MRI: Development of an Angle-Dispersive Brillouin Imaging Spectrometer

布里渊光谱是一种非弹性光散射技术，可以精确测量材料内部的高频纵向和横向声速。声速和声衰减的测定进一步允许测定体力学性能，包括弹性、体模量、劳多-普拉西克比、折射率和泊松比。从历史上看，扫描法布里-珀罗干涉仪的液体和固体材料布里渊光谱测量非常困难，并且需要在实验持续时间内保持湿度和温度的稳定性，这可能需要几个小时。这就是它的模糊和其他类型的弹性测量（如超声波和应力应变技术）的主导地位的一个原因。我们的小组计划通过创建一个更快、更容易使用的布里渊光谱仪，使布里渊光谱成为一个更有效的光谱，它允许显微镜和成像技术的性能。最近的研究表明，光学技术的进步可以用来设计一种易于使用和快速采集角色散型法布里-珀罗干涉仪。角色散共焦布里渊仪器的设计将允许在几毫秒到几秒钟内获得大多数材料的声学特性。本课题组提出了一种基于角度色散型法布里-珀罗干涉仪的布里渊光谱仪，具有显微镜和成像功能。这种提议的仪器将是同类仪器中的第一种，并将为新型的原位无损机械测量和机械对比成像打开大门。目前用于确定材料机械性能的许多方法都会破坏原始材料。然而，布里渊光谱方法可以用无损的方式来测量材料的“硬度”和弹性。以其发现者马塞尔·布里渊的名字命名，它是揭示与材料有关的动力和机械特性的最有力的方法之一。布里渊光谱学直接测量照射在固体或液体样品上的激光的频移（类似于警用雷达使用频移来测量速度）。这允许确定许多机械性能，包括弹性（刚度），体积模量（压缩性）和折射率。J.L. Yarger的研究小组最近开发了一种角色散法布里-珀罗干涉仪（ADFPI），用于布里色光谱。我们建议使用最近设计的ADFPI作为构建共聚焦布里渊显微镜和成像系统的基础，以扩展成像和光谱技术可用于表征材料的机械和弹性性能。

Technical AbstractBrillouin spectroscopy is an inelastic light scattering technique that allows for accurate measurement of high frequency longitudinal and transverse sound velocities within materials. Determination of sound velocity and acoustic attenuation further permits the determination of bulk mechanical properties including the elasticity, the bulk modulus, the Laudau-Placzek ratio, refractive index, and the Poisson's ratio. Historically, scanning Fabry-Perot Interferometer Brillouin spectroscopy of liquid and solid materials has been very difficult to measure and has required humidity and temperature stability for the duration of the experiment, which can be many hours. This is the one reason for its obscurity and the dominance of other types of elastic measurements such as ultrasonics and stress-strain techniques. Our group plans to make Brillouin spectroscopy a more utilized spectroscopy by creating a much faster and easier to use Brillouin spectrometer that allows performance of both microscopy and imaging techniques. It has recently been shown that advents in optical technologies can be used to design an easy-to-use and fast collecting angle dispersion type Fabry-Perot interferometer. The design of an angle-dispersive confocal Brillouin instrument will allow the acoustic properties of most materials to be obtained in a few milliseconds to seconds. Our group proposes to develop an angle dispersion type Fabry-Perot interferometer based Brillouin spectrometer with microscopy and imaging capabilities. This proposed instrument will be the first of its kind and will open the doors to new types of in-situ non-destructive mechanic measurements and mechanical contrast imaging. Non-Technical AbstractMany of the methods currently used to determine the mechanical properties of a material result in destruction of the original material. Brillouin spectroscopy methods can, however, be used to gauge both the 'hardness' of a material as well as the elasticity in a nondestructive manner. Named after its discoverer, Marcel Brillouin, it is among the most powerful methods of revealing the dynamical and mechanical properties associated with materials. Brillouin spectroscopy directly measures the frequency shift in laser light impinging on a solid or liquid sample (similar to police radar that use a frequency shift to measure speed). This allows the determination of many mechanical properties including the elasticity (stiffness), the bulk modulus (compressibility) and refractive index. J.L. Yarger's research group has recently developed an angle-dispersive Fabry-Perot interferometer (ADFPI) for use in Brillouin spectroscopy. We propose using the recently designed ADFPI as the bases for constructing a confocal Brillouin microscopy and imaging system to extend the imaging and spectroscopy techniques available for characterization of the mechanical and elastic properties of materials.