  The applied method of the amplitude envelopes give us the possibility to
describe a new class of amplitude equations governing the propagation of
optical pulses in media with dispersion, dispersionless media and vacuum. We
normalized these amplitude equations and obtained five dimensionless parameters
that determine different linear and nonlinear regimes of the optical pulses
evolution. Surprisingly, in linear regime the normalized amplitude equations
for media with dispersion and the amplitude equations in dispersionless media
and vacuum are equal with precise - material constants. The equations were
solved for pulses with low intensity (linear regime), using the method of
Fourier transforms. One unexpected new result was the relative stability of
light bullets and light disks and the significant reduction of their
diffraction enlargement. It is important to emphasize here the case of light
disks, which turn out to be practically diffractionless over distances of more
than hundred kilometers.
