The diffraction efficiency of M holograms superimposed in the volume of the
recording medium is proportional to 1/M-2, me present a method, based on n
ondestructive localized holograms in a doubly doped LiNbO3 crystal, that al
lows us to also record M holograms in the same volume without an exposure s
chedule or a diffraction efficiency that has 1/M dependence. We compare exp
erimentally the final diffraction efficiency obtained with the localized an
d distributed recording methods. (C) 2000 Optical Society of America OCIS c
odes: 090.0090, 210.0210.