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Final accepted manuscripts of parts 4 and 5 from Roadmap on Structured Light, authored by Masud Mansuripur, College of Optical Sciences, The University of Arizona.

In addition to intensity and colour, the retinas of many invertebrates are capable of light detection based on its linear polarization (Wehner, 1983). The detection mechanism permitting this capability is based on the intrinsic dichroism of chromophores oriented along rhabdomeric microvilli. In vertebrates, however, except for anchovies (Fineran & Nicol, 1978), such axial dichroism is absent rendering vertebrate outer segments insensitive to the polarization of axially incident light. Nonetheless, there is evidence for polarization sensitivity in a few species of fish (goldfish, rainbow trout and sunfish). But the findings for goldfish and rainbow trout appear contradictory to those for the green sunfish (Parkyn & Hawryshyn, 1993), and a detection mechanism that could explain polarization sensitivity for lower vertebrates in general is unknown. This thesis was undertaken to try to solve some of these unknowns by investigating: 1) the neural polarization signal, at the level of the optic nerve, in fish species from four groups with distinct retinal cone mosaics (rainbow trout, green and pumpkinseed sunfishes, common white sucker, and northern anchovy), 2) the ultrastructure and light transmission properties of different cone types (single, twin and double cones) , and 3) the characteristics of the underwater polarized light field that could permit the observed laboratory behaviours in nature. I measured compound action potential (CAP) responses from the optic nerve of live anaesthetized fish to evaluate the possibility that a fish could detect the orientation of the electric field of linearly polarized light (mathematically-designated as the E-vector) . Results from these studies showed that rainbow trout and the northern anchovy were polarization-sensitive, but both species of sunfish and the common white sucker were not. In addition, CAP measurements conducted with rainbow trout exposed to light stimuli of varying polarization percentages showed, in conjunction with underwater polarized light measurements, that the use of polarized light in this animal was restricted to crepuscular time periods. To try to understand why some fish species were polarization-sensitive and others were not, I carried out microscopy studies of retinal cones. Optical measurements of transmitted polarized light through the length of cones showed: 1) small cone birefringence (retardance < 2nm) , and 2) preferential transmission of polarized light that was parallel to the partition dividing twin and double cones (single cones were isotropic). In addition, histological studies showed that the partition in trout double cones was tilted with respect to the vertical while that of twin cones in sunfish was straight. We envisioned that the higher index of refraction of the partition with respect to the surrounding cell cytoplasm would make it behave as a mirror, reflecting and polarizing incident light. A large optical model was built to test this idea consisting of two photodiodes evenly spaced on either side of a cover-slip "partition" upon which physiologically-relevant illumination was incident. Measurements using this model and theoretical calculations with refractive indices approaching those expected for double cone partitions and cytoplasm (Sidman, 1957) were consistent with the optical results obtained in situ. Thus the tilt in the partition of trout double cones relayed different amounts of light to each outer segment depending on the polarization of incident light, whereas a straight partition, as in sunfish, did not. Comparison of signals from orthogonally-arranged double cones and single cones in the centro-temporal retina of trout thus became the basis for a model neural network that could reproduce all the polarization sensitivity results known to date. To support the idea that an ordered (e.g. orthogonal) arrangement of double cones was a necessity for polarization detection, I showed that the common white sucker, a fish with double cones, had these arranged randomly in the centro-temporal retina (hence its lack of polarization sensitivity). Finally, the northern anchovy exhibited unique cones with lipid lamellae parallel to their lengths, forming a dichroic system for polarization detection somewhat analogous to that of cephalopods and decapod crustaceans. / Graduate

