JPS5953555B2 - Digital ultrasonic holography device - Google Patents

Description

[Detailed Description of the Invention] - (1) Field of Application of the Invention The present invention uses a time coincidence signal between a clock pulse and a received pulse based on an ultrasonic reflected wave from an object or a transmittance (hereinafter simply referred to as an object wave). The present invention relates to a deciphthal ultrasonic holographic flaw detection apparatus for producing a 0-1 pattern hologram, and more particularly to an ultrasonic holographic flaw detection apparatus for producing a hologram incorporating intensity information of an ultrasonic object wave.

(2) Conventional technology In conventional digital ultrasonic holography equipment,
Using a time coincidence signal between a clock pulse with a constant period synchronized with the transmission timing of the ultrasonic pulse and a received pulse obtained by digitizing the object wave, for example, the time coincidence signal is 1 when the time coincidence is established, and 0 when it is not established. -1 pattern of hologram is being produced.

The hologram produced in this manner contains only phase difference information between the reference wave and the object wave, and does not contain amplitude information of the object wave.

Therefore, when such a hologram is reproduced, high-order interference fringes appear in the reproduced image, making the reproduced image unclear.

(3) Purpose of the Invention The purpose of the present invention is to provide a digital ultrasonic holography flaw detection device that eliminates the drawbacks of the prior art described above and can produce holograms that can be reproduced clearly.

(4) General description of the invention The principle of the apparatus of the present invention will be explained using figures while comparing it with the principle of a conventional ultrasonic holographic flaw detection apparatus.

Assume that a reflected wave (object wave) from an object 4 is observed using a probe with a frequency of NHZ under the geometrical conditions shown in FIG.

In the figure, reference numeral 1 indicates a probe, which scans on the XY plane along a scanning line 6. A probe 1 emits a focused beam 2. Further, a reference wave is incident on the probe 1 from the direction shown by the dotted line 3. Ru. A solid line 5 indicates an example of an ultrasonic object wave reflected from one reflecting surface from the object 4. Object 4 has a plurality of circular reflecting surfaces and is a reflector arranged in the shape of G on a plane parallel to the XY plane. A hologram obtained by brightness modulating the interference wave amplitude obtained by interference between the object wave 5 from the reflector 4 received by the probe 1 and a reference wave, or the received pulse by the object wave 5 and the ultrasonic transmission timing A hologram obtained using a time coincidence signal with a synchronized clock pulse is displayed as a set of interference fringes 7, as shown in FIG. The x and Y axes in FIG.
They correspond to the x and y axes on the probe scanning plane in the figure, respectively. In the hologram shown in FIG. 2, a straight line X parallel to the x-axis. Typical examples of the luminance signal for displaying the interdigitated stripes 7 on XJ are shown in FIGS. 3 and 4. The horizontal axis X in FIGS. 3 and 4 corresponds to the X axis on the scanning plane of the probe 1, and the vertical axis Z represents the brightness signal level for displaying the hologram. The brightness signal shown in FIG. 3 is a time coincidence signal between a clock pulse and an object wave in a conventional digital ultrasonic holographic flaw detector, and has the same signal level regardless of the intensity of the object wave. When an image is reproduced using a hologram displayed with this signal, a reproduced image G as shown in FIG. 5 is obtained, but blurring of the image as shown by 8 occurs. On the other hand, in the case of a luminance signal in which the amplitude of the interference wave generated by the interference between the reference wave and the object wave is modulated in brightness, as shown in Fig. 4, the signal level at which each interference wave is displayed is as shown by Z1 to Z7. , changes in proportion to the object wave intensity. When reproducing an image using a hologram displayed with this signal, the 6th
A reproduced image G shown in the figure is obtained, and the blurring of the image is less than that of the reproduced image shown in FIG. Therefore, in the apparatus of the present invention, a time coincidence signal as shown in FIG. 3 is used to generate a signal whose brightness level is changed in proportion to the object wave intensity, for example, a brightness signal as shown in FIG. 7. Display ribogram. A dotted line 9 in the figure is a scanning line X. X
This is a curve showing changes in object wave intensity on J. If the image is reconstructed using a hologram that is displayed using such a luminance signal,
As shown in FIG. 6, a reproduced image with less blurring is obtained.
(5) Examples Hereinafter, the present invention will be explained in detail with reference to examples.

