\begin{table}%T5
\caption{CIV VUV etalon parameters.}             
\label{table:5}      
%\centering
 \small         
\begin{tabular}{l l l l }     % 6 columns 
\hline\hline   
   Scan                    &  A1(2) &   B1(2) &    C   \\
\hline                   
   Gap ($\mu$m) & 201.6  & 205.2   & 200.0  \\
   Effective reflectivity  & 0.590  & 0.561   & 0.490  \\
   Step size (nm)          & 0.425  & 0.423   & 0.430  \\
   Aperture size (mm)      & 2      & 2       & 2      \\
   ${\it FSR}$ (nm)                & 0.0616 & 0.0610  & 0.0620 \\
   Measured {\it FWHM} (pm)      & 11.56  & 11.48   & 12.30  \\
   at 157~nm & & & \\
   Effective finesse       & 5.34   & 5.27    & 5.05   \\
   {\it FWHM} of F$_2$ laser (pm)& 30(10) & 30 (10) & 10     \\
   Finesse corrected for   & 5.43 (5.71)   & 5.36 (5.63)    & 5.36   \\
   F2 laser width & & & \\
   Reflectance finesse     & & &  \\
   157~nm ($R=0.74$)         & 10.4    & 10.4      & 10.4     \\
   155~nm ($R=0.77$)         & 12.0    & 12.0      & 12.0     \\
   Defect finesse         & 6.37 (6.85) & 6.25 (6.70)    & 5.88     \\
   Effective finesse      & 5.26 (5.95) & 5.54 (5.95)    & 5.55     \\
   at 155~nm (pm) & & &  \\ 
\hline                  
\end{tabular}
\end{table}