JPS5826528B2 - Vibration measurement method using pulsed laser holography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration measurement method using pulsed laser holography that allows vibration equal amplitude lines as well as vibration nodes and phases to be displayed on a single hologram.

FIG. 1 is a block diagram showing a pulse laser holography device applied to a conventional vibration measurement method.

1 in FIG. 1 is a double pulse laser device.

The double pulse laser device 1 is operated by applying a trigger voltage and oscillates two pulse lasers at an interval.

A laser beam emitted from this double pulse laser device 1 is split into two beams by a beam splitter 2.

One of them is reflected by a plane mirror 3 as a reference beam, and passed through a concave lens 4, a collimator lens 5, and an attenuator 6 to a plane mirror 7.
The photographic plate 8 is exposed by reflecting the light.

A photographic plate 8 is set in a holder 9.

Furthermore, the other of the two light beams is irradiated as object illumination light onto a specimen 11, which is an object to be measured, through a concave lens 10.

This reflected light from the specimen 110 exposes the photographic plate 8 from an angle different from that of the reference light.

The laser beam emitted from the double pulse laser device 1 is detected by a photodetector 12, and the detection output is displayed on an oscilloscope 13.

On the other hand, reference numeral 14 denotes a phase variable two-output oscillator, and one of the two outputs is input to an amplifier 15 and a frequency counter 19.

The output of the amplifier 15 is input to an exciter 16, and when the output of the amplifier 15 is input to the exciter 16, the exciter 15 excites the specimen 11. .

The other output of the variable phase two-output oscillator 14 is input to a pulse oscillator 20.

The output of this pulse oscillator 20 is input to the tuple laser device 20 via a switch 21, and a part of the output of this pulse oscillator 20 is input to the oscilloscope 13.

In addition, 17 is a vibration meter, which is fixed to the specimen 11,
This vibration of the specimen 11 is picked up and output to an oscilloscope 13 via an amplifier 18.

Next, a vibration measuring method using the holography apparatus shown in FIG. 1 will be explained.

First, a variable phase 2-output oscillator 14, a pulse oscillator 20,
Using the oscilloscope 13 and the switch 21, two pulsed laser beams generated from the double pulse laser device 1 are synchronized with the vibration of the specimen 11, and for example, the first pulsed laser beam is set to the maximum positive amplitude of the vibration. Fire it in the condition.

Further, the second pulsed laser beam is emitted in the negative maximum amplitude state of vibration.

In this case, the emission time of the double-pulse laser beam is delayed by a certain delay time TD unique to the device after the trigger pulse is applied from the outside to the double-pulse laser device 1, so that the external The phase of the trigger voltage pulse is advanced by a delay time TD.

In addition, Pl in FIG. 1 is the first pulsed laser beam,
P2 is the second pulsed laser beam.

In addition, the laser beam generated from the double pulse laser device 1 is guided to a beam splitter 2, where it is divided into two beams, one of which is connected to a plane mirror 3, a concave lens 4, a collimator lens 5, an attenuator 6 for attenuating the laser beam intensity, and a plane mirror. 7, the photographic plate 8 is irradiated with the reference light.

The other half of the beam split by the beam splitter 2 is expanded by the concave lens 10 and irradiates the specimen 11 as illumination light.

The first shot of this illumination light is the specimen 11 at the maximum positive amplitude.
The second shot is reflected from specimen 1, which is at the maximum negative amplitude.
1 and are respectively irradiated onto a photographic plate 8 as object light.

In this way, the photographic plate 8 doubles the object light of the specimen 11 in the positive maximum amplitude state by exposing it to the reference light and exposing the specimen 11 to the object light in the negative maximum amplitude state and the reference light. exposed to light.

Then, the photographic plate 8 is developed and fixed, washed with water and dried to create a hologram.

Next, using the apparatus shown in FIG. 2, the hologram is reproduced by the method described below.

In FIG. 2, as a continuous wave laser beam generator 30, for example, a laser beam generated from a helium neon laser device is converted into a parallel beam by a convex lens 31 and a collimator 32, and then passed through a plane mirror 33 to a hologram 8a.
When set to have the same incident angle with respect to the illumination light flux as the reference light during hologram production, dark interference fringes 11b corresponding to the vibration amplitude distribution of the specimen 11 appear as a reconstructed image (virtual image) 11a.

These dark interference fringes appear at positions having the following relationship, where a(P) is the amplitude of an arbitrary point P on the surface of the specimen 110.

In this formula (1), m=1.2.3,...
, where m represents the fringe order.

Further, λ is the wavelength of the pulsed laser light (λ-0.6943μ771 in the case of a ruby laser), and θ1 and θ2 are the angles formed by the vibration vector, the illumination light, and the object light.

Since the dark interference fringes 11b represent amplitude contour lines, by photographing this reconstructed image with the camera 34, the amplitude distribution of the specimen 11 can be measured as a print.

However, as an example of a reproduced image obtained by such a conventional vibration measurement method, the peripheral fixed and flat plate vibration measurement results are as shown in FIG. 3 (a diagram reproduced by depicting Reference Material 1).

The dark interference fringes in Figure 3 indicate the equal amplitude line A of the amplitude mode, but in Figure 3, information about vibration nodes and vibration phases cannot be obtained, so accurate vibration mode analysis cannot be obtained. The drawback was that it was not possible.

This invention was made in order to eliminate the above-mentioned conventional drawbacks, and the double pulse laser beam emitted from the double pulse laser device is split into two beams by a beam fritter.
In the method of creating a hologram by projecting one of the two beams as a reference beam and the other as an object irradiation beam onto an object to be measured, a rotating reflecting means is provided between the beam splitter and the object to be measured. the rotating reflecting means rotates, the rotating reflecting means reflects two shots of illumination light, and the first and second shots of the illumination light projected onto the object to be measured are different from each other. By emitting light from an angle, vibration mode nodes,
To provide a vibration measurement method using pulsed laser holography that allows relative phase to be obtained together with information on amplitude distribution, enables accurate analysis of vibration modes, and displays vibration nodes and phases along with equal amplitude lines of vibration on a single hologram. The purpose is to

Examples of the vibration measurement method using pulsed laser holography according to the present invention will be described below.Before explaining the specific examples, first, for ease of understanding, an overview of the features of the present invention will be explained in detail. It's about enumerating.

(1) In photographic plate exposure using double-pulse laser light for vibration measurement, the angle of the illumination light of the specimen during exposure with the double-pulse laser light of the first emission is changed, and interference fringes are created by changing the angle of the illumination light. appears in the hologram reproduction image.

(2) In order to realize the above item (1), in a hologram production optical system composed of a beam splitter, a concave lens, a plane mirror, etc., a plane mirror for illuminating the specimen is rotated.

(3) In order to emit the first emission of the double-pulse laser beam from the double-pulse laser device in synchronization with the rotation angle of the plane mirror for the illumination light of the specimen described in (2) above and the vibration of the specimen, the illumination light of the specimen is Rotate a plane mirror using an electromagnet and a spring,
A voltage signal was generated in response to changes in the electromagnet's current, and was used as an open signal for a gate circuit to apply a voltage pulse synchronized to the vibration of the specimen to a double-pulse laser device.

Next, we will move on to a description of specific embodiments of this invention.

FIG. 4 is a block diagram showing the configuration of a pulse laser holography apparatus applied to one embodiment.

In FIG. 4, in order to avoid duplication, the same parts as in FIG. 1 will be given the same reference numerals and their explanation will be omitted, and the parts different from FIG. 1 will be mainly described.

In this FIG. 4, the parts from reference numeral 1 to reference numeral 20 in FIG. 1 are the same as in FIG. 1, and the switch 21 is omitted.

Now, 23 is a rotating plane mirror.

The rotating plane mirror 23 reflects one of the light beams split by the beam splitter 2 on the reflecting mirror 22, and further receives and reflects this light beam via the concave lens 10, and projects it onto the specimen 11.

