A method and apparatus for reading in a three-dimensional information carrier
are
presented. The three-dimensional information carrier is formed with a plurality
of spaced-apart data regions, each surrounded by surrounding-regions. The data
regions are made of a material capable of generating an output excited radiation,
when interacting with a predetermined incident exciting radiation, while the surrounding
regions are substantially optically transparent. The apparatus comprises an illumination
unit, a light directing unit and a detector unit. The illumination unit produces
a scanning beam of the incident radiation. The light directing unit projects the
incident radiation onto a scan region located in an addressed plane inside the
carrier and collects the output radiation. The light directing unit is capable
of picking up a predetermined portion of the collected output radiation, so as
to provide spatial separation of the output radiation components produced by the
data regions located in the addressed plane and the output radiation components
produced by the data regions located at any other location inside the carrier.