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A Broadly Tunable Surface Plasmon-Coupled Wavelength Filter for Visible and Near Infrared Hyperspectral Imaging

机译:适用于可见光和近红外高光谱成像的可广泛调谐的表面等离子耦合波长滤波器

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摘要

Hyperspectral imaging is a set of techniques that has contributed to the study of advanced materials, pharmaceuticals, semiconductors, ceramics, polymers, biological specimens, and geological samples. Its use for remote sensing has advanced our understanding of agriculture, forestry, the Earth, environmental science, and the universe. The development of ultra-compact handheld hyperspectral imagers has been impeded by the scarcity of small widefield tunable wavelength filters. The widefield modality is preferred for handheld imaging applications in which image registration can be performed to counter scene shift caused by irregular user motions that would thwart scanning approaches. In the work presented here an electronically tunable widefield wavelength filter has been developed for hyperspectral imaging applications in the visible and near-infrared region. Conventional electronically tunable widefield imaging filter technologies include liquid crystal-based filters, acousto-optic tunable filters, and electronically tuned etalons; each having its own set of advantages and disadvantages. The construction of tunable filters is often complex and requires elaborate optical assemblies and electronic control circuits. I introduce in the work presented here is a novel widefield tunable filter, the surface plasmon coupled tunable filter (SPCTF), for visible and near infrared imaging. The SPCTF is based on surface plasmon coupling and has simple optical design that can be miniaturized without sacrificing performance. The SPCTF provides diffraction limited spatial resolution with a moderately narrow nominal passband (<10 nm) and a large spurious free spectral range (450 nm-1000 nm).;The SPCTF employs surface plasmon coupling of the pi-polarized component of incident light in metal films separated by a tunable dielectric layer. Acting on the pi-polarized component, the device is limited to transmitting 50 percent of unpolarized incident light. This is higher than the throughput of comparable Lyot-based liquid crystal tunable filters that employ a series of linear polarizers. In addition, the SPCTF is not susceptible to the unwanted harmonic bands that lead to spurious diffraction in Bragg-based devices. Hence its spurious free spectral range covers a broad region from the blue through near infrared wavelengths. The compact design and rugged optical assembly make it suitable for hand-held hyperspectral imagers. The underlying theory and SPCTF design are presented along with a comparison of its performance to calculated estimates of transmittance, spectral resolution, and spectral range. In addition, widefield hyperspectral imaging using the SPCTF is demonstrated on model sample.
机译:高光谱成像是一套有助于研究先进材料,药物,半导体,陶瓷,聚合物,生物标本和地质样品的技术。它用于遥感的知识使我们对农业,林业,地球,环境科学和宇宙有了更深入的了解。超小型手持式高光谱成像仪的发展受到小型广域可调波长滤波器的匮乏的阻碍。对于手持成像应用而言,广域模态是优选的,在手持成像应用中,可以执行图像配准以抵消由不规则的用户运动导致的场景偏移,这会阻碍扫描方法。在本文介绍的工作中,已经开发出了一种电子可调式广域波长滤波器,用于可见光和近红外区域的高光谱成像应用。常规的电子可调广域成像滤波器技术包括基于液晶的滤波器,声光可调滤波器和电子调谐的标准具。每个都有自己的优点和缺点。可调滤波器的结构通常很复杂,并且需要复杂的光学组件和电子控制电路。我在这里介绍的工作中介绍了一种新型的宽视场可调滤光片,即表面等离激元耦合可调滤光片(SPCTF),用于可见光和近红外成像。 SPCTF基于表面等离子体激元耦合,并具有简单的光学设计,可以在不牺牲性能的情况下使其小型化。 SPCTF提供了衍射受限的空间分辨率,具有适度狭窄的标称通带(<10 nm)和较大的杂散自由光谱范围(450 nm-1000 nm).; SPCTF采用入射光的pi偏振分量的表面等离子体激元耦合。由可调介电层隔开的金属膜。该器件作用于pi偏振组件上,只能透射50%的非偏振入射光。这高于采用一系列线性偏振器的类似的基于Lyot的液晶可调滤波器的吞吐量。此外,SPCTF不会受到不希望的谐波带的影响,而这些谐波带会导致基于布拉格的设备发生伪衍射。因此,它的杂散自由光谱范围覆盖了从蓝色到近红外波长的广阔区域。紧凑的设计和坚固的光学组件使其适用于手持式高光谱成像仪。介绍了基础理论和SPCTF设计,并将其性能与计算出的透射率,光谱分辨率和光谱范围的估计值进行了比较。此外,在模型样品上还演示了使用SPCTF进行的宽视野高光谱成像。

著录项

  • 作者

    Zalavadia, Ajaykumar.;

  • 作者单位

    Cleveland State University.;

  • 授予单位 Cleveland State University.;
  • 学科 Chemistry.;Physics.;Analytical chemistry.;Optics.
  • 学位 Ph.D.
  • 年度 2018
  • 页码 151 p.
  • 总页数 151
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:41:23

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