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QC 351 A7 no. 74 / Measurements of the scattering of reflected light as a function of angular separation from the specular direction were made on aluminum-coated flat glass samples with surface roughnesses ranging from 1.0 nm to 70 nm rms deviation from the mean surface. Small -angle scatter (measured between 0.33° and 1° away from the specular direction) was investigated using light that had passed through a narrow slit; a measure of the scattering magnitude was provided by comparison of the far -field diffraction patterns produced by the slit, reflected from the samples and without the samples in place. The slit used to produce the diffraction patterns was optically processed to be smooth enough so that without the sample in place the minima of the diffraction pattern would be well defined and of lower magnitude than the scattered flux produced when the samples were in place. By considering the effects of the scanning aperture, it was determined that the measured magnitude of the minima agreed with those predicted by the use of Kirchhoff theory to within a factor of three. Comparison of small-and large-angle scatter measurements made on the same set of samples indicated that a transition region between the two types of scatter may exist in the region of 1° to 5° away from the specular direction. Because separate instruments were used for the small-and large-angle measurements, the results are expressed in terms independent of the measuring instrument's geometry. The measured results were compared to a theory in which the choice of the scatter function, and by implication the autocorrelation function, could be arbitrary. This comparison revealed that the choice of the hyperbolic secant function, rather than a Gaussian function, provided a good fit to the small-angle data. By fitting a curve to the small -angle data, it was possible to estimate the autocorrelation length of the surface roughness as well as the peak value of the scattering profile. The scatter measurements for the smoothest sample ranged from approximately 3 X 10' per µsr near the specular direction to 10 -13 per µsr at wide angles. For the roughest sample, the range was from 3 X 10-4 per µsr to 10-10 per µsr.

Approved for public release; distribution is unlimited. / SeaWiFS data converted to optical properties of the ocean in the form of vertical and horizontal underwater visibility products are compared to in-water diver and optical instrument measurements during the Model Diver Visibility (MoDiV) experiment. Results were collected from 19 to 21 August in the Mississippi Bight region of the United States. The SeaWiFS satellite data was processed with the Automated Processing System (APS), developed by the Naval Research Laboratory (Code 7333). APS converted radiance values into specific parameters studied: the beam attenuation coefficient, the diffuse attenuation coefficient, vertical visibility and horizontal visibility. These values were compared to the AC-9instrument, a-Beta instrument, Secchi disk and the observed visibilities from the divers. The results indicated that the beam attenuation coefficient and the diffuse attenuation coefficient are underestimated as compared to the in-situ measurements. These values then overestimate the vertical and horizontal visibility as compared to the Secchi disk and diver sightings. The visibility products from SeaWiFS should be used on an experimental basis for Naval Operational Planning. It is recommended that the use of in-water diver reports noting variability of SeaWiFS visibility product estimates are necessary for validation and offers feedback to the research and development field for algorithm improvement. / Lieutenant, United States Navy

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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, May 3, 2016. / Spatial modes of light hold the possibility to power the next leap in classical and quantum communications. They provide the ability to pack more information into light, even into single photons themselves, while increasing the level of information security. In this quest, spatial modes carrying orbital angular momentum (OAM) have come under the spotlight due to their discrete in nite dimensional Hilbert space allowing, in theory, for an in nite amount of information to be carried by a photon. Here we study, theoretically and experimentally, spatial modes of two avours: scalar and vector modes. the dichotomy between the two avours is in their polarisation characteristics: scalar modes have spatially homogeneous polarisation elds, while vector modes do not. One facet of our work focusses on scalar mode carrying OAM; using digital holographic methods, we demonstrate the techniques used to tailor and analyse scalar optical elds. We discuss principles of generation and detection for scalar modes based on manipulations of the dynamic phase of light with spatial light modulators. We apply these techniques to characterise free-space and optical bre links, and demonstrate an increase in bandwidth with the additional modal channels. In the other facet of our work, we study vector vortex modes. A particular property exhibited by these modes is the non-separability of their degrees of freedom, a property traditionally associated with entangled quantum states. This raises the question: could quantum entangled systems be modelled with bright sources of vector vortex modes? We answer this question by applying vector vortex modes to the study of quantum transport of entangled states. We borrow techniques from quantum mechanics to evaluate the degree of non-separability of vector vortex modes, using the concurrence as our measure. By determining the evolution of the concurrence, and therefore the entanglement, of vector vortex modes in bres and free-space turbulent channels, we show that indeed, bright classical sources can be used to model the evolution of entangled quantum states in these channels. / TG2017

An Zhong. / "November 30, 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. [167]-173). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.