JPS59111058A - Structural analysis method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and device for non-destructive structural analysis of solid objects.

Non-destructive structural analysis that does not damage solid objects is becoming increasingly important in evaluating material composition, structure, defects, homogeneity, etc.

However, many nondestructive testing techniques are more art than science, and often provide only qualitative information.

Much research has focused on the use of ultrasound as a means of detecting flaws, as the ultrasound retains information about the flaw even after traveling the distance between the flaw in the material and the receiving sensor. It is being done.

Early attempts to quantify results were essentially based on calibration techniques against standard samples designed to provide a series of known reflection widths. These attempts were at best only partially successful because of the difficulties in preparing reference samples of the mark.

To obtain more information, one could use a set of sensors or apply scanning with one sensor to record the scattered ultrasound pattern. However, this introduces further complications since elastic waves in solids have three possible polarities.

Therefore, the problem posed is to estimate the structure of an object from the scattering pattern. Imaging can help solve complex mathematical problems from scattering patterns if it is possible to provide an accurate visual picture of a structure without requiring theorists to do so.

These methods have a number of inherent problems that limit the extent to which the information obtained can be quantified. In particular, these problems include generating wave patterns with sufficient precision and consistency on the order of the tip of a pin, mechanically sensing wave patterns with sufficient resolution, and detecting wave patterns continuously with sufficient precision and resolution. To! It is based on the difficulty in determining wave patterns from moving wave patterns.

The present invention relates to a method for non-destructive structural analysis of solid objects,
applying a wave-generating pulse at a frequency selected to an input surface of the object to generate an elastic wave pattern in the object, and at a frequency that is a multiple of the wave-generating pulse frequency to obtain an output signal; The generated wave pattern is scanned in a vacuum chamber using an electron beam scanning device over the output surface of the object, and the operation of the scanning device is controlled in relation to the wave generation pulses to scan the wave pattern at preselected instantaneous times. processing the output signal to generate a display signal representing the pattern; generating a composite signal from the display signal and a reference signal related to the wave-generating pulse; and reconstruction means for reconstructing a representation of the object. processing said composite signal to give .

Further, according to the present invention, an apparatus for non-destructive structural analysis of solid objects is provided. The device includes a pulse generator that generates pulses that are applied at a selected frequency to its input surface to generate an elastic wave pattern in the object being analyzed, and a pulse generator that generates pulses at a selected frequency to obtain an output signal. an electron beam scanning device that scans the generated wave pattern over the output surface of the object in a vacuum chamber at frequencies that are multiples; a control device that controls the operation of the scanning device in conjunction with a pulse generator; A processing device that processes an output signal that generates a display signal that displays a wave pattern 2 in instantaneous time, a signal generator that generates a composite signal from this display signal and a reference signal related to the generated pulse frequency, and a signal generator that represents an object. and a processing unit for processing the composite signal to provide a means for reconstructing the signal.

In one embodiment of the invention, the display signal is generated by progressively changing the phase difference between the scan frequency and the wave generation pulse frequency and at regular time intervals relative to the wave generation pulse. Occurs due to periodic processing.

In a corresponding embodiment of the device invention, the control device is adapted to the control operation of the scanning device in relation to the pulse generator by progressively changing the phase difference between the scanning frequency and the pulse frequency, and the processing device is adapted to control operation of the scanning device in relation to the pulse generator. It is adapted to generate a display signal by processing the output signal periodically at regular time intervals related to the pulse frequency.

The output signal is processed periodically at regular time intervals related to the wave generation pulses, with gradual changes in the phase difference between the scan frequency and the pulse generation frequency, so that the displayed signal is a continuous output that is scanned. Displaying the surface [7, generated from each part of the output signal provided by the scanning device.

The display signal is thus a sample of the wave pattern on the preselected output surface.

It is understood that the phase difference may vary continuously or in steps, and that the rate or magnitude of the step change may determine the degree of resolution provided by the display signal.

