JPH08240478A - Laser vibrometer - Google Patents

Abstract

PURPOSE: To enable a highly accurate measurement by a small vibrometer even in a condition where itself vibrates by correcting vibrational information by fixing a transmitting characteristic of a passage into which vibration of the vibrometer itself is mixed, from vibrational information obtained from a vibratory object and an output signal of a vibrational signal processing means. CONSTITUTION: A measuring signal SL is outputted from the laser vibrometer main device 1, and self-oscillation of the device 1 is measured by accelerometers 2X, 2Y and 2Z arranged in X, Y and Z directions in a sensor head 5. Output signals of the accelerometers 2X, 2Y and 2Z are respectively inputted to integral amplifiers 3X, 3Y and 3Z, and are converted into self-oscillation signals NX, NY and NZ. First of all, the measuring signal SL is inputted to a signal correcting device 4X together with the self-oscillation signal NX, and a vibrational level difference and a phase difference by a transmitting characteristic in an X directional passage are corrected. Similar correction is performed by Y directional and Z directional signal correcting devices 4Y and 4Z, and an output signal from which self oscillation in three directions is removed, is finally outputted from the signal correcting device 4Z.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser vibrometer for contactlessly measuring vibrations of pipes, equipment, structures and the like, and more particularly to a laser vibrometer actually used in plants.

[0002]

2. Description of the Related Art Techniques for transmitting and receiving laser light to and from an oscillating object and measuring the oscillation speed by optical heterodyne detection of Doppler shift components contained in the received light are described in the literature and laser oscillation products that have been commercialized in the past. It has already been widely known from catalogs of meters.

However, in actual measurement, since the laser vibrometer itself vibrates, its influence is eliminated,
A method capable of accurately measuring the vibration of the measurement target has been considered. For example, Japanese Patent Application Laid-Open No. 5-288760 has already proposed a method of subtracting a measurement error equivalent value converted from a measurement value of vibration of the laser vibrometer itself (hereinafter referred to as self-vibration) from an output signal of the laser vibrometer. ing.

Further, in order to carry the laser vibrometer freely, it is desired to reduce the size and weight of the laser vibrometer. For example, a method using a semiconductor laser as a light source has been proposed.

Further, when measuring vibrations at a plurality of points on a vibrating object or measuring vibration distribution over a wide area, a method of scanning laser light with a uniaxial or biaxial galvano-scanner mirror or the like is used. There is. In this method, when a specific point is scanned once, the continuous moving speed due to the vibration of the target point is measured, and the amplitude of the vibration is obtained from the maximum value.

On the other hand, when measuring the vibrations of pipes and rotating equipment and diagnosing these equipments, vertical and horizontal vibration trajectories (Lissajous) of the rotation axis are measured and recorded to judge the abnormality of the equipment. ing. In the prior art, the measurement of this Lissajous waveform was carried out by mounting an accelerating clock in the vertical and horizontal directions with respect to the rotation axis of the vibrating object and synchronizing them.

Finally, as a method of grasping the state of the object to be measured by non-contact vibration measurement and confirming the measurement data on the spot, generally, the output signal of the laser vibrometer is observed with an oscilloscope or spectrum analyzer. Is taken. An auscultation stick is used as the contact method.

[0008]

As described above, in the conventional laser vibrometer, the vibrometer itself is not vibrating, and the vibration velocity of the object to be measured is measured on the assumption that the optical element in the vibrometer is stationary. To do.

However, for example, when the laser vibrometer is mounted on a moving mechanism such as a robot and the vibration is measured by sequentially pausing the measuring points, the vibration on the moving mechanism side propagates through the support portion, and the vibrometer It vibrates itself. Further, even when the laser vibrometer is fixed to the floor surface with a tripod or the like, it is possible that the vibration of the floor surface causes the laser vibrometer to vibrate. When vibration measurement is performed in such a state, the laser light is Doppler-shifted by the vibration of each optical element in the vibrometer, and the output signal is mixed with the vibration signal of the vibrating object, resulting in a measurement error. There was a point.

As a method of removing this measurement error, a value equivalent to the measurement error converted from the measured value of self-vibration is
Although a method of subtracting from the output signal of the laser vibrometer is conceivable, this method is simple, but if a phase difference occurs in the process of mixing the measured self-vibration into the output signal of the laser vibrometer, it causes a large measurement error. May cause

Further, in order to miniaturize the device, it is possible to use a semiconductor laser as a light source. However, this method has a problem that the measuring distance cannot be long because the coherence length of the semiconductor laser is significantly shorter than that of, for example, a He-Ne laser.

Further, in the case of measuring the vibration distribution, in the method of measuring the continuous moving speed of a specific point at one time of scanning, the vibration frequency which can be measured by the measuring time of each point at the time of scanning is It will be limited. For example, if each point is measured for 10 msec during scanning, the correct amplitude cannot be calculated from the measured speed for vibrations with a frequency of 100 Hz or less. Therefore, when measuring low-frequency vibration, it is necessary to scan the laser light at a very constant speed, which causes a problem that the measurement time becomes long.

Further, when measuring the Lissajous, it is necessary to attach a plurality of accelerometers to the measuring object in the horizontal and vertical directions, and it is necessary to synchronize these measuring instruments. With such a method, it is difficult to measure the vibration of a device placed in a narrow place or contaminated with radiation or the like. Further, even if the remote measurement is performed, it is necessary to arrange a plurality of laser vibrometers for remote measurement and measure them in synchronization with each other, which is not realistic considering the labor and cost of arranging the equipment.

Further, the conventional technique of grasping the state of the object to be measured by vibration measurement and checking the measured data on the spot has the following problems. First, observing the output signal of a laser vibrometer with an oscilloscope or spectrum analyzer is a method that has already been put into practical use, but the physical quantity of the entire device increases and the state of the measurement target is grasped from the signal waveform. However, much experience and knowledge is required. Next, the method using an auscultation stick has the advantages that it is convenient to carry and the measurement data can be easily confirmed, but it is not possible to make measurements outside the audible range, and recording is poor.

