UNFILTERED TRAP-BASED PHOTOMETER CALIBRATION

2021 ◽  
Author(s):  
P. Kliment ◽  
M. Šmíd ◽  
G. Porrovecchio
Keyword(s):  
Spectral Properties ◽  
Uncertainty Budget ◽  
Spectral Irradiance ◽  
Light Sources ◽  
White Led ◽  
Spectral Responsivity ◽  
Reflection Effect ◽  
Calibration Methods ◽  
Measurement Uncertainties ◽  
Photometer Calibration

LED-based light sources have replaced massively traditional sources. The metrology traceability chains realised in leading European NMIs utilise the absolutely calibrated broadband radiometers (three-element silicon trap detectors) for calibrating primary photometers. Specific spectral properties of white LED allow to apply the trap detectors directly as new primary photometers. The unfiltered technique (Dӧnsberg at al., 2014) is used and the calibration of spectral irradiance responsivity is needed. We have a long experience in detector-based spectral irradiance responsivity calibrations declared by particular CMC’s published in BIPM KCDB. The aim of this work was to revise the uncertainty budget in order to reduce the measurement uncertainties for specific application of calibration of the trap-based unfiltered primary photometers UPP. The two calibration methods were used to analyse the occasional back-reflection effect of the UPP front aperture. The measurement was performed using our reference spectral responsivity facility in spectral range 350 nm – 900 nm.

scholarly journals Progress in Traceable Nanoscale Capacitance Measurements Using Scanning Microwave Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 820
Author(s):  
François Piquemal ◽  
José Morán-Meza ◽  
Alexandra Delvallée ◽  
Damien Richert ◽  
Khaled Kaja
Keyword(s):  
Uncertainty Budget ◽  
Dielectric Constants ◽  
Electrical Measurements ◽  
Capacitance Measurements ◽  
Uncertainty Sources ◽  
Microwave Microscopy ◽  
Calibration Methods ◽  
Combined Uncertainty ◽  
Calibration Samples ◽  
Scanning Microwave Microscopy

Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a detailed investigation of most possible error sources that affect the uncertainty of capacitance measurements on the reference calibration samples. We establish a comprehensive uncertainty budget leading to a combined uncertainty of 3% in relative value (uncertainty given at one standard deviation) for capacitances ranging from 0.2 fF to 10 fF. This uncertainty level can be achieved even with the use of unshielded probes. We show that the weights of uncertainty sources vary with the values and dimensions of measured capacitances. Our work offers improvements on the classical calibration methods known in SMM and suggests possible new designs of reference standards for capacitance and dielectric traceable measurements. Experimental measurements are supported by numerical calculations of capacitances to reveal further paths for even higher improvements.

Highway Tunnel Lighting Research Based on Mesopic Vision

2011 ◽  
Vol 71-78 ◽  
pp. 4061-4064
Author(s):  
Yong Yang ◽  
Chuan Zheng Zhu ◽  
Lei Wang
Keyword(s):  
Reaction Time ◽  
Design Method ◽  
B Value ◽  
Light Sources ◽  
White Led ◽  
Mesopic Vision ◽  
Highway Tunnel ◽  
Function Fitting ◽  
Sodium Lamp ◽  
High Pressure Sodium Lamp

The white LED and high-pressure sodium lamp (HPS) are used to simulate highway tunnel lighting under different background brightness (abbreviated as B) conditions, from a series of reaction time tests, the result shows that white LED can provide shorter reaction time for observers compared with HPS, further research suggests under the mesopic vision, different kinds of light sources maybe have unlike brightness, although which is identical under the photopic vision. From the luminous spectrum test and mesopic vision spectral luminous efficiency function fitting calculation, the mesopic equivalent brightness can be determined with certain light source and B value. This conclusion would provide a more accurate and lower energy consumption lighting design method for highway tunnel.

The Chromaticity Shift of White-LED Light Sources Passing through Fog

2013 ◽  
Author(s):  
Chiu-Chung Yang ◽  
Chien-Sheng Huang ◽  
Ching-Huang Lin ◽  
Chien-Yue Chen ◽  
Shao-Ciang Gan
Keyword(s):  
Light Sources ◽  
White Led ◽  
Led Light

scholarly journals The GOES-R EUVS model for EUV irradiance variability

2019 ◽  
Vol 9 ◽  
pp. A43 ◽  
Author(s):  
Edward M. B. Thiemann ◽  
Francis G. Eparvier ◽  
Don Woodraska ◽  
Phillip C. Chamberlin ◽  
Janet Machol ◽  
...  
Keyword(s):  
Solar Flare ◽  
Space Weather ◽  
Extreme Ultraviolet ◽  
Spectral Irradiance ◽  
Weather Data ◽  
New Era ◽  
X Ray ◽  
Calibration Methods ◽  
Rapid Dissemination ◽  
Primary Space

The Geostationary Operational Environmental Satellite R (GOES-R) series of four satellites are the next generation NOAA GOES satellites. Once on orbit and commissioned, they are renamed GOES 16–19, making critical terrestrial and space weather measurements through 2035. GOES 16 and 17 are currently on orbit, having been launched in 2016 and 2018, respectively. The GOES-R satellites include the Extreme Ultraviolet (EUV) and X-ray Irradiance Sensors (EXIS) instrument suite, which measures calibrated solar irradiance in eight lines or bands between 25 nm and 285 nm with the Extreme Ultraviolet Sensors (EUVS) instrument. EXIS also includes the X-Ray Sensor (XRS) instrument, which measures solar soft X-ray irradiance at the legacy GOES bands. The EUVS Measurements are used as inputs to the EUVS Model, a solar spectral irradiance model for space weather operations that predicts irradiance in twenty-two 5 nm wide intervals from 5 nm to 115 nm, and one 10 nm wide interval from 117 to 127 nm at 30 s cadence. Once fully operational, NOAA will distribute the EUVS Model irradiance with 1 min latency as a primary space weather data product, ushering in a new era of rapid dissemination and measurement continuity of EUV irradiance spectra. This paper describes the EUVS Model algorithms, data sources, calibration methods and associated uncertainties. Typical model (relative) uncertainties are less than ~5% for variability at time-scales longer than 6 h, and are ~25% for solar flare induced variability. The absolute uncertainties, originating from the instruments used to calibrate the EUVS Model, are ~10%. Examples of model results are presented at both sub-daily and multi-year timescales to demonstrate the model’s capabilities and limitations. Example solar flare irradiances are also modeled.

scholarly journals Supplementary Light Source Affects Growth, Metabolism, and Physiology ofAdenophora triphylla(Thunb.) A.DC. Seedlings

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Ya Liu ◽  
Xiuxia Ren ◽  
Byoung Ryong Jeong
Keyword(s):  
Light Source ◽  
Soluble Sugar ◽  
Antioxidant Systems ◽  
Light Sources ◽  
White Led ◽  
Medicinal Species ◽  
Shoot Ratio ◽  
Practical Strategy ◽  
Supplementary Lighting ◽  
Cancer And Inflammation

Adenophora triphylla(Thunb.) A.DC., a well-known herbaceous medicinal species, has been reported to protect against human obesity, cancer, and inflammation. Supplementary lighting is a practical strategy to improve crop quality, especially at a propagation stage. However, there has been no study available on the optimal supplementary light source for the commercial production ofA. triphyllaseedlings. In this study, plug seedlings were cultivated in a greenhouse for four weeks under an average daily light intensity of 490μmol·m−2·s−1PPFD coming from the sun and a supplemental lighting (16 h per day) at 120μmol·m−2·s−1PPFD provided by high pressure sodium (HPS), metal halide (MH), far-red (FR) light, white LED (red: green: blue = 2:4:3, LED-w), or mixed (red: green: blue = 4:1:4) LED (LED-mix). The results showed that LED-mix, with a higher percentage of red and blue light, substantially promoted seedling growth compared to other treatments by increasing stem diameter, biomass, specific leaf weight, and root to shoot ratio. The LED-mix also promoted accumulation of soluble sugar, starch, and chlorophyll in the tissue and increased contents of total phenols and flavonoids. Moreover, stomata density and pore area per leaf area under the LED-mix were remarkably greater than those under other treatments. Furthermore, the Western blot analysis revealed that the expression of photosynthetic protein, D1, was notably enhanced by the LED-mix as compared with other light sources. In addition, the LED-mix alleviated the oxidative damage of seedlings by improving enzymatic and nonenzymatic antioxidant systems. Collectively, these results suggest that the LED-mix was the optimal supplementary light source for the production of highest qualityA. triphyllaseedlings.

scholarly journals A Correction Method for Measuring Spectral Irradiance of Light Sources Based on Differential Quadrature Method

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Yanfei Wang ◽  
Caihong Dai ◽  
Zhifeng Wu ◽  
Binhua Chen
Keyword(s):  
Experimental Validation ◽  
Differential Quadrature Method ◽  
Correction Method ◽  
Differential Quadrature ◽  
Spectral Irradiance ◽  
Light Sources ◽  
Quadrature Method ◽  
Spectrum Measurement ◽  
True Value ◽  
Narrow Bandwidth

A novel correction method was demonstrated for measuring spectral irradiance of light sources with a narrow bandwidth. Using the correction method based on differential quadrature method, an estimate of the true value was achieved with measured values of seven adjacent points. The formula of this correction method was derived. Numerical simulations and experimental validation of this correction method were also performed, respectively. This correction method could be used in radiometry, photometry, colorimetry, and other spectrometry fields, especially in the spectrum measurement of LED lamp.

Sign in / Sign up

Export Citation Format

Share Document