JPH0257971A - Method and apparatus for computing reflecting function of object to be measured in ultrasonic microscope - Google Patents

Abstract

PURPOSE:To compute the reflection function of a sound wave in the heterogeneous sound surface in a material by expanding a method for obtaining the reflection function from the Fourier transformation of V(Z) into a method for obtaining the reflection function at the reflection surface in the material. CONSTITUTION:In one step, a reflected signal from the inside of a material is received as a complex signal V(Z) 1. The signals are separated time wise and obtained by changing the distance between an acoustic lens and a material to be measured. The signal undergoes Fourier transformation 2. In the other step, a product 7 is obtained by multiplying the following functions: the square of the known pupil function of a sound lens 3; a first transmittance function wherein an angle, when an ultrasonic wave is transmitted from the surface of a material into the inside of the material, is a variable 4; a second transmittance function wherein an angle, when the ultrasonic wave is transmitted from the inside of the material to the outside of the material, is a variable 5; and a phase delay function wherein the incident angle of the ultrasonic wave, which is obtained from the sound speed of the main body of the material, is a variable. The result of the Fourier transformation is divided 8 by the product. Thus the reflecting function in the material is computed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention uses an acoustic lens to generate a focused spherical wave of ultrasonic waves, and the reflected waves from the surface and inside of a substance to be measured are reflected back into the acoustic lens. This method is applied to an ultrasonic microscope configured to perform acoustic-to-electrical conversion on the captured signal and record the reflected signal in a time-separated manner, and is used to calculate the reflection function of the substance being measured, especially the reflection function inside the substance. and regarding its equipment.

[Conventional technology]

2. Description of the Related Art Devices are known in which an acoustic lens is used to generate a focused spherical wave of ultrasonic waves, and a reflected wave from the surface of a solid sample, which is an object to be measured, is captured again by the acoustic lens to perform acousto-electrical conversion. In such a device, when the distance Z between the acoustic lens and the surface of the solid sample is changed from the in-focus state to the direction in which it is shortened, the electrical output V changes uniquely depending on the material that makes up the solid sample. Are known. This change in output is called the V (Z) curve, and is attracting attention as powerful information when investigating the acoustic properties of materials.

Furthermore, in recent years, attention has been paid to the fact that the above V (Z) curve is expressed by the Fourier transform of the product of the square of the pupil function P (kr) of the acoustic lens and the reflection function R (k') of the sample surface. )
By performing inverse Fourier transform on the reflection function R(kr)
Attempts are being made to find out. The technique related to the above-mentioned attempt is described, for example, in the document rMaterral Chara.
cterization by theInversi
on of' V(Z) J (G, S, KINOet
al, 1EEETRANS, 5ONIC8&ULTR
ASONIC8, Vol, 5U-32NO, 2P213
MARCI+ 1985).

In other words, if P(kr) is known, R(kr) −F−' fV (Z) 1/P2
(kr)...It is determined by the formula (1). Here, p-1 represents the inverse Fourier transform, and kr is the lens radial direction component in the propagation constant of each plane wave constituting the focused spherical wave formed by the acoustic lens. Note that the lens radial direction component corresponds to the incident angle θ of the sound wave, and has the following relationship.

θ-s in-' (kr/kO) (kO:
2πν/Cw, Cv: Speed of sound in water.

C: Frequency of sound wave) The pupil function P is ideally 1, but if it includes aberrations etc., it is necessary to measure it separately. The method is also disclosed in the above document.

The reflection function R(kr) measured by the method described above is a function of the incident angle of the sound wave, and variously reflects the acoustic properties of the material. For example, the critical angles θL and θT of longitudinal waves and transverse waves
Therefore, each sound speed is CL-Cw/sinθL
−(2) CT=Cv/sinθT −
(3) (However, CW speed of sound in two water) It can be found by the following formula. In addition, the reflectance R(0) of a vertically incident wave is calculated as R(o) = (pi C-po Cw )/(ρIc
L+ρ0CW) (4) (where ρ0: density of water, ρl: density of solid), the density pl of the solid can be found from this.

