\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}