In order to solve the above problems,
A laser vibrometer satisfying the following items is required.・ Even if the instrument itself vibrates, its influence can be removed and the vibration of the measurement target can be measured accurately. ・ Small size and weighing, which is convenient to carry. ・ Vibration in a wide area can be accurately measured in a short time. To be able to observe the correlation (Lissajous waveform) of horizontal and vertical vibrations of pipes and rotating shafts ・ To be able to easily confirm the condition of the measurement target and the measurement data on the spot. The present invention is intended to realize the above functions. , It is possible to perform accurate measurement even when the vibrometer itself is vibrating, and it is possible to reduce the size, and it is possible to accurately measure vibration in a wide area in a short time, and to measure horizontal and vertical directions of pipes and rotary shafts. It is an object of the present invention to obtain a laser vibrometer capable of observing vibration correlation (Lissajous waveform) and easily confirming data simultaneously with measurement.

[0016]

A laser vibrometer according to a first aspect of the present invention irradiates a vibrating object with laser light, and vibrates the vibrating object based on vibration information contained in reflected light from the vibrating object. A laser vibrometer or its supporting portion, a vibration detecting means provided for measuring a predetermined vibration direction of the laser vibrometer or the supporting portion itself, and an output signal from the vibration detecting means. The transfer characteristic of the path in which the vibration of the laser vibrometer or the supporting part itself is mixed is identified by using the vibration signal processing means for amplifying the vibration signal, the vibration information obtained from the vibrating object, and the output signal of the vibration signal processing means, and the identification is performed. And a signal correction means for correcting the vibration information of the laser vibrometer using the transfer characteristic and the output signal of the vibration detection means.

According to a second aspect of the present invention, in the laser vibrometer according to the second aspect, the signal correcting means according to the first aspect converts the output signals of the vibration information and the vibration signal processing means from analog signals into digital signals, respectively. And second analog-to-digital converters, and adaptive filters for adjusting the output signals from the first and second analog-to-digital converters so that the respective correlation components are minimized, and the output signals of the adaptive filters. And a digital / analog converter for converting the digital signal from the analog signal to the analog signal.

A laser vibrometer according to a third aspect of the present invention is a gain control for adjusting the levels of the vibration information and the output signal of the vibration signal processing means before the signal correcting means according to the first or second aspect. It is characterized in that means is further provided.

A laser vibrometer according to a fourth aspect of the present invention is characterized in that the signal correcting means according to the first or second aspect of the present invention applies to all the frequency bands included in the vibration of the laser vibrometer or the support unit in advance. It is characterized by being identified as a transfer characteristic.

A laser vibrometer according to a fifth aspect of the present invention is selected from a bandpass filter for selecting a frequency band of interest from an output signal from the signal correcting means according to any one of the first to fourth aspects. It is characterized by further comprising frequency conversion means for converting the frequency band signal into the frequency range of audible sound and sound generation means for reproducing the converted signal.

A laser vibrometer according to a sixth aspect of the present invention comprises a recording means for recording / reproducing an output signal corrected by the signal correcting means according to any one of the first to fifth aspects, and a signal correcting means. It is characterized by further comprising simultaneous display means for displaying the corrected output signal and the waveform or frequency spectrum of the corrected output signal which has already been recorded, individually or simultaneously.

A laser vibrometer according to claim 7 of the present invention splits a laser beam into object light and reference light, irradiates the vibrating object with the object light, and interferes the reflected light with the reference light. And measuring the vibration of the vibrating object, the optical path length of the reference light is adjusted to the length of the average value of the maximum optical path length and the minimum optical path length of the object light that can be measured by the laser vibrometer. An optical waveguide means is provided.

The laser vibrometer according to claim 8 of the present invention is for irradiating a vibrating object with a laser beam and measuring the vibration of the vibrating object from the vibration information contained in the reflected light from the vibrating object. A uniaxial or biaxial laser light scanning unit that scans the laser light with a cycle shorter than the vibration cycle of the vibrating object and scans the same point of the vibrating object a plurality of times, and each of the laser light scanning means observed during the plurality of times of scanning. And a vibration calculation unit that stores the speed of the scanning point and obtains the vibration of the vibrating object.

According to a ninth aspect of the present invention, in the laser vibrometer according to the eighth aspect, the vibration calculation means for the vibration obtains the amplitude or standard deviation of the velocity at each of the scanning points by parallel arithmetic processing. It is characterized by further comprising a vibration distribution image display means for displaying the amplitude or standard deviation of the velocity of each scanning point on the display screen corresponding to the coordinates of each scanning point.

A laser vibrometer according to a tenth aspect of the present invention irradiates a vibrating object having surfaces with different inclinations with a laser beam, and based on vibration information contained in reflected light from the vibrating object, vibrates the vibrating object. Laser light scanning means for irradiating each surface of the vibrating object with laser light with respect to the laser light, and each laser light from the laser light scanning means at a reflection point on the vibrating object of the laser light, Two or three directions orthogonal to each other at the reflection point from the angle detection means for obtaining the angle with each surface of the vibrating object and the vibration information contained in the reflected light from each laser beam and the angle obtained by the angle detection means. And a vibration component display device for displaying the value of the vibration component as a two-dimensional locus diagram.

According to a eleventh aspect of the present invention, in the laser vibrometer according to the tenth aspect, the angle detecting means according to the tenth aspect emits a continuous wave of a laser light source, and the continuous wave and an oscillation signal from an oscillation circuit. Phase difference detection that detects the phase difference between the amplitude modulation circuit that performs amplitude modulation, the oscillation signal from the oscillation circuit, and the reflected light from the vibrating object via the mirror, converts this to distance information, and obtains the angle of the measurement target point. And a circuit.

A laser vibrometer according to a twelfth aspect of the present invention is characterized in that the angle detecting means according to the tenth aspect is a laser range finder located at the same place as the laser vibrometer.

[0028]

In the laser vibrometer according to the first aspect, the signal correcting means identifies the vibration information of the laser vibrometer and the vibration signal of the laser vibrometer itself.

This makes it possible to eliminate the influence of camera shake from the output of the laser vibrometer.

A laser vibrometer according to a second aspect is the first aspect.
The described laser vibrometer uses an adaptive filter for identifying the characteristics of the transmission path and correcting the signal.

As a result, the transfer characteristic can be automatically identified, and the influence of the vibration of the laser vibrometer itself can be eliminated.

The laser vibrometer according to claim 3 is the same as that according to claim 1.
Alternatively, a gain adjusting means for comparing the signal level of the vibration information of the laser vibrometer with the output signal level of the vibration signal processing means and adjusting the balance thereof is further provided in front of the signal correcting means described in 2. is there.