In this way, an extremely rich amount of information can be read.

[Problem to be solved by the invention]

The conventional method of determining the reflection function described above is a method of determining the reflection function exclusively at the surface of a solid sample (solid-liquid interface). As is well known, one of the major characteristics of ultrasonic waves is that they can easily reach the inside of solids. Therefore, in order to effectively utilize this feature, it is important to have a means that can quantitatively capture the acoustic properties of reflective objects that exist inside a solid. However, with conventional ultrasonic microscopes, it is possible to know the presence of reflected waves from inside the object to be measured, but for example, it is possible to determine whether the reflected waves are due to the presence of a denser substance or due to low density due to cracks or peeling. It was not easy to even know whether the reflection was due to an interface with a dense substance, much less to quantify it.

Therefore, an object of the present invention is to be able to easily and accurately determine the reflection function of a sound wave on an acoustically non-uniform surface existing inside a substance, and to quantitatively determine the acoustic internal structure of a substance that constitutes an object to be measured. It is an object of the present invention to provide a method and apparatus for calculating the reflection function of a measurement object in an ultrasonic microscope, which allows the calculation of the reflection function of an object to be measured using an ultrasonic microscope.

[Means and effects for solving the problems] In order to solve the above problems and achieve the objects, the present invention takes the following measures.

(1) In the "method for calculating the reflection function of a measurement object in an ultrasonic microscope" of the present invention, on the one hand, the time-separated interior of the material obtained by changing the distance between the acoustic lens and the measurement object The reflected signal from the complex V (Z)
It is captured as a signal and Fourier transformed, and on the other hand, the square of the pupil function of the acoustic lens, which is known, and the angle at which the ultrasonic wave passes from the surface of the substance toward the inside of the substance are used as variables. 1 transmittance function, a second transmittance function whose variable is the angle at which the ultrasonic wave is transmitted from the inside of the substance to the outside of the substance, and the incident angle of the ultrasonic wave determined from the sound speed of the substance body. Find the product with the phase delay function as a variable.

Then, by dividing the Fourier transformed result by this product, the reflection function inside the material is calculated.

(2) Furthermore, in the "method for calculating the reflection function of a measurement object in an ultrasonic microscope" of the present invention, in the method for calculating the reflection function described in (1), the reflection signals from the surface of the material separated in time are The complex V (Z) signal of the reflection signal from inside the material is measured simultaneously, the reflection function of the material surface is determined from the complex V (Z) signal of the material surface, and the sound velocity of the material itself is determined from the reflection function of the material surface. The product of the first and second transmittance functions obtained by calculating The reflection function inside the material is calculated by dividing the result of Fourier transform of the complex V (Z) signal of the reflected signal from inside the material.

That is, the reflection function calculation method of the present invention described in (1) and (2) above is a method of calculating a reflection function from the Fourier transform of V (Z) described as the conventional technique by using a reflection surface existing inside a material. It is characterized by an extension to the method for determining reflection functions.

(3) The "device for calculating the reflection function of a measurement object in an ultrasound microscope" of the present invention includes a clock generation circuit that generates a high-frequency basic clock, and a clock generated by this clock generation circuit that is used to generate ultrasonic waves. A gate that allows the pulse to pass in synchronization with the generation of the pulse, a counter that is provided to allow the clock to pass through the gate, and a setting means that sets a first integer value by performing an external setting operation. and a calculation means for calculating a second integer value by calculating OUT=2fΔz/Cv based on the amount of change in the distance between the acoustic lens and the object to be measured, and a first integer value set by the setting means. means for adding or subtracting a second integer value calculated by the calculation means to the integer value and providing the addition/subtraction output to the counter as a preset value in synchronization with the generation of the ultrasonic pulse; means for cutting off the gate and generating a time gate signal when counting of the corresponding clock is completed; and using the time gate signal generated by this means, at least a signal reflected from inside a substance constituting the object to be measured is detected. means for time-separating and extracting, means for orthogonally detecting the reflected signal extracted by this means to produce a complex V (Z) signal, a memory for storing the output obtained by this means, and a memory for storing the output obtained by this means; and calculation means for calculating a reflection function inside the substance based on the information obtained.

