  The SAFARI Detector Test Facility is an ultra-low background optical testbed
for characterizing ultra-sensitive prototype horn-coupled TES bolmeters for
SAFARI, the grating spectrometer on board the proposed SPICA satellite. The
testbed contains internal cold and hot black-body illuminators and a light-pipe
for illumination with an external source. We have added reimaging optics to
facilitate array optical measurements. The system is now being used for optical
testing of prototype detector arrays read out with frequency-domain
multiplexing. We present our latest optical measurements of prototype arrays
and discuss these in terms of the instrument performance.
