The present invention relates to an optical telemetry system for measuring the distance between two vehicles comprising a first optoelectronic assembly formed by at least one light source SLs and at least one photosensitive sensor CP+, which source and sensor are oriented towards in front of the vehicle, and a second optoelectronic assembly formed by at least one light source SLc (6) and at least one photosensitive sensor CPc (5) that is oriented towards behind the vehicle, characterized in that said light sources SLs and SLc are conventional light sources, the light source SLs being modulated by a signal of frequency Fs, said light source SLc (6) of the target (4) being modulated by a clock of frequency controlled by a phase-locked loop driven by the electrical signal delivered by said photosensitive sensor CPc, said first optoelectronic assembly furthermore comprising a circuit for measuring the phase shift between the electrical signal delivered by said photosensitive sensor CPs (5) and the signal modulating the paired light source SLs (6), said system furthermore comprising a computer for determining the distance depending on the frequency Fs and the measured phase shift. The invention also relates to an optoelectronic assembly for an optical telemetry system, to a vehicle equipped with such a system and to a telemetry method.