Furthermore, it will be appreciated that the scan frequency, which is a multiple of the pulse frequency, may be easily controlled by the scanning device to provide a manageable frequency.

In an alternative embodiment of the invention that generates a display signal displaying a wave pattern at preselected instantaneous times, the rate of scan may be varied progressively to accomplish the same objective. However, it will be appreciated that this requires further processing of the output signal to adjust the generated display signal in relation to the particular scan rate at the time the display signal is generated.

In one embodiment of the invention, the processing means comprises optical processing means providing reconstruction means in the form of an optical hologram.

In an alternative embodiment of the invention, the processing means comprises a programmed computer providing reconstruction means in the form of a computer hologram.

Conveniently, the computer is programmed to provide a digital hologram while allowing the computer to effectively cancel out extraneous noise, influencing disturbances, etc., for example.

A suitable computer may be selected from any of the many types commonly available.

The structural analysis device has a display module that provides holograms from holograms.

If desired, conventional techniques, either optical holograms or computer holograms produced, can be used to reconstruct the required cross-section of the object to be analyzed.

Although any of the conventional types of ultrasonic pulse generators can be used to generate elastic wave patterns in objects,
Conveniently, in one embodiment of the invention, the pulse generator comprises a laser for generating laser beam pulses.

Lasers have the advantage of providing sufficiently narrow beam pulses to enable precise, tip-of-the-line pulsed illumination by increasing high resolution and accurate and efficient frequency control capabilities.

The electron beam scanning device may be any conventional electron beam scanning device having a narrow enough electron beam to provide effective reconstruction means for reconstructing a representation of the object being analyzed and to provide a suitable degree of resolution.

For example, the scanning device is Vldicon
It may also be in the form of an indirect scanning device such as an electron tube. The vidicon tube typically requires a transducer, either a high vacuum or a liquid containing a high electric current, between the object to be analyzed and the tube.

In another embodiment of the invention, the scanning device is a type of scanning electron microscope housed in a vacuum chamber.A scanning electron microscope has the advantage of considering the scanning of a very narrow electron beam that gives high resolution and is externally This combination has the advantage of being able to directly scan the output surface of an object while reducing disturbances.

In this example of this embodiment of the invention, the vacuum chamber has a conventional type of support for supporting the analyte within the vacuum chamber.

In this example of the invention, in order to reduce pulse generation on objects that cause disturbances as well as pressure in such vacuum chambers, the pulse generator uses a laser that generates laser beam pulses, contouring the vacuum chamber. A sealed wall punching has a beam guiding fiber that directs the laser beam pulses directly to the analyte.

Various types of scanning electron microscopes are available that are suitable for use with this invention.

Similarly, the control, processing, and generating means of the present invention may be of any conventional type.

The base signal related to pulse frequency may be generated or obtained by any conventional technique.

Thus, for example, the violent signal may be obtained by splitting the wave-generating pulse before it reaches the object to be analyzed, or by using an energy transducer between the object to be analyzed and the wave-generating pulse. Also, even if it is obtained by detecting the electronic control of the pulse generator,
Other items may also be used.

The method of the present invention includes treating the output surface of the object to be analyzed to reduce interference caused by imperfections in the output surface.

Thus, for example, if the object is capable of being polished, its surface will be polished.

Alternatively, or if the object to be analyzed cannot be polished sufficiently, the output surface of the object is treated so as to be covered with a coating film.

Conveniently, such coatings are polished after being applied.

Although various materials are suitable for coating the output surface, it is advantageous for the coating material to be selected from the group consisting of metals and metalloids (10 Thus, for example, the coating material may be silicon, potassium, kermanium, etc.). , bismuth, etc.) or any suitable metalloid.

In another embodiment of the invention, the output surface of the object to be analyzed is provided with an electrostatic layer capable of being electrostatically responsive to the generated wave pattern to facilitate detection of the wave pattern by the scanning device. will be processed.

Conveniently, the electrostatic layer is a metal layer.

The electrostatic layer offers the advantage that the electrostatic charge can be changed rapidly in response to the generated wave pattern without delay, with improved shape effects and improved resolution.

The method and apparatus of the present invention are used for quantitative structural analysis of solid objects, and are particularly suitable for non-destructive quantitative structural analysis of solid objects.

Although the method and apparatus of the present invention may have various applications in the quantitative structural analysis of solid objects, it has particular application in the geological analysis of various objects, components, structural components, etc. .

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows equipment 1 for non-destructive quantitative structural analysis of solid objects.
0.

A device 10 converts elastic waves 20 inside an object 12 into an object 1.
a laser 14 that generates laser beam pulses 16 that are applied to an object 120 and a force surface 18 at a selected frequency to obtain as an acoustic wave pattern 22 on an output surface 24 of 2;
It has a pulse generator in the form of a.

The apparatus 10 further includes an electron beam scanning device 26 for scanning the wave pattern 22. A conventional vacuum chamber for an electron beam device has been omitted for clarity of the drawing.

Electron beam scanning device 26 has an electron beam generator path that generates an electron beam 30 and causes it to scan output surface 24 at a scan frequency that is a multiple of the frequency of laser beam pulses 16.

The electron beam scanning device 26 further includes a sensor device 32 for detecting the electrostatic response produced by the electron beam 30 on the output surface U in response to the wave pattern 22 and generating an output electrical signal via an output line 34.

The generated elastic wave 20 passing through the object 12 is transmitted to the output surface 24
A topographical map or elastic wave pattern 22 is created. The concentration of all electrons created at the output surface array is directly related to the topography of the surface created by the acoustic waves 20 and determines the magnitude of the output signal created by the sensor device 32.

The device 910 further includes a control device 36 adapted to control the operation of the scanning device 26 in relation to the laser 14 by progressively changing the phase difference between the scan frequency and the pulse frequency at preselected instants. It comprises a processing device 38 for generating a display signal representing a wave pattern in time, and generating means 40 for generating a composite signal 42 from the display signal and a substrate signal related to the generated pulse frequency. Control device 36, processing device 38, generation means 4
0 is conventional and is a system well known to those skilled in the art. These systems can therefore be readily selected from those available by each person skilled in the art and adapted and combined in a conventional manner to operate in accordance with the invention.

The controller 36 serves to synchronize the scanning frequency to the pulse frequency and to vary the phase difference that produces a display signal representing the wave pattern occurring at a preselected instantaneous time. Its operation can therefore be easily compared with conventional control devices for controlling scanning coils in conventional scanning electron microscopes, for example.

The reference signal is conveniently an electrical signal applied to the generating means 40 via line 43 and is generated in response to electronic control of the laser 14 which generates laser beam pulses 16 of the required constant frequency.

The composite signal 42 is sent to either a computer 44 that generates a computer hologram or an optical processing device 46 that generates an optical hologram.

Computer holograms or optical holograms can be reconstructed by conventional techniques to provide a hologram of object 12, as the case may be. Additionally, a hologram of any desired cross-section of object 12 may be obtained, optionally by conventional refining or focusing means.

The control device 36 is adapted to continuously vary the phase difference;
It is useful for applications in changing the phase difference in steps between successive scan operations or selected multiples of successive scan operations.

The operation of the processing device 38 is similar to changing the phase difference by the control device 36, and the processing device 38 changes the laser beam pulse 1.
scanning device 2 at regular time intervals related to the frequency of 6.
6. Generates a quantity reference signal for the scan operation.

With the gradual change in phase difference, the display signal generated by the processing device 38 during a particular scan by the electron beam 30 results in a signal representing the surface area that the electron beam 30 is presenting at that moment.

Therefore, as the phase difference changes progressively, the particular area of the output surface 24 that the electron beam 30 represents at the moment when the display signal is generated from the output signal will change from the output signal to the output surface 24 at regular time intervals related to the laser beam pulse frequency. It is understood that the display signal is generated by periodically processing the data and therefore changes gradually.

In this way, the display signal generated by processing device 38 displays a particular instantaneous time wave pattern. The waves displayed by the full display signal then result in the wave pattern 22 being displayed as if it were stationary or frozen during the selected time interval.

Accordingly, the processing unit 38 operates to distribute data according to the coordinates and depth of the wave scan pattern and the electron beam scanning unit 26 is controlled by the controller 36.
It is understood that combining the accumulation of set point data obtained by Accordingly, the processing device may be conventional, eg, operating like an analog system (eg a television screen) or operating like a digital system (eg a computer).

By supplying a display signal of a complete wave pattern 22 over the entire surface of the output light surface as if it had occurred in a certain period of time, the continuous vibration of the wave pattern can be This provides the important advantage of reducing the complexity of the analysis of the problem posed, thereby facilitating the analysis of the wave pattern and the quantitative analysis of the structure of the object 12.

Generating means 40 compares the display signal and the reference signal in accordance with conventional holographic techniques to provide a hologram for visual or other reconstruction representing object 12.

It will be appreciated that the generating means 40 functions purely as a conventional signal mixing device, commonly referred to as a heterodyne.

In the case of an analog system, the generating means 40 is the processing unit 38
and a heterodyne connected to the electronic control of the laser 14. In the case of a digital system, the generating means 40 operates like a computer program which distributes the reference data according to the coordinate addresses of the scan pattern.

The details of the wave pattern 220 resolution depend on the rate and extent to which the phase difference changes over time and is effectively controlled.

Therefore, depending on the degree of resolution required for a particular object 12, the proportion of phase differences and the degree of successive phase differences may be advantageously controlled with a minimum of manipulation consistent with the dynamic capabilities of scanning device 26. Therefore, scanning device 2
It provides a resolution dependent on the ability of 6.

In the embodiment shown in FIG. 1, the object 12 is, for example, a rock that cannot provide a sufficiently smooth output surface even after polishing to avoid interference in the wave pattern 22 due to surface imperfections. It is an object.

In this embodiment, therefore, the exit surface is coated with a thin metal or metalloid coating layer 48 having a highly polished surface as shown.

Coating layer 48 has the advantage of reducing interference due to possible imperfections in output surface 24.

The polished surface of coating layer 48 has an electrostatic layer 50 provided thereon to improve the sensing capabilities of scanning device 26.
have.

Although electrostatic layer 50 is a separate gold striped layer disposed over coating layer 48, coating layer 48 may conveniently be any suitable metal that serves as both coating layer 48 and an electrostatic layer.

Electrostatic [#SO allows it to react electrostatically to the wave pattern 22 without any inertia, thereby facilitating electrostatic interaction with the electron beam 30 and detecting the wave pattern by the sensing device. This provides the advantage of increasing the detection ability of 22.

With reference to FIG. 2, reference numeral 110 indicates another embodiment for non-destructive quantitative structural analysis of solid objects 112.

Device 110 substantially corresponds to device 10, and corresponding parts are designated by corresponding numbers, except that reference numbers are in the 100s in FIG.

In device 110, electron beam scanning device 26 comprises a scanning electron microscope, and device t11o scans object 11.
2 or a visual reconstruction of the object 112 itself.

Scanning electron microscope 126 has a vacuum chamber 54 .

Vacuum chamber 54 has a support platform 56 for supporting object 112 therein.

Device 110 further includes a laser beam guiding fiber 58 for guiding laser beam pulses 116.

The guiding fiber 58 may be of any conventional type and extends in a sealed manner through a bottom plate 60 that defines the vacuum chamber 54.

Sealing is provided by a sealing sleeve 62.

The guiding fiber 58 penetrates the support base 56 to the object 112.
has reached the input surface 118 of.

