SHADOWS Micro Spectro-Gonio Radiometer
Laboratory Experiment facility
Facility name:
Micro Spectro-Gonio Radiometer
Location: Institut de Planétologie et Astrophysique de Grenoble (IPAG)
CNRS - Université Grenoble Alpes
Saint Martin d’Hères, France
Persons in charge:
- Scientific : Pierre Beck, Assistant Professor & Bernard Schmitt, Research director
- Technical : Olivier Brissaud, Engineer
General description
The new micro spectro-gonio radiometer currently under developement will be optimized for the measurement at low temperature of bidirectional reflectance spectra, over the visible and near-IR (at least from 350 to 4800 nm), of dark and very small samples (organics, meteorites…) down to a few mm3 in volume.
It will have 2 major sample holder configurations:
- Open sample holders (various sizes) in cold chamber over -20°C ─ +20°C temperature range.
- The SERAC environmental cell with cryostats, pumps, pressure and temperature controllers, which allows us to introduce gas(es) of known composition and pressure (10-6 mb - 1 bar) over the sample and controlling and measuring the temperature over the -40°C ─ +80°C range. It will have a set of sample holders (small sizes) adapted to this new setup.
A number of sample preparation tools and experiment sub-systems are available to the facility:
- For samples preparation: another cold chamber (down to -20°C), set of sample holders, several specific tools for ice sample preparation, 2 sets of sieves, grinders, mortars, saw, balances, microscope, owen, ultra-pure water, several pure gasses, wet chemistry materials a, several owens (up to 1200°C) for sample treatments.
- For the experiment: a thermodynamic volumetric system with high accuracy pressure gauges (10-6 to 1 bar), a flow meter (1-10 sccm) and pumps. He-Ne laser + detectors, camera for sample monitoring, …
Technical characteristics:
Spectral range : 0.35 - 4.5 µm (< 0.35 & > 4.8 µm: lower S/N) (4.2-4.3µm: atm. CO2 limited)
Spectral resolution : variable
- mini: < 0.1 nm (but S/N limited)
- maxi: 3 nm (<700nm), 7 nm (<1600nm), 12 nm (<3000nm), 26nm (>3000nm) [May change with future new monochromator]
- Incidence angle: 0° to 75° ; resolution: 2° (can be reduced to 1°) ; maximum sampling : 0.1°
- Emergence angle: 0° to 80° for dark / fine grained samples ; resolution : ± 2° (may be reduced to < ± 0.5°, but S/N limited) ; max. sampling : 0.1°
- Azimuth angle: 0° to 180° ; resolution : ± 2° (may be reduced to < ± 0.5°, but S/N limited) ; max. sampling : 0.1°
- Phase angle: up to to 155° ; mini : ~ 7° for dark / fine grained samples
- Illumination diameter (nadir): 7.5 mm
- Observation diameter (nadir): 20 mm
Absolute: [will be determined during calibration and test phase end 2015 - 2016]
- 0.35-1.0 µm: expected better than 1% over all configurations (relative to a calibrated Spectralon 0.99 reference panel)
- 1.0-2.5 µm: expected better than 1% over all configurations
- 2.5-4.5 µm : expected better than 2% over all configurations
Relative :
- better than 0.5% (0.35-4.5 µm)
Picture: sketch of the micro spectro-gonio radiometer under building at IPAG
Types: cosmo-materials, synthetic and terrestrial carbonaceous materials, minerals
Texture: compact (dark) or granular (dark and/or fine grained < 200µm)
Grain size: sub-µm to a 200 µm
Size:
- 32 mm diameter (for full BRDF down to 75° observation)
- 8 mm x 32 mm (for principal plane observation down to 75°)
- 8 mm x 16 mm (for principal plane observation down to 60°)
Thickness:
- 0.1 mm for dark & fine grained samples (< 20 µm)
- up to 5 mm for 'gray' & medium grained samples (< 200 µm)
- up to 10 mm for bright & medium/fine grained samples (< 100 µm)
- room temperature or heated
- down to -20°C (in cold room)
- down to -40°C (in SERAC environmental cell)
- PC/Windows, fully software controlled (LabView©). Automatic acquisition of all spectral/geometric configurations
Acquisition time: [will be determined during calibration and test phase end 2015 - 2016]
- typical: 1 mn for 200 spectral channels in visible (S/N dependent)
- total: <1 hour for 100 spectral channels and 100 geometries
- Visible 0.3 - 1 µm range: under development, testing and buiding [2013-2015]. Ready for full testing end of 2015
- Infrared 1 - 4.8µm range: extension planned in 2015-2017 (if EPN2020-RI program accepted)
- low temperature: to be tested in cold room down to -20°C (end 2015)
- Characteristics: Micro-Spectro-Gonio_characteristics.pdf (TBD)
- Article:
Availability to community:
2016-2017:
- Technical improvements/calibration (40%)
- IPAG + associated laboratories measurements (60%)
after 2017:
- Technical improvements/calibration (20%)
- IPAG + associated laboratories measurements (60%)
- open as facility or to specific collaborations w. funding (20%)
References: