This PDF file contains the front matter associated with SPIE Proceedings Volume 11099, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

The beauty of gems and minerals have been examined and appreciated by optical tools for centuries. Current methods for examining the interior structure of gems and minerals typically requires a sample to be cut and polished prior to imaging. In this presentation, we introduce a new tool for imaging gems and minerals in three dimensions, the multiphoton microscope. We have demonstrated that the multiphoton microscope can capture fascinating information from natural gems and minerals with sub-micron resolution at depths up to the millimeter scale. This new application of multiphoton microscopy may open the doors to non-destructive characterization leading to new information on the formation, structure, and appearance of these stones that have fascinated the eye for centuries.

Optical vortex possesses helical wave-front and carries orbital angular momentum. This peculiar light has been produced artificially in laboratories and investigated toward various applications. Recently, is was experimentally demonstrated that radiation emitted from relativistic electrons in helical motion possesses helical wave-front. Based on the classical electrodynamics, it was shown that radiation from electrons in circular or helical motion possesses helical phase structure and carries orbital angular momentum. Such electrons should exist in various situations in nature, for example, in magnetospheres around stars or in intense circularly polarized light fields created in explosive phenomena. Therefore, optical vortices (vortex electromagnetic waves) should exist widely in nature and their wavelengths extend to the entire range from radio-waves to gamma-rays.

In natural viewing, numerous depth cues are available to the visual system, but their significance varies considerably depending on the viewing distance. How is it reflected in the outcome of depth judgements? We have designed a psychophysical experiment with a limited number of depth cues to examine distance-related changes in the correct response rate and time. Twenty young adults evaluated relative depth of stimuli in physical space. Each time four constant angular size achromatic stimuli were presented on a volumetric multi-planar display. One of these stimuli was demonstrated closer to the observer comparing to others. The experiment followed the four-interval forced-choice procedure. On any given trial, observers determined which one of four stimuli was located closest to them. The nine viewing distances ranged from 0.5 m to 2.5 m. Overall, the depth judgements were correct and fast at the close viewing distances. However, the correct response rate dropped markedly at 1.0 m distance and continued declining gradually at larger distances. The average response time experienced the linear growth with increasing distance. In total, we showed that the relative depth judgements based on binocular depth cues changed the most at the viewing distances that exceeded 1.0 m, as well as the response time and correctness were affected to varying degrees.

Spatially incoherent light can result from nonlinear processes where a group of photons are emitted in entangled states of spatial modes, which results in an incoherent mixture of constituting spatial modes when the photons are assessed one by one. In this paper we explore a method which uses a tilted lens to probe the orbital angular momentum (OAM) spectrum of such a mixture. We examine the general case where the photons are in mixtures of both different OAM and radial modes, resulting in a 2-dimensional random distribution that creates a more difficult challenge compared to mixtures of OAM only.

The aurora is a beautiful night sky optical phenomenon that is readily seen at high-latitude locations, but with more effort can also be seen and enjoyed at mid-latitude locations. Guidelines for when and where to look are presented, along with a rich array of photographic examples of mid-latitude auroras exhibiting all the usual range of green, red, and purple colors.

Following up on recent work involving investigation of polarization states and Fresnel coefficients (FCs) at an achiral/chiral (ACC) interface, this paper will consider extensions to the case of two interfaces whereby the front end will be ACC and the back end chiral/achiral (CAC) leading to entirely different optical characteristics. Specifically, the work examines the FCs for ACC and CAC, and explores the corresponding changes in the polarization states of the reflected and transmitted light-waves. Additionally, the paper tracks the nature of the transmission through the chiral slab and the emerging fields corresponding to linear as well as arbitrary input polarizations. Keeping in mind that left- and right-circular modes are characteristic of propagation in a chiral material, amplitude and power reflection and transmission characteristics are also examined for the device.

Even though James Clerk Maxwell (1831-1879) is justly famous for his pioneering work on electromagnetism, kinetic theory of gases and thermodynamics (amongst others) he also made fundamental contributions to our understanding of color and of color vision. In particular, he studied additive color mixing by use of the “color top”. From these experiments he determined color equations which quantified how much of each primary color was necessary to create any specific perceived color. He also devised ‘the color box’ to mix colors more precisely and performed psychophysical experiments. From these he went on to show that all colors can be represented in a two-dimensional space, a color triangle. This color triangle is a projection onto a two-dimensional plane, a three-dimensional color space. This research can be considered to be the basis of chromaticity diagrams which are widely used for defining color and color representation. Maxwell, studied color blindness using color matching experiments, with his color box. From these studies he concluded that color blindness was due to the absence of one of the three sets of receptors. He can rightly be called as one of the major contributors to color science and a co-developer of the “Young-Helmholtz” theory of color vision. These aspects are discussed in this paper.

Microglia are central nervous system (CNS) resident macrophages. They play a prominent role in virtually all neurodegenerative and traumatic brain injuries. Visualizing microglia using label-free methodologies will allow a better understanding of how microglia participate in CNS disorders in the absence of perturbations from external fluorescent dyes. Fluorescence Lifetime Imaging (FLIM) of NADH is an effective tool for monitoring cell intrinsic metabolic changes, and can imply metabolic state based on free/bound NADH lifetime quantification. Recently, FLIM based NADH lifetime quantification was used to characterize macrophages and other immune cell types. Here, we use a lifetime-based, label-free method to characterize microglia in vitro. We have found that there is a unique and statistically significant difference (p<0.05, n=5) in the NADH lifetime and free/bound NADH levels in microglia compared to other CNS cell types. Activated (i.e. inflammatory) microglia play a particularly important role in CNS diseases compared to quiescent microglia, and to our knowledge, there are no markers that can uniquely identify activated microglia, and distinguish them from related immune cell types. Thus, we have extended our NADH FLIM-based approach to differentiate quiescent microglia from activated microglia and found that there is a statistically significant difference (p<0.05,n=5) in NADH mean lifetime in the activated cells. Identifying microglia in a mixed population of CNS cells, and distinguishing activated from quiescent microglia will pave the way to better understanding their roles in the healthy and diseased brain.

Domestic and mineralogical waste, as well as the one produced from various industries is thrown mostly in rivers, generating high amounts of heavy metals, becoming a threat for the health for residents in the areas near the river. Established techniques of polluted water can be used in order to determine the heavy metal concentration, however, some of them require high energy consumption and sophisticated equipment. An alternative method is an indirect analysis that consists in the measurement of cadmium levels with the application of the optical study of the flora of the region near the river using UV-VIS basic spectroscopy. This analysis allow us to measure the amount of cadmium (a metal that directly affects health) found in the grown plant. Therefore, the specie Raphanus sativus was used due to its fast growth, and the fact that it requires high amounts of water for its growth. The optical study was performed applying different concentrations of the metal. Such concentrations were kept within then maximum of heavy metals allowed in river water. UV-VIS spectroscopy was performed with light sources of unpolarized light and polarized light, allowing performing the purposed research, determining a trend line between the concentration of cadmium and the intensity of light around 675nm of the spectrum.