SU997093A1 - Device for observing acoustic waves in piezoelectrics - Google Patents

Description

The invention relates to electronics and can be used in the development of acoustoelectronic? devices.

A known method for observing acoustic waves in piezoelectric eukvukoprovoda based on laser sounding £ 1}.

However, this method does not allow to obtain a visual image of the car. The amplitude of vibrations along the entire surface of the sound duct and is associated with a long analysis.

The closest to the invention in terms of technical nature and the achieved result is a method for observing acoustic waves in piezoelectrics using a scanning electron microscope, which uses the principle of television scanning and image transmission (the surface of the investigated piezoelectric) with a scanning electron beam of £ 2}.

The disadvantage of this method is that it does not give an indication of the direction of propagation and the configuration of the front of traveling acoustic waves, for example, surface acoustic waves.

The purpose of the invention is to increase the information content of observation by indicating the direction of propagation and - configuration of the front of traveling acoustic waves.

This goal is achieved by the fact that, according to the method for observing acoustic waves in piezoelectrics using a scanning electron microscope, amplitude modulation of the probing electron beam by a signal with a phase-modulated frequency of acoustic oscillations is carried out.

The drawing shows a block diagram of a device that implements the method. · The studied piezoelectric sound pipe 1, in which acoustic waves are excited by an electro-acoustic transducer 2 connected to the generator z? high-frequency voltage, placed in a raster electronic low-voltage microscope containing a vacuum column 4, collector 5, video amplifier 6, video monitoring device 7, a scan generator 8, an adjustable phase shifter 9 and an electron-optical system with a cathode 10, a modulator 11, 0 deflecting coils 12.

997093 4

The method is implemented as follows.

Using an electron-optical microscope system, a probing electron beam, which is pulled out, is directed onto the surface of the studied piezoelectric sound duct 1. secondary electrons from the surface of the piezoelectric sound duct 1. Acoustic propagating in a piezoelectric sound pipe 1: waves are accompanied by surface electric charges that affect the magnitude of the electron emission coefficient of secondary electrons. Therefore, when reproducing the video signal taken from the collector 5, on the screen of the video monitoring device 7, along with the contour of the sound pipe, a brightness picture of the distribution of the amplitudes of the oscillations is reproduced. Brightness sections of the pattern of distribution of vibrations depends not only on the amplitude, but also on the phase of the vibrations. Thanks to the gating carried out by pos. By means of amplitude modulation of a probe (scanning) electron beam with a frequency of acoustic oscillations, traveling acoustic waves are observed on the screen in the form of alternating dark and light bands separated by gaps equal to the wavelength. Changing the phase of the electrical signal using the phase shifter 9 in the circuit of the modulator 11 causes phase, modulation of the probe (scanning) beam. If the phase is positive during rotation, each band in the image of the oscillation pattern corresponding to points with the same oscillation phase, i.e. wave front, moves in the direction of propagation of the acoustic wave, i.e. in the direction of the wave vector, outlining a new geometrical place for points whose phase of oscillation differs from the original one by the increment of the phase of the probe beam

VNIIIPI Order 941/70 Circulation 380 Subscribed

This method provides an increase in the information content of observation and visual assessment of such parameters of a traveling acoustic wave as the configuration of the front, the direction of the wave vector, and wavelength.

The method also makes it possible to distinguish between the standing and traveling components of the waves on the surface of the piezoelectric sound duct depending on whether the luminance bands move along the image of the sound duct surface when the phase of the probe beam changes (in the case of a traveling wave) or remain stationary (in the case of a standing wave). the degree of brightness of the bands corresponding to the standing and running component waves, we testify to the ratio of the amplitudes of these components. The application of this method allows substantially simplify and accelerate the development and improvement of acoustoelectronic devices.

Claims (2)

The method is implemented as follows. Using an electron-optical system of a microscope, a probing electron beam is directed onto the surface of the piezoelectric sounding duct 1 under study, which is picked out. Secondary electrodes from the surface of the piezoelectric duct 1 are connected. The propagation of Qadiaz in the piezoelectric sound conduit 1 is acoustic: WAVES are accompanied by surface electric charges that affect the value of the electron emission coefficient of the secondary electrons. Therefore, when playing a video signal taken from collector 5, on the screen the view of the monitoring device 7, along with the duct contour, reproduces the luminous picture of the distribution of the amplitudes of the oscillations. The brightness of the parts of the pattern of the distribution of the oscillations depends not only on the agglutrium, but also on the phase of the oscillations. Due to the strobing carried out by means of amplitude modulation of the probe (scanning) electron beam with the frequency of the acoustic frequency. A bani, traveling acoustic waves are observed on the screen in the form of alternating dark and light bands separated by intervals equal to the wavelength. The change of the phase of the electric signal in the circuit of the modulator 11 by means of a phase shifter 9 causes phase modulation of the probe (scanning) beam. With a positive phase increment, each band in the image of the oscillation pattern corresponds to points with the same oscillation phase, i.e. the wave front moves in the direction of propagation of the acoustic wave, i.e. in the direction of the wave vector, outlines the new locus of the points whose phase of oscillations differs from the initial one by the phase increment value. This method increases the informativity of the observation and visual assessment of such parameters of the traveling acoustic wave as the front configuration, the direction of the wave vector, the wavelength. The method also makes it possible to distinguish the standing and traveling components of the waves on the surface of the piezoelectric sound duct depending on whether the: bright bands move along the image of the surface of the sound duct when the probing phase changes (in the case of a traveling wave) or remain stationary . The degree of brightness of the bands, corresponding to the dix-to-stand and traveling components of the waves, indicates the ratio of the amplitudes of these components. The application of this method allows to significantly simplify and accelerate the development and improvement of acoustoelectronic devices. The method of observing acoustic waves in piezoelectrics using a scanning electron microscope, characterized in that, in order to increase the information content by indicating the direction of propagation and configuration of the front of traveling acoustic waves, amplitude modulation of the entire electron beam by a frequency signal is performed. kribaniyt modulated - on a phase. Sources of information taken into account during the examination 1. R.e. Wiltiamson, IEEE Trans. Sonics Ultrasonics, SU-19,4, 1972, c. 436-441 .. - 2. Electronic technology. Ser.IX, Radio Components, 1969, vol. 2, p.104