The Planetary Spectroscopy Laboratory (PSL): wide spectral range, wider sample temperature range

Abstract

The Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin provides spectral measurements of primarily planetary analogues from the visible to the far-infrared range. PSL has supported the data analysis as well as the development and calibration of instruments for planetary missions from ESA, NASA and JAXA. For this purposes PSL provides reflection, transmission and emission spectroscopy of target materials. Currently PSL operates two identical Bruker Vertex 80V vacuum FTIR spectrometer, one spectrometer is equipped with aluminum mirrors optimized for the UV, visible and near-IR, the second features gold-coated mirrors for the near to far IR spectral range. External simulation chambers are attached to each of the instruments for emissivity measurements. The chamber at the near to far IR instruments allows emissivity measurements from 0.7-200 μm under vacuum for sample temperatures from 320K to above 900K, using an innovative induction system. The second chamber (purged with dry air and water cooled to ≤270K) allows emissivity measurements of samples with surface temperature from 290 to 420K. We measure bi-directional reflectance of samples, with variable incidence and emission angles between 13° and 85°. Samples are measured currently at room temperature and 170K, with a planned extension for temperatures below 100K. Bi-directional and hemispherical reflectance is measured under purging/vacuum conditions, covering the 0.2 to above 200 μm spectral range. Transmission of thin slabs, optical filters, optical windows, pellets, and others is measured in the complete spectral range from UV to FIR using a parallel beam configuration to avoid refraction.