  State-of-the-art polarimeter calibration is reviewed. Producing many
quasi-random polarization states and moving/bending a fiber without changing
power allows finding a polarimeter calibration where the degree-of-polarization
reaches unity and parasitic polarization-dependent loss is small. Using a
polarization scrambler/transformer and a polarimeter a device-under-test can be
characterized. Its Mueller matrix can be decomposed into a product of a
nondepolarizing Mueller-Jones matrix times a purely depolarizing Mueller
matrix. Test polarizations may drift over time. With help of an optical switch
the reference device can be measured against an internal reference path. Later,
with possibly different test polarizations, the actual device-under-test is
measured against the internal reference. Polarization drift and need for
repeated reference device measurement are thus overcome. When a patchcord is
inserted, connector PDL can be measured, provided that errors are calibrated
away, again by fiber moving/bending. Experimentally we have measured PDL with
errors <0.004 dB. This easily suffices to measure connector PDL, which is
demonstrated. PDL >60 dB was measured when the device under test was a good
polarizer. A 20 Mrad/s polarization scrambler with LiNbO3 device generates the
test polarizations. The polarimeter can sample at 100 MHz and can store 64M
Stokes vectors. During laser frequency scans Mueller matrices can be measured
in time intervals as short as 5 us.
