A method for the static characterisation of the CMS Tracker analogue optical links

Analogue optical links are being developed for the CMS Tracker. The large number of optical channels (over 50,000) requires semi-automated test procedures and efficient evaluation criteria to compare different link solutions and to optimise their performance, whilst complying with system specifications. In addition, selftriggered calibration schemes need to be developed to maintain the readout chain accuracy during the detector lifetime (10 years). In this paper we present a method for the static characterisation of the CMS analogue optical links, relying on an automated set-up for gain, rms-noise and linearity measurements, and on a software program for off-line processing of the test data. We propose a set of evaluation criteria and describe a compact representation of the results in the operational parameter space (dc working point, operating range). This representation allows quantification and comparison of the performance of links based on different components, as well as allowing development and simulation of practical testing and calibration procedures.