This means that the laser beam enters the input surface 118 in the vacuum chamber 54.
can be directly irradiated with the laser beam pulse 116.
This provides the advantage of reducing interferences that may occur due to indirect irradiation of the vacuum chamber 54 and due to pressure reduction within the vacuum chamber 54 during use.

By aligning object 112 within vacuum chamber 54,
Compared to other conventional electron beam scanning devices, scanning electron microscopes offer high resolution and efficient scanning ability for objects.
It can be used in a particularly dynamic manner for efficient and detailed quantitative analysis of 12 structures.

Accordingly, the embodiment of the invention illustrated in FIG. The advantages of accurate and efficient quantitative analysis of the structure of the object 112 obtained by the method can also be obtained.

The device 110, like the device 10, generates a display signal that displays a wave pattern at specially selected instantaneous times so that the generated wave pattern can be imaged with minimal interference from continuous imaging motion of the object. It also has the additional advantage of facilitating resolution since it also reconstructs the 112 display.

Referring to FIG. 3, reference numeral 210 designates yet another embodiment of an apparatus according to the present invention.

Device 210 generally corresponds to device 110. Corresponding parts are therefore designated with corresponding reference numbers in the 100 series, with 12'' used instead of 11''.

The device 210 has a vidicon electron tube 226 as an electron beam scanning device.

Since the vidicon tube 226 cannot directly scan the surface of the object 212, a suitable transducer 64 is included between the vidicon tube's vacuum chamber 66 and the object 212.

The vidicon tube 226 is connected to a housing sleeve 68 for sealingly positioning the transducer 64 in place.
have.

Apparatus 210 is used to analyze the structure of a large object, such as object 212, by analyzing selected portions of the object.

The embodiment of the invention illustrated in FIG.
After a particular portion of the object 212 has been analyzed, the laser 214 and vidicon tube 226 can be advantageously moved together to analyze other selected portions of the object 212.

Device 210 has the disadvantage of not being able to provide the same degree of resolution or precision as device 110, but may nevertheless have applications involving larger objects 212 that do not require as rigorous an analysis.

As far as the parts of the apparatus of the invention are concerned, it is convenient to use a laser of the type supplied by Spectrophysics of the United States of America as a suitable pre-L laser. As a scanning electron microscope, one of the models listed in the Catalog of Coats Anduelta is convenient. (Record 106A
SIICM Ultra High Resolution, USA April 1, 1975) The control device may be of any conventional type. Conveniently, it is a digital timer controlled by a special program.

For the types of scanning electron microscopes described above, it is convenient to be able to vary the sample range used down to samples that are approximately % inches in diameter.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of one embodiment of the apparatus according to the present invention, FIG. 2 is a block diagram showing the structure of another embodiment of the present invention, and FIG. 3 is a block diagram showing the structure of another embodiment of the present invention. FIG. 2 is a configuration diagram showing the configuration of. 10, 110, 210... structural analysis device, 12
, 112.212... object to be analyzed, 14, 114
, 214... Laser, 16,116° 216... Laser beam pulse, 18, 118... Input surface,
20...Elastic wave, 22, 122...Elastic wave pattern, 24, 124...Output surface, 26, 126...
... Electron beam scanning device, 226 ... Vidicon tube, 28 , 128 , 228 ... Electron beam generator, 30 , 130 , 230 ... Electron beam, 32
, 132° 232°...sensor device, 36 , 136
, 236...control device, 38, 138, 238...
...Processing device, 40, 140, 240... Generation means, 42, 142, 242... Composite signal, 44
, 144. 244... Computer, 46... Optical processing device,
48... Coating layer, 50, 150... Electrostatic layer, 52, 152... Display module, 5
4... Vacuum chamber, 56... Support stand, 58...
Guiding fiber, 64...transducer. Applicant's agent Kiyoshi Inomata Procedural amendment (method) April 7, 1945 Director-General of the Patent Office Kazuo Wakasugi 1, Indication of the case 1982 Patent Application No. 214093 2, Invention name structure analysis method and Device 3, Relevance to the Amended Person Case Patent Applicant George Markin

