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Transcript of “Traceability for surface spectral solar ultraviolet ... · PDF file“Traceability...
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EMRP ENV03
“Traceability for surface spectral solar
ultraviolet radiation”
Julian Gröbner
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center,
Davos Switzerland
The European Metrology Research Programme (EMRP) is jointly funded by the EMRP
participating countries within EURAMET and the European Union.
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Duration: August 2011 to July 2014
Total Budget: 3.9 M€
Project coordinator : Julian Gröbner Davos, Switzerland
8 Partners from European Metrology Institutes and 2 from Industry
4 Researcher Excellence Grants (REG) from Universities & Health Institute
6 Collaborators
Project Overview
http://projects.pmodwrc.ch/env03/
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Motivation
Challenges
Large natural variability
Dynamic range >105
Radiation levels as low as µW m-2nm-1
Wavelength uncertainty <0.02% (0.05 nm)
500
10
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Project Objectives
• Enhance the reliability of spectral solar UV radiation measured at the Earth
surface
• Improved SI traceability, improved methodologies, improved devices
• Uncertainties better than 2% in the wavelength region 300 nm – 400 nm
(current state of the art is 5%)
• Develop techniques and devices for using cost-effective array-
spectroradiometers for solar UV measurements
Primary Irradiance
Standard
Transfer Standard Reference
Spectroradiometer
End-User Devices Calibrated UV Network
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WP WP Name WP Leader Active JRP Partners
WP1 Spectral Irradiance Traceability
Saulius Nevas PTB, METAS, SFI Davos, VSL, Kipp
WP2 Array Spectroradiometer Characterisation
Peter Blattner METAS, Aalto, LNE, PTB, PMOD/WRC, VSL, REG(IMU)
WP3 Improvement of Reference Spectroradiometers
Marek Šmíd CMI, INRIM, PTB, PMOD/WRC
WP4 New Technologies Petri Kärhä Aalto, CMI, METAS, INRIM, LNE, PTB, PMOD/WRC, CMS, Kipp, REG(IMU)
WP5 Impact Julian Gröbner PMOD/WRC, All
WP6 Management Julian Gröbner PMOD/WRC, All
Project Structure
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Devices:
• UV LED-based transfer standards (WP 1)
• Transfer standard based on Laser Driven Light Source LDLS (WP 1)
•Wavelength scale characterisation devices (WP2)
•Solid state detectors to replace PMTs (WP 3)
• Modified Fourier-Transform Spectrometer (WP 3)
• UV hyperspectral imaging camera (sky radiance) (WP 4)
• Global input optics (improved diffuser design) (WP 4)
• Two array spectroradiometers optimized for UV (WP 4)
Project Outputs
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Software: Tool to determine the uncertainty budget for array spectroradiometers (WP 2)
Tool for bandwidth and wavelength homogenisation and stray light correction (WP 2)
Knowledge Transfer: Guidelines (WP 2)
Conference Presentations (WP 5)
Technical Workshops (WP 5)
Refereed publications (WP 5)
Intercomparison campaign at Davos
Project Outputs
Takes place now!!
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Goal: Shorten the traceability chain of solar UV measurements to SI units and reduce transfer uncertainties (U = 1 - 2%)
1 Detector-based traceability chain using an absolute radiometer and tunable UV laser facility (PTB)
•Tuneable laser source 280 – 400 nm
• Traceability to the primary standard cryogenic radiometer via a trap detector
2 Development of stable, portable and robust reference sources based on UV-LEDs (PTB)
• For monitoring purposes, near-field conditions
• Replacement of halogen lamps susceptible to transportation and aging
3 Compact laser-induced UV source as transfer standard (VSL)
• Laser Driven Light Source (LDLS™) from Energetic
WP 1: Spectral Irradiance Traceability (PTB)
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Cryogenic radiometer
Spectral irradiance
standard
cw-Laser Sources
Si-trap detector + aperture
Filter Radiometer
Blackbody + aperture
Detector
Source
Spectroradiometer
Spectrally tuneable source
QASUME
EMRP ENV03: Traceability chain for spectral irradiance
(QASUME was calibrated directly against the blackbody in 2004 and 2013)
Stability controlled by relative measurements using portable Sources
(Aim of the project)
Tunable Lasers
QASUME
Validated
in this
Project
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Validation of the QASUME irradiance reference at PTB
Blackbody BB3200pg at PTB
Gröbner J., and P. Sperfeld, Direct
traceability of the portable QASUME
irradiance scale to the primary irradiance
standard of the PTB, Metrologia, 42, 134—
139, 2005.
