The advanced design of the video inspection system GeoKam for optical inspection of deep boreholes requires the joining of a transparent ceramic window to the Inconel® 718 housing. Active brazing using Incusil ™ ABA as active brazing material gave the best results. Detailed design calculations were performed using the codes ABAQUS® and STAU. Design optimizations resulted in the construction of a sleeve as an adapter part between the ceramic and the Inconel® 718 housing. An important result of the calculations was to avoid sharp edges of the sleeve by realization of a chamfer in order to reduce the fracture probability. The results of the design calculations could be verified with model experiments.