FIG. 8 shows an example of the configuration of the digital ultrasonic holographic flaw detection apparatus of the present invention.

In FIG. 8, devices other than those indicated by thick frames have the same functions as the conventional device.

In particular, the parts surrounded by dotted lines have the same functions as conventional digital ultrasonic holography flaw detection equipment. Therefore,
Equipment other than those shown in thick boxes will only be briefly explained. The scanning device 1'1 scans the probe 1 along a scanning path 6 on the XY plane.

Scanning control device 10 outputs a control signal for driving scanning device 11 . The output signals are A, B, C, and
The signals shown in D and E include a set pulse, an x drive pulse, a Y drive pulse, an x coordinate signal, and a Y drive pulse, respectively.
It is a coordinate signal. When x drive pulse B is output, probe 1
is driven in the x direction, and when the Y drive pulse C is output, the probe 1 is driven in the Y direction, thereby driving the probe along the scanning path shown by 6 in FIG. Reset pulse A
is a pulse output at the start of scanning. X coordinate signal D
．． The Y coordinate signal E is a signal indicating the position of the probe 1 on the XY plane, and is output as an analog quantity obtained by digital-to-analog conversion of the number of x or Y drive pulses after outputting the reset pulse, for example. Next, along with Figure 8,
Refer to Figure 0.

The twin clock pulse generator 13 outputs the NHz clock pulse F and the NHz clock pulse G whose frequency is divided by 1/n. The transmission controller 14 outputs a trigger pulse H in synchronization with, or delayed from, the rising edge of the NHz clock pulse G. In the case of delay, the delay time corresponds to the number of NNHz clock pulses proportional to the number of x drive pulses B after the output of the reset pulse A or the Y drive pulse C. The spike pulse generator 15 outputs a high voltage spike pulse I in synchronization with the trigger pulse H. The isolator 16 supplies the spike pulse I to the probe 1 , and conversely supplies the object wave signal of the reflector 4 output from the probe 1 to the amplifier 17 . The amplifier 17 outputs a signal J obtained by amplifying the object wave signal to the waveform shaper 18. The waveform diagram of the signal J in FIG. 10 shows the transmitted pulse observed in synchronization with the spike pulse I and the amplified signal of the object wave from the reflector 4 observed thereafter. The waveform shaper 18 detects the amplified signal J to obtain a signal K. Further, the detected signal K is converted into a digital pulse L whose TTL level is "1" when the detected signal K exceeds the threshold level ΔV.
Out of the received pulses L supplied from the waveform shaper 18, a gate pulse M of a certain width is created after a certain period of time has elapsed after the output of the trigger pulse, and set with the gate pulse among the received pulses L supplied from the waveform shaper 18 using an AND gate. Only the pulses obtained at this time, that is, the pulses received by the object wave from the target reflector 4 are extracted. Next, the output level of the NHz clock pulse G is read at the rising edge of the extracted pulse, and that level is output. This output level will be read at the O level with the next received pulse, but will be held until the gate pulse falls, and this signal will be output as a coincidence pulse N. Next, the operation contents of the equipment shown in thick boxes in FIG. 8 will be described. FIG. 12 shows a detailed circuit diagram of the peak detector 20.

