annotated by a processor with a precise timestamp.

[0031] In the example embodiment, the light projected from the three light sources is coherent. In some implementations, it is assumed that the three light sources operate at three different wavelengths. Note that the three light sources and the three detectors are positioned in a plane above the surface of the object. This plane is parallel to the surface of the object and is referred to herein as the base plane 6. An imaginary line drawn perpendicularly from the point of interest to the base plane is referred to as the principal observation axis 22 (i.e., z-axis) and serves as the z-axis of the Cartesian coordinate system. The remaining Cartesian coordinate system (i.e., the xy-plane) is defined by the plane in which the surface of the object lies.

[0032] From the light captured by the three photodetectors, the vertical displacement of the surface, the rotational displacement of the surface about the x-axis, and the rotational displacement of the surface about the y-axis can be calculated. Figures 3A-3C show the geometrical relationship for each of these displacements. The vertical displacement dz is calculated according to Figure 3A. The rotational displacement Δ of the surface about the x-axis is calculated according to Figure 3B, and the rotational displacement ρ of the surface about the y-axis is calculated according to Figure 3C.

[0033] In one example embodiment, the three emitter / detector pairs are positioned with respect to each other as seen in Figure 4. A first emitter / detector pair P1 is positioned opposite a second emitter / detector pair P2 such that both pairs are on the x-axis, and a third emitter / detector pair P3 is positioned laterally relative to the other two pairs on the y-axis.

[0034] In this arrangement, the measurement signal from each emitter / detector pair contains two components of the desired displacement, which must be separated using simultaneous linear equations. Specifically, the first emitter / detector pair P1 detects dz1+dz2, the second emitter / detector pair P2 detects dz1-dz2, and the third emitter / detector pair P3 detects dz1+dz3. The individual components are then extracted using a set of equations as follows: dz1=(p1+p2) / 2 dz2=(p1-p2) / 2 dz3=p3-dz1 Finally, quantiles are calculated from these components using the geometric relationships shown in Figures 3A-3C. A given set of quantiles is tagged with a timestamp associated with the measurements used to determine that given set of quantiles.

[0035] In another example, three emitter / detector pairs are positioned with respect to each other as seen in Figure 5. That is, a first emitter / detector pair P1 is positioned on the x-axis, a second emitter / detector pair P2 is positioned directly above the point of interest on the z-axis, and a third emitter / detector pair P3 is positioned on the y-axis.

[0036] The measured signal from the emitter / detector pairs in this arrangement also contains a component of the desired displacement, which must be separated using simultaneous linear equations. Specifically, the first emitter / detector pair P1 detects dz1+dz2, the second emitter / detector pair P2 detects dz2, and the third emitter / detector pair P3 detects dz1+dz3. The individual components are then extracted using a set of equations as follows: dz1=p1-p2 dz2=p2 dz3=p3-dz1 Again, three displacement values ​​are calculated from these components using the geometric relationships shown in Figures 3A-3C. In this way, the displacement of the surface at the point of interest is measured in three degrees of freedom, and displacement values ​​exhibiting amplitudes ranging from 10 micrometers to 100 millimeters (or more) can be measured.

[0037] In some embodiments, as seen in FIG. 6, an interferometric device, such as a grid, is used to split the light from a given light source into multiple light beams that are periodically spaced apart from one another.

[0038] The displacement of the surface at a given point of interest is indicative of the vibration experienced by the surface of the object. By measuring and calculating the above three displacement values ​​over time, a time series of displacement values ​​may be generated to determine a vector representing the wave propagating along the surface of the object at the point of interest. The vector representing the propagating wave indicates the direction, amplitude, and frequency of the wave at the point of interest. In one example, the direction of the propagating wave is calculated as follows: Direction angle = arctan(sin(rotational displacement about the x-axis) / sin(rotational displacement about the y-axis)) A direction angle may be calculated for each set of displacement values ​​in the time series, but a more accurate direction angle is determined by calculating the direction angle for multiple instances over a period of time and then averaging the values. For example, a moving average may be used to calculate the direction angle, where the window size is preferably larger than the length of the propagating wave. The amplitude of the propagating wave is calculated as the difference between the maximum and minimum vertical displacement values, while the frequency is derived from the time difference between the peaks of the propagating wave. In this manner, a vector representing the wave propagating along the surface of the object at the point of interest may be constructed. It is readily understood that other computational techniques may be used to determine from the displacement values ​​a vector representing the wave propagating along the surface of the object at the point of interest.

[0039] In one embodiment of the disclosure, a system for measuring vibrations on a surface of an object may be constructed, which includes one or more observation devices. FIG. 7 shows an example implementation for the observation device 70. In this example, the observation device 70 has a disk shape, with four cube elements 80 embedded along the circumference of the disk. As seen in FIG. 8, the cube elements 80 are configured to house a laser diode 81, a linear CCD (e.g., 1024x1 pixels) 82, and supporting electronics on a printed circuit board 83. An interference device 84 may be disposed in the projection path of the laser diode 81. In addition, a cover 85 may be placed over the linear CCD 82. The cover is designed to obscure the linear CCD and prevent stray and undesired light from reaching the detector, thereby improving the signal-to-noise ratio of the measurement.

[0040] Continuing with reference to Figures 4 and 7, cube 1 houses the CCD for the third emitter / detector pair P3, cube 2 houses the laser diode for the first emitter / detector pair P1 and the CCD for the second emitter / detector pair P2, cube 3 houses the CCD for the first emitter / detector pair P1 and the laser diode for the second emitter / detector pair P2, and cube 4 houses the laser diode for the third emitter / detector pair P3. One or more QR codes may be disposed on the outer surface of the observation device. For example, one QR code may be disposed on a given observation device to uniquely identify a given observation device in an array of observation devices, or alternatively, four QR codes may be disposed on a given observation device, with each QR code disposed adjacent to one of the cubes. In this manner, each cube of a given observation device is uniquely identified.

[0041] The observation device 70 is supported above a point of interest on the surface of the object by a support mechanism. As described above, the light source and the light detector are housed in the observation device and are arranged in a geometric plane substantially parallel to the surface of the object. This geometric plane serves as the xy plane of a Cartesian coordinate system. Meanwhile, an imaginary line drawn from the point of interest to the geometric plane serves as the z-axis of the Cartesian coordinate system. For calibration purposes, the support mechanism is configured to adjust the position of the observation device with respect to the surface of the object along five degrees of freedom. That is, the position of the observation device can be rotated about the x-axis, rotated about the y-axis, or translated along any of the three axes of the Cartesian coordinate system. It is envisioned that the position of the observation device can be adjusted manually by an operator or in an automated manner, for example using a servo motor or the like. Suitable support mechanisms are readily found in the art. A graphical interface may be used to assist in the positioning of the observation device. The graphical interface operates to display the current observation position and orientation of the observation device with respect to the point of interest on the surface and an a priori CAD model of the surface. The operator can observe the graphical interface and adjust the observation device accordingly.

[0042] An example of a calibration and setup procedure for an observation device is further described. First, the correct vertical (z) and planar (XY) orientation of a given observation device is established to focus the observation device on the point of interest on the surface under investigation. To do so, the support mechanism is adjusted, for example by manipulating the support fixture orientation adjustment mechanism, to achieve that the X and Y orientation of the base plane of the observation device is parallel to the XY plane of the surface of the point of interest (or perpendicular as derived from the average of the inclination if it is observed to have a sharp maximum at its zenith). After completion of this step, the distance along the vertical z axis between the base plane of the observation device and that of the surface at the point of interest is adjusted, for example by a rack and pinion gear set. Using the surface topography provided by a 3D rendering, for example a CAD, a photogrammetry file, or a high-resolution photographic image, the operator can make a judgment on the selection of the desired point of interest on the surface.

[0043] In order to observe and quantify the effects of undesired external (uncontrolled) sources of mechanical excitation acting on the surface under investigation, one may begin projecting light from a light source at a prescribed level of intensity onto the surface under investigation at a desired point of interest in order to accurately quantify any acoustic excitations being transmitted onto the surface by uncontrolled external forces, if any. During the course of this static characterization procedure, the frequency content, amplitude, and velocity of such external excitations are quantified.

[0044] To quantify the effect of unwanted external (uncontrolled) sources of illumination that may interfere with correct observation by the photodetectors, one may begin projecting light from the light sources at a prescribed level of intensity onto the surface under investigation, and compare the detected levels of illumination received by each photodetector of the observation device by subtracting the level of illumination projected from each light source to determine the effect of any stray light at the desired point of interest.

[0045] In some embodiments, a system for measuring vibrations on a surface of an object includes a plurality of observation devices positioned spatially apart from one another above the surface of the object, each observation device configured to survey a different point of interest on the surface of the object.

[0046] To coordinate reports from the multiple observation devices, each observation device is in data communication (or interfaced) with a central computing device. More specifically, each observation device is configured to receive the same reference clock signal from the central computing device. The reference clock signal serves as a trigger for a photodetector present in a given observation device to acquire light measurements. Each observation device also includes at least one QR code or another type of unique identifier that can be used to uniquely identify a given observation device among the multiple observation devices.

[0047] In addition, the central computing device also knows the position of each observation device in the common coordinate system. For example, the positions of the observation devices may be known in advance from CAD data and / or other design documents. Alternatively, an independent camera system may be used to determine the position of each observation device in the common coordinate system. Other techniques for determining the positions of the observation devices relative to each other and / or the common coordinate system are known in the art.

[0048] Data from two or more observation devices may then be used to quantify other metrics related to the vibrations experienced by the surface of the object. For example, the speed of a wave propagating between two observation devices and observed by them may be calculated. If the distance between the two observation devices is known, the speed of the propagating wave is determined by dividing this distance by the time it takes for the wave to propagate between the two observation devices. This simplified example assumes that the wave propagates along a straight line connecting the two observation devices.

[0049] More practically, as seen in Figure 9, the wave propagates along a line that passes through one observation device P1 but between two other observation devices P3, P4. In this case, the wave travels in the x direction. The angle from the x axis is measured counterclockwise. This angle can be determined using the direction of the wave calculated by the observation device P1. The line from P1 to P3 forms the adjacent leg (A) of a right triangle. Meanwhile, the line from P3 to the intersection with the x axis, perpendicular to the adjacent leg A, forms the opposite leg (O) of the right triangle. The part of the x axis from P1 to the intersection forms the hypotenuse (H). Two different periods need to be measured. The first of them is the period between signal peaks in one pod. This period is called T(freq). It should be the same in both P1 and P3 and is the inverse of the frequency f, i.e. f=1 / T(freq). The second time is the travel time of the wave between P1 and P3. In other words, it is the time between when the peak is observed at P1 and when the peak is observed at P3. This time is called T(trav). The distance D that the wave travels during T(trav) is the distance along the x-axis, i.e., the length of H. The distance along A (P1 to P3) is known. The angle theta has been determined from the directional measurements. The ratio of A to H is the cosine of theta. Therefore, the distance D along H is A divided by the cosine of theta, i.e., H=A / cos(theta). Dividing the distance D by the period T(trav) gives the velocity V of the wave, i.e., V=D / T(trav). Multiplying the velocity V by the period T(freq), which is related to the frequency, gives the wavelength lambda, i.e., V*T(freq)=lambda.

[0050] As described above, a display device may be interfaced with the processor. During the investigation, a priori CAD or photographic representations of the surface may be displayed on the display. Metrics related to the vibrations experienced by the object's surface and observed by the system may also be displayed on the display device. In some embodiments, the vibrations experienced by the surface, including the different propagating waves, are animated or otherwise visualized on a graphical user interface (e.g., with an illustration of a waterfall).

[0051] The calculation and measurement techniques described herein may be implemented by one or more computer programs executed by one or more processors. The computer programs include processor-executable instructions stored in a non-transitory tangible computer-readable medium. The computer programs may also include stored data. Non-limiting examples of non-transitory tangible computer-readable media are non-volatile memory, magnetic storage, and optical storage.

[0052] Some portions of the above description present the techniques described herein in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. It will be understood that these operations, whether described functionally or logically, are implemented by computer programs. Further, it has proven convenient at times to refer to these arrangements of operations as modules or by functional names, without loss of generality.

[0053] As is apparent from the above discussion, unless specifically stated otherwise, it is recognized that throughout this description, discussions using terms such as, for example, "processing" or "calculating" or "computing" or "determining" or "displaying" refer to the activities and processes of a computer system or similar electronic computing device that manipulates and transforms data, which is represented as physical (electronic) quantities within the memory or registers of the computer system or other devices for storing, transmitting, or displaying such information.

[0054] Certain aspects of the described technology include process steps and instructions described herein in the form of an algorithm, which may be embodied in software, firmware, or hardware, and when embodied in software, may be downloaded to reside on and operated from different platforms used by a real-time network operating system.

[0055] The present disclosure also relates to an apparatus for performing the operations herein. The apparatus may be specially constructed for the required purposes or may include a computer selectively activated or reconfigured by a computer program stored in a computer-readable medium accessible by the computer. Such a computer program may be stored on a tangible computer-readable storage medium, such as, but not limited to, a floppy disk, an optical disk, a CD-ROM, a magneto-optical disk, a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic or optical card, any type of disk including an application specific integrated circuit (ASIC), or any type of medium suitable for storing electronic instructions, each of which is coupled to a computer system bus. Furthermore, the computers referred to herein may include a single processor or may be architectures using multiple processor designs to increase computing power.

[0056] The algorithms and operations presented herein are not inherently related to any particular computer or other apparatus. A variety of systems may also be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will be apparent to those skilled in the art, along with equivalent variations. In addition, the present disclosure has not been described with reference to any particular programming language. It will be recognized that a variety of programming languages ​​may be used to implement the teachings of the present disclosure as described herein.

[0057] The foregoing description of the embodiments has been provided for the purpose of illustration and description. The foregoing description is not intended to be exhaustive or to limit the present disclosure. Individual components or features of a particular embodiment are generally not limited to that particular embodiment, and even if not specifically shown or described, may be interchangeable when applicable and used in selected embodiments. In addition, the same may be modified in various ways. Such modifications are not considered to be departures from the present disclosure, and all such modifications are intended to be within the scope of the present disclosure.

Claims

1. 1. A non-contact method for measuring vibrations on a surface of an object, comprising: projecting light by a light source along a projection axis toward a point of interest on a surface of an object; detecting, with a detector, the light reflected from the point of interest on the surface; determining, by a processor, a change in position over time of the reflected light detected by the detector, the processor being interfaced with the detector; and calculating, by the processor, from the change in position using triangulation, at least three measurements of vertical displacement of the surface.

2. 2. The non-contact method of claim 1, comprising: If the change in the position of the reflected light on the detector is dz1 and the angle between the projection axis and the base surface is Θ, then dz=dz1 / (2*sin(Θ)) and calculating the vertical displacement according to A non-contact method, wherein the line between the light source and the detector lies in the base plane, and the base plane is parallel to the surface of the object.

3. 10. The non-contact method of claim 1, wherein the light source is further defined as a laser.

4. 10. The non-contact method of claim 1, wherein the detector is further defined as a charge coupled device.

5. 2. The contactless method of claim 1, wherein the processor is further defined as a field programmable gate array.

6. 10. The non-contact method of claim 1, wherein the detector detects light reflected from the point of interest on the surface at greater than 40,000 frames per second.

7. 1. A non-contact method for measuring vibrations on a surface of an object, comprising: projecting light from three light sources towards a point of interest on a surface of an object, the light projected from the three light sources being coherent; detecting the light reflected from the point of interest on the surface with three detectors, each of the three detectors capturing light from a corresponding one of the three light sources; calculating a vertical displacement of the surface at the point of interest using triangulation from the light captured by the three detectors, by a processor, the processor being interfaced with each of the three detectors; calculating, by the processor, a rotational displacement of the surface at the point of interest about an x-axis using triangulation from the light captured by the three detectors; and calculating, by the processor, a rotational displacement of the surface at the point of interest relative to a y-axis using triangulation from the light captured by the three detectors, wherein the x-axis and the y-axis define a plane parallel to the surface of the object.

8. 8. The non-contact method of claim 7, further comprising arranging the three light sources and the three detectors in a base plane parallel to the surface of the object.

9. 8. The non-contact method of claim 7, further comprising positioning the three light sources and the three detectors relative to the surface of the object such that each light source and detector pair forms an isosceles triangle with the point of interest, and the point of interest is a common vertex for each of the isosceles triangles.

10. 8. The non-contact method of claim 7, further comprising integrating the three light sources and the three detectors into an observation device.

11. 8. The non-contact method of claim 7, further comprising splitting the light from each of the three light sources into a plurality of light beams periodically spaced from one another.

12. 9. The non-contact method of claim 8, further comprising arranging a first light source and detector pair and a second light source and detector pair on the x-axis and arranging a third light source and detector pair on the y-axis such that the first light source is adjacent to the second detector and the second light source is adjacent to the first detector.