That is, the device for calculating the reflection function of the object to be measured in the ultrasonic microscope of the present invention described in (3) above uses the conventional pulse-type ultrasonic microscope as a means for determining V (Z) on the reflective surface inside the substance. ■ Vertical direction of the acoustic lens (Z
A means for generating a time gate signal that follows the reflected signal from a certain depth inside the sample with respect to movement in the sample direction); , means for calculating a reflection function inside the substance based on the stored information, and the like.

〔Example〕

First, a method for determining the reflection function at a reflective surface inside a substance will be explained.

FIG. 1 is a block diagram showing the steps of a method for calculating a reflection function of a substance constituting a measurement object according to the present invention. 1st
As shown in step 1 in the figure, first, the time-separated reflected signals from inside the material obtained by changing the distance between the acoustic lens and the material constituting the measurement target are captured as a complex V (Z) signal. .

Next, as shown in step 2, the complex V (Z) signal is Fourier transformed. On the other hand, as shown in steps 3, 4, and 5.6,
the square of the known pupil function of the acoustic lens; a first transmittance function whose variable is the angle at which ultrasonic waves are transmitted from the surface of the substance to the inside of the substance; A second transmittance function whose variable is the angle at which the ultrasonic wave is transmitted toward the outside, and a phase lag function whose variable is the incident angle of the ultrasonic wave determined from the sound speed of the substance body. And as shown in step 7, step 3.4
, 5. Multiply each digit obtained in 6 to find the product. Next, as shown in step 8, the reflection function R' (kr) inside the material is calculated by dividing the Fourier transformed result by the product obtained as described above.

Next, by the method described above, the reflection function R' inside the material is
The reason why (kr) can be calculated will be explained. V (Z) on the surface of the material can be calculated from the above-mentioned reference as V (Z) - Cf P2 (kr) R (k
r 3 (kr/kz) -expc-j2kzZ)dkr (5) (where C: standard factor, (kr/kz): factor representing the difference in energy between the inner circumference and the outer circumference).

By performing appropriate variable conversion on the above equation, V (u)−
ClF3 (t)R(t)-eχp(-j2πut)d
oV'(u), which can be expressed as t - (6), is P2 (t
)R(t). Therefore, let us consider extending equation (5) inside the material. To simplify the explanation, only longitudinal waves inside the material will be considered.

As shown in FIG. 2, it can be seen that the reflected wave from the reflective surface 9 inside the material travels through the sample 22 times longer than the reflected wave from the material surface 10. Considering this point, equation (5) becomes V (Z)-CJ'P2 (kr)R' (kr)(
kr /kz )exp C-j2kz Z)-ezp
It can be extended as [j21cz' z]dkr - (7). Here, R' (kr) is the reflection function inside the material, 1(z' is the Z component of the propagation constant inside the material, and kZ' = (kQ'-kr") (however, ko'-2πν/CL, Si : frequency of sound wave,
CI: velocity of sound in longitudinal waves). CL is performed by a known method or the conventional method described above.
Z4τCL (8) can be determined by measuring the time of the reflected wave, which will be described later. 2 is invariant to changes in Z. Therefore, eχI)(j2kz' z) is a phase term with only k as a variable, so it can be seen that it can be treated in the same way as P(kr).Next, we can see that the sound wave travels back and forth across the solid-liquid interface on the material surface. Consider the impact of

The angular dependence of reflectance and transmittance at the solid-liquid interface has already been analyzed in detail and formulated as follows.

