Spectrometer Boosts Analysis of Extremely Dark Materials

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Researchers from University Grenoble Alpes developed a novel instrument capable of analyzing light reflected from very small or extremely dark materials

Spectroscopy can measure patterns of light reflections off a surface to offer information on the physical and chemical properties of a sample material. However, meteorites samples and other similar extremely dark materials reflect very less light that challenges this type of analysis.  Now, a research led by Sandra Potin from Institut de Planétologie et Astrophysique de Grenoble (IPAG) of University Grenoble Alpes in France, devised a novel instrument dubbed as SHADOWS. The instrument can be used for reflectance spectroscopy of samples that measure less than one millimeter cubed and reflecting less than 0.03% of light illuminating the sample. The instrument can be used for in-depth study of meteorites’ composition and its origin. Moreover, it can analyze spacecraft surfaces that possess dark coatings.

The novel spectroscopy instrument is known as a spectro-gonio radiometer and it shines light on a sample from a precise direction and detects light reflected back from a different direction. This bi-directional reflectance spectroscopy calculates the reflectance of a material based on the direction of the illumination light and the direction of the reflected light. The spectra produced by this measurement can be used to determine a sample’s composition. In previous research, the team developed a radiometer for large and bright samples, which was upgraded with improved sensitivity by reducing the illumination to a diameter of around 5.2 mm. Moreover, the illumination spot can shrink even more to map heterogeneous surfaces.

SHADOWS uses multiple colors of light and moves the light source and the detector around the sample to measure light coming from and reflected to multiple directions. The information obtained is later used to build a 3D angular map of the sample’s light reflection, which offers more information about the sample. The instrument can analyze samples at -20 degrees C up to 250 degrees C and can be upgraded to operate at temperatures down to -210 degrees C. The research was published in The Optical Society’s (OSA) journal Applied Optics on September 26, 2018.

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Bill Carr is a Senior Editor at Plains Gazette, based in Austin. Previously he has worked for FOX Sports and MSNBC's "Morning Joe." he is a graduate of the Annenberg School at the University of Southern California. You can reach Bill via email or by phone