The detected signal obtained by the waveform shaper 17 (Figs. 10 and 11)
K) in the figure is converted into the peak detection signal shown in O in FIG. 11, and its value is further converted into a 7-bit binary digital layer. Heater detection in this circuit is performed by the waveform shaper 18
A negative logic pulse with a width longer than the pulse width of the received pulse (L in FIG. 11) from the main signal is created using the monostable multipipelator 133, and the maximum value of the detected signal is set at a time τ corresponding to the pulse width of the main signal. This is done by keeping the above constant. The time period during which the maximum value is held constant is determined by the difference between the time constants of the resistive element 195 and the capacitor 196 attached to the monostable multipipelator 133 and the pulse width of the received pulse L. A peak detection element 197 is used to convert the detection signal K into a peak detection signal 0.
is used. An analog-to-digital converter 198 is used to convert the voltage value of the peak detection signal 0 into a 7-bit binary digital value. Furthermore, the 12th
In the figure, IC element 103 represents an inverter element. A detailed circuit diagram of the arithmetic unit 21 is shown in FIG.

At the rise of the gate pulse (M in FIGS. 10 and 11), the register 191-a is set to 0. Thereafter, the received pulse (L in Fig. 11) received during gate pulse output
) The peak value from the peak detector 20 at the time of falling (binary number 7
A digital quantity of bits) is read. When the output level of the coincidence pulse (N in Figures 10 and 11) at that time is "1", it is added, and when it is "0", it is subtracted.The read peak value is sent to the addition/subtraction 1C element 192. Therefore, it is added or subtracted. The calculated value for each calculation is latched into register 191-b. The latched value is loaded into the addition/subtraction IC element 192 again, and the calculation is repeated in order such that the peak value at the falling edge of the next received pulse is added or subtracted. The contents of register 191-b are latched into register 191-C at the falling edge of gate pulse M, and the contents of register 191-C are digitally output as a calculated value. However, when the calculation value is negative, O is output. An example of the latched contents of register 191-b is shown at P in FIG. P in Figure 11
Integer values N2, N3, N4, N5 are each O
The peak voltages V2, V3, V4 at the peak detector 20 shown in
, V5 is a digital value obtained by analog-to-digital conversion. The calculated value output from the calculator 21 is shown at Q in FIG. The calculated value output at the falling edge of the gate pulse is held until the falling edge of the next gate pulse. Note that the IC element 133 shown in FIG. 13 represents a monostable multipipulator. The multivibrator 133 provides a negative logic pulse with a pulse width determined by the time constants of the resistive element 193 and the capacitor 194. This pulse is delayed from the fall time of the received pulse L to latch the register 191-b. The IC element 103 is an inverter, an IC
The element 118 is a NAND gate, and the IC element 132 is an AND gate.
The gate, IC element 190 shows an EXCLUSIVE-0R gate. The data converter 22 converts the calculated value from the arithmetic unit 21 from a digital quantity to an analog quantity and outputs it to the display device 12.

In the display device 12, x from the scanning control device 10
A hologram is displayed by using the coordinate signal and the Y coordinate signal as polarization signals and the signal from the data converter as a luminance signal. The above is an example of the operation of the digital ultrasonic holographic flaw detection apparatus of the present invention.

In addition, for example, a digital comparator may be used as the data converter 22 in FIG. 8 instead of the digital-to-analog conversion function, and when the calculated value from the calculator 21 is O and a positive value, it will be "0" and "0", respectively. If a "1" level signal is output, an O-1 pattern hologram can be displayed on the display device 12.

In this case, the hologram is the same as the conventional device in that it is a 0-1 pattern hologram, but whereas the conventional device judges the temporal coincidence of one reflected wave with the black pulse, the present invention Since the apparatus comprehensively and accurately determines the temporal coincidence with the clock pulse for all of the plurality of reflected waves numerically, it is possible to produce a hologram in which the individual holograms of the plurality of reflectors are superimposed into one. (6
) Summary As explained above, the device of the present invention has the advantages of the conventional digital ultrasonic holographic flaw detection device, namely:
A spike-like pulse can be used as the emitted pulse.

2. The spacing of interference fringes on a hologram can be controlled regardless of the ultrasonic frequency used.

The following effects are produced without impairing the above.

