\begin{table}%ta2 \caption{\label{selector}Optical paths in meters introduced by the beam selector on the Chara output pupil image.} \small %\centerline { \begin{tabular}{cllllll} \hline\hline & S1 & S2 & W1 & W2 & E2 & E1\\ \hline V1 & 0 & DF & DT+DF & DT+2F & 2DT+2DF & 2DT+3DF\\ V2 & DV & DF+DV & DT+DF+DV & DT+2DF+DV & 2DT+2DF+DV & 2DT+3DF+DV\\ V3 & 2DV & DF+2DV & DT+DF+2DV & DT+2DF+2DV & 2DT+2DF+2DV & 2DT+3DF+DV\\ V4 & 3DV & DF+3DV & DT+DF+3DV & DT+2DF+3DV & 2DT+2DF+3DV & 2DT+3DF+DV\\ V5 & 4DV & DF+4DV & DT+DF+4DV & DT+2DF+4DV & 2DT+2DF+4DV & 2DT+3DF+DV\\ V6 & 5DV & DF+5DV & DT+DF+5DV & DT+2DF+5DV & 2DT+2DF+5DV & 2DT+3DF+DV\\ \hline \end{tabular}} \smallskip $\rm DT=1.2446$~m is the distance before the selector between the beams of telescopes S2 and W1 and between W2 and E2. $\rm DF=0.5842$~m is the distance between two beams before the selector and for telescopes located on the same arm (East, West or South). $\rm DV=0.0762$~m is the distance between two beams after the selector. \end{table}