A5091153500- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- GaN-based semiconductor devices and materials
- Advanced Sensor Technologies Research
- Scientific Measurement and Uncertainty Evaluation
- Advanced Measurement and Detection Methods
- Semiconductor Quantum Structures and Devices
- Photopolymerization techniques and applications
- Spectroscopy and Laser Applications
- Semiconductor Lasers and Optical Devices
- Impact of Light on Environment and Health
- Color Science and Applications
- Atmospheric and Environmental Gas Dynamics
- Infrared Target Detection Methodologies
- Engineering Applied Research
- Additive Manufacturing and 3D Printing Technologies
- Sensor Technology and Measurement Systems
- Nanowire Synthesis and Applications
- Atmospheric aerosols and clouds
- Manufacturing Process and Optimization
- Ga2O3 and related materials
- Optical and Acousto-Optic Technologies
- Spectroscopy and Chemometric Analyses
- Interactive and Immersive Displays
- Optical Imaging and Spectroscopy Techniques
National Institute of Standards and Technology
2015-2024
Government of the United States of America
2024
National Institute of Standards
2005-2022
United States Department of Commerce
2022
Physical Measurement Laboratory
2021
A simple, practical method has been developed to correct a spectroradiometer's response for measurement errors arising from the instrument's spectral stray light. By characterizing set of monochromatic laser sources that cover range, one obtains light signal distribution matrix quantifies magnitude within instrument. use these data, correction is derived and can be corrected with simple multiplication. The implemented validated commercial CCD-array spectrograph. Spectral after was applied...
Numerous studies have demonstrated that SARS-CoV-2 can be inactivated by ultraviolet (UV) radiation. However, there are few data available on the relative efficacy of different wavelengths UV radiation and visible light, which complicates assessments decontamination interventions. The present study evaluated effects monochromatic at 16 from 222 nm through 488 in liquid aliquots dried droplets water simulated saliva. were used to generate a set action spectra quantify susceptibility genome...
We report a bright fin light-emitting diode pixel that with increasing electrical current flux, can switch to laser.
An algorithm is presented that corrects a multichannel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of evaluated based on series validation measurements sources with different spectral distributions. This first application scattered-light correction to hyperspectral spectrograph. algorithm, characterization using tunable laser system, can be extended correct finite point-spread response in imaging systems.
Recent developments at the National Institute of Standards and Technology's facility for Spectral Irradiance Radiance responsivity Calibrations using Uniform Sources (SIRCUS) are presented. The is predicated on use broadly tunable narrow-band lasers as light sources in two key radiometric calibration applications. In first application, used to calibrate spectral power responsivities primary standard detectors against an absolute cryogenic radiometer (ACR). second function radiance irradiance...
Improperly imaged, or scattered, optical radiation within an instrument is difficult to properly characterize and often the dominant residual source of measurement error. Scattered light can originate from spectral components a "point" spatial elements extended source. The scattered are commonly referred as stray be described by instrument's line spread function (SLSF) point (PSF), respectively. In this paper, we present approaches that response describe matrices have been developed correct...
Continuous-wave (CW) tunable lasers have been used for detector calibrations, especially spectral irradiance and radiance responsivity, many years at the National Institute of Standards Technology (NIST) other national metrology institutes. These CW lasers, however, are expensive difficult to automate. To address these issues, we developed a new method responsivity calibrations using relatively low cost, fully automated kilohertz pulsed optical parametric oscillators (OPOs). The is based on...
Various new light-emitting diodes (LEDs) including white LEDs are being actively developed for solid-state lighting and many other applications, there great needs accurate measurement of various optical quantities LEDs. Traditional lamp standards do not suffice specific The National Institute Standards Technology (NIST) has recently established calibration services photometric (luminous intensity luminous flux) LEDs, but the expanding. This paper covers current capabilities NIST provides...
Sub-micron-size light sources are currently extremely dim, achieving nanowatt output powers due to the current density and temperature droop. Recently, we reported a droop-free fin light-emitting diode (LED) pixel that at high densities becomes laser with record power in microwatt range. Here, show scalable method for selectively metallizing fins via their nonpolar side facet allows electrical injection sub-200 nm wide n-ZnO on p-GaN least 0.8 μm2 active area. Electrically addressable LEDs...
New commercial-off-the-shelf imaging spectrometers promise the combination of high spatial and spectral resolution needed to retrieve solar induced fluorescence (SIF). Imaging at multiple wavelengths for individual plants even leaves from low-altitude airborne or ground-based platforms has applications in agriculture carbon-cycle science. Data these instruments could provide insight into status photosynthetic apparatus scales space time not observable with tools based on gas exchange,...
The Moderate Resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System (EOS) Aqua platform has 9 spectral bands with center wavelengths from 412nm to 870nm that are used produce standard ocean color data products. Ocean scenes usually contain high contrast due presence of bright clouds over dark water. MODIS been characterized for straylight effects prelaunch. In this paper, we derive Point-Spread Functions based prelaunch Near-Field Response measurements. We use...
We describe the characterization of a group NIST spectral irradiance lamps at longer distances and larger angles than are typically issued by NIST. The irradiances from FEL were measured 50 cm to 150 8 different using cosine-corrected filter radiometer determine if adhere inverse square law. Using radiometer, spatial uniformities also mapped over 20 area 135 cm, 143 151 cm. In gonio-spectroradiometer facility, selected for angular dependences distance 123 spectrograph which measures 300 nm...
Alternating-current (AC) driven high-power light-emitting diodes (LEDs) have become available and introduced into solid-state lighting (SSL) products. AC LEDs operate directly from a mains supply with no need of drivers, thus can simplify the design SSL product potentially increase product's reliability lifetime. Similar to direct-current (DC) optical electrical properties are strongly dependent on LED junction temperature. In addition, instantaneous temperature an changes rapidly within...
Previously, we showed within a sub-micron fin shape heterojunction, as current density increases, the non-radiative Auger recombination saturates mediated by extension of depletion region into fin, resulting in droop-free behavior. Here, investigate dependence aspect ratio (height to width ratio) on external quantum efficiency (EQE) single n-AlGaN fin/p-GaN heterojunctions. Fins are arranged an array format varying from 3000 200 nm. In this architecture, n-metal contact is interfaced with...