SILENT: Spectrograph simulation and emulation tool

A software tool which was designed to compute basic optical parameters of spectrographs is presented. The idea is to find a first layout of the spectrograph by focusing on the science goal to which the instrument needs to be adapted. We focus on systems used in astrophysical instrumentation. These include classical, 3D and echelle spectrographs. The code also computes efficiencies of the specified systems, expected signal-to-noise ratios, layout of the spectral orders on the detector, etc. Furthermore, a complete image seen by the detector can be simulated. This artificial data are used to compare the performance of different designs and to test data reduction pipelines, before the system is being physically build. Some additional tools are implemented to characterise special optical devices, for example the telescope-spectrograph-interface and to support the design process. Hence, SILENT is a pre-design tool to determine the required optical paraxial parameters of the system to meet the science application.