Search results for "Spectrograph"
showing 10 items of 33 documents
Laser-induced plasma spectroscopy in near vacuum ultraviolet using ordinary spectrograph and ICCD
2002
An experimental setup to measure laser-induced plasma emission spectra with an ordinary Czerny-Turner spectrograph and intensified charge-coupled device in the near vacuum ultraviolet down to 130 nm is described. Spectra of bromine, chlorine and iodine were recorded to demonstrate the performance of the setup.
iLocater: a diffraction-limited Doppler spectrometer for the Large Binocular Telescope
2016
We are developing a stable and precise spectrograph for the Large Binocular Telescope (LBT) named "iLocater." The instrument comprises three principal components: a cross-dispersed echelle spectrograph that operates in the YJ-bands (0.97-1.30 microns), a fiber-injection acquisition camera system, and a wavelength calibration unit. iLocater will deliver high spectral resolution (R~150,000-240,000) measurements that permit novel studies of stellar and substellar objects in the solar neighborhood including extrasolar planets. Unlike previous planet-finding instruments, which are seeing-limited, iLocater operates at the diffraction limit and uses single mode fibers to eliminate the effects of m…
Microreflectivity studies of wavelength control in oxidised AlGaAs microcavities
2003
Wet oxidation of GaAs/AlGaAs structures is an important technique in the processing of advanced devices such as vertical cavity surface emitting lasers (VCSELs). In one VCSEL application, the low-index and electrically-insulating AlxOy layers have been used to obtain high-reflectivity and broad bandwidth distributed Bragg reflector mirrors (DBRs). A further recent development has shown that combined lateral–vertical oxidation of intracavity AlGaAs layers can be used to tune the resonant wavelength of a semiconductor microcavity. The slow oxidation rate limits the lateral scale of practical wet oxidation to mesas structures of 50–100 μm in width. Therefore post-processing assessment of spect…
Unveiling the nature of six HMXBs through IR spectroscopy
2008
The International Gamma-Ray Astrophyiscs Laboratory (INTEGRAL) is discovering a large number of new hard X-ray sources, many of them being HMXBs. The identification and spectral characterization of their optical/infrared counterparts is a necessary step to undertake detailed study of these systems. In particular, the determination of the spectral type is crucial in the case of the new class of Supergiant Fast X-ray Transients (SFXTs), which show X-ray properties common to other objects. We used the ESO/NTT SofI spectrograph to observe proposed IR counterparts to HMXBs, obtaining Ks medium resolution spectra (R = 1320) with a S/N >= 100. We classified them through comparison with publishe…
In-scene atmospheric correction of hyperspectral thermal infrared images with nadir, horizontal, and oblique view angles
2012
Atmospheric corrections for hyperspectral thermal images acquired with nadir, horizontal, and oblique views have typically relied on atmospheric modelling software, such as Moderate Resolution Atmospheric Transmission MODTRAN, to estimate atmospheric parameters. Data-only corrections, which require only information from the scene, are more versatile and less labour intensive, but do not yet seem to have been applied to horizontal and oblique views. Here, we apply, and modify where necessary, one published data-only algorithm in-scene atmospheric correction ISAC to nadir, horizontal, and slanted views The Aerospace Corporation's Spatially Enhanced Broadband Array Spectrograph System SEBASS a…
Spectro-Temporal Weighting of Loudness
2012
Real-world sounds like speech or traffic noise typically exhibit spectro-temporal variability because the energy in different spectral regions evolves differently as a sound unfolds in time. However, it is currently not well understood how the energy in different spectral and temporal portions contributes to loudness. This study investigated how listeners weight different temporal and spectral components of a sound when judging its overall loudness. Spectral weights were measured for the combination of three loudness-matched narrowband noises with different center frequencies. To measure temporal weights, 1,020-ms stimuli were presented, which randomly changed in level every 100 ms. Tempora…
Cry characteristics of 172 healthy 1-to 7-day-old infants.
2002
A total of 1,836 cry signals from 172 healthy babies, 1–7 days old, were analysed with sound spectrography. The mean values for the 8–15 cries from each infant were calculated and used for the statistical analyses. The mean duration of the cry signals was 1.4 ± 0.6 s. The mean fundamental frequency was 496 ± 95 cps (Hz). Fifty percent of the mean fundamental frequencies in the 8–15 cries analysed from each baby varied between 450 and 520 Hz. Of the children, 93% had cries with a mean fundamental frequency below 600 Hz. The mean value of the highest point of the fundamental frequency was 583 ± 151 Hz and of the lowest point 398 ± 75 Hz. The melody type had mainly a rising-falling contour, th…
Multisensory integration of drumming actions: musical expertise affects perceived audiovisual asynchrony
2009
We investigated the effect of musical expertise on sensitivity to asynchrony for drumming point-light displays, which varied in their physical characteristics (Experiment 1) or in their degree of audiovisual congruency (Experiment 2). In Experiment 1, 21 repetitions of three tempos x three accents x nine audiovisual delays were presented to four jazz drummers and four novices. In Experiment 2, ten repetitions of two audiovisual incongruency conditions x nine audiovisual delays were presented to 13 drummers and 13 novices. Participants gave forced-choice judgments of audiovisual synchrony. The results of Experiment 1 show an enhancement in experts' ability to detect asynchrony, especially fo…
Laser-induced plasma spectroscopy to as low as 130 nm when a gas-purged spectrograph and ICCD detection are used.
2003
An experimental setup is described for measuring laser-induced plasma emission spectra in the near vacuum UV with a Czerny-Turner spectrograph and intensified charge-coupled device under atmospheric pressure. With a simple gas-purge technique, emission lines down to 130 nm could be recorded. The strongest emission lines of bromine, chlorine, and iodine in the near vacuum UV are easily detected.
A review of the development of portable laser induced breakdown spectroscopy and its applications
2014
Abstract In this review, we present person-transportable laser induced breakdown spectroscopy (LIBS) devices that have previously been developed and reported in the literature as well as their applications. They are compared with X-ray fluorescent (XRF) devices, which represent their strongest competition. Although LIBS devices have advantages over XRF devices, such as sensitivity to the light elements, high spatial resolution and the possibility to distinguish between different layers of the sample, there are also disadvantages and both are discussed here. Furthermore, the essential portable LIBS instrumentation (laser, spectrograph and detector) is presented, and published results related…