Schalwat, M. Bandelmann, R. Daniel, A. Krupka, N. Matheisen, A. Sievers, S.T. JACoW Geneva, Switzerland 978-3-95450-191-5 10.18429/JACoW-SRF2017-MOPB003 English 47-50 MOPB003 ion cavity gun SRF MMI Contribution to a conference proceedings 2018 2018-01 https://doi.org/10.18429/JACoW-SRF2017-MOPB003 http://jacow.org/srf2017/papers/mopb003.pdf Optical inspection of the inner surface of superconducting resonators was established during European XFEL cavity production by usage of the so called OBACHT optical inspection. In addition to the surface inspection by OBACHT a new optical inspection system with integrated high resolution camera is set up at DESY. It allows inspection of multi-cell resonators as well as gun cavity resonators with only single side accessibility to the inner surface. A prototype was commissioned and optical inspections were done with OBACHT and the new system in parallel. Two SRF gun cavities were inspected by this optical system and origin of limitations of the resonators were identified.