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Spectroscopy is one of the most important fields in astrophysics as it delivers many physical quantities of
distant sun-systems. A typical example is the radial velocity method, that can be used to detect exoplanets.
However, spectroscopic instruments are never stable enough and calibration methods are required.
One of the most prominent type of calibrators are Fabry-Perots (FP). They are simple to build, costeffective and easy to use. Nonetheless, they must be put into a stabilized environment to be stable enough to suite as a relative calibrator. The bandwidth of the FP is typically on the order of 100 nm - 400 nm depending on the reflectivity and configuration of the mirrors. The large bandwidth can only be achieved with dielectric coatings, which are typically stacked, so that different wavelengths are reflected in different depth of the coating. Accordingly, a high dispersion can be observed, i.e. the group velocity dispersion is high, which makes it difficult to predict the position of each resonance of the FP.
Due to these shortcomings and the impossibility to use the reflected light of the FP without higher losses,
we developed a triple-mirror FP as shown in figure 1. The triple-mirror FP prototype is currently in the
students laboratory of the group.

Understanding of optical setups. Experimental skills.