This makes it possible to effectively remove only self-vibration in order to balance the signal levels of both.

A laser vibrometer according to a fourth aspect is the first aspect.
Alternatively, the signal correcting means described in 2 identifies beforehand the transfer characteristic of the path mixed in the measurement signal of the laser vibrometer.

With this, since the transfer characteristic is identified in advance, it is possible to effectively remove only self-vibration by a simpler process.

The laser vibrometer according to claim 5 is the same as that according to claim 1.
From the output signal from any of the signal correcting means, only the frequency band of interest is taken out by the band pass filter, converted into an audible sound range, and reproduced from the speaker.

As a result, not only can the measured data be confirmed on the spot, but it is also possible to observe vibrations in the ultrasonic range that could not be observed with a stethoscope or the like.

The laser vibrometer according to claim 6 records / reproduces the output signal from the signal correcting means according to any one of claims 1 to 4 by the recording means, and the output signal and the already recorded signal. The waveform or frequency spectrum of the signal is displayed individually or simultaneously.

This makes it possible to record the measurement data so that the past and present situations can be easily compared.

In the laser vibrometer according to the seventh aspect, the optical path length of the reference light is increased by using the optical waveguide means to reduce the difference in propagation distance between the reference light and the object light.

Thus, if the vibration frequency of the vibrating object to be observed is in the range of 5 Hz or higher, the laser vibrometer of this embodiment can perform vibration measurement very efficiently.

The laser vibrometer according to claim 8 has a scanning means for scanning the same point a plurality of times at high speed. The vibration calculation means stores the speed of vibration observed at the time of scanning at each point, and obtains a measured speed sequence for each scanning point arranged in order of scanning time at each point. The vibration calculation means interpolates the waveform from these measured speeds, and also obtains the frequency amplitude and phase.

As a result, appropriate vibration data can be obtained for a vibration having a period sufficiently longer than the scanning period and shorter than the time for performing a plurality of scans.

A laser vibrometer according to a ninth aspect is the eighth aspect.
The vibration calculator means described obtains the amplitude or standard deviation by parallel calculation from the velocity sequence of each measured scanning point, and the amplitude or standard deviation is displayed on the display screen.

Thus, the amplitude of vibration having a frequency of 5 to 500 Hz can be displayed on the screen in real time.

The laser vibrometer according to claim 10 is:
Laser light is radiated to multiple points on a vibrating object that have different inclinations with respect to the laser beam, and the reflected light is detected, and the vibration of the specified point of the vibrating object is measured from the vibration information contained therein. . The angle between the direction of the laser beam and the surface of the vibrating object at the point where the laser beam is irradiated is detected to calculate two vibration components in the direction parallel to the laser beam and the direction perpendicular to the laser beam, and the vibration value is calculated in two dimensions. It is displayed as a locus diagram.

Thus, the vibration of the vibrating object having different inclinations with respect to the laser light can be measured, and the measurement result can be displayed as a two-dimensional locus result.

In the laser vibrometer according to claim 11, the angle detecting means according to claim 10 amplitude-modulates the laser light source which emits the continuous wave of the laser and the continuous wave and the oscillation signal from the oscillation circuit. A modulation circuit, and a phase difference detection circuit that detects the phase difference between the oscillation signal from the oscillation circuit and the reflected light from the vibrating object via a mirror, converts this to distance information, and obtains the angle of the measurement target point. ing.

With this, the angle between the laser beam and the surface of the vibrating object can be obtained.

A laser vibrometer according to a twelfth aspect of the present invention is a laser distance meter in which the angle detecting means according to the tenth aspect is placed at the same place as the laser vibrometer.

Thus, it is possible to detect the angle between the laser beam and the surface of the vibrating object using the laser range finder.

[0052]

EXAMPLE A first example of a laser vibrometer according to claim 1 of the present invention will be described below.

First, the principle of operation of the first embodiment will be described below.

Consider a case where a measurer holds a laser vibrometer in his / her hand and measures a vibrating object. Here, for simplification of explanation, it is assumed that the vibrating object vibrates according to the following equation at a constant level of amplitude V ₀ and a single frequency ω ₀ . v = V _o sin (ω _O t) (1) If the laser light is transmitted and received accurately, the laser vibrometer should output the measurement signal v corresponding to the equation (1). . However, when the laser vibrometer is supported by hand, camera shake occurs, which affects the measurement signal v.

Here, it is assumed that the vibration v due to the camera shake is generated in one direction at a constant level of amplitude V ₁ and a single frequency ω ₁ for the sake of simplicity. v = V ₁ sin (ω ₁ t) (2) In this embodiment, since the vibration shown by the equation (2) is detected,
For example, a vibration detecting means for detecting the vibration and a vibration signal processing means for processing an output signal from the vibration detecting means are provided in a casing supporting the laser vibrometer.

Here, in the vibration due to the camera shake of the formula (2),
This includes attenuation / increase of the amplitude level of vibration and phase delay / advance due to the transfer characteristics of the paths of the casing, the optical element support portion, the optical element, and other members. That is, the measurement signal input by the laser vibrometer cannot be represented by the equation (2) alone, but includes the following vibrations. v = αV ₁ sin (ω ₁ t + φ) (3) where α is a proportional coefficient that represents the attenuation / increase of the amplitude level due to the transfer characteristic of the path, and φ represents the phase delay / advance due to the transfer characteristic of the path. It is an angle. Therefore, it is not possible to remove the influence of the signal due to camera shake from the measurement data input by the laser vibrometer simply by using the vibration signal processing means described above.

Therefore, the measurement signal of the laser vibrometer and (2)
If α and φ are identified by comparing with the vibration represented by the equation, using the output signal of the vibration signal processing means and the transfer characteristics α and φ,
It becomes possible to remove the influence of the vibration of the camera shake from the measurement signal of the laser vibrometer.

When the self-vibration of the laser vibrometer is generated in the three directions, the self-vibrations in the three directions may be measured and the same processing as described above may be sequentially performed. Also in this case, one direction having the greatest influence may be measured in advance and only that direction may be corrected.

The first embodiment realizes such an operation, and its block diagram is shown in FIG.

