Scientific simulations on the VLT Interferometer

By the middle of the year 2000 the VLT interferometer will become operational. The design of the telescopes, Coude trains and delay lines is finished and the different beam combination instruments for use in the near and mid-IR are under design. Our goal is to understand this complex machine in full detail and analyze the influence of the several subsystems on the data formation process. ESO has already started to model the interferometer from an optomechanical point of view which resulted in the VLTI end-to-end model. The end-to-end model includes the complete optical trains for the 4 unit telescopes and up to 4 auxiliary telescopes located on nay of the 30 telescopes stations. The optical trains consist of 16 mirrors from the primary mirror to the beam combination lab. The model also includes seismic noise, wind load, atmospheric effects, delay line control, fringe sensor unit, and fast image stabilization. The output of this model enters the scientific simulations, where the beam combination instruments are modeled. We will explain the underlying philosophy of our model and show first illustrations from the simulations.