Improved REM telescope interface with a new simultaneous multiband visible camera

A new mechanical interface between the telescope Nasmyth derotator and the focal plane instrumentation has been developed and built for the robotic REM telescope in La Silla. A light-weighted flange will substitute the existing one in order to improve performances in term of mechanical flexures. A new ghost-free, high performances, dichroic has been designed and installed inside the new mechanical flange, improving the efficiency of the wavelength splitting between the visible and the near-infrared channels. The visible camera has been completely redesigned in order to get simultaneous multi-band coverage within the existing 10'x10' field of view. Four bands will be observed onto the same 2kx2k, 13.5 micron pixel, detector. Band splitting is obtained with plate dichroics, working at 45 deg of incidence angle. It will allow to fast observe gamma-ray burst afterglow from the 400 nm up to 2.5 micron, to better characterize spectral features of these fastly evolving sources.