A rod-shaped rotating jig 24 projects from the back of the rotating plane mirror 23 and is pivoted at a fulcrum 0.

A spring 25 is fixed to one end of the rotating jig 24, sandwiching this end, and is constantly pulled.

Further, an electromagnet 26 is provided close to the other end of the rotating jig 24 and is connected to a DC power source 28 and a differential circuit 29 via a switch 27.

By turning on this switch 27, the electromagnet 26 is energized by the DC power supply 28, and the end of the rotating jig 24 is rotated by the spring 2.
It is designed to be pulled against the elastic force of 5.

The DC power supply 28 is a power supply for operating the electromagnet 26.

Further, the differentiating circuit 29 inputs the output signal of the DC power supply 28, differentiates it, and sends the differentiated output to the delay circuit 30.

The output of this delay circuit 30 is output to a gate circuit 31.

The gate circuit 31 receives the output signal of the delay circuit 30 and the output signal of the pulse oscillator 20, generates a gate signal, and outputs it to the double pulse laser device 1.

Other parts are the same as in FIG.

Next, a vibration measuring method using pulsed laser holography according to the present invention will be explained using the pulsed laser holography apparatus shown in FIG.

In order to make this explanation easier to understand, we will use the following (a)
The procedure will be explained in terms of items () to c).

(a) First, the output of the variable phase two-output oscillator 14 is passed through the amplifier 15 and the exciter 16 causes the specimen 11 to vibrate.

The vibration state of the specimen 11 is picked up by a vibration meter 17, and the pickup output is amplified by an amplifier 18 and then supplied to an oscilloscope 13.

As a result, the vibration state of the specimen 11 is adjusted to the oscilloscope 1.
Observed at 3.

As a result, it is confirmed that the specimen 11 is in a predetermined resonance state.

At the same time, the output of the phase variable two-output oscillator 14 is sent to the frequency counter 19, and the resonant frequency of the specimen 11 can be confirmed from the count value of the frequency counter 19.

(b) Oscilloscope 7”l Monitor 3,
This is the delay time TD for applying an external trigger voltage for emitting the first double pulse laser beam of the double pulse laser device 1 with respect to the zero vibration position where the output pulse train of the pulse oscillator 20 is picked up by the vibration meter 17. Ge,
Advance the phase.

(c) Next, turn on the switch 27 and turn on the DC power supply 28.
Power is then supplied to the electromagnet 26 via the switch 27.

As a result, the electromagnet 26 is excited, and the rotating jig 24 is attracted and fixed to the electromagnet 26 against the elasticity of the spring 25.

(d) Next, apply an external trigger voltage to the double-pulse laser device 1 to generate a double-pulse laser beam from the double-pulse laser device 1, so that the ratio of the light intensities of the reference beam and the object beam is approximately 4 to The photodetector 12 (
Check with a pulsed laser photometer).

(e) Confirm that the optical path difference between the reference beam and the object beam is within the coherence distance of the pulsed laser beam generated from the double pulse laser device 1.

(f) The interval AT of the double-pulse laser beams generated from the double-pulse laser device 1 is set to 1/4 period of the vibration of the specimen 11 using the results of section a) above.

(g) Set the unexposed hologram photographic plate 8 on the hologram photographic plate 9.

(h) Next, turn on the switch 27 and turn on the electromagnet 2.
6 is turned off, and the rotating jig 24 is rotated by the force of the spring 25.
is pulled away from the electromagnet 26.

In this manner, after the operations in sections (a) to (h) have been performed, a hologram can be obtained by the following operations.

(i) The rotating jig 24 to which the rotating plane mirror 23 is fixed is separated from the electromagnet 26 and rotates.

On the other hand, the differentiating circuit 29 generates a pulse voltage by differentiating the change in the current of the electromagnet 26, that is, the change when the DC power supply 28 is supplied to and cut off from the electromagnet 26.

This pulse voltage is delayed by a delay circuit 30, for example, by 5×10 −3 seconds (it may be arbitrary, but the delay time of the delay circuit 30 needs to be determined by taking into account the rotational inertia of the rotating jig 24). The voltage is applied to the gate circuit 31.

Thereby, the pulse train of the pulse oscillator 20 is applied as a trigger voltage to the double pulse laser device 1 through the gate circuit 31.

(j) The double-pulse laser device 1 to which the pulse train of the pulse oscillator 20 is applied is triggered by the first pulse voltage of the pulse train, and emits double-pulse laser light.

(k) In the above item (b), the double pulse laser beam of the first emission generated from the double pulse laser device 1 is synchronized with the state of zero vibration amplitude of the specimen 11, so the vibration of the specimen 11 is The object light reaches the photographic plate 8 at the same time as the reference light.

(1) Following the first pulsed laser beam, the double pulse laser device 1 generates the second pulsed laser beam after ten cycles of vibration of the specimen 11.

(When the second double pulse laser beam is emitted,
Since the rotating plane mirror 23 is being rotated by the rotating jig 24, it is emitted at a different angle from the double pulse laser beam of the first emission.
The specimen 11 in the negative maximum amplitude state is illuminated, and the object light reaches the photographic plate 8 at the same time as the reference light.

(n) In this way, the photographic plate 8 can be used to determine whether the vibration state of the specimen 11 is at zero vibration or at the maximum positive amplitude.
Two object beams are exposed with different illumination angles.

(0) After the double-exposed photographic plate 8 is developed and fixed as described above, it is washed with water and dried to obtain a hologram.

A hologram can be obtained by the operating procedure described in item a) to item 0) above, and a supplementary explanation will be given regarding this.

The double pulse laser device 1 generates two flash pulses of approximately 50X10-9 seconds, and the interval is a minimum increment lXl0 in the range of about lXl0-6 seconds to 1000XIO-6 seconds.
' Can be set to any value in seconds.

The first double-pulse laser beam is emitted for a certain delay time TD (1000 to 1500
0-6 seconds).

The double pulse laser beam generated from the double pulse laser device 1 is two flash laser beams separated by an interval setting value AT, and these are each split into two by a beam splitter 2.

One of the flash laser beams reaches the photographic plate 8 as a reference beam, and the other beam illuminates the specimen 11 as an illumination light, just as in the conventional case.

Further, the phase variable two-output oscillator 14 is a two-output oscillator, and fixes the phase of one of the two outputs, a sine wave signal.
The phase of the other sine wave signal can be arbitrarily set within the range of 0° to 3600 degrees, and the phase-fixed output is used to excite the specimen 11, while the other one drives the pulse oscillator 20, and this pulse drives the double pulse It is designed to be used as an external trigger for the laser device 1.

Then, the phase-fixed output of the phase-variable two-output oscillator 140 is used to monitor the resonance state of the specimen 11 using the vibration meter 17, the frequency counter 19, and the oscilloscope 13.

On the other hand, the output of the phase variable two-output oscillator 14 drives a pulse oscillator 20, and a pulse train from this pulse oscillator 20 is used as an external trigger signal for the double pulse laser device 1 through a gate circuit 31.

A part of this external trigger signal is sent to the oscilloscope 1.
In addition to step 3, the phase relationship between the vibration of the specimen 11 and the output of the pulse oscillator 20 can be confirmed by displaying it on the oscilloscope 13.

Further, the differentiating circuit 29 is for differentiating the change in the current flowing from the DC power supply 28 to the electromagnet 26 to generate a pulse voltage when the switch 27 is turned off. output pulse lXl0
It can be varied from 'seconds to 1 second, and can be delayed in increments of lXl0' seconds.

After application of the output pulse signal of the delay circuit 30, the output pulse voltage of the pulse oscillator 20 is allowed to pass for 1/10 seconds (any number of seconds is acceptable) and is applied to the double pulse laser device 1 as a trigger signal.

In this way, by applying the trigger signal to the double pulse laser device 1, the double pulse laser device 1
As described above, the double-pulse laser beam is generated, and this double-pulse laser beam is detected by the photodetector 12, and the detection result is displayed on the oscilloscope 13.

The double pulse interval setting value JT of this double pulse laser device 1 is + of the vibration period, that is, (T=-(f: resonance frequency)...
...(2) Set to f.

Then, when the switch 27 is turned off, the change in the current in the circuit of the electromagnet 26 is converted into a pulse voltage by the differentiating circuit 29, which is input to the gate circuit 31 through the delay circuit 30.

As a result, the output pulse voltage of the pulse oscillator 20 passes through the gate circuit 31 and is applied to the double-pulse laser device 1, so that two double-pulse laser beams synchronized with zero vibration and a positive maximum amplitude state are emitted.

The first double pulse laser beam is split into two by beam splitter 2, one of which is used as a reference beam and is attached to a photographic plate 8.
On the other hand, w(p,
tl), and its reflected light reaches the photographic plate 8 as object light.

In the second double pulse laser beam, the reference beam is the same as the first beam, but the illumination light has a slight rotational change in the angle of the rotating plane mirror 23, so the maximum positive amplitude state is the same as the first beam. Light at different angles.

Considering the basic arrangement shown in FIG. 5, the illumination angle is as follows.

That is, if the angle of the rotating plane mirror 23 is a small angle ε, then
The angle of the second illumination light B2 is tilted by 2ε.

As a result, the propagation direction of the object light changes from the solid line Σ1 to the dotted line Σ
2, resulting in a direction change of αf:2ε.

The angular change α of the object beam B1 that occurs in FIG.
The result is the same as when the specimen 11 is rotated by ε, and the specimen 11 has an apparent displacement δR(P), that is, δR(1=l tanε...
...(3) can be considered to have occurred.

However, P is any one point on the surface of the specimen, l is the distance from the apparent rotation center of the specimen to point P, It is.

Therefore, the second object light is the rotating plane mirror 2 for illumination light.
A state in which the apparent displacement δR of the specimen 11 due to 30 rotations and the actual displacement W (P, t2) due to vibration are superimposed,
That is, w'(P, t2)=δR(P)+w(P, t2
) "・"' It reaches the photographic plate 8 as reflected from (4).

In this way, the photographic plate 8 is double exposed with the object light and the reference light synchronized with the zero vibration and positive maximum amplitude state w(P, t2).

On the other hand, the reproduction of the hologram can be carried out using the reproduction apparatus shown in FIG. 7 by the operations in (P) to r)11 described below.

(p) First, the reproducing apparatus shown in FIG. 7 is constructed.

In FIG. 7, a laser beam 40a generated from a helium-neon laser device 40 is made into a parallel beam by a convex lens 41.42, then reflected by a plane mirror 43, and a hologram 8
illuminate a.

In this case, the angle of incidence of the illumination light on the hologram 8a is made the same as the angle of incidence of the reference light on the photographic plate 8 shown in the fourth figure.

((1) In this way, a reconstructed image with interference fringes appears at the position of the specimen 11.

(r) When this reproduced image is photographed by the camera 44, pulsed laser holography interference fringes representing the vibration mode are recorded as the applied paper.

Items p) to (r) above are simple operating procedures for hologram reproduction, which will be explained in more detail below.

In FIG. 7, when the hologram 8a is illuminated with neon helium laser light at the same angle as the incident angle of the reference light on the photographic plate 8 during hologram creation, the following interference fringes are obtained.

That is, if the specimen 11 is not vibrating, the apparent displacement of the specimen 11 due to the rotation of the rotating plane mirror 23 is δR.
(P), dark interference fringes, for example, parallel fringes X as shown in FIG. 8, occur at a position P that satisfies *.

However, in this equation (5), n = 1.2.3, λ is the wavelength of the double pulse laser beam, and θ'1 and θ'2 are the apparent direction of displacement of the specimen 11 and the illumination. The angle between the light and the object light is .

When the specimen 11 is vibrating, the state corresponding to the first object beam is zero amplitude, and the state corresponding to the second object beam is v/(P, t2) in equation (4), so the equation (4) is satisfied. Dark interference fringes occur at position P.

However, in equation (6), N=1.2.3, .

Equation (6) shows that the angles θ'1 and θ'2 formed by the direction of apparent displacement of the specimen 11 and the illumination light and object light are the angles θ1 and θ'2 formed by the vibration vector and the illumination light and object light, respectively.
Equal to 2.

That is, if it is regarded as θ'1-θ1 and θ'2-02, the following will be obtained.

However, n = 1.2.3, ... (order of interference fringes due to apparent displacement of the specimen), N = 1.2.3, ...... (order of interference fringes due to apparent displacement of the specimen), The order of interference fringes due to displacement and vibration on the shadow) is .

This equation (7) is expressed as the fringe shift amount S, 5=N−n
If defined as, however, the case is 00 in θ1f-θ2.

This equation (8) is expressed in Figure 9a (a diagram showing the equal amplitude curve AO when the vibration direction of specimen 1 is positive) and Figure 10a (equal amplitude curve when the vibration direction of specimen 11 is negative). Diagram showing curve AO)
As shown in the figure, the sign (positive and negative) of the fringe shift amount S and Is
It shows that it is represented by I.

For example, Figure 9b (diagram showing the equal amplitude curve of Figure 9a)
The sign of S is positive at 11 points, S = 1, and the sign of S is negative at 22 points in Figure 10b (a diagram showing the amount of fringe shift corresponding to the equal amplitude curve in Figure 10a). , 1s
As l=2, the direction and amplitude value of vibration become clear.

Therefore, according to this method, the amplitude and direction of vibration can be measured as Norse laser holographic interference fringes.

Next, an experimental example according to the present invention will be explained.

Figures 11, 12, and 14 show holograms created using the method of the present invention regarding the vibration state of a peripherally fixed flat plate.
Photographs of the reconstructed image (Reference Material 2, Reference Material 3,
This is a depiction and reproduction of Reference Material 4).

In addition, Figure 13 is based on Reference Material 2 and Reference Material 3.
This is an example of analyzing.

The parallel interference fringes L1 in FIG. 11 and Reference Material 2 are reproduced images in a state where the vibration amplitude is zero, and are interference fringes caused by the rotation of the rotating plane mirror 230 given by the above equation (5).

FIG. 12 is a reproduced image depicting Reference Material 3 when it vibrates in the same resonance mode as shown in FIG. It is distorted by the amplitude.

That is, it can be seen that there is a fringe shift.

In the analyzed Figure 13, since the striped pattern is distorted upward, a convex vibration mode appears upward from the plane of the paper toward the medium-sized circular pattern with constant amplitude. ing.

Then, the amplitude is +0 corresponding to the fringe shift amount S=1.
．． Since it is pre-calculated that the flow is 35μ, this pattern has an amplitude of +2.10μ at the position of the highest order fringe.
It is shown to be a door.

The analytical diagram in Figure 13 obtained from Figure 12 above showed an amplitude distribution in the positive vibration direction, but Figures 14 (showing a reconstructed image of the hologram with an amplitude distribution in the negative vibration direction) and (Analysis diagram obtained from FIG. 4) shows a negative amplitude distribution in the vibration direction.

In this way, vibration mode nodes and relative phases, which cannot be measured using conventional methods, can be obtained together with information on amplitude distribution.

Although the nodes are not illustrated, they can be easily illustrated by determining the positive and negative phases.

As described in detail above, according to the vibration measurement method using pulsed laser holography of the present invention, the double pulse laser beam emitted from the double pulse laser device is split into two beams by a beam splitter, and one of the two beams is divided into two beams. In the method of creating a hologram by projecting one beam as a reference beam and the other beam as object irradiation light onto an object to be measured, a rotating reflecting means is provided between the beam sifter and the object to be measured, and the rotating reflecting means While rotating, the two illumination lights are reflected by the rotating reflection means, and the first and second views of the illumination light to be projected onto the object to be measured are projected from different angles. Since the gist is what we did,
Vibration mode nodes and relative phases can be obtained along with amplitude distribution information, enabling accurate vibration mode analysis, and has the effect of displaying vibration equal amplitude lines as well as vibration nodes and phases on a single hologram. be.

