  The RD52 (DREAM) collaboration is performing R\&D on dual readout calorimetry
techniques with the aim of improving hadronic energy resolution for future high
energy physics experiments. The simultaneous detection of Cherenkov and
scintillation light enables us to measure the electromagnetic fraction of
hadron shower event-by-event. As a result, we could eliminate the main
fluctuation which prevented from achieving precision energy measurement for
hadrons.
  We have tested the performance of the lead and copper fiber prototypes
calorimeters with various energies of electromagnetic particles and hadrons.
During the beam test, we investigated the energy resolutions for electrons and
pions as well as the identification of those particles in a longitudinally
unsegmented calorimeter.
  Measurements were also performed on pure and doped PbWO$_{4}$ crystals, as
well as BGO and BSO, with the aim of realising a crystal based dual readout
detector. We will describe our results, focusing on the more promising
properties of homogeneous media for the technique. Guidelines for additional
developments on crystals will be also given.
  Finally we discuss the construction techniques that we have used to assemble
our prototypes and give an overview of the ones that could be industrialized
for the construction of a full hermetic calorimeter.
