The use of fibre optics for the detection of contact loss and the estimation of contact force between pantograph and catenary is experienced in a laboratory test bench. Preliminary results show the capabilities of this measurement system with respect to traditional measurement system for contact force, with the advantage of a negligible impact on the mass and geometry of the collector, and greater capability to withstand disturbances from the electrical environment. A simplified approach is adopted for the reconstruction of the contact force, based on the transfer function between strain and contact force determined experimentally on the collector, for the centred position of the contact force. For conditions in which the contact losses are isolated, the method proves to be adequate in estimating a low value of the contact force, considering a frequency range broader than the standard frequency band (0÷20) Hz, typical of the current measurement systems.