Tuneable Laser facility TULIP
QASUME Validation at PTB in 2004 and 2013 and 2014
±1.2%
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Portable sources using UV-LEDs
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Compact LDLS source as transfer standard
Source stability < 0.2%
Spectral Irradiance output :
• comparable to 1000 W FEL Lamp
• Nearly Constant output over UV range
Preliminary results
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Goal: New characterisation techniques for the most relevant uncertainty components – stray light, bandwidth, linearity, wavelength
1 “A guide to measuring solar UV spectra using array spectroradiometers” (IMU)
• Specification of array spectrometers to meet the requirements for solar UV measurements
• Recommended measurement sequences for typical measurement setup
• A standardized protocol for saving measurement data, and ancillary information
2 “Uncertainty estimation in array spectroradiometer measurements of Solar UV spectra” (LNE)
• Guideline, software and methodology
3 Stray light characterisation and correction methods (PTB)
WP 2: Array Spectroradiometer characterisation (METAS)
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Stray-Light in Array Spectroradiometers
Main Problems:
Out-of-band stray-light
Spectrally variable slit function
Line Spread Function PSR_003
Array SRM have Si-detectors with Sensitivites
up to 1100 nm,
in contrast to solar-blind PMTs from scanning
SRMs
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Goal: New characterisation techniques for the most relevant uncertainty components – stray light, bandwidth, linearity, wavelength
1 “A guide to measuring solar UV spectra using array spectroradiometers” (IMU)
• Specification of array spectrometers to meet the requirements for solar UV measurements
• Recommended measurement sequences for typical measurement setup
• A standardized protocol for saving measurement data, and ancillary information
2 “Uncertainty estimation in array spectroradiometer measurements of Solar UV spectra” (LNE)
• Guideline, software and methodology
3 Stray light characterisation and correction methods (PTB)
WP 2: Array Spectroradiometer characterisation (METAS)
Talks by
Saulius Nevas
JG and Natalia Kouremeti,
Jimmy Dubbard
Posters by
Antonio Serrano,
Betty Hooke
JA Bogeat,
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Open-source Wavelength shift and bandwidth homogenisation software matSHIC
Same concept as shicRIVM,
PLUS: Adapt for array spectroradiometers:
Variable slit-width
extension to 1000 nm
matlab interface
open-source
Ask [email protected] or [email protected]
Soon to be available via http://projects.pmodwrc.ch/env03/
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WP 2: Development of two wavelength scale
characterisation devices (METAS, VSL)
For scanning and array spectroradiometers: U = 0.01 nm, wavelength 280 nm - 400 nm.
1. Fabry-Perot (FP) etalon (METAS) 2. Polarisation gradient Filter (VSL)
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Goal: New detection systems and entrance optics for scanning spectroradiometers to achieve field measurement uncertainties of 2% for solar UV measurements
1 New detection system for reference scanning spectroradiometers (CMI)
• Solid state detectors (Si, SiC, ZnO) and switched integrator amplifier
• High sensitivity, high dynamic range, low noise
• Substitute to PMT
2 Validation of optimised transportable QASUME reference spectroradiometer (PMOD/WRC)
• New Detector-System
• New Entrance Optic with improved Cosine response
• Improved traceability to SI and stability check using UV LEDs
3 Adaptation of a Fourier-transform spectroradiometer as reference instrument for solar UV irradiance measurements (PTB)
• Evaluate suitability of Fourier -transform spectroradiometer as a reference instrument for solar UV irradiance measurements
WP 3: Improvement of Reference Spectroradiometers (CMI)
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1 Realisation of a UV hyperspectral camera (INRIM)
• Imaging device for spectral UV sky radiance measurements
• Fish-eye UV collection optics
• Scanning Fabry-Perot device
• Improve cosine correction methods
2 Improved entrance optics for global solar UV spectroradiometers (Aalto)
• Cosine error less than ±1 % downto 80°
• Material studies and design software
• Study new fused silica-based diffuser materials
• Two designs for Brewer and fiber coupled optics
WP 4: New Technologies (Aalto)
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Hyperspectral fisheye UV Camera Fabry-Perot Cavity Spectroradiometer
Catadioptric Design
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Hyperspectral fisheye UV Camera
Catadioptric Design
390 370
350 330
310320
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Task 4.2 New Diffuser design
1) Design software
2) Validation through prototype
measurements
3) Realisation and commercialisation
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3 Array spectroradiometer with improved stray light rejection using adaptive optics (CMI)
• Studies and comparison of methods
• MEMS tuneable grating technology
• Digitally modulated micro mirror devices (DMD).
• Prototype of improved spectrograph
4 Array spectroradiometer with improved stray light rejection using band pass filters (LNE)
• Jobin-Yvon spectroradiometer optimized for solar UV measurements
• Target value for stray light rejection using a tailored band pass filter 106
WP 4: New Technologies …
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• UVNET Mailing list at http://metrology.tkk.fi/uvnet/source/lists.html
Spectral solar UV Intercomparison at Davos & Final ENV03 Workshop, 7-16 July 2014
Knowledge Dissemination & Training
http://projects.pmodwrc.ch/env03/
Presentations, Guidelines, Publications can be found at the project web-site: