  We present the capabilities of our new code for obtaining Doppler maps
implementing the maximum likelihood approach. As test data, we used
observations of the dwarf nova V2051 Ophiuchi. The system was observed in
quiescence at least 16 d before the onset of the next outburst. Using Doppler
maps obtained for ten emission lines covering three orbital cycles, we detected
spiral structures in the accretion disc of V2051 Oph. However, these structures
could be biased as our data sampled the orbital period of the binary at only
eight different orbital phases. Our Doppler maps show evolution from a one-arm
wave structure in H$\alpha$ to two-armed waves in the other lines. The location
of the two-arm structures agrees with simulations showing tidally driven spiral
waves in the accretion disc. During consecutive cycles, the qualitative
characteristics of the detected structures remained similar but the central
absorption increased. For the first time, using the Doppler tomography method,
we obtained temperature maps of the accretion disc. However, taking into
account all the assumptions involved when using our method to retrieve them,
the result should be treated with caution. Our maps present a relatively flat
distribution of the temperature over the disc, showing no temperature increase
at the location of the spiral arms. Using `ring masking', we have revealed an
ionized region located close to the expected location of stream--disc
interactions. We found the average temperature of the accretion disc to be 5600
K, which is below the critical limit deduced from the disc instability model.
