  We report on the ab-plane reflectance of the high temperature superconductor
Bi2Sr2CaCu2O8+d (Bi-2212). Samples spanning the doping range from under doped
with Tc = 67 K(UD), to optimally doped with Tc = 96 K (OPT), to over doped with
Tc = 60 K (OD) were measured from room temperature down to the superconducting
state. The measured reflectance data were analyzed to extract the optical
conductivity and the real and imaginary parts of the free carrier optical
self-energy. We get an estimate of the dc resistivity from the low frequency
extrapolation of the optical conductivity and the superfluid density from the
imaginary part of the optical conductivity. The conductivity sum rule can be
related to the changes of the kinetic energy of the system. When this system
becomes a superconductor, the kinetic energy decreases in the underdoped
samples and increases in overdoped ones. The optical self-energy, obtained from
the extended Drude model, is dominated by two channels of interaction, a sharp
mode and a broad background. The amplitude of the mode is strongly doping and
temperature dependent whereas the background decreases weakly with doping and
is nearly temperature independent.
