  In this thesis feasibility of the precise measurement of the Higgs-boson
production cross section gamma+gamma->higgs->b+bbar at the Photon Collider at
TESLA is studied in detail.
  The study is based on the realistic luminosity spectra simulation. The heavy
quark background is estimated using the dedicated code based on NLO QCD
calculations. Other background processes, which were neglected in the earlier
analyses, are also studied. Also the contribution from the overlaying events,
gamma+gamma->hadrons, is taken into account. The non-zero beam crossing angle
and the finite size of colliding bunches are included in the event generation.
The analysis is based on the full detector simulation with realistic b-tagging,
and the criteria of event selection are optimized separately for each
considered Higgs-boson mass.
  For the Standard-Model Higgs boson with mass of 120 to 160 GeV the partial
width \Gamma(h->gamma+gamma)BR(h->b+bbar) can be measured with a statistical
accuracy of 2.1-7.7% after one year of the Photon Collider running. The
systematic uncertainties of the measurement are estimated to be of the order of
2%.
  For MSSM Higgs bosons A and H, for M_A=200-350 GeV and tan(beta)=7, the
statistical precision of the cross-section measurement is estimated to be
8--34%, for four considered MSSM parameters sets. As heavy neutral Higgs bosons
in this scenario may not be discovered at LHC or at the first stage of the e+e-
collider, an opportunity of being a discovery machine is also studied for the
Photon Collider.
