Implementation of a real-time differential path-length spectrometer system

2005 ◽  
Author(s):  
T. P. Moffitt ◽  
S. A. Prahl
Keyword(s):  
Real Time ◽  
Path Length ◽  
Time Differential ◽  
Spectrometer System

Applications of a Scattering Spectrometer System for Marine Aerosol Measurement

1977 ◽  
Vol 99 (4) ◽  
pp. 533-536
Author(s):  
C. N. Shen ◽  
E. W. Mihalek
Keyword(s):  
Laser Radiation ◽  
Real Time ◽  
Data Reduction ◽  
Coherent Scattering ◽  
Distribution Data ◽  
Marine Aerosol ◽  
Marine Aerosols ◽  
Aerosol Measurement ◽  
Spectrometer System ◽  
Resolution Data

A newly developed instrument has been successfully evaluated and applied to the measurement of marine aerosols. The instrument, known as the Scattering Spectrometer System (SSS), utilizes coherent scattering of laser radiation to size marine aerosols in flight and produce size distribution data in real time. Compared to current methods of using source cascade impactors, the SSS was found superior in terms of resolution, data reduction simplicity, and real-time capability. The application of the SSS at the Naval Air Propulsion Test Center (NAPTC) includes real-time facility diagnostics, control, and calibration. Novel information concerning aerosol separators has also been uncovered using the SSS.

scholarly journals Vertical Measurement Accuracy of Mapping-Grade Global Positioning Systems Receivers in Three Forest Settings

2008 ◽  
Vol 23 (2) ◽  
pp. 83-88 ◽  
Author(s):  
Michael G. Wing ◽  
Aaron Eklund
Keyword(s):  
Real Time ◽  
Measurement Accuracy ◽  
Gps Receiver ◽  
Gps Receivers ◽  
Positioning Systems ◽  
Young Forest ◽  
Open Canopy ◽  
Time Differential ◽  
Closed Canopy ◽  
Differential Corrections

Abstract Elevation or height differences are necessary measurements for many forest operation activities. We rigorously examined the vertical measurement performance of five mapping-grade GPS receivers in three forest settings representing open-sky,young-forest, and closed-canopy conditions. The mapping-grade GPS receivers collected data simultaneously at each of the three forest settings and had different hardware and data-collection configurations, including internal and external antennas, and real-time differential corrections. We evaluated the influence of forest setting and postprocessed differential corrections on all GPS receiver measurements, including those that were collected with real-time differential corrections. We also compared the effect of 1-, 30-, and 60-point averaging intervals on vertical measurement accuracy. We found average vertical accuracies for unprocessed GPS receiver measurements of 0.9, 1.7, and 2.8 m in the open-sky, young-forest, and closed-canopy settings, respectively. The influence of data postprocessing was inconsistent under closed canopy and resulted in average vertical GPS accuracies of 0.2, 0.4, 3.3 m in open-canopy, young-forest, and closed-canopy settings, respectively. Different point averaging intervals did not result in statistically significant differences in vertical accuracies for either unprocessed or postprocessed GPS data.

scholarly journals Toward monochromated sub-nanometer UEM and femtosecond UED

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xi Yang ◽  
Weishi Wan ◽  
Lijun Wu ◽  
Victor Smaluk ◽  
Timur Shaftan ◽  
...  
Keyword(s):  
Electron Beam ◽  
Real Time ◽  
Beam Energy ◽  
Path Length ◽  
Energy Spread ◽  
Single Shot ◽  
Accumulation Mode ◽  
Length Difference ◽  
Path Length Difference ◽  
Energy Dependent

Abstract A preliminary design of a mega-electron-volt (MeV) monochromator with 10−5 energy spread for ultrafast electron diffraction (UED) and ultrafast electron microscopy (UEM) is presented. Such a narrow energy spread is advantageous in both the single shot mode, where the momentum resolution in diffraction is improved, and the accumulation mode, where shot-to-shot energy jitter is reduced. In the single-shot mode, we numerically optimized the monochromator efficiency up to 13% achieving 1.3 million electrons per pulse. In the accumulation mode, to mitigate the efficiency degradation caused by the shot-to-shot energy jitter, an optimized gun phase yields only a mild reduction of the single-shot efficiency, therefore the number of accumulated electrons nearly proportional to the repetition rate. Inspired by the recent work of Qi et al. (Phys Rev Lett 124:134803, 2020), a novel concept of applying reverse bending magnets to adjust the energy-dependent path length difference has been successfully realized in designing a MeV monochromator to achieve the minimum energy-dependent path length difference between cathode and sample. Thanks to the achromat design, the pulse length of the electron bunches and the energy-dependent timing jitter can be greatly reduced to the 10 fs level. The introduction of such a monochromator provides a major step forward, towards constructing a UEM with sub-nm resolution and a UED with ten-femtosecond temporal resolution. The one-to-one mapping between the electron beam parameter and the diffraction peak broadening enables a real-time nondestructive diagnosis of the beam energy spread and divergence. The tunable electric–magnetic monochromator allows the scanning of the electron beam energy with a 10−5 precision, enabling online energy matching for the UEM, on-momentum flux maximizing for the UED and real-time energy measuring for energy-loss spectroscopy. A combination of the monochromator and a downstream chicane enables “two-color” double pulses with femtosecond duration and the tunable delay in the range of 10 to 160 fs, which can potentially provide an unprecedented femtosecond time resolution for time resolved UED.

scholarly journals Lift: An Educational Interactive Stochastic Ray Tracing Framework with AI-Accelerated Denoiser

2021 ◽  
Author(s):  
Gonçalo Soares ◽  
João Madeiras Pereira
Keyword(s):  
Computer Graphics ◽  
Real Time ◽  
Ray Tracing ◽  
Path Length ◽  
Image Resolution ◽  
Light Transport ◽  
Lighting Conditions ◽  
Educational Framework ◽  
Physically Based ◽  
Physically Based Rendering

Real-time physically based rendering has long been looked at as the holy grail in Computer Graphics. With the introduction of Nvidia RTX-enabled GPUs family, light transport simulations under real-time constraint started to look like a reality. This paper presents Lift, an educational framework written in C++ that explores the RTX hardware pipeline by using the low-level Vulkan API and its Ray Tracing extension, recently made available by Khronos Group. Furthermore, to accomplish low variance rendered images, we integrated the AI-based denoiser available from the Nvidia ́s OptiX framework. Lift’s development arose primarily in the context of the graduate 3D Programming course taught at Instituto Superior Técnico and Master Theses focused on Real-Time Ray Trac- ing and provides the foundations for laboratory assignments and projects development. The platform aims to make easier students to learn and to develop, by programming the shaders of the RT pipeline, their physically-based ren- dering approaches and to compare them with the built-in progressive unidirectional and bidirectional path tracers. The GUI allows a user to specify camera settings and navigation speed, to select the input scene as well as the rendering method, to define the number of samples per pixel and the path length as well as to denoise the generated image either every frame or just the final frame. Statistics related with the timings, image resolution and total number of accumulated samples are provided too. Such platform will teach that nowadays physically-accurate images can be rendered in real-time under different lighting conditions and how well a denoiser can reconstruct images rendered with just one sample per pixel.

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