SU1449891A1 - Transceiving device of acoustic microscope - Google Patents

Abstract

This invention relates to instrumentation technology. The aim of the invention is to increase the sensitivity of the device by replacing the acoustic reception channel with. optic. The optical radiation source 1 generates a luminous flux, which is directed to the vibrating surface of the object 5. The reflected luminous flux is detected by a fiber-optic converter 6, and an electrical signal is generated at the output of the fiber-optic converter 6, the value of which is proportional to the amplitude and phase of the acoustic wheel. baths on the surface of the object. 2 Il. (L with 1 "ib: about x with

Description

1

This invention relates to instrumentation technology.

The purpose of the invention is to increase the sensitivity of the device by replacing the acoustic reception channel with the optical one.

Figure 1 shows the diagram of the device; figure 2 - structural diagram of a fiber-optic vibrometer.

The device contains an acoustically coupled acoustic wave emitter 1, a sound duct 2, a lens 3, a liquid cell 4, an object 5 and a receiving element 6 made in the form of a fiber-optic vibrometer and optically coupled to an object 5,

The fiber-optic vibrometer consists of optically coupled optical radiation source 7, the first polarizer 8, the divider 9, the optical fiber 10, the second polarizer 11, the photodetector 12, the demodulator 13 connected in series, and the recorder 14. The photodetector output 12 connected to the input of the demodulator 13.

The device works as follows.

From the emitter of acoustic waves, acoustic waves propagate along the sound duct 2 and the lens 3 is focused on the object 5, in which acoustic oscillations are excited, which are recorded by a fiber-optic vibrometer with the help of a light flux emitted by the output end of the optical fiber 10. The oscillations are recorded is

in the following way. Optical wave -

FROM Optical Radiation Source 7

passes through the first polarizer 8 and the beam divider 9, then enters the optical fiber 10, in which it propagates to the output end of the optical fiber 10, on which part of the optical wave reflects back, and forms a reference optical wave. Another part of the optical wave emerges from the optical fiber 10 and hits the vibrating surface of the object 5, from which it is reflected and through the output end of the optical fiber again enters the optical fiber 10. The reflected (measuring) from the surface of the object 5 has an optical wave

d

five

0 5

0

n 0

0

the reference optical wave phase shift, depending on the amplitude and frequency of vibrations of the surface of the object 5. The reference and measuring optical waves pass through the optical fiber 10 and on the beam divider 9 are directed to the photodetector 12 through the second polarizer 11. Polarized reference and measurement optical waves interfere with the photodetector 12,

The zero zone of the interference pattern varies in intensity with the frequency of the acoustic waves on the surface of the object 5. At the output of the photodetector 12, an electrical signal is generated, which is fed to the demodulator 13, which processes the electrical signal proportional to the amplitude of the acoustic vibrations of the surface of the object 5, Increased sensitivity (low level noise) is a consequence of the use of an optical source 7 with a small coherence length. In this device, the minimum coherence length can be chosen to be equal to or slightly more than twice the distance between the end of the optical fiber 10 and the surface of the object 5,

The main advantage that is achieved when using a fiber-optic vibrometer is the elimination of 50-60 dB of signal loss due to the optical transparency of the receiving channel (water + sapphire, -granate + translucent film).

Formula inventions

An acoustic microscope receiving and transmitting device containing a receiving element and an acoustically connected acoustic emitter. pulses, an acoustic lens and a liquid cell, characterized in that, in order to increase the sensitivity by replacing the acoustic receiving channel with an optical emitter of acoustic pulses, the acoustic lens and the liquid cell are made optically transparent, the receiving element is designed as an optical vibrometer mounted in analysis plane from the side of the emitter of acoustic pulses.

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Claims (1)

Claim An acoustic microscope receiving and transmitting device comprising a receiving element and acoustically coupled acoustic pulse emitter, an acoustic lens and a liquid cell, characterized in that, in order to increase sensitivity by replacing the acoustic receiving channel with an optical acoustic pulse emitter, an acoustic lens and a liquid cell optically transparent, the receiving element is made in the form of an optical vibrometer installed acoustically in the plane of analysis from the side of the emitter pulses.