In FIG. 1, a laser vibrating device (not shown) is irradiated with laser light, and the Doppler shift amount contained in the reflected light is detected to measure the vibration velocity of the vibrating object. The signal SL is output. The self-vibration of the laser vibrometer main device 1 is measured by a laser vibrometer sensor head 5 installed inside the laser vibrometer main device 1 or in its supporting portion (not shown) as shown in FIG. 2, for example. The laser vibrometer sensor head 5 includes, for example, X, Y,
It is measured by each accelerometer 2X, 2Y, 2Z installed in three directions of Z. The output signals of the accelerometers 2X, 2Y, and 2Z are integrated amplifiers 3 provided for each direction.
X, 3Y, 3Z are input to the appropriate self-vibration signal N, respectively.
Converted to X, NY, NZ. The measurement signal SL of the laser vibrometer main device 1 is first input to the X-direction signal correction device 4X together with the X-direction self-vibration signal NX, where the amplitude level difference α and the phase difference φ due to the transfer characteristics of the X-direction path described above. Etc. are corrected. Next, the corrected output signal from the signal correction device 4X is input to the Y-direction signal correction device 4Y together with the Y-direction self-oscillating vibration NY, where the amplitude level difference α due to the transfer characteristic of the Y-direction path and The phase difference φ and the like are corrected. Finally, the output signal from the signal correction device 4Y is compared with the signal correction device 4Z in the Z direction, and Z
Amplitude level difference α and phase difference φ due to transfer characteristics of directional path
Etc. are corrected. Finally, the output signal from the Z-direction signal correction device 4Z is the signal from which self-vibration in the three directions has been removed.

Also, self-vibration in three directions can be eliminated by the embodiment shown in the block diagram of FIG.

As shown in the figure, the measurement signals SL from the laser vibrometer main unit 1 are simultaneously corrected by the signal compensators 4X, 4Y and 4.
Input to Z and remove each self-vibration signal NX, NY, NZ. The output signals of the respective signal correction devices 4X, 4Y, 4Z are input to the signal switch 8 and the output signal which is most appropriately corrected can be selected.

This is effective since it is possible to remove the self-vibration component in a certain direction when the self-vibration in one direction particularly affects the measurement. In addition, of the self-vibrations in the three directions, if there is a particularly permanent one, it is of course possible to correct only the vibration of the directional components.

A second embodiment of the laser vibrometer according to claim 2 of the present invention will be described based on the embodiment of FIG.

The second embodiment uses an adaptive filter for identifying the transfer characteristic of the vibration path as a signal correction device for eliminating self-vibration.

The adaptive filter is described in "Adaptive" by B. Widrow et al.
Although it is detailed in "Signal Processing" (Prentice-Hall) and the like, it is for minimizing two components of two input signals that are correlated with each other.

In FIG. 4, the filter unit 10 has an A / D
It has converters (analog / digital converters) 10A and 10B, an adaptive filter 10F, and a D / A converter (digital / analog converter).

Measurement signal SL from the laser vibrometer main unit 1
Is A / D converter (analog / digital converter) 10A
In addition, the self-vibration signal N from the accelerometer 2 is passed through the integrating amplifier 3 to the A / D converter (analog / digital converter) 10
Each signal is input to B and converted into a digital signal. Two
Digital output signals from the two A / D converters 10A and 10B are input to the adaptive filter 10F, where the self-oscillation component is removed as described above. Adaptive filter 10
The output signal from F is again a digital-analog converter) 1
The output signal SO is converted into an analog signal by 0C and corrected.

As a result, the transfer characteristics represented by the amplitude level difference α due to the transfer characteristics and the phase difference φ due to the transfer characteristics are automatically identified, and the correlation component of the self-vibration included in the output signal of the laser vibrometer is automatically identified. Can be removed.

A third embodiment of the laser vibrometer according to claim 3 of the present invention will be described.

The third embodiment compares the measured signal level of the laser vibrometer with the level of the self-vibration signal N before the signal correction device of the first or second embodiment, and adjusts the balance thereof. A gain adjusting means is provided.

The operation of the gain adjusting means will be described below.

As shown in FIG. 5, when the output signal S of the laser vibrometer main unit 1 and the frequency of the self-vibration signal N are very close to each other, the level of the output signal N of the laser vibrometer main unit 1 and the level of the self-vibration signal S are set. If the balance is not correct, even if each signal is corrected in the adaptive filter of the signal correction device, the level of the signal from the vibrating object will drop together with the self-vibration component (see FIG. 6). However, as shown in FIG.
If the levels of the output signal N and the self-vibration signal S are balanced, only the self-vibration signal N can be effectively removed (see FIG. 8). Therefore, a gain adjusting means is provided to adjust the signal levels of both.

As described above, when the frequencies of the measurement signal and the self-vibration signal are well balanced, both signals are converted into digital signals and the signals are passed through a filter to obtain the components of the self-vibration signal. Can be removed.

A fourth embodiment of the laser vibrometer according to claim 4 of the present invention will be described.

In the fourth embodiment, as shown in the block diagram of FIG. 9, correction is made for each direction, and each is identified in advance as the transfer characteristic of the path mixed in the measurement signal of the laser vibrometer. A / D converters 10BX and 10B for each direction component
A filter unit 10 having Y and 10BZ is provided.

Self-vibration signals NX, NY, NZ for each direction
Are A / D converters 10BX, 10BY, 10BZ, respectively.
Is input to and converted into a digital signal. The output signals from the A / D converters 10BX, 10BY, 10BZ are
It is input to the adaptive filter 10F together with the measurement signal SL converted into a digital signal by the A / D converter 10A, where the self-signal component is removed from the measurement signal SL, and the signal is converted into an analog signal by the D / A converter 10C. It is converted and the correction signal SO is generated.

As a result, it is not necessary to identify each signal for each measurement, and it becomes possible to effectively remove only self-vibration by a simpler process.

A fifth embodiment of the laser vibrometer according to claim 5 is shown in the block diagram of FIG.

As shown in the figure, in the tenth embodiment, the measurement signal SL of the laser vibrometer is the same as in the second embodiment shown in FIG.
Are processed, and the correction signal SO is output. Correction signal SO
Is amplified to an appropriate level by the amplifier 42, and further, a bandpass filter 43 that allows only a necessary frequency band to pass.
Through, only the necessary information is selected. Thus, the selected signal is converted by the frequency converter 44 into a frequency band in the range of 10 Hz to 20 kHz which can be heard by humans, and then reproduced through the speaker 15.

As a result, the measured correction signal can be heard as a sound.

A sixth embodiment of the laser vibrometer according to claim 6 is shown in the block diagram of FIG.

As shown in the figure, the correction signal SO is converted into a frequency spectrum by the computer means 38 if necessary, and is compared with the standard spectrum value stored separately by the simultaneous display device 39 and displayed. Further, the frequency spectrum is stored by the recording device 40 as a raw correction signal or frequency spectrum data as required.

This makes it possible to record the correction signal.

A seventh embodiment of the laser vibrometer according to the seventh aspect of the present invention is shown in the block diagram of FIG.

First, the laser beam 20a oscillated from the semiconductor laser light source 19 is split into the object beam 20b and the reference beam 20c by the first beam splitter 21A. The object light 20b passes through the second beam splitter 21B and the condensing optical system device 22 and is applied to the vibrating object 23. The scattered light 20d scattered on the surface of the vibrating object 23 returns to the beam splitter 21B via the condensing optical system device 22, is reflected there, and is guided to the photodetector 24.

On the other hand, the reference light 20c is emitted from the first optical system device 2
5A to the fiber 26, and is collimated by the second optical system device 25B via the fiber 26,
It becomes the reference light 20e which propagates again in space. The reference light 20e is refracted by the first mirror M1, modulated by the acousto-optic element 28 driven by the driver 27, refracted by the second mirror M2, passes through the second beam splitter 21B, and is detected by the photodetector. It is incident on 24. The photodetector 24 detects the interference signal of the scattered light 20d and the reference light 20e from the second mirror M2, and the vibration information is detected by the signal processing device 29.

Here, it is considered that the optical path length of the reference light 20e is increased by optimizing the length of the fiber 26 to reduce the difference in propagation distance between the reference light 20e and the object light 20b. This is because the coherence of laser light generally depends on the difference between the two optical path lengths that interfere with each other. Therefore, if the difference in the propagation distance between the object light and the reference light is made small, the propagation distance of the object light, that is, the measurement distance can be made long. This is because you can

Therefore, first, the optical path length of the object light 20b will be considered separately for inside the interference system and outside the interference system.

First, the optical path length Lc of the object light 20b in the interference system
Is the length from the first beam splitter 21A to the second beam splitter 21B to the focusing optical system device 22 to the second beam splitter 21B to the photodetector 24.

On the other hand, the optical path length L of the object light 20b outside the interference system
s is the length of the path from the condensing optical system device 22 to the vibrating object 23 to the condensing optical system device 22, which is twice the measurement distance L.

That is, when the range of the limit measurement distance of this laser vibrometer is from Lm to LM, 2Lm <Ls <2LM (4).

On the other hand, the optical path length of the reference light 20e is set to the fiber 2
A length xl of 6 and a length yl other than that are considered separately. In FIG. 11, yl corresponds to the length from the first beam splitter 21A to the first optical system device 25A and the second optical system device 25B to the first mirror M1 to the acousto-optic device 28 to the second optical system device 25B. Of the mirror M2 → the second beam splitter 21B → the photodetector 24.

Assuming that the refractive index of the fiber 26 is n,
Although the optical length of the fiber 26 is xl × n, it is generally considered that the relationship of Lc + Ls> (xl × n) + yl (5) holds. Considering a laser vibrometer with a fixed focus, that is, a constant measurement distance, the object beam 20
When the optical path lengths of b and the reference light 20e are equal, that is, when Lc + Ls = (xl × n) + yl (6), the coherence is the best, so the fiber 26
It is understood that the length xl of x is preferably xl = (Lc + Ls-yl) / n (7).

On the other hand, considering the case where the variable focus, that is, the measurement distance is changed according to the measurement environment, the fiber length xl has the shortest coherence when it is between the maximum value LM and the minimum value Lm of the measurement distance. Since the distance can cover the entire measurement range, the length of the fiber 26 can be determined as follows: xl = {Lm + LM + (Lc-yl)} / n (8)

In this way, even if a semiconductor laser having a short coherence length is used, the device can be downsized without degrading the performance.

An eighth embodiment of the laser vibrometer according to the eighth aspect of the present invention will be described with reference to the block diagram of FIG.

In this embodiment, the laser beam is applied to the vibrating object 2.
3 is operated in a range of ± 15 ° in both horizontal and vertical directions.

As shown in the figure, a horizontal axis scanning polygon mirror 32 and a vertical axis scanning polygon mirror 31 are connected to the tip of the condensing optical system device 22 shown in FIG. A vibration calculator that processes measurement data from the horizontal-axis scanning polygon mirror 32 and the vertical-axis scanning polygon mirror 31 via a scanning control device 34 that controls the axis-scanning polygon mirror 32 and the vertical-axis scanning polygon mirror 31, respectively. 33 is connected.

A horizontal axis scanning polygon mirror 32 for horizontally scanning the vibrating object 23 with a laser beam.
Is, for example, from 15 ° left to 15 ° right in the SC direction of FIG.
Repeat 3 scans, 101st scan is 4msec in horizontal direction
Scan 0.125 ° at every interval. Therefore, 101
The scanning for the second time takes 3960 msec in one cycle.

On the other hand, a vertical axis scanning polygon mirror 3 for scanning a laser beam in a direction perpendicular to the vibrating object 23.
1 is from the upper 15 ° to the lower 15 °, similarly to the 101st repeated scanning operation of the horizontal axis scanning polygon mirror 32.
101 minute scanning is discretely performed at intervals of 0.125 °. Thus, galvanometer mirrors may be used, as vertical motion is much slower than horizontal motion.

Polygon mirror 3 for scanning vertical and horizontal axes
The operations of 1 and 32 are respectively controlled by the scanning control device 34, and the measurement speeds measured by the polygon mirrors 31 and 32 are stored. A method of scanning with this laser beam is shown in FIG. First, the horizontal scanning operation will be described. 0.12 in the horizontal direction until the horizontal scanning operation is completed
Each speed value measured at 5 ° intervals is stored. The speed observation value of one point, which is up to 100 times of scanning at a higher speed than before, is obtained 100 times every 2 msec. This velocity observation value is set to V ₁ , V ₂ , ... V ₁₀₀ .

The actual vibration of the vibrating object 23 and the first 10
14A and 14B show examples of the velocity observation values obtained for the scanning points which are the scans up to 0 times. 14A shows the vibration of the vibrating object, and FIG. 14B shows the measurement data obtained by such high-speed scanning.