Claims (1)

[Claims] 1. A structural analysis method for non-destructively analyzing a solid object, comprising: applying a wave generating pulse at a frequency selected to an input surface of the object to generate an elastic wave pattern in the object; and scanning the generated wave pattern over the output surface of the object using an electron beam scanning device in a vacuum chamber at a frequency that is a multiple of the frequency of the wave generation pulse to obtain an output signal. controlling operation of the scanning device in relation to the wave generating pulses and processing an output signal to generate a display signal displaying the wave pattern at a preselected instantaneous time; and a structural analysis method comprising generating a composite signal from reference signals related to said wave generating pulses, and processing said composite signal so as to provide a reconstruction means for a reconstruction representing said object. 2. Periodically processing the output signal by means of which the display signal gradually changes the phase difference between the scan frequency and the wave generation pulse frequency and at regular time intervals related to said wave generation pulse frequency; A structural analysis method according to claim 1, which is generated by. 3. A structural analysis method according to claim 1 or 2, wherein the composite signal is processed by a computer programmed to provide reconstruction means in the form of a convector hologram of the object. . 4. The structure of claim 3, wherein the computer is programmed to provide a digital hologram of the object, and a display module is coupled to the computer to provide a hologram of the object from the digital hologram. analysis method. 5. 5. A structural analysis method as claimed in any one of claims 1 to 4, further comprising the step of applying a coating to the output surface of the object to reduce interferences resulting from imperfections in the output surface. 6. Introducing an electrostatic layer on the output surface to enable an electrostatic response to the wave pattern to facilitate detection of the wave pattern by a scanning device. The structural analysis method described in any of the above. 7. The wave-generating pulse is provided by a laser, the scanning device is in the form of a scanning electron microscope housed in a vacuum chamber, and the object is enclosed in the vacuum chamber, as claimed in claim 1. The structural analysis method according to any one of Items 1 to 6. 8. A structural analysis method according to claim 7, wherein the laser beam pulses are transmitted to the input surface by means of a beam-guiding fiber that penetrates the contoured wall of the vacuum chamber in a sealed manner. 9. In a structural analysis device for nondestructively analyzing a solid object, a pulse generator for generating pulses applied at a selected frequency to an input surface of the object to generate an elastic wave pattern in the object. an electron beam scanning device for scanning the generated wave pattern over the output surface of the object in a vacuum chamber at a frequency that is a multiple of the frequency of the wave generating pulse to obtain an output signal; and the pulse generating device. a control device for controlling the operation of said scanning device in relation to said scanning device; a processing device for processing an output signal to generate a display signal displaying said wave pattern at a preselected instantaneous time; A structural analysis apparatus comprising generating means for generating a composite signal from generated pulse frequencies and processing means for processing said composite signal to provide a reconstruction means for reconstructing a representation of said object. 10. The control device is adapted to control operation of the scanning device in relation to the pulse generator by progressively changing the phase difference between the scanning frequency and the pulse frequency, and the processing device is adapted to control operation of the scanning device in relation to the pulse generator. 10. A structural analysis device as claimed in claim 9, adapted to generate a display signal by periodically processing the output signal at regular time intervals. 11. Structural analysis apparatus according to claim 10, wherein the processing device comprises a computer programmed to provide reconstruction means in the form of a computer hologram. 12. Claim 10 or 11, wherein the scanning device is a scanning electron microscope housed in a vacuum chamber, and the vacuum chamber includes a support stand for supporting the object to be analyzed. Structural analysis device described in Section 1. 13. The pulse generator has a laser for outputting laser beam pulses, and the device is sealed in a wall defining the vacuum chamber and the piercing includes a beam-guiding fiber reaching the support base. Structural analysis device described in Section 1.