\begin{table}%t2
%\centering
\par
\caption{Initial thermal design requirements with $R=0.9$.\label{tab2}  } % title of Table
\begin{tabular}{lll }        % centered columns (1 columns)
\hline\hline                 % inserts double horizontal lines
 & $\lambda_V$ = 630.2 nm & $\lambda_{\rm IR} = 1564.85$ nm \\
\hline                        % inserts single horizontal line
 {\it FWHM}               & 0.10 pm       & 0.40 pm  \\ % inserting body of the table
 {\it FSR}                & 2 pm          & 15 pm    \\
 Step Size          & 0.02 pm       & 0.08 pm  \\
(at 5pts/{\it FWHM})      &               &          \\
Number of points to & 100           & 188      \\
cover the full {\it FSR}  &               &          \\
Change in temperature &  10C         & 19C      \\
required to cover {\it FSR} &             &          \\
\hline                                   %inserts single line
\end{tabular}
\end{table}