  We implement a photon-counting Optical Time Domain Reflectometer (OTDR) at
1.55um which exhibits a high 2-point resolution and a high accuracy. It is
based on a low temporal-jitter photon-counting module at 1.55um. This detector
is composed of a periodically poled Lithium niobate (PPLN) waveguide, which
provides a wavelength conversion from near infrared to visible light, and a low
jitter silicon photon-counting detector. With this apparatus, we obtain
centimetre resolution over a measurement range of tens of kilometres.
