  The analog hadron calorimeter for the International Linear Collider (ILC) of
the CALICE collaboration utilized novel silicon detectors, the Sillicon
Photomultipliers (SiPMs), for the detection of scintillation light coming from
very small scintillator cells 3x3x0.5 cm^3. This technology allows the
construction of highly granular calorimeters used for excellent shower
separation and therefore outstanding jet energy resolution using the particle
flow concept. Since the SiPMs still have potential for further improvements, we
developed a setup dedicated to the measurement of parameters like the areal
distribution of relative photon detection efficiency and crosstalk probability
which are used to characterize and compare different devices. Thanks to the
precise positioning system together with excellent focusing of the light source
we are capable of scanning whole SiPMs with an area of ca. 1 mm^2 at a
sub-pixel resolution of 1-2 \mu{}m. A further alignment compensation feature
allows us to conduct separate analysis on each single pixel of a SiPM. We
present the technical description of our measurement setup and results obtained
for two types of SiPMs. The first one is a commercial Hamamatsu MPPC with 50
\mu{}m pixel size, the second one was the second iteration series SiMPl device
developed and manufactured in the Semiconductor Laboratory of the Max Planck
Institute.
