ACOUSTIC MICROSCOPY WITH MECHANICAL SCANNING - REVIEW
ACOUSTIC MICROSCOPY WITH MECHANICAL SCANNING - REVIEW
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DOI：
10.1109/proc.1979.11406
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发表时间：
1979-01-01
影响因子：
20.6
通讯作者：
WICKRAMASINGHE, HK
中科院分区：
文献类型：
--
作者：
QUATE, CF;ATALAR, A;WICKRAMASINGHE, HK
如果频率在千兆赫范围内，液体中的声波的波长与可见光的波长相当。液体中的布里渊散射现象就是基于这种波。大约十年前，加州大学洛杉矶分校在氦气中研究了波长为 2000 Å 的接近 2 K 的声波。从这些观察结果可以看出，如果能够找到一种没有像差的理想透镜，那么基于声辐射的成像系统的分辨率可与光学显微镜相媲美，那么这种成像系统就可以实现。这样的镜头一开始是难以捉摸的，现在是一个简单的设备，它是声学显微镜的基本组件，构成了本次审查的基础。在本文中，我们将确定这种新仪器的特性。我们将回顾声波的一些简单特性，并展示在固液界面形成的单个球面如何充当这种没有像差并能够产生衍射限制光束的理想透镜。当将其合并到机械扫描系统中并用微波范围内的声频激发时，可以用等于可见光波长的声波波长来记录图像。我们将展示显示材料科学、集成电路和细胞生物学领域样本的弹性特性的图像。这些图像中的信息内容通常会超过光学显微照片的信息内容。在反射模式下，我们用高度会聚的声束照射晶体材料的光滑表面。反射场以一种独特的方式受到扰动，该方式由反射表面的弹性特性决定，并显示在反射声场的相位中。当物体和镜头之间的间距变化时，输出端会出现明显的特征响应。声反射显微镜中的这种行为为监测固体表面的弹性参数提供了一种相当简单和直接的方法。很容易区分不同的材料，确定层厚度，并在微观尺度上显示弹性常数的变化。这些特征使我们相信声学显微镜领域有着广阔的前景。
Acoustic waves in liquids are known to have wavelengths comparable to that of visible light if the frequency is in the gigahertz range. The phenomena of Brillouin scattering in liquids is based on such waves. In helium near 2 K acoustic waves with a wavelength of 2000 Å were studied some ten years ago at UCLA. It follows from these observations that an imaging system based on acoustic radiation with a resolving power competitive with the optical microscope is within reach if an ideal lens free from aberrations could be found. Such a lens, which was so elusive at the beginning, is now a simple device and it is the basic component in the acoustic microscope that forms the basis for this review. In this article we will establish the characteristic properties of this new instrument. We will review some of the simple properties of acoustic waves and show how a single spherical surface formed at a solid liquid interface can serve as this ideal lens free from aberrations and capable of producing diffraction limited beams. When this is incorporated into a mechanical scanning system and excited with acoustic frequencies in the microwave range images can be recorded with acoustic wavelengths equal to the wavelength of visible light. We will present images that show the elastic properties of specimens selected from the fields of material science, integrated circuits, and cell biology. The information content in these images will often exceed that of the optical micrographs. In the reflection mode we illuminate the smooth surface of a crystalline material with a highly convergent acoustic beam. The reflected field is perturbed in a unique way that is determined by the elastic properties of the reflecting surface and it shows up in the phase of the reflected acoustic field. There is a distinct and characteristic response at the output when the spacing between the object and the lens is varied. This behavior in the acoustic ieflection microscope provides a rather simple and direct means for monitoring the elastic parameters of a solid surface. It is easy to distinguish between different materials, to determine the layer thickness, and to display variations in the elastic constants on a microscopic scale. These features lead us to believe there is a promising future for the field of acoustic microscopy.