Similar to an ultrasonic holographic flaw detection device in which a reference wave is made to interfere with a reference wave or a reflected wave with a transmittance of 1, a hologram that can reproduce an image with less blurring can be produced.

If there are two or more reflectors, a hologram can be produced by superimposing individual holograms into one.

[Brief explanation of the drawing]

Figure 1 shows the geometric arrangement of the probe and object during flaw detection using ultrasonic holography, and Figure 2 shows the hologram obtained under the geometric conditions shown in Figure 1. Figure 3 is a diagram showing the time coincidence signal of a conventional digital ultrasonic holographic flaw detector used to display the hologram shown in Figure 2, and Figure 4 is a diagram showing the hologram shown in Figure 2. Figure 5 shows a hologram obtained by a conventional digital ultrasonic holographic flaw detection device, which shows a 1,000-wave signal of a general ultrasonic holographic flaw detection device that interferes with an object wave and a reference wave used for display. 6 is a diagram showing an image reproduced using a general ultrasonic holographic flaw detection device that interferes with an object wave and a reference wave, and a diagram showing an image reproduced using a hologram obtained by the device of the present invention. FIG. 7 is a diagram showing a signal for displaying the hologram shown in FIG. 2 with the device of the present invention, and FIG. 8 is a diagram showing one of the configurations of the digital ultrasonic holographic flaw detection device of the present invention.
It is a figure showing an example. 9 is a diagram showing a time chart of signals output by the scan control device 10, FIG. 10 is a diagram showing a time chart of input/output signals of each device surrounded by dotted lines in FIG. 11 is a diagram showing a time chart of the input/output signals of each device indicated by thick frames in FIG. 8, FIG. 12 is a detailed configuration diagram of the peak detector 20 shown in FIG. 8, and FIG. is the 8th
FIG. 2 is a detailed configuration diagram of the arithmetic unit 21 shown in the figure. 1...
...Probe, 4...Reflector, 10...
Scanning control device, 11...Scanning device, 12...
... Display device, 13 ... Twin clock pulse generator, 14 ... Transmission controller, 15
...Spike pulse generator, 16...
Isolator, 17...Amplifier, 18...
...Waveform shaper, 19...Coincidence detector, 20...Peak detector, 21...
Arithmetic unit, 22...Data converter.

Claims (1)

[Claims] 1. Means for generating a first clock pulse of a constant period;
means for transmitting an ultrasonic pulse to the object to be inspected in synchronization with a pulse obtained by frequency-dividing the first clock pulse;
means for receiving the object wave of the ultrasonic pulse and converting the object wave into a digital pulse; and detecting the output level of the first clock pulse at the time of receiving the digital pulse received during a predetermined gate period. and a means for outputting a coincidence signal when the detected output level reaches a predetermined level, and a digital ultrasonic holography apparatus for creating a hologram of an object to be inspected using the coincidence signal, a first means for holding the peak value of the detection signal of the object wave obtained from the pulse conversion means for a certain period; and a coincidence between the coincidence signal and the peak value signal held by the first means within the predetermined gate period. or a second means for respectively adding or subtracting the peak value signal in response to the mismatch, and a third means for holding the output value of the second means at the end of the gate period for a certain period of time; A digital ultrasonic holography device characterized in that a hologram of an object to be inspected is created using output signals from three means. 2. The apparatus according to claim 1, characterized in that a fourth means for driving the ultrasonic pulse emitting probe included in the ultrasonic pulse emitting means to a desired position is provided. Digital ultrasonic holography device. 3. The apparatus according to claim 1, further comprising: a fifth means for converting the output signal of the third means into an analog signal; and means for displaying a holography of the object to be tested;
Digital ultrasound characterized in that the output signal of the fifth means is a luminance signal, the position coordinate signal of the fourth means is a deflection signal of the luminance signal, and a holography of the object to be inspected is displayed on the display means. Holographic device.