Application of ultrasonic technology in medical field

Beam characteristics

Due to the length of the ultrasonic waves, ultrasonic rays can be as light reflection, refraction, can, can also be focused, and comply with the laws of geometrical optics. USM ultrasonic rays from a material surface reflection, the incident angle is equal to the angle of reflection, when ray through a substance into another density different substances can produce refraction, is to change its propagation direction, two kinds of material density difference is larger, the larger refractive index.

Absorption characteristics

Acoustic wave propagation in a variety of substances, with the increase of propagation distance, the strength will be weakened gradually, this is because the material to absorb its energy. For the same material, the higher the frequency of sound waves, the stronger the absorption. For a frequency of a certain sound wave propagation in gas absorption, the calendar harm, in liquid communication when the absorption is relatively weak, propagation in solid absorption minimum.

The ultrasonic energy transmission characteristics

Ultrasonic so to various industrial sectors in a wide range of applications, the main point is much more powerful than the acoustic wave has the power. Why there is strong power? Because when sound waves to reach a certain materials, due to the effect of sound wave so that the elements in the material also with vibration, vibration frequency and acoustic frequency, sample, molecular vibration frequency determines the molecular vibration speed. The higher frequency velocity increases. Materials molecular due to the vibration of the energy acquired by except with molecular quality related, was made by molecular vibration velocity squared decision, so if the wave frequency is higher, also is the material molecular healing can obtain higher energy, ultrasonic frequency than sound waves can be much higher, so it can make the material molecules obtained great energy; in other words, the ultrasonic can supply enough power material.

Ultrasonic sound pressure characteristic

When sound waves leads to a certain object, due to acoustic vibration of molecules to produce compression and rarefaction effect, will make the material by pressure change. Due to the acoustic vibration caused by the additional pressure phenomenon called the sound pressure.

Because the ultrasonic wave has a lot of energy, it is possible to make molecules produced significantly the pressure effect, such as when the water through the general intensity of ultrasonic, the additional pressure can reach several atmospheric pressure. Liquid storage plays such a large role in the sound pressure, will cause a noticeable phenomenon. When ultrasonic vibration makes the liquid molecules when compressed, like molecules by direct pressure from all sides; when ultrasonic vibration makes the liquid molecules are sparse, as if by outward spread tension, for the liquid, they have endured additional pressure, so when subjected to compressive forces when; is short, instantaneous will close up. Cavity closure times will produce great instantaneous pressure, in general can reach thousands or even tens of thousands of atmospheric pressure. The liquid in this powerful instantaneous pressure, the temperature will suddenly increase. The fracture caused by the mutual large instantaneous pressure, can make the floating in the liquid solid surface by rapid destruction. We often call cavitation phenomenon.

Ultrasonic application has the following characteristics:

1, ultrasonic has good directivity -- the higher the frequency, the more points. This such as detection and underwater acoustic communication applications are the main factors to consider.

2, if the frequency is high, the corresponding to the wavelength will be shorter, so the wavelength and propagation of ultrasonic sample material size comparable with the wavelength, and even can be much smaller than the size of the sample material. The thickness of very small size measurement applications as well as in the high resolution applications of detection is very important.

3, ultrasonic use very quiet, people could not hear it. This point is especially important in high intensity work. The high intensity of work with audible frequency sound waves to complete the often more effective, unfortunately, audible sound produced during working noise was unbearable, sometimes even harmful to the human body.

 

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