Design and manufacturing of high performance notch filters

Rugate designs for the realization of notch filters are well known in the literature. The required deposition of gradient index layers is difficult to manufacture. In our approach we apply the equivalent index theory to replace the gradient index profile of a notch filter design. We produce single and multiple notch filters with plasma ion-assisted deposition and broad-band optical monitoring. As examples, a 500nm notch filter for the GREGOR telescope and a 589nm notch filter for the GALACSI instrument of the VLT are discussed. Additionally, a 4-line multiple notch filter and a 218nm notch filter made for fluorescence spectroscopy applications are presented.