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A dual-beacon Hartmann Turbulence Sensor (HTS) was used to estimate atmospheric turbulence profiles along a 1.8 km long slant path. This HTS uses a 16“ telescope and has 700 active subapertures. Its camera can take frames as fast as 8 kHz. The laser beacons were placed near the top of a 12 story high tower while the HTS telescope was located in a field 1848 meters away. While the field where the HTS was located was mostly flat for the first few hundred meters in the direction of the tower the ground then sloped up gradually gaining 60 meters by the time the path reached the tower. The terrain beneath the beam path was quite variegated with grassy fields, roads, forested areas and buildings giving the potential for changing turbulence along the path. The experiment was also conducted at different times of day and night and in different weather conditions to further vary the turbulence encountered. The techniques used to profile turbulence with this dual-beacon HTS will be reviewed and the results from this experimental campaign will be presented. Several other turbulence measurement systems were operating at locations near and along this path providing some other measurements for comparison.

Atmospheric turbulence profiles were estimated for a horizontal path based upon measurements made with a dual beacon Hartmann Turbulence Sensor (HTS) using simulation derived weighting functions. These results are compared to estimates made using a weighting functions computed from theory. These results are further compared to anemometer and scintillometer based turbulence estimates for the same path. The previously published theoretical weighting functions for this situation are based upon some presumptions of geometric optics and thus ignore both diffraction and scintillation effects. All of these weighting functions quantify how turbulence at different distances along the path contributes to the expected value of the differential tilt variances measured by the HTS. In the experiment, the HTS used a 16” Meade telescope with 700 subapertures along a 511 m path roughly 2 meters above the ground. Two HeNe lasers separated by 11 cm served as beacons, each was beam expanded to well overfill the telescope aperture. The same situation was simulated with wave optics. To create simulated weighting functions, a single (usually weak) random turbulence screen was inserted at a single plane perpendicularly to the propagation path. Light from one beacon was then numerically propagated to the telescope aperture where the tilts were computed over each subaperture and saved. This propagation was then carried out for the second beacon. This random phase screen was then inserted at a different propagation plane and this procedure was repeated. When all the desired positions along the beam path had been sampled a new random phase screen was generated and this whole procedure was repeated hundreds of times. The desired weighting functions were then generated by computing the differential tilt variance between the beacons and all pairs of horizontally separated subapertures for each path position. All equivalent subaperture separations within each range bin were then averaged together to produce weighting functions which depend on path position and subaperture separation distance. The weighting functions produced in this fashion showed some differences from the theoretical ones. They were a little weaker far from the telescope, and they showed a somewhat broadened notch where the beacons overlapped compared to the theoretical ones. The effect of these differences on the resulting turbulence profile estimates will be discussed.

Turbulence distribution along a path is estimated from differential motion of pairs of LEDs on a target board, sensed by a single camera and between two cameras. The method is compared to point measurements from sonic anemometers.

We report long-range trapping of vanadium dioxide (VO2) and vanadium oxyhydroxide (H2V3O8) nanowires at a distance as large as 50 mum outside the laser spot using plasmonic tweezers and controlled rotation of the nanowires by combining trapping with microfluidic drag force. The plasmonic tweezers are built upon a self-assembled gold nanoparticle array platform. In addition to the long-range trapping and rotation capability, the required optical intensity for the plasmonic tweezers to initiate trapping is much lower (8 muW/mum2) than that required by conventional optical tweezers for similar nanowires. We also investigate possible mechanisms for the unique long-range trapping of nanowires through performing control experiments.

We propose a compact and low-cost design for a variable wave plate using tunable form-birefringent grating structures in polydimethylsiloxane (PDMS). The described device operates through PDMS deformation via electrostatically actuated transparent electrodes. The optical and mechanical properties of tunable form-birefringent structures are modeled using birefringence, rigorous coupled-wave analysis, and simple structural mechanics theory. The device is fabricated by a form of soft nanoimprint lithography. The optical properties are characterized for different structure geometries. Operating principles were verified through testing of the completed device. The experimental results and theoretical study show that an irregular grating structure performs better than a periodic subwavelength structure. [2007-0303].

This paper reports the phase behavior of a multi-component borosilicate glass melt with 0–3 mass% Cr 2 O 3 at 800–1500 °C in equilibrium with air. Both upper and lower liquidus temperatures were observed. When the temperature was between the upper and lower liquidus temperatures, eskolaite (Cr 2 O 3 ) formed in melts with >2 mass% Cr 2 O 3 . Below the lower liquidus temperature, a dispersed chromate phase appeared in the melt that eventually became macroscopically segregated. The chemical durability of the glasses was virtually unaffected by chromium concentration. The particular glass studied was prototypic for vitrifying high-Cr high-level radioactive wastes stored in underground tanks at the Hanford site. The results suggest a significant potential cost benefit for Hanford tank waste cleanup through increased waste solubility in glass.

Avalanche concentration, a rapid, long-range accumulation of particles around a laser spot in a liquid sample, is demonstrated and characterized for various nanoparticles (NPs). The effect is driven by a convective flow in the sample, caused by efficient heating of NPs with high absorption efficiencies. Several types of concentration behavior were observed and characterized. Control of optical power and initial particle density was found to be effective in determining the assembly process. VO(2) nanowires, carbon nanotube (CNT), and quantum dot (QD) electrode gap bridges were assembled with a variety of sizes and geometries to show the utility of the method for nano-assembly. Bridges were assembled from as many as thousands to as few as one NP and were found to form solid electrical contact between the electrodes, as verified by measuring the current--voltage (I-V) characteristic.

We propose and demonstrate a dark-field imaging technique capable of automated identification of individual bacteria. An 87-channel multispectral system capable of angular and spectral resolution was used to measure the scattering spectrum of various bacteria in culture smears. Spectra were compared between various species and between various preparations of the same species. A 15-channel system was then used to prove the viability of bacterial identification with a relatively simple microscope system. A simple classifier was able to identify four of six bacterial species with greater than 90% accuracy in bacteria-by-bacteria testing.