The distribution of laser light for the calibration and monitoring system of the ATLAS hadronic calorimeter

In this paper we describe the design and preliminary results of a system to distribute light from a laser to 10,000 photomultiplier tubes (PMTs) in the ATLAS hadronic calorimeter. This system uses optical devices, plastic optical fibers and fibers connectors, specially designed for this application. The uniformity of distribution is reasonable and the light losses are acceptable within the light budget available and the range required.