13. 13. The non-contact method of claim 12, comprising: Let dz1 be the change in the position of the reflected light due to a change in the vertical displacement of the surface, and Θ be the angle between the projection axis of the light toward the object and the base surface. dz=dz1 / (2*sin(Θ)) and calculating a vertical displacement (dz) according to A non-contact method, wherein the line between the light source and the detector lies in the base plane, and the base plane is parallel to the surface of the object.

14. 13. The non-contact method of claim 12, comprising: Let dz be the change in the position of the reflected light due to a change in rotational displacement about the x-axis, b be the length of the base of a triangle formed by a light source, a detector corresponding to the light source, and the point of interest, and L be the height of the triangle relative to the base. Δ=arctan(dz / sqrt(L*2+b*2)) / 2 Calculating a rotational displacement (Δ) about the x-axis according to:

15. 13. The non-contact method of claim 12, comprising: Let dy be the change in position of the reflected light due to a change in rotational displacement about the y-axis, b be the length of the base of a triangle formed by a light source, a detector corresponding to the light source, and the point of interest, and L be the height of the triangle relative to the base. ρ=arctan(dy / sqrt(L*2+b*2)) / 2 and calculating a rotational displacement (ρ) about the y-axis according to:

16. 9. The non-contact method of claim 8, further comprising: positioning a first light source and detector pair on the x-axis, a second light source and detector pair directly above the point of interest, and a third light source and detector pair on the y-axis.

17. 8. The non-contact method of claim 7, wherein the light source is further defined as a laser and the detector is further defined as a charge coupled device.

18. 8. The non-contact method of claim 7, further comprising: calculating a vertical displacement of the surface at the point of interest over time; calculating a rotational displacement of the surface at the point of interest about the x-axis over time; calculating a rotational displacement of the surface at the point of interest about the y-axis over time; and using the vertical displacement of the surface over time, the rotational displacement of the surface about the x-axis over time, and the rotational displacement of the surface about the y-axis over time to determine at least one of a direction or a frequency of waves propagating along the surface at the point of interest.

19. 1. A system for measuring vibrations on a surface of an object, comprising: a first light source configured to project light along a first projection axis toward a point of interest on a surface of the object; a first light detector configured to primarily detect light from the first light source, the light reflected from the point of interest on the surface; and a second light source configured to project light along a second projection axis toward the point of interest on the surface of the object; and a second light detector configured to primarily detect light from the second light source, the light reflected from the point of interest on the surface; and a third light source configured to project light along a projection axis towards the point of interest on the surface of the object; and a third light detector configured to primarily detect light from the third light source, the light reflected from the point of interest on the surface; and a processor in data communication with the first photodetector, the second photodetector, and the third photodetector; The system, wherein the processor determines a change in position of the reflected light detected by at least one of the first optical detector, the second optical detector, or the third optical detector, and calculates a vertical displacement of the surface at the point of interest from the change in position using triangulation.

20. 20. The system of claim 19, wherein the processor further calculates a rotational displacement of the surface at the point of interest about an x-axis using triangulation and a rotational displacement of the surface at the point of interest about a y-axis using triangulation, the x-axis and the y-axis defining a plane parallel to a surface of the object.

21. 21. The system of claim 20, wherein the first light source, the first photodetector, the second light source, the second photodetector, the third light source, and the third photodetector are disposed in a base plane that is parallel to the surface of the object.

22. 22. The system of claim 21 , wherein the first light source, the first photodetector, the second light source, the second photodetector, the third light source, and the third photodetector are positioned relative to the surface of the object such that each light source and detector pair forms an isosceles triangle with the point of interest, and the point of interest is a common vertex for each of the isosceles triangles.

23. 22. The system of claim 21, wherein the three light sources and the three detectors are integrated within an observation device.

24. 22. The system of claim 21, wherein the first light source, the first photodetector, the second light source, and the second photodetector are disposed on the x-axis and the third light source and the third photodetector are disposed on the y-axis such that the first light source is adjacent to the second photodetector and the second light source is adjacent to the first photodetector.

25. 22. The system of claim 21, wherein the first light source and the first photodetector are positioned on the x-axis, the second light source and the second detector are positioned directly above the point of interest, and the third light source and the third photodetector are positioned on the y-axis.

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