MRI/RUI: Development of a Michelson Interferometric Imaging Refractometer for Optical Polymer Characterization

RUI的这一主要研究仪器开发项目扩展了基于氦氖（HeNe）激光器和迈克尔逊干涉仪的低成本光学仪器的功能，该仪器可用于测量平面聚合物样品的折射率和膜厚变化。该开发采用了可调光源和可见近红外数码相机成像系统。在当前系统中使用相干HeNe激光光源极大地限制了设备的通用性，因为它限于差示折射率测量。这些测量只能在633 nm处进行。用可调谐低相干弧光灯光源代替相干HeNe激光器，可以测定绝对折射率和微分折射率。这些测量可以在任何波长下进行，从而允许表征样品的色散特性。增加可见光近红外数码相机和硬件软件图像捕获系统将通过允许解析光学材料中的渐变折射率分布来提高装置的能力。成像系统将允许一个面对光学波前失真的问题，所产生的表面粗糙度和样品的不均匀性，困扰以前的干涉仪系统。这项研究涉及一个非博士学位的本科生。此外，作为资助机构，还将通过将研究纳入教育过程来促进培训和学习。互联网的广泛使用以及随之而来的对高带宽传输介质的需求，激发了人们对“全光”网络的兴趣。聚合物由于其柔韧性、重量轻、制造成本低以及具有创造具有各种物理和光学性质的材料的潜力，正在成为光网络发展中的关键材料。光学聚合物的研究和开发目前受到阻碍，由于缺乏仪器来充分表征候选材料在可见光和近红外（NIR）光谱区域的带宽容量。特别地，人们对开发光学成像系统感兴趣，该光学成像系统允许人们表征新聚合物材料的绝对折射率、折射率稳定性和整体色散特性。本研究的第二个目标是使用新的仪器来测量各种新制备的聚合物薄膜的差示和绝对折射率。中央佛罗里达大学的一项合作研究将集中在掺杂候选光致变色化合物的聚合物薄膜的折射率特性上。这些有机化合物能够双光子诱导光异构化。当掺入聚合物薄膜中时，这些化合物的“开关”特性使三维全息数据存储成为可能。

This Major Research Instrumentation RUI development project expands the capabilities of a low-cost optical apparatus based on a Helium-Neon (HeNe) laser and a Michelson interferometer that can be used to measure refractive index and film-thickness variations in planar polymer samples. The development incorporates a tunable light source and a visible-NIR digital camera imaging system. The use of a coherent HeNe laser light source in the current system greatly limits the versatility of the apparatus because it is limited to differential refractive index measurements. These measurements can only be carried out at 633 nm. The replacement of the coherent HeNe laser with a tunable, low-coherence arc-lamp source makes possible the determination of absolute and differential refractive index. These measurements can be performed at any wavelength, thereby permitting one to characterize the dispersion properties of samples. The addition of a visible-NIR digital camera and a hardware-software image capture system will advance the capabilities of the apparatus by allowing one to resolve graded refractive index profiles in optical materials. An imaging system will permit one to confront optical wave-front distortion problems, arising from surface roughness and sample inhomogeneity, that have plagued previous interferometer systems. The study, involving undergraduate students at a non-Ph.D. granting institution, will also promote training and learning through the integration of research in the educational process. The expanding use of the internet and the accompanying demand for high-bandwidth transmission media has fueled interests in 'all-optical' networking. Polymers are emerging as key materials in the development of optical networks, owing to their flexibility, light weight, low cost of fabrication, and the potential to create materials with a variety of physical and optical properties. Research and development of optical polymers is currently hindered due to a lack of instrumentation for fully characterizing the bandwidth capacity of candidate materials in the visible and near-infrared (NIR) spectral regions. In particular, there is interest in developing optical imaging systems that allow one to characterize the absolute refractive index, refractive index stability, and overall dispersion properties of new polymeric materials. A secondary goal of this study is to use the new instrument to measure differential and absolute refractive indices in a wide range of freshly prepared polymer films. A collaborative study at the University of Central Florida will focus on the refractive index characteristics of polymer films doped with candidate photochromic compounds. These organic compounds are capable of two-photon induced photoisomerization. When incorporated into a polymer film, the 'switching' characteristics of these compounds make possible three-dimensional holographic data storage.