Opto-Mechanical Design and Testing of a Fabry-Pérot Infrared Spectrometer

Kurzfassung

This thesis presents the development of a compact infrared spectrometer designed for planetary surface characterization. The system, based on a thermopile detector and a tunable MEMS Fabry-Perot filter, is developed based on simulated predictions of the relevant key performance parameters, which include signal strength, spectral resolution and the noise equivalent emissivity difference. These parameters are chosen to enable the detection of diagnostic spectral features in the thermal infrared range, which provide insights into surface composition and structure. The mechanical design of the sensor head, including the integration of an optical system and an external bandpass filter, is described. Design priorities include compatibility of the sensor head with the available optical bench for testing, thermal stability and control, as well as vacuum compatibility to allow for testing in a mission-specific relevant environment. A data acquisition and testing setup is implemented to operate the FPF and thermopile detector while maintaining a controlled test environment. The influence of individual components in test setup and sensor head is depicted and analyzed with regard to the further testing strategy. The spectrometer’s key performance parameters, including repeatability, accuracy, signal-to-noise ratio and signal strength, are analyzed based on measured data, giving an overview of its operational capabilities. Lastly, a comparison between the predicted and testing results allows for the adaption of the simulation to include setup-specific factors, such as readout electronic noise and changes of sensitivity in the detector depending on ambient pressure, facilitating further developments of the prototype with more accurate predictions.