Reference material 1 is a photograph corresponding to Fig. 3, which shows the results of flat plate vibration measurement of the reconstructed hologram image obtained by the conventional vibration measurement method using pulsed laser holography.
Reference material 2 is a photograph corresponding to FIG. 11, which shows a reconstructed image of a hologram with zero vibration amplitude obtained by an embodiment of the vibration measurement method using pulsed laser holography of the present invention, and reference material 3. is a photograph corresponding to FIG. 12, which is a reconstructed image of the hologram in a fringe-shifted state obtained in the same example, and Reference material 4 is the negative amplitude distribution in the vibration direction obtained in the same example. This is a photograph corresponding to FIG. 14, which shows a reproduced image of the hologram.

[Brief explanation of drawings]

Figure 1 is a block diagram of a pulsed laser holography device applied to the conventional vibration measurement method using pulsed laser holography, and Figure 2 is a block diagram for explaining a method for reproducing a hologram obtained by the vibration measurement method using pulsed laser holography. 3 is a hologram diagram of the vibration state of the peripheral fixed plate obtained by the vibration measurement method using pulsed laser holography, and FIG. 4 is a hologram diagram of the vibration state of the peripheral fixed plate obtained by the vibration measurement method using pulsed laser holography according to the present invention. A block diagram showing the configuration of a pulsed laser holography device, FIGS. 5 and 6 are diagrams for explaining the method of irradiating the specimen with illumination light in the same example, and FIG. 7 is a block diagram showing the configuration of the pulsed laser holography apparatus. FIG. 8 is a diagram for explaining the hologram reproduction method; FIG. 8 is a diagram for explaining the state of the hologram when the specimen is not vibrating in the same example and corresponds to the rotation angle of the rotary reflecting means; FIG. 9a is a diagram showing the equal amplitude curve when the vibration direction of the specimen in the same example is positive, FIG. 9 is a diagram showing the amount of fringe shift corresponding to the equal amplitude curve of FIG. 9a, and FIG. A diagram showing equal amplitude curves when the vibration direction of the specimen in the same example is negative, 1st
Figure 0 shows the amount of fringe shift corresponding to the equal amplitude curve in Figure 10a, and Figure 11 shows a reconstructed image when the parallel interference fringes of the hologram obtained by the same example have zero vibration amplitude. Figure 12 is a diagram showing a reconstructed image when the parallel interference fringes of the hologram obtained by the same example are distorted in the vibration direction and amplitude direction, and Figure 13 is an analysis diagram obtained from Figure 12. FIG. 14 is a diagram showing a reproduced image of the amplitude distribution of the color in the vibration direction of the hologram obtained in the same example.
FIG. 5 is an analytical diagram obtained from FIG. 14. 1°°°・°°Tuful pulse laser device, 2°...
・Beam splitter, 3...Plane mirror, 7...
... Reflector, 8... Photographic plate, 10...
...Specimen, 12...Photodetector, 13...
... Oscilloscope, 14... Phase variable 2-output oscillator, 16... Exciter, 17... Exciter, 19... Frequency counter, 20...・・・
...Pulse oscillator, 23...Rotating plane mirror, 24
...Rotating jig, 26...Electromagnet, 28
・・・・・・DC power supply, 29・・・Differential circuit, 3
0...Delay circuit, 31...Gate circuit.

Claims (1)

[Claims] 1 The double pulse laser beam emitted from the double pulse laser device is split into two beams by a beam splitter, one of these two beams is used as a reference beam, and the other is used as an object irradiation beam and is projected onto the object to be measured. In the method for creating a hologram, a rotating reflecting means is provided between the beam splitter and the object to be measured, and while the rotating reflecting means rotates, two shots of illumination light are reflected by the rotating reflecting means,
A vibration measurement method using pulsed laser holography, characterized in that the first and second views of the illumination light projected onto the object to be measured are projected from different angles.