\subsection{Effective cross section}
With the help of formula \ref{effekt} we get the effective cross section 
for the process $\gamma\gamma \rightarrow t \bar{t}$ resp. $\gamma\gamma 
\rightarrow t \bar{t} g$ including the toponium resonances. 
Polarized electrons or photons for compton scattering leading 
to different spectral luminosities for different helicities of the high 
energy photons. Therefore the cross sections for $\gamma\gamma 
\rightarrow t \bar{t} g,\esn$ with initial state polarization are necesary to 
evaluated the effective cross section if we use polarization to optimize the 
luminosity. Due to our ignorance of these cross section we omitted 
polarization effects in this section. 
\begin{figure}
\begin{center}
\mbox{\epsfig{file=bild10.eps,width=12cm}}
\end{center}
\caption{Effective cross section including QCD corrections and bound state 
contributions.}
\label{eff_wq}
\end{figure}
