Within the Intelligence for Soil (I4S) framework, our project aims to develop a portable and robust diode laser based measurement system using Shifted Excitation Raman Difference Spectroscopy (SERDS) for the efficient separation of Raman signals from disturbing interferences. A compact prototype for on-site Raman measurements to assess relevant soil properties will be realized. The instrument will comprise an innovative diode laser based excitation light source for SERDS (785 nm wavelength, up to 1 W optical output power), a rugged optical system, customized control electronics and a robust housing. In close collaboration with the I4S project partners the developed system will be used for soil measurements under field conditions.
The planned work is divided into two major topics, the development of the diode laser based measurement system itself and fundamental research to gain a better understanding of the Raman spectroscopic signatures of soils to draw conclusions about characteristic soil properties.
For the first topic, during the previous project phase suitable diode lasers have been already developed and subsequently integrated into a compact setup to detect selected constituents in soil samples for the first time using Raman spectroscopy in general and SERDS in particular. The key project task is now to further develop the existing setup into a prototype suitable for Raman experiments under real-world conditions in the field. Furthermore, the long-term stability and reliability of the applied diode lasers will be investigated.
In the second topic, initially Raman spectroscopic experiments in the laboratory will be conducted on pure substances relevant to the soil to obtain reference data. This data is needed for the better understanding and evaluation in the subsequently performed measurements on test specimens and real soil samples. The resulting better understanding of the spectra of the selected soil constituents will offer the opportunity to better characterize and classify different soils.
I4S (duration 01.10.2018 - 30.09.2021)
Funding: BMBF grant number 031A564C