Dear Jose' A. Feijo':
The part number for the Carl Zeiss adapter to go from a 160mm tube lens
objective design to infinity design is (44 49 04 ADAPTER 160/0.8 to
Infinity 0.8). Zeiss also has a UV version, part number 44 49 05. If
your older 160mm objective has an N.A. greater than 1.0 for example the
Plan Apo 63/1.4, most infinity microscopes produce a nice image without
the adapter and the parfocality is acceptable. By not using the adapter
with High N.A. objectives on an infinity microscope, it acts as a long
tube length microscope for the 160mm objectives.
Cheers
Kevin Coonan