CW, ρ: sound speed and density of water CL, Cs: sound speed of longitudinal and transverse waves in a solid ρl: solid density, the propagation constant in water is kQ −2πν/CW. The propagation constant in a solid is kO' for longitudinal waves and transverse waves.
-2πν/CL ko'-2πν/C3, where the incident angle θ, longitudinal wave refraction angle θl, and transverse wave refraction angle γ
are respectively θ−s i n' (kr / ko )θl −s
in'(kr/kO')7-sin-'
It is expressed as (kr/RO'). Therefore, if Z-ρC/cosθ Znomρlc/cosθI Zt ””11)l Cs/cos7, the transmittance of longitudinal waves from water to solid T(kr) is T(kr)=(2ρ/ρl)ZJcos2
γ(Z) COS22 γ +zt sin227+Z)-t ・-
(9) becomes. Conversely, the permeability from solid to water T' (
kr) is φ= (Z+Zt s i n227 − Zfcos 227) / (Z+Zt s i n227 + Z , f? cos 227 ) −(1
0), then T' - (Cv cosθl/CLcosθ・cos
2γ)(1-φ) (11). In addition, as a reference for the above calculation, please refer to “So^VES
IN LAYERED MEDIAJ (Second
dEdition by L, M BREKIIOVS
KIKH, Acadea+Ic press.

1980).

As is clear from the above equation (11), T.

T' is ρ1. If CL, , Cs are known, then k
It can be calculated as a function of r only. Therefore, equation (7) is: V (Z)-ClF3 (kr)T (kr)・T'
(kr)Q(kr)R' (kr)(kr/kz) ・eZp(-j2kz Z]dkr・ (12) (However, it is extended as Q (Rr)=exp (j2kz' z). Therefore, V If (Z) is determined as AJj, the reflection function R' (Rr) at the reflective surface 9 inside the substance is R' (kr) -F-' fV (Z)
1/P2 (kr)T (kr)-T'
(kr) Q (kr) −(
13) can be obtained using the following formula.

In addition, in the reflection function calculation method shown in Fig. 1, the time-separated reflection signal from the material surface and the complex V (Z) signal of the reflection signal from inside the material are measured simultaneously, and the V of the material surface is calculated. (Z) The first and second transmittance functions and the phase lag function obtained by determining the reflection function of the material surface from the signal and calculating the sound velocity and density of the material body from the reflection function of the material surface. By calculating the product of A reflection function may also be calculated.

According to the method of the present embodiment described above, in ultrasonic measurement using a focused spherical wave, the reflection function of an acoustic reflecting surface existing inside a substance can be easily and accurately determined, and the reflection function of an acoustic reflecting surface existing inside a substance can be easily and accurately determined. It is possible to quantitatively understand the distribution of various acoustic properties. As a result, it is possible to make full use of the characteristics of ultrasonic waves, which enable inspection of the inside of materials without rupturing them, which is useful in the fields of new materials and biology.

It is possible to obtain a reflection function calculation method that is extremely useful in a wide range of fields such as the semiconductor field and has great practical effects.

Next, an apparatus for carrying out the method for calculating the internal reflection function described above will be described.

FIG. 3 is a block diagram showing the configuration of the device. Third
In the figure, 11 is a central processing unit (hereinafter abbreviated as CPU), which controls the operation of each part and calculates a reflection function. The transmitting circuit 12 controlled by the control signal from the CPU 1 outputs a transmitting pulse having a frequency of, for example, about 30 MHz to 100 MHz. This transmitted pulse is applied to the piezoelectric transducer 14 through the circulator 13. The ultrasonic pulse generated by electro-acoustic conversion in the piezoelectric transducer 14 becomes a focused spherical wave by the acoustic lens 15, propagates through the Kabra liquid (water) 16, and is irradiated onto the measurement object 17. A part of the irradiated ultrasonic pulse is applied to the measurement target 17
is reflected from the surface of the material, but the other part reaches the interior of the material. The reflected waves reflected from the material surface and the acoustically non-uniform surfaces inside the material pass through the acoustic lens 15 again and return to the piezoelectric transducer 14, where they are subjected to acoustic-to-electrical conversion.

The electrical signal corresponding to the reflected wave thus obtained, that is, the reflected signal, passes through the circulator 13 and is input to the receiving circuit 18 where it is amplified. The amplified reflected signal is supplied on the one hand to an oscilloscope 19 and on the other hand to a time separation gate circuit 20 as an input signal.

On the other hand, in response to a control signal from the CPU 11, the time gate signal generating circuit 30 starts operating at the same time as the transmitting circuit 12. This time gate generation circuit 30 includes a pulse from a high-speed pulse generator 21 as a basic clock generation circuit, and an acoustic lens vertical position detection circuit as a means for detecting the amount of change in the distance between the acoustic lens 15 and the measurement object 17. A digital signal from 22 is supplied. The output signal of this time gate signal generation circuit 30 is supplied to the oscilloscope 19 on one side and as a gate control signal for the time separation gate circuit 20 on the other side.

FIG. 4 is a block diagram showing the detailed configuration of the time gate signal generation circuit 30. As shown in FIG. 4, this time gate signal generation circuit 30 includes a gate 31, a counter 32, an addition/subtraction circuit 33, a setting circuit 34 as means for setting a first integer value, and a second integer value. It is composed of an arithmetic circuit 34 as a numerical value calculation means.

The addition/subtraction/arithmetic circuit 33 adds or subtracts the second integer value from the arithmetic circuit 35 to the first integer value from the setting circuit 34, and outputs the result to the counter in synchronization with the generation of the ultrasonic pulse. 32 as a preset value. The setting circuit 34 is for setting a first integer value consisting of an arbitrary digital value by an observer performing a setting operation from the outside. The arithmetic circuit 35 has a terminal 36
Based on the digital signal Δ2 from the vertical position detection circuit 22 given to .

Therefore, when a signal from CPUI 1 is applied to terminal 37, gate 31 is opened to allow the pulse from high speed pulse generator 21 applied to terminal 38 to pass through. At the same time, the counter 32 is loaded with a preset value from the addition/subtraction circuit 33.

When the counter 33 finishes counting the preset value, the gate 31 is shut off by the counting end signal, and the counter output signal is output from the output terminal 39 as a time gate signal.

As described above, this time gate signal is supplied to the oscilloscope 19 together with the received signal corresponding to the reflected wave and displayed on the screen.

Figure 5 shows the received signal SA displayed on the oscilloscope 19.
and a time gate signal SB. FIG. SAI indicates the surface reflection signal, and SA2 indicates the internal reflection signal.

The explanation returns to FIG. 3. The observer first uses an oscilloscope 1.
The surface reflection signal SAI is identified from the waveform of the received signal SA shown in FIG.
After moving the acoustic lens 15 to a position where the surface is in focus, the vertical position detection circuit 22 is reset (ΔZ-0). From this position, the acoustic lens 15 is moved in a direction closer to the measurement target/object 17, so that the reflected signal from inside the substance constituting the measurement target 17 can be sufficiently recognized. Here, the setting circuit 34 is operated to set the time gate signal SB to a state that allows the reflected signal SA2 from inside the substance to pass, as shown in FIG.

When set to such a state, no matter which direction the acoustic lens 15 is moved up or down from the above state, the up/down movement information detected by the up/down position detection circuit 22 is given to the time gate signal generation circuit 30. Therefore, the time gate signal SB shown in FIG. 5 always moves following the reflected signal SA2 caused by reflection from inside the original substance.

Therefore, the observer moves the acoustic lens 15 to the measurement start point of V (Z), and then starts a program for determining V (Z) ApJ. In the 1lfll constant routine of V (Z), the C'P U 11 places the acoustic lens 15 or the measurement object 17 on the XYZ drive mechanism 23 every time the transmission control described above is performed once. A signal is sent to move the XYZ stage 24 in the Z direction (vertical direction) at a predetermined pitch.

In this way, the distance between the acoustic lens 15 and the measurement object 17 changes, and the plurality of reflected signals SA2 resulting from reflection inside the substance are temporally separated by the time gate signal SB in the time separation gate circuit 20. is extracted.

The reflected signal that has passed through the time separation gate circuit 20 is sine-detected by the quadrature detection circuit 25.

The complex signals are cos-detected and peak-held by peak-hold circuits 25a and 26b (including an integrating circuit if necessary), and then an A/D conversion circuit 27a.

27b, each signal is converted into a digital signal and stored in the memory 28. By performing a series of scans in the Z direction in this manner, at the end of the scan, the V from the reflective surface inside the substance of the measurement object 17 is stored in the memory 28.
The data of (Z) will be imported in the form of complex data. The storage information stored in this memory 28 is
In U11, the calculation according to the above-mentioned equation (13) is performed, and the reflection function R' (R
r) is required. Time delay τ between surface reflection and internal reflection.

Sound velocity of measurement object 17 CI4. It is assumed that necessary parameters such as CS and density pl have already been input. Furthermore, C
The operation details of the PUI 1 are displayed on the display device 29.

According to the above device shown in this embodiment, the quadrature detection circuit 25
Complex signals can be easily obtained by orthogonal detection at
Furthermore, since the time gate signal SB can always capture the reflected signal SA2 of interest by following the vertical movement of the acoustic lens 15, it is possible to measure V (Z) at high speed.

Note that the time gate signal generation circuit 30 may be configured as shown in FIG. That is, as shown in FIG. 6, the gate 31. Counter 32, addition/subtraction circuit 3
3. The part consisting of the setting circuit 34 is made into a unit, a plurality of blocks 40a to 4On that are made into units are connected in parallel, each output of each block 40a to 40n is taken out via an OR gate 41, and the OR output signal is timed. This is used as a gate signal. With this configuration, as shown in FIG. 7, the reflected signals SA2 . It becomes possible to simultaneously capture and calculate V (Z) for SA3.... Especially in this case, since V (Z) on the surface of the material can be captured at the same time,
CL, C8, and ρ1 can be calculated. Therefore, even if the sound speed and density of the material itself are unknown, by simultaneously measuring the surface reflection V (Z), there is an advantage that the reflection function at the reflective surface inside the target material can be determined in a short time. , it becomes an extremely advantageous measurement method for unknown measurement objects.

Note that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the method of the present invention, the conventional method of determining a reflection function from the Fourier transform of V (Z) is extended to a method of determining a reflection function at a reflective surface existing inside a material.
Ultrasound makes it possible to easily and accurately determine the reflection function of sound waves on acoustically inhomogeneous surfaces that exist inside a material, and quantitatively understand the internal acoustic structure of the material that makes up the object to be measured. A method for calculating the reflection function of an object to be measured in a microscope can be provided.

Furthermore, according to the device of the present invention, a complex signal can be easily obtained by orthogonal detection, and an internal reflection signal can be extracted accurately by a time gate that follows the amount of change in the distance between the acoustic lens and the object to be measured. Therefore, it is possible to provide an apparatus for calculating a reflection function of an object to be measured in an ultrasonic microscope, which is extremely useful in carrying out the method described above.

[Brief Description of the Drawings] Figures 1 and 2 are diagrams showing an embodiment of the method of the present invention. Figure 1 is a block diagram showing the procedure for calculating the reflection function inside a material, and Figure 2 is a block diagram showing the procedure for calculating a reflection function inside a material. FIG. 3 is a diagram showing patterns of reflection of sound waves on the surface of a material and inside the material. 3 to 5 are diagrams showing one embodiment of the device of the present invention, in which FIG. 3 is a block diagram showing the overall configuration, FIG. 4 is a block diagram showing the configuration of a time gate signal generation circuit, and FIG. The figure is a waveform diagram schematically showing a reflected signal and a time gate signal. FIG. 6 is a block diagram showing a modification of the time gate signal generation circuit in the above embodiment, and FIG. 7 is a waveform diagram schematically showing a reflected signal and a time gate signal in the modification. 11...CPU, 14...Piezoelectric transducer,
15...Acoustic lens, 17...Measurement object, 2o.
・・Gate circuit for time separation, 25 ・・Quadrature detection circuit,
30...Time gate signal generation circuit. 1st! ! ! I

Claims (3)

[Claims] (1) A focused spherical wave of ultrasound is generated using an acoustic lens, and the reflected waves from the surface and inside of the substance to be measured are captured again by the acoustic lens to perform acousto-electrical conversion.
A method for calculating the reflection function of a substance to be measured, which is applied to an ultrasonic microscope configured to time-separately record the reflected signals, includes changing the distance between the acoustic lens and the substance. The obtained reflected signals from inside the time-separated substance are expressed as complex V
(Z) Capture as a signal and Fourier transform it, and use the known square of the pupil function of the acoustic lens and the angle at which the ultrasonic wave passes from the surface of the substance toward the inside of the substance as variables. a first transmittance function, a second transmittance function whose variable is the angle at which the ultrasound passes from the inside of the substance to the outside of the substance, and an incident angle of the ultrasound determined from the sound speed of the substance itself. An object to be measured in an ultrasonic microscope, characterized in that the reflection function inside the substance is calculated by calculating the product with a phase lag function with a variable, and dividing the Fourier transformed result by this product. Reflection function calculation method. (2) In the method for calculating a reflection function according to claim 1, the time-separated reflection signal from the material surface and the complex V(Z) signal of the reflection signal from inside the material are simultaneously measured, and the reflection function of the material surface is measured simultaneously. The first and second transmittance functions obtained by determining the reflection function of the material surface from the complex V(Z) signal and calculating the sound velocity and density of the material body from the reflection function of the material surface; By calculating the product of the phase lag function and the square of the known pupil function, and dividing the result of Fourier transform of the complex V(Z) signal of the time-separated reflection signal from inside the substance by this product. A method for calculating a reflection function of an object to be measured in an ultrasonic microscope, characterized in that the reflection function inside the substance is calculated. (3) Using an acoustic lens, a focused spherical wave of ultrasound is generated, and the reflected waves from the surface and inside of the substance to be measured are captured again by the acoustic lens to perform acousto-electrical conversion.
A clock generation circuit that generates a high frequency basic clock in a device that is applied to an ultrasonic microscope configured to time-separate and record the reflected signals and calculates the reflection function of a substance to be measured; a gate that allows the clock generated by the clock generation circuit to pass through in synchronization with the generation of ultrasonic pulses;
A counter provided to be able to count the clocks that have passed through this gate, and a first
a setting means for setting an integer value of , a calculation means for calculating a second integer value by performing the calculation OUT=2fΔz/Cw based on the amount of change in the distance between the acoustic lens and the object to be measured; means for adding or subtracting a second integer value calculated by the calculation means to a first integer value set by the means, and providing the output of the addition/subtraction calculation to the counter as a preset value in synchronization with the generation of the ultrasonic pulse; , means for cutting off the gate and generating a time gate signal when the counter finishes counting the clocks corresponding to the preset value, and forming at least a measurement object using the time gate signal generated by the means. means for time-separating and extracting reflected signals from inside a substance; means for orthogonally detecting the reflected signals extracted by this means to produce a complex V(Z) signal; and storing the output obtained by this means. 1. An apparatus for calculating a reflection function of an object to be measured in an ultrasonic microscope, comprising: a memory; and calculation means for calculating a reflection function inside the substance based on information stored in the memory.