Soil penetrometer with Ramon sampling, fluorescence and reflected light imaging : a feasibility study

Abstract

This thesis describes the feasibility and capabilities of a Fluorescence Imaging and Raman Probe (FIRP). This miniature instrument will combine reflected light and fluorescence imaging and Raman spectroscopy for potential exobiology or terrestrial environmental use. With the help of a penetrometer, the probe might be used to assess the presence of life on Mars and gain an understanding of Martian soil. Furthermore, this thesis will delineate how this penetrometer may be used to detect underground constituents and pollutants present on our own planet. The proposed FIRP will be incorporated into a penetrometer that will go several meters below the surface seeking bio-signatures and information about soil composition. Microscopic imaging with reflected light will provide morphological context, fluorescence imaging can provide biomass detection, and Raman spectrometry can provide chemical identification of imaged material. The fluorescence technique will mainly depend on the performance of a non-cooled low-noise monochrome imaging camera, optical filters, and high efficiency light emitting diodes in the UV and visible. This miniature instrument will be connected by optical fiber to a surface platform that will host the Raman spectrometer and Raman laser excitation source. This thesis will show the experimental results of a bench-top proof of concept system. Images and spectra were collected and analyzed. Important choices and characteristics of the optical design are discussed relative to Raman and fluorescence detection. Finally, the thesis will propose a prototype of a compact device that combines both sensing methods and is compatible with a penetrometer platform.