JPH0219762A - Sample surface inclination adjusting device for ultrasonic microscope - Google Patents

Abstract

PURPOSE:To easily and with high accuracy set a sample by detecting directly the parallelism of a focus scanning plane of an ultrasonic beam and the surface of the sample as an intensity variation of an ultrasonic receiving signal and adjusting a sample holding base. CONSTITUTION:The title device is provided with a control part 1, high frequency pulse oscillator 2, circulator 3, transducer 4, acoustic medium 5, sample holding base 12, scanning part 13, SH circuit 14, standard voltage generator 15, differential amplifier 16, integration circuit 17 and a display device 18. By using that which has integrated a difference between ultrasonic receiving signal values in each point on the surface of a sample at the time when the surface of the sample 6 has been scanned linearly in one direction by an ultrasonic beam, and the maximum value among them, as an inclination signal of the sample surface, an inclination of the sample surface is detected directly as a variation of an ultrasonic receiving signal. Subsequently, by adjusting an inclination of the holding base 12 or the transducer 4 so that its inclination signal value shows a zero value, the parallelism of the focus scanning surface of the ultrasonic beam and the sample surface can be adjusted easily and with high accuracy.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an ultrasonic microscope that irradiates an ultrasonic beam onto the surface of a sample and observes the properties of the sample substance from the reflected waves obtained, and in particular, the invention relates to an ultrasonic microscope that irradiates the surface of a sample with an ultrasonic beam and observes the properties of the sample substance from the reflected waves obtained. This invention relates to a sample surface tilt adjustment device for an ultrasonic microscope.

[Conventional technology]

As a conventional sample surface tilt adjustment device of this type, by scanning the sample surface with an ultrasonic beam, the time delays of the ultrasonic reception signals from the reference time at multiple locations on the sample surface are detected, and the time delays are detected. A method is known in which the inclination of the sample holder is adjusted so that the values become equal. FIG. 3 shows a system block diagram of such a sample surface tilt adjustment device. In FIG. 3, the output of a high-frequency pulse oscillator 2 controlled by a pulse signal of a constant period generated by a control unit 1 is transmitted through a circulator 3 to an ultrasonic transducer for transmitting and receiving waves (hereinafter referred to as "wave transmitting/receiving ultrasonic transducer") consisting of a piezoelectric element 4a and an acoustic lens 4b. , simply referred to as a transducer) 4 to generate an ultrasound beam. This ultrasonic beam propagates through the acoustic medium 5 and enters the sample 6 to generate a reflected wave, but this reflected wave passes through the transducer 4 again and is converted into an electric signal, passes through the circulator 3, and then passes through the receiving section 7. will be received. Delay time detection section 9
converts the received detection signal from the receiving section 7 into an analog signal corresponding to the time delay from transmission using the pulse signal from the control section 1 as a reference. On the other hand, the scanning section 8 whose timing is controlled by the control section 1 moves the transducer 4 in the X direction shown in the figure to scan the sample surface with an ultrasonic beam. Therefore, the analog signals corresponding to the time delays of the reflected waves at two different points on the sample surface are simultaneously sent from the delay time detection section 9 to the differential amplifier 10. The output of this differential amplifier 10 is sent to a slope adjustment mechanism 11, and this slope adjustment mechanism 11
Accordingly, the inclination of the sample holding table 12 in the X direction is automatically adjusted so that the output of the differential amplifier 10 becomes zero. Next, the sample holding table 12 is manually rotated 90 degrees to adjust the inclination in the same manner, thereby completing the adjustment of the inclination in the XY plane.

[Problem to be solved by the invention]

However, such conventional sample surface tilt adjustment devices have the following drawbacks. (1) The conventional device described above detects changes in the distance between the acoustic lens of the transducer and the sample surface based on changes in the arrival time of the received detection signal, but in the case of a focused ultrasonic lens, changes in the distance The amplitude change of the received detection signal is large, and even if the sample surface deviates even slightly from the ultrasonic beam focal plane, the amplitude becomes extremely small (and detection becomes difficult. For example, in the case of a 200M7 high-frequency pulse signal, if the sample surface A shift of just 10 μm from the focal plane will reduce the amplitude of the received detection signal by more than 20 dB depending on the sample. (2) The ratio of the change width of the arrival time of the received detection signal to the ultrasonic pulse width used is the difference between the acoustic lens and the sample surface. If the distance between the sample surface and the sample surface changes by one wavelength, it is approximately 1/20, and detection is quite difficult with such a change in arrival time. For example, it has been difficult to precisely adjust the inclination of the sample surface so that no interference fringes occur.This invention takes other measures without depending on the above-mentioned change in arrival time, and the ultrasonic beam It is an object of the present invention to provide a sample surface tilt adjustment device for an ultrasonic microscope that can adjust the parallelism between the focal scanning plane and the sample surface with higher precision.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a sample surface tilt adjustment device for an ultrasound microscope for setting the focal scanning plane of an ultrasonic beam from an ultrasonic transducer for transmitting and receiving waves parallel to the sample surface. a scanning unit that linearly scans a sample surface in one direction with an ultrasonic beam from an ultrasonic wave transducer; and an ultrasonic reception signal value at each point on the sample surface during scanning and a maximum value among these; and a detection unit that integrates and outputs the difference between the two.

[For use]

When the sample surface is linearly scanned in one direction with an ultrasonic beam, the difference between the ultrasonic reception signal value at each point on the sample surface and the maximum value among these values is integrated, and the result is called the sample surface tilt signal. By doing so, the inclination of the sample surface can be directly detected as a change in the ultrasonic reception signal. By adjusting the inclination of the sample holder or transducer so that this inclination signal value shows a zero value, the parallelism between the focal scanning plane of the ultrasonic beam and the sample surface can be easily adjusted with high precision. can.

Embodiment FIG. 1 shows a system block diagram of an embodiment of the present invention. In FIG. 1, 1 is a control unit that performs timing control using pulse signals of a constant period, 2 is a high-frequency pulse oscillator, 3 is a circulator, 4 is a transducer consisting of a piezoelectric element 4a and an acoustic lens 4b, 5 is an acoustic medium, and 6 1 is a sample, and 12 is a sample holder, which are essentially the same as those in the conventional apparatus shown in FIG. 13 is the ultrasonic beam from the transducer 4 that
This is a scanning unit that linearly scans the surface of the camera in one direction (X direction in the drawing). Further, 14 is a receiving SH circuit that receives and amplifies and detects the electrical signal of the reflected wave, 15 is a standard voltage generator, and 1
6 is a differential amplifier, and 17 is an integration circuit, which constitute a detection unit that integrates and outputs the difference between the ultrasonic reception signal value at each point on the sample surface during scanning and the maximum value among them. It is something. Furthermore, 18 is a display device that displays the output from the integrating circuit 17. In such a configuration, first, the sample holding table 12 is moved in the X direction in the figure without scanning, and the surface of the sample 6 is set at the focal scanning plane of the acoustic lens 4b. At this time,
The ultrasonic reception signal of the reception SH circuit 14 becomes maximum. In this state, when the transducer 4 is moved linearly in the X direction by the scanning unit 13, the surface of the sample 6 is
If it is not parallel to the focal scanning plane of a, one side of the surface of the sample 6 approaches the acoustic lens 4b, and the other side moves away from it. Therefore, the ultrasonic reception signal received by the receiver 38 circuit 14 at a point closer to both ends of the sample 6 is a signal farther from the focal scanning plane of the acoustic lens 4b and has a lower value. Therefore, the target <
The output of the rod voltage generator 15 is sent to the receiving 38 circuit 14 at that time.
If the sample surface is scanned linearly in the X direction, the differential amplifier 16
The output becomes larger as the ultrasonic reception signal is closer to the edge of the sample 6 and as the parallelism of the sample surface becomes worse. The output of this differential amplifier 16 is input to an integrating circuit 17 that is reset at the scanning period in the X direction by the scanning section 13.
Its output is input to the display device 1. Therefore, by manually adjusting the inclination of the sample holder 12 in the X direction so that the display on the display device 18 becomes smaller, the parallelism between the focal scanning plane and the sample surface in the X direction can be adjusted. For the X direction, the sample holding table 12
Rotate the plane by 90 degrees and adjust in the same way. FIG. 2 is a system block diagram of another embodiment of the invention. The difference between this embodiment and the embodiment shown in FIG. 1 is that a tilt adjustment mechanism 19 is provided to automatically adjust the tilt of the sample holding table 12. That is, in FIG. 2, the control function of the inclination adjustment mechanism 19 is added to the control section 1, and the output of the integrating circuit 17 is inputted to the control section 1.
Tilt adjustment mechanism 19 so that the output of 7 becomes the smallest value.
The tilt adjustment of the sample holding table 12 is automated. [Effects of the Invention] According to the present invention, the parallelism between the focal scanning plane of the ultrasound beam and the sample surface is directly detected as a change in the intensity of the ultrasound reception signal, and the detected values at each point on the sample surface are integrated. Therefore, the signal level is much higher than that in the case where the slope of the sample surface is detected by a change in the arrival time of the received detection signal. Therefore, even minute deviations on the sample surface can be reliably detected, and by adjusting the sample holder so that this detection signal value shows a zero value, the sample can be easily set with high precision.

[Brief explanation of the drawing]

Figure 1 is a system block diagram of an embodiment of this invention, Figure 2 is a system block diagram of an embodiment of this invention.
Figure 3 is a system block diagram of another embodiment of this invention.
The figure is a system block diagram of a conventional device. ■...Control unit, 2...High frequency pulse oscillator, 3...
・Circulator, 4... Ultrasonic transducer for transmitting and receiving waves, 5... Acoustic medium, 6... Sample, 12...
Sample holding table, 13... Scanning section, 14... 38 receiving circuits, 15... Standard voltage generator, 16... Differential amplifier, 17... Integrating circuit, 18... Display device, 19...
・Tilt adjustment mechanism.

Claims (1)

[Claims] 1) In the specimen surface tilt adjustment device of an ultrasound microscope for setting the focal scanning plane of the ultrasonic beam from the ultrasonic transducer for transmitting and receiving parallel to the sample surface, the ultrasonic beam from the ultrasonic transducer for transmitting and receiving a scanning unit that linearly scans the sample surface in one direction; and a detection unit that integrates and outputs the difference between the ultrasonic reception signal value at each point on the sample surface during scanning and the maximum value among these values. A sample surface tilt adjustment device for an ultrasonic microscope, comprising: