SHADOWS Micro Spectro-Gonio Radiometer

General description

The new SHADOWS micro spectro-gonio radiometer is optimized for the measurement of bidirectional reflectance spectra (illumination and observation up to almost 80°, all azimuths, phase angle > 4-10° ), over the visible and near-IR (from 350 to 4800 nm), of dark and very small samples (organics, meteorites…) down to a few mm3 in volume. The instrument is fully described in Potin et al. 2018.

The instrument is located in a dark cold room that can be cooled down to -10°C. It is fully automatized and the data calibration and reduction are made with homemade softwares. Two thermal and cryogenic environmental cells are available: MIRAGE and IceBERG (under test).

Various types of measurements can be programmed: simple reflectance spectra at one geometry (but possibly varying with time, temperature, or physical/chemical process), full BRDF (only in open sample holder), limited angle BRDF spectra or at few wavelengths (MIRAGE and IceBERG cells), …

Availability to community:

– Technical improvements/calibration (15%)
– IPAG + associated laboratories measurements (60%)
– open as Europlanet 2024-RI facility (TNA) ( 15%)
– open to specific collaborations w. funding ( 10%)

SHADOWS instrument, showing all instrumentation and goniometer parts
Type:Laboratory Experiment facility

Facility name: SHADOWS Micro Spectro-Gonio Radiometer (Spectro-photometer with cHanging Angles for Detection Of Weak Signals)

Institut de Planétologie et Astrophysique de Grenoble
CNRS – Université Grenoble Alpes
Batiment D de Physique, 3rd level
124, rue de la Piscine
38400 Saint Martin d’Hères, France

Persons in charge:
– Scientific: Pierre Beck (Assistant Professor) & Bernard Schmitt (Research director)
– Technical: Olivier Brissaud (Engineer)

References: Potin et al. 2018

Technical characteristics

Spectral range:
– 0.4 – 4.7 µm (< 0.4 & > 4.7 µm: lower S/N) (4.2-4.35µm: atm. CO2 limited)
Spectral resolution: variable
– mini: < 0.1 nm (but S/N limited) – maxi: 3.8 nm (350 – 1400 nm), 7.7 nm (600 – 2500 nm), 15.4 nm (1100 – 3600 nm), 31 nm (> 2500 nm)
Bidirectional Reflectance:
– Incidence angle: 0° to 70° (60° for bright samples) ; resolution: 2.9°; min. sampling : 0.1° – Emergence angle: 0° to 85°; resolution : ± 2.05° (options: 0.8°, 1.25°, 1.65° but lower S/N) ; (…)

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Sample holders

SHADOWS has currently 2 major sample holder configurations:
– Open sample holders (various sizes) in cold chamber over -10°C ─ +20°C temperature range.
Sample holders (aluminum): – cylindrical, d= 2 mm, h= 0.5 mm (for micro-beam) – cylindrical, d= 3 mm, h= 1 mm (for micro-beam) – cylindrical, d= 7 mm, h= 1 mm – cylindrical, d= 14 mm, h= 1 mm – cylindrical, d= 20 mm, h= 1 mm – cylindrical, d= 20 mm, h= 2 mm – cylindrical, d= 35 mm, h= 2 mm – cylindrical, d= 35 mm, h= 5 mm – (…)

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Tools and sub-systems

A number of sample preparation tools and experiment sub-systems are available to the facility:
– For samples preparation: a 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, several owens (up to 1200°C) for sample treatments.
– For the experiment: a thermodynamic volumetric system with high accuracy (…)

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