本文選題：超聲換能器 + 鈮酸鋰　； 參考：《鄭州大學》2014年碩士論文

【摘要】：在超聲診斷和治療中，由于超聲功率過大可能引起人體細胞破壞性形變的空化效應，超聲診斷安全性逐漸成為醫(yī)用超聲的重要問題。在我國，計量部門主要采用毫瓦級或者瓦級超聲功率計來檢測各種醫(yī)用超聲設備的輸出功率，而超聲功率計則需要通過上一級計量部門進行定期檢定或校準，可見，超聲量值傳遞的準確性為超聲技術使用的可靠性提供了保障。 本文從壓電超聲換能器的工作原理出發(fā)，理論上分析了鈮酸鋰單晶材料的壓電機理，壓電振子的振動模式和壓電方程，并由壓電方程推導出壓電換能器在厚度伸縮振動模式下的機電等效電路；在壓電材料的選擇方面，研究了鈮酸鋰單晶不同切割方向的振動特性和機電耦合系數(shù)，確定壓電晶片的最佳切型及振動模式；在壓電振子的設計方面，合理設計振子厚度與直徑的尺寸比例，并用濺射法在壓電振子表面鍍上金層電極薄膜；在換能器的制作方面，從換能器整體裝配和電極焊接角度出發(fā)，設計了超聲換能器的外殼，有效地降低了裝配難度。本文嚴格遵循“毫瓦級超聲功率計檢定規(guī)程”的要求，研制了標稱頻率為5MHz的標準超聲換能器。 鈮酸鋰壓電超聲換能器的性能測試主要包括兩部分，分別為聲場特性測試和超聲輸出功率的標定。聲場特性測試原理為水聽器法，本文設計了確定換能器工作頻率的實驗，，并測試了其在工作頻率下的聲場空間分布特性。按照毫瓦級標準超聲源的標定要求，在毫瓦級國家基準裝置上，采用輻射力天平法測量所研制的超聲換能器的輸出功率，并對實驗結(jié)果進行了不確定度評定。實驗結(jié)果表明，所研制的換能器滿足“毫瓦級標準超聲源”的要求，達到了預期設計指標，一定程度上克服了標準石英晶體超聲換能器的缺點。
[Abstract]:In ultrasonic diagnosis and treatment, the supersonic power may cause the cavitation effect of the destructive deformation of human cells. The safety of ultrasonic diagnosis has gradually become an important problem of medical ultrasound. In our country, the Metrology Department mainly uses milliwatt grade or watt grade ultrasonic power meter to detect the output power of various medical ultrasonic equipment, and the ultrasonic work The rate meter needs to be regularly calibrated or calibrated through the upper level measurement department. It can be seen that the accuracy of the transmission of ultrasonic values provides a guarantee for the reliability of ultrasonic technology.
Based on the working principle of the piezoelectric ultrasonic transducer, the piezoelectric mechanism of the lithium niobate single crystal material, the vibration mode and the piezoelectric equation of the piezoelectric vibrator are analyzed theoretically, and the electromechanical equivalent circuit of the piezoelectric transducer under the thickness expansion vibration mode is derived from the piezoelectric equation. The optimum cutting and vibration modes of the piezoelectric wafers are determined by the vibration characteristics and the electromechanical coupling coefficient of the crystal. In the design of the piezoelectric vibrator, the size ratio of the thickness and diameter of the vibrator is rationally designed, and the gold layer electrode film is plated on the surface of the piezoelectric vibrator by sputtering; the transducer is made from the transducer as a whole. In the angle of assembly and electrode welding, the outer shell of the ultrasonic transducer is designed, which effectively reduces the difficulty of assembly. In this paper, a standard ultrasonic transducer with a nominal frequency of 5MHz is developed in strict compliance with the requirements of the "milliwatt ultrasonic power meter verification regulation".
The performance test of the piezoelectric ultrasonic transducer for lithium niobate mainly consists of two parts, which are the sound field characteristic test and the calibration of the ultrasonic output power respectively. The sound field characteristic test principle is the hydrophone method. This paper designs the experiment to determine the working frequency of the transducer, and tests the spatial distribution characteristics of the sound field at the working frequency. The calibration requirement of the ultrasonic source is to measure the output power of the ultrasonic transducer developed by the radiation force balance method on the milliwatt national benchmark device, and evaluate the uncertainty of the experimental results. The experimental results show that the developed transducer meets the requirements of the "milliwatt standard super sound source" and has reached the expected design index. It overcomes the shortcomings of the standard quartz crystal transducer.
【學位授予單位】：鄭州大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TB552

【參考文獻】

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本文編號：2065988