The vibration calculator 33, which inputs the measurement data via the scanning control device 34, interpolates the data of every four adjacent points by a cubic expression to obtain a continuous waveform which is secondarily differentiated. create. Also, by applying a Fast Fourier Transform to these 100 velocity value columns,
Period of 4 msec or more and 200 msec or less, that is, 5 to 250 H
Obtain the amplitude and phase of the oscillatory component of z. Further, since the last 101st time of the repeated horizontal scanning operation is a low speed scanning, vibration data of a high frequency of 250 Hz or higher is obtained by the same method as the conventional method.

With respect to the vertical scanning operation, since the scanning is performed at a low speed, vibration data having a high frequency of 250 Hz or higher is obtained by the same method as the conventional method.

In this way, in this embodiment, 240 points for both the horizontal and vertical axes, totaling 57,600 points, totaling 5 to 2 points.
Vibration of low frequency of 50Hz is 2 × 100 × 240/100
0 = 48 sec and high frequency vibration of 250 Hz or more at 960 × 240/1000 = 230.4 sec,
The total measurement is 278.4 seconds. With a laser vibrometer using a conventional scanning method, it is necessary to measure the vibration at each point for 200 msec or more in order to measure the vibration at 5 Hz.
It takes 11520 seconds to measure the points.

As described above, when the vibration frequency of the vibrating object to be observed is in the range of 5 Hz or higher, the laser vibrometer of this embodiment can measure vibration very efficiently.

FIG. 1 shows a ninth embodiment according to claim 9 of the present invention.
A description will be given based on the block diagram of No. 5.

As shown in FIG. 14, in this embodiment, a vibration distribution image display device 35 for displaying the measured amplitude of the vibrating object in real time is further connected to the vibration calculator 33 of the eighth embodiment. is there.

As described above, the vertical and horizontal scanning axis scanning polygon mirrors 31 and 32 of the present embodiment scan the vibrating object 23 both vertically and horizontally within a range of ± 15 °.

The horizontal scanning axis scanning polygon mirror 32 is
Laser beam left 15 times in horizontal direction at 1 msec cycle
The scanning is continuously performed at a high speed from 0 ° to 15 ° to the right, but the low speed scanning is not performed at the 101st time as in the first embodiment. The vertical scanning axis scanning polygon mirror 31 has a top 15 ° to a bottom 15
Up to 90 °, the scanning is discretely performed 100 times in the vertical direction at intervals of 0.125 °. The vibration calculator 33 uses the scanning control device 34 for controlling the scanning-axis scanning polygon mirrors 31 and 32 until the repetitive horizontal scanning operation is completed.
The speed value measured at 125 ° intervals is stored. The velocity observation value of one point, which is 100 times of each horizontal scanning operation, is 2
Obtained 100 times every msec. This velocity observation value is V ₁ , V
_2, ..., and V _100.

The vibration calculator 33 selects the maximum value and the minimum value from these values and calculates the amplitude from the difference. This calculation is performed in parallel for 240 scan points obtained by repeated horizontal scanning. The horizontal angle of a certain scanning point is A °, the vertical direction angle is B °, the front is 0 ° in both horizontal and vertical directions, and the left and upper directions are negative angles. The display screen of the display device 35 is
It is possible to display pixels from 0 to 959 from left to right in the horizontal direction and from 0 to 959 in the vertical direction from 0 to 959 in the vertical direction. Here, x = 4 (A + 15) /0.125 and y = 4 (B + 15) /0.125, the display device is the following pixels corresponding to the scanning point (x, y), (x + 1, y). , (X + 2, y), (X +
3, y), (x, y + 1), (x + 1, y + 1), (x
+2, y + 1), (X + 3, y + 1), (x, y +
2), (x + 1, y + 2), (x + 2, y + 2), (X
+3, y + 2), (x, y + 3), (x + 1, y +
3), (x + 2, y + 3), and (X + 3, y + 3) 16 grid points, the brightness corresponding to the amplitude calculated by the vibration calculator 33 is displayed. The laser vibrometer of this embodiment is
240 points on both horizontal and vertical axes, or 5760
Vibration of 0 to 5 to 500 Hz is 1 × 100 × 240/1
Measure at 000 = 24 sec. With the conventional scanning laser vibrometer, it is necessary to measure the vibration at each point by 20
It is necessary to measure 0 msec or more, and it takes 11520 sec to measure 57600 points.

As described above, since the amplitude of vibration having a frequency of 5 to 500 Hz can be displayed on the display screen in real time, efficient vibration display can be performed if the vibration frequency to be observed is in the range of 5 Hz or more. Can be done.

The tenth embodiment according to claim 10 of the present invention will be described with reference to the block diagram of FIG.

As shown in the figure, in the tenth embodiment, the vibrating object 23 vibrating at an angle θ with respect to the surface perpendicular to the optical axis X direction of the laser beam (in the drawing, a, b) A laser light source 19 that emits laser light, a reflected light detection unit 30 that detects reflected light from the vibrating object 23, and a vibration measuring unit 33a that measures the vibration velocity v of the vibrating object 23 from the reflected light. (Velocities va, vb in the drawing), an angle detection unit 40 (in the drawing, for detecting the angle θ between the optical axis of the laser and the surface of the vibrating object on which the laser light is reflected, for each of the emitted laser lights. (Angles θa, θb), the vibration velocity v of the vibration measurement unit 33a and the orthogonal component calculation unit 33b that calculates the velocity component in the XY direction from the corresponding angle θ of the angle detection unit 40, and the velocity component in the XY direction are displayed. 2D trajectory display device 3 5a and.

The detailed operation will be described below.

Generally, when measuring the vibration of an object which is three-dimensionally vibrating in the XY directions using a laser vibrometer, when the laser beam hits the surface of the object perpendicularly from the x-axis direction, the object is The vibration speed in the XY directions can be easily measured.

Here, as shown in FIG. 17, the optical axis X direction of the laser beam and the vertical surface of the vibrating object 23 form an angle θ, and the vibrating object 23 is centered on the coordinates (x0, y0). Consider a case where the vibrating object 23 itself vibrates at (x1 (t), y1 (t)). At this time, the coordinates of the point (x (t), y (t)) irradiated with the laser beam are x (t) = [-sin θ × yr + cos θ × {x0 + x1 (t)} + sin θ × {y0 + y1 (t)}] / Cos θ (9) y (t) = yr (10) The Y coordinate yr of the point irradiated with the laser light is a constant value independent of time.

Here, when the time change of the angle θ is small, the velocity v (t) of the point to be measured is dx (t) / dt = dx1 (t) / dt + tan θ · dy1 ( t) / dt (11) That is, the measured vibration is the vibrating object 2
The vibration including the X-direction component and the Y-direction component of 3 will be measured. Therefore, by measuring the vibrations at two points a and b on the surface of the vibrating object 23 having different inclinations as shown in FIG. 18, the two points a and b on the surface of the vibrating object 23 are measured as follows. Velocities va and vb are obtained. va (t) = v (t) x + v (t) y × tan θa (12) vb (t) = v (t) x + v (t) y × tan θb (13) where v (t) = dx (t ) / Dt, v (t) x,
And v (t) y are the X-direction component and the Y-direction component of the velocity v (t).

From this, the velocity components in the X and Y directions are obtained by the following equation. v (t) y = (va (t) -vb (t)) / (tan θa-tan θb) (14) v (t) x = (v (t) a × tan θb · va (t) -vb (t) ) .Times.tan .theta.a) / (tan .theta.a-tan .theta.b) (15) That is, by measuring the vibration and the tilt of the surface measured with the laser light on the surfaces having different tilts, The vibration component and the horizontal vibration component can be obtained, and the three-dimensional vibration can be calculated. In the above example, the velocity va (t) at point a and the velocity vb at point b
Although (t) can be measured simultaneously at the time t, this does not necessarily have to be the same. For example, in the case where the measurement is performed at the point a at t ₁ , t ₃ , t ₅ , t ₇ , ..., And at the point b at the time t ₂ , t ₄ , t _6, ... Can be used for interpolation. However, t ₁ <t ₂ <t ₃ <t ₄ <t ₅ <t ₆ , ... va (t ₄ ) = f (va (t ₁ ), va (t ₃ ), va (t ₅ ), va (t ₇ ), ... t ₄ ) ... (16)

FIG. 19 is a display screen on the two-dimensional locus display device 35a showing the measurement data of the vibration velocity at points a and b in FIG. 18, and FIG. 20 plots the three-dimensional vibration from this measurement data. It is a display screen on the two-dimensional trajectory display device 35a.

Thus, the vibration of the vibrating object having different inclinations with respect to the laser light can be measured, and the measurement result can be displayed as a two-dimensional trajectory result.

Next, the first laser vibrometer according to claim 11
One embodiment will be described with reference to FIG.

FIG. 21 is a block diagram showing the angle detector 40 included in the eleventh embodiment.

The angle detector 40 of this embodiment has the function of a laser range finder, and outputs the laser light source 19a that emits a continuous wave of the laser and the continuous wave and the oscillation signal from the oscillation circuit 52. An amplitude modulation circuit 51 for performing amplitude modulation,
A phase difference detection circuit 53 that detects the phase difference between the oscillation signal from the oscillation circuit 52 and the reflected light from the vibrating object 23 via the mirror M, converts this into distance information, and obtains the inclination of the surface of the measurement target point. Is equipped with.

By using a three-dimensional shape model such as three-dimensional CAD or the like, the inclination of the measurement point can be known from the three-dimensional shape model by measuring this or aligning the measured images. .

Thus, the angle between the laser beam and the surface of the vibrating object can be obtained.

The twelfth embodiment according to claim 12 is the eleventh embodiment.
An angle detector is not provided inside the laser vibrometer as in the embodiment, but a laser distance meter is externally provided at the position of the laser vibrometer.

FIG. 22 shows a screen in which the three-dimensional CAD is superimposed on the screen in which the vibration distribution of the pipe measured by the laser vibrometer is displayed in contour lines and the position is adjusted.

Thus, the measurement data of the vibration distribution and the inclination of the surface of the measurement point can be known, and the three-dimensional vibration of the device can be displayed and measured two-dimensionally by the above method.

[0131]

According to the invention of claim 1, it is possible to provide a laser vibrometer capable of eliminating the influence of self-vibration.

According to the second aspect of the invention, when the self-vibration in one direction influences the measurement particularly greatly, the self-vibration component in that direction can be removed.

According to the third aspect of the present invention, when the frequencies of the measurement signal and the self-vibration signal are well balanced, both signals are converted into digital signals, and those signals are passed through a filter. It becomes possible to remove the component of the self-oscillation signal.

According to the invention of claim 4, it is not necessary to identify each signal for each measurement, and it is possible to effectively remove only self-vibration by a simpler process.

According to the fifth aspect of the invention, the measuring person can hear the correction signal as a sound.

According to the invention of claim 6, it becomes possible to record the correction signal.

According to the invention of claim 7, even if a semiconductor laser having a short coherence length is used, the device can be downsized without deteriorating the performance.

According to the eighth aspect of the present invention, if the vibration frequency of the vibrating object to be observed is in the range of 5 Hz or higher, the laser vibrometer of this embodiment can perform vibration measurement very efficiently.

According to the invention of claim 9, 5 to 5 in real time
The amplitude of vibration with a frequency of 00 Hz can be displayed on the screen.

According to the invention of claim 10, the vibration of the vibrating object having different inclinations with respect to the laser light can be measured, and the measurement result can be displayed as a two-dimensional trajectory result.

According to the invention of claim 11, three-dimensional CAD
Since a three-dimensional shape model such as is used, the inclination of this measurement point can be known from the three-dimensional shape model by measuring itself or aligning it with the measurement image.

According to the twelfth aspect of the invention, it is possible to detect the inclination of the surface of the measurement target point using the laser range finder.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a laser vibrometer according to claim 1 of the present invention.

FIG. 2 is a perspective view showing the sensor head of the first embodiment.

FIG. 3 is a block diagram showing another embodiment of the laser vibrometer according to claim 1 of the present invention.

FIG. 4 is a block diagram showing a second embodiment of the laser vibrometer according to claim 2 of the present invention.

FIG. 5 is a graph for explaining a third embodiment of the laser vibrometer according to claim 3 of the present invention.

FIG. 6 is a graph for explaining a third embodiment of the laser vibrometer according to claim 3 of the present invention.

FIG. 7 is a graph for explaining a third embodiment of the laser vibrometer according to claim 3 of the present invention.

FIG. 8 is a graph for explaining a third embodiment of the laser vibrometer according to claim 3 of the present invention.

FIG. 9 is a block diagram showing a fourth embodiment of the laser vibrometer according to claim 4 of the present invention.

FIG. 10 is a block diagram showing fifth and sixth embodiments of the laser vibrometer according to claims 5 and 6 of the present invention.

FIG. 11 is a seventh laser vibrometer according to claim 7 of the present invention.
The block diagram which shows an Example.

FIG. 12 is an eighth laser vibrometer according to claim 8 of the present invention.
The block diagram which shows an Example.

FIG. 13 is a view for explaining the eighth embodiment.

FIG. 14 is a diagram for explaining an eighth embodiment.

FIG. 15 is a ninth laser vibrometer according to claim 9 of the present invention.
The block diagram which shows an Example.

FIG. 16 is a block diagram showing a tenth embodiment of the laser vibrometer according to claim 10 of the present invention.

FIG. 17 is a block diagram for explaining a tenth embodiment.

FIG. 18 is a block diagram for explaining a tenth embodiment.

FIG. 19 is a screen showing the vibration speed for each point.

FIG. 20 is a screen showing the vibration speed for each point.

FIG. 21 is a block diagram showing an eleventh embodiment of a laser vibrometer according to claim 11 of the present invention.

FIG. 22 is a screen displayed on the display screen of the twelfth embodiment of the laser vibrometer according to claim 12 of the present invention.

[Explanation of symbols]

 1 Laser Vibrometer Main Device 2 Accelerometer 3 Integral Amplifier 4 Signal Correction Device 5 Laser Vibrometer Sensor Head SL Measurement Signal SO Correction Signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshiaki Hattori Inventor Yoshiaki Hattori 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center (72) Inventor Shigeru Kanemoto Small, Saiwai-ku, Kawasaki, Kanagawa Mukai Toshiba Town 1 Stock Company Toshiba Research and Development Center

Claims (12)

[Claims] 1. A laser vibrometer for irradiating a vibrating object with laser light, and measuring the vibration of the vibrating object from vibration information contained in reflected light from the vibrating object, the laser vibrometer or a supporting portion thereof. A vibration detecting means provided to measure a predetermined vibration direction of the laser vibrometer or the supporting portion itself; a vibration signal processing means for amplifying an output signal from the vibration detecting means; The transmission characteristic of the path in which the vibration of the laser vibrometer or the supporting unit itself is mixed is identified by using the obtained vibration information and the output signal of the vibration signal processing means, and the identified transmission characteristic and the output signal of the vibration detecting means are identified. And a signal correction unit that corrects the vibration information of the laser vibrometer by using the laser vibrometer. 2. The signal correcting means includes first and second analog-digital converters for converting the output signals of the vibration information and the vibration signal processing means from analog signals into digital signals, and first and second analog-digital converters thereof. An adaptive filter that adjusts the output signal from the analog-digital converter 2 of 2 so that the respective correlation components are minimized, and a digital-analog converter that converts the output signal of the adaptive filter from a digital signal to an analog signal. The laser vibrometer according to claim 1, wherein the laser vibrometer is provided. 3. The gain control means for adjusting the levels of the vibration information and the output signal of the vibration signal processing means is further provided in the preceding stage of the signal correction means. Laser vibrometer. 4. The signal correction means is characterized by being identified in advance as a transfer characteristic of the entire frequency band included in the vibration of the laser vibrometer or the support unit itself. Item 2. The laser vibrometer according to Item 2. 5. A bandpass filter for selecting a frequency band of interest from the output signal from the signal correction unit, a frequency conversion unit for converting the selected frequency band signal into a frequency range of audible sound, and the converted signal. 5. A sound generating means for reproducing the sound is further provided.
The laser vibrometer according to any one of 1. 6. A recording means for recording / reproducing the output signal corrected by the signal correcting means, a waveform of the output signal corrected by the signal correcting means and a waveform of the corrected output signal already recorded, or a frequency thereof. The laser vibrometer according to any one of claims 1 to 5, further comprising: simultaneous display means for displaying the spectra respectively or simultaneously. 7. A laser vibration for splitting laser light into object light and reference light, irradiating the vibrating object with the object light, and causing the reflected light and the reference light to interfere with each other to measure the vibration of the vibrating object. A light guide means for adjusting the optical path length of the reference light to an average value length of the maximum optical path length and the minimum optical path length of the object light that can be measured by a laser vibrometer. And a laser vibrometer. 8. A laser vibrometer for irradiating a vibrating object with laser light, and measuring the vibration of the vibrating object from vibration information contained in reflected light from the vibrating object, the laser vibrometer comprising: A uniaxial or biaxial laser beam scanning means for scanning the laser beam in a short cycle and scanning the same point of the vibrating object a plurality of times, and the speed of each scanning point observed during the plurality of scannings are stored. A laser vibrometer, further comprising: a vibration calculation unit that obtains the vibration of the vibrating object. 9. The vibration calculation means obtains the velocity amplitude or standard deviation of each scanning point by parallel arithmetic processing, and the velocity amplitude or standard deviation of each scanning point corresponds to each scanning point coordinate. 9. The laser vibrometer according to claim 8, further comprising vibration distribution image display means for displaying on the display screen. 10. A laser vibrometer for irradiating a vibrating object having surfaces having different inclinations with laser light, and measuring the vibration of the vibrating object from vibration information contained in reflected light from the vibrating object. Laser light scanning means for irradiating each surface of the vibrating object with laser light, and each laser light from the laser light scanning means at each reflection point of the laser light on the vibrating object and each surface of the vibrating object. From the angle detection means for obtaining the angle, the vibration information included in the reflected light from each laser beam and the angle obtained by the angle detection means, the vibration components in two or three directions orthogonal to each other at the reflection point. A laser vibrometer, comprising: a calculation device for calculating the value and a vibration component display device for displaying the value of the vibration component as a two-dimensional locus diagram. 11. The angle detecting means includes a laser light source for emitting a continuous wave of a laser, an amplitude modulation circuit for amplitude-modulating the continuous wave and an oscillation signal from an oscillation circuit, and an oscillation signal from the oscillation circuit. A phase difference detection circuit for detecting a phase difference from the reflected light from the vibrating object via the mirror, converting the phase difference into distance information, and obtaining the angle of the measurement target point. Item 11. The laser vibrometer according to Item 10. 12. The laser vibrometer according to claim 10, wherein the angle detecting means is a laser range finder located at the same place as the laser vibrometer.