Search results for " Optics"

Howard–Dolman stereovision test at different opponent colour stimuli

2011

The purpose of this study was to investigate visual depth perception of real physical colour stimuli with red-green and blue-yellow opponency. We modified the Howard–Dolman stereotest where subjects should determine the closer of two bars emitting the light of definite colour placed in front of a CRT monitor served as colour background. Two-alternative forced-choice paradigms were used to determine depth perception threshold values. Thresholds close to 5–10 arcsec for luminance and colour contrast stimuli were revealed both for red-green and blue-yellow stimuli. A term, stereosensitivity – a reciprocal magnitude of the stereothreshold – was introduced to separately analyse luminance and col…

Volcanic CO_2 detection with a DFM/OPA-based lidar

2015

The DFM/OPA-based lidar BILLI was used to investigate the volcanic plume released by the hydrothermal vent of Pisciarelli, in the Campi Flegrei volcano. BILLI remotely measured CO2 concentrations in cross-sections of the nearvent plume using the differential absorption technique. To our knowledge, this is the first example of lidar-based measurement of volcanic CO2 . The spatial resolution was 1.5 m and the temporal resolution 20 s. © 2015 Optical Society of America.

Fast tracking of wind speed with a differential absorption LiDAR system: First results of an experimental campaign at Stromboli volcano

2017

Carbon dioxide ( CO 2 ) is considered a precursor gas of volcanic eruptions by volcanologists. Monitoring the anomalous release of this parameter, we can retrieve useful information for the mitigation of volcanic hazards, such as for air traffic security. From a dataset collected during the Stromboli volcano field campaign, an assessment of the wind speed, in both horizontal and vertical paths, performing a fast tracking of this parameter was retrieved. This was determined with a newly designed shot-per-shot differential absorption LiDAR system operated in the near-infrared spectral region due to the simultaneous reconstruction of CO 2 concentrations and wind speeds, using the same sample o…

Corrigendum: A new archive of large volcanic events over the past millennium derived from reconstructed summer temperatures (2017 Environ. Res. Lett.…

2017

First-time lidar measurement of water vapor flux in a volcanic plume

2011

Abstract The CO 2 laser-based lidar ATLAS has been used to study the Stromboli volcano plume. ATLAS measured water vapor concentration in cross-sections of the plume and wind speed at the crater. Water vapor concentration and wind speed were retrieved by differential absorption lidar and correlation technique, respectively. Lidar returns were obtained up to a range of 3 km. The spatial resolution was 15 m and the temporal resolution was 20 s. By combining these measurements, the water vapor flux in the Stromboli volcano plume was found. To our knowledge, it is the first time that lidar retrieves water vapor concentrations in a volcanic plume.

Glyphosate Sensor Based on Nanostructured Water-Gated CuO Field-Effect Transistor

2022

This research presents a comparative analysis of water-gated thin film transistors based on a copper oxide (CuO) semiconductor in the form of a smooth film and a nanostructured surface. A smooth CuO film was deposited through reactive magnetron sputtering followed by annealing in atmosphere at a temperature of 280 (Formula presented.) C. Copper oxide nanostructures were obtained by hydrothermal synthesis on a preliminary magnetron sputtered 2 nm thick CuO precursor followed by annealing at 280 (Formula presented.) C. An X-ray diffraction (XRD) analysis of the samples revealed the presence of a tenorite (CuO) phase with a predominant orientation of (002). Scanning electron microscopy (SEM) a…

Epistemic network analyses of economics students' graph understanding. An eye-tracking study

2020

Learning to solve graph tasks is one of the key prerequisites of acquiring domain-specific knowledge in most study domains. Analyses of graph understanding often use eye-tracking and focus on analyzing how much time students spend gazing at particular areas of a graph&mdash

Transient guided-mode resonance metasurfaces with phase-transition materials

2023

We investigate transient, photo-thermally induced metasurface effects in a planar thin-film multilayer based on a phase-transition material. Illumination of a properly designed multilayer with two obliquely incident and phase-coherent pulsed pumps induces a transient and reversible temperature pattern in the phase-transition layer. The deep periodic modulation of the refractive index, caused by the interfering pumps, produces a transient Fano-like spectral feature associated with a guided-mode resonance. A coupled opto-thermal model is employed to analyze the temporal dynamics of the transient metasurface and to evaluate its speed and modulation capabilities. Using near-infrared pump pulses…

The influence of the quantum nature of nuclei in high harmonic generation from H$_2^+$-like molecular ions

2013

We study the full quantum dynamics of a simple molecular ion driven by an intense laser field. In particular we show that the quantum nature of the nuclear dynamics affects the emitted high harmonic generation (HHG) spectra, strongly reshaping the plateau region. In fact, it is evident that the characteristic flat trend is transformed into a descending trend, with the lower harmonics being two orders of magnitude more intense than the higher harmonics. We show that this effect is more pronounced in the lighter isotopic species of H$_2^+$ molecular ions and we also demonstrate that in this case the contribution to HHG from the antibonding electronic energetic surface is of the same order of …

Anomalous electrical parameters improvement in Ruthenium DSSC

2018

. In this work, we present a series of measurements carried out on Ruthenium-based Dye Sensitized Solar Cells (DSSCs) after the application of different external electrical field values. Such measurements have been performed both in the dark and by illuminating the sample with sunlight emitted by a solar simulator (AM1.5G spectrum with a power irradiance of 1000 W/m2). Our results demonstrate that the initial electrical bias field modifies in both cases the behavior of the cell in terms of an anomalous improvement of the main electrical parameters.