New Paradigms in Light-Based Measurements Using Unconventional Polarization States

偏振光(具有方向性振动的光，其影响有时可以从旋转偏振太阳镜时衰减的变化中看出)无处不在--它存在于蓝天中，来自池塘的反射，来自天然和人造空气颗粒物的光散射，以及我们智能手机的显示屏上。对偏振光的理解和使用对光科学和从医学到消费电子产品的各种应用都是至关重要的。例如，计算机信息革命的一些胜利是建立在制造技术之上的，这些技术需要几乎难以想象的测量精度--其中许多是基于光的，并以可以精确控制和测量的方式使用光的偏振。这项拟议的研究使用了“非传统偏振态”的概念--一种特殊的光形式，即偏振态在激光束的宽度上有所不同--从根本上探索了进行基于光的测量的新方法。结合一些特殊的光学设备，可以使用普通相机在一张图像中创建偏振光的可视地图，这通常需要四张或更多图像的序列和伴随的算法。这些测量方法还将促使人们思考如何在微电子制造中同时测量亚纳米工艺误差。表征超快激光脉冲或单个光子的偏振所需的多次测量需要时序操作或将幅度显式划分到不同的探测器端口。虽然这些方法中的每一个都取得了很大的成功，但是仍然需要以从每个测量的光子(在低光级的情况下)或每个脉冲(在超快脉冲表征的情况下)提取最大量的偏振信息的方式来真正扩展偏振测量。由于该方法可扩展到采样图像场上的偏振映射，因此可以将该概念扩展到捕获单个图像中的角度或频率分辨的偏振信息。这项研究还将新的非传统偏振态物理学应用到现在著名的弱测量物理学中，通过使用非常规偏振光在一次测量中测量两个或更多物理量。这一概念将通过测量配备液晶控制器的显微镜中的纳米级特征来测试，该控制器定义了用于聚焦光束散射测量的具有任意偏振、幅度和相位的场。这项工作预计将影响物理学(通过引入新的测量方法)、光学工程(具体地说，偏振工程和成像)、生物医学光学(医学成像和光谱学)、环境科学(通过使用偏振光散射来表征气溶胶)和半导体检查的相关领域。

Polarized light (light with directional vibrations whose effects can sometimes be seen in changes in attenuation while rotating polarizing sunglasses) is everywhere--it is in the blue sky, the reflection from a pond, in light scattering from natural and manmade airborne particles, and in the display screens on our smartphones. The understanding and use of polarized light is central to both the science of light and to applications ranging from medicine to consumer electronics. For example, some of the triumphs of the computer information revolution have been built around manufacturing technologies that require almost unimaginable precision in measurements--many of which are light-based and use the polarization of light in ways that can be precisely controlled and measured. The proposed research uses the concept of an "unconventional polarization state" - a special form of light in which the polarization varies across the width of a laser beam - to explore fundamentally new ways of carrying out light-based measurements. In conjunction with some special optical devices, it is possible to use an ordinary camera to create a visual map of the polarization in a single image, something that ordinarily requires a sequence of four or more images and accompanying algorithms. These measurement methods will also spur new ways of thinking about how to execute the simultaneous measurement of sub-nanometer process errors in microelectronics manufacturing.The multiple measurements required to characterize the polarization of an ultrafast laser pulse or individual photon require either a time-sequential operation or explicit division of the amplitude into different detector ports. While each of these has been used to good success, there is a need to truly extend polarization measurements in a way that the maximum amount of polarization information is extracted from each measured photon (in the case of low light levels) or each pulse (in the case of ultrafast pulse characterization). Because the method is extendable to the mapping of polarization over a sampled image field, it is possible to extend the concept to capture either angle- or frequency-resolved polarization information in a single image. The investigation also applies the new physics of unconventional polarization states to the now-famous physics of weak measurements by using unconventionally polarized light to measure two or more physical quantities in a single measurement. This concept will be tested by measuring nanoscale features in a microscope equipped with a liquid crystal controller that defines a field with arbitrary polarization, amplitude, and phase for focused beam scatterometry. The work is expected to impact allied areas of physics (through the introduction of new measurement methods), optical engineering (specifically, polarization engineering and image formation), biomedical optics (in medical imaging and spectroscopy), environmental science (through the use of polarimetric light scattering for aerosol characterization), and semiconductor inspection.