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本文利用激光超声技术测量了ＣＶＤ金刚石膜的纵波声速。１原理激光超声法就是利用激光照射到固体薄膜试样表面，激发超声波，对此超声波进行检测分析，从而获得材料的声学特性。本文通过测定声脉冲传过试样所需的声时Δｔ和试样厚度Ｌ，用公式ＣＬ＝Ｌ／Δｔ就可以得到薄膜中的纵波声速ＣＬ。声脉冲的传播时间Δｔ，可以采用直达波法和反射回波法测量。直达波法是以激光脉冲为声脉冲产生的时间起点，测量声脉冲透过金刚石膜和铝延迟块的直达声脉冲的声时ｔ和声脉冲仅通过铝延迟块的声时ｔＡＬ，得到相应声速为：ＣＬ＝Ｌ／Δｔ＝Ｌ／（ｔ－ｔＡＬ）（１）反射回波法是通过测量相邻反射回波之间的声时Δｔ２Ｌ，以及声脉冲来回一次的声程２Ｌ，就可用公式（２）得到薄膜的纵波声速：Ｃ２Ｌ＝２Ｌ／Δｔ２Ｌ（２）反射回波法可消除耦合层对测量的影响，这对于Δｔ２Ｌ很小的试样，尤其对象金刚石膜有高声速的试样是很合适的。本文采用反射回波法测定金刚石膜的纵波声速，同时用直达波法进行校验和比较。２实验结果与讨论实验样品为人工晶体研究所用ＥＡ－ＨＦＣＶＤ方法制备的２片Ｆｒｅｓｔａｎｄｉｎｇ金刚石膜，厚度分别为０．５２４ｍｍ和０．５３７ｍｍ。样品光照面涂硅油，利用油膜的吸收光能和?
In this paper, the longitudinal wave velocity of CVD diamond films was measured by laser ultrasonic technique. 1 Principle Laser Ultrasound is the use of laser light to the surface of the solid film samples, excitation of ultrasound, ultrasonic testing of this analysis to obtain the acoustic properties of the material. In this paper, by measuring the acoustic pulse transmitted through the sample required Δt and sample thickness L, with the formula CL = L / Δt can be obtained in the film longitudinal wave velocity CL. Acoustic pulse propagation time Δt, can be measured by direct wave method and reflected echo method. The direct wave method uses the laser pulse as the starting point of the time of the acoustic pulse to measure the acoustic velocity of the direct pulse of the acoustic pulse passing through the diamond film and the aluminum delay block t and the acoustic pulse only passes through the acoustic time of the aluminum delay block tAL to obtain the corresponding sound velocity Is: CL = L / Δt = L / (t-tAL) (1) Reflected echo method is measured by measuring the echo between adjacent echo Δt2L, and the sound pulse back and forth once the sound path 2L, (2) Obtain the longitudinal wave velocity of the film: C2L = 2L / Δt2L (2) The reflection echo method can eliminate the influence of the coupling layer on the measurement. This is especially true for specimens with very small Δt2L, Very suitable. In this paper, using the reflection echo method to measure the longitudinal wave velocity of the diamond film, while using the direct wave method to verify and compare. 2 Experimental results and discussion Experimental samples for the study of artificial crystal EA-HFCVD method using two Fre -standing diamond films, the thickness of 0.524mm and 0.537mm. Samples of light coated silicone oil, the use of oil absorption of light energy and?