Magnification of the phase-shift for laser distance measurement

The design of a phase-shift expander used for measuring distances in phase-shift rangefinder is presented. The system uses two coherent indirect frequency synthesisers with the photoelectric signal and the reference signal as input voltages. Theory demonstrates that a great improvement for phase-shift measurement resolution may be achieved. The main error sources are analysed: the influence of the output frequency modulation and the influence of the output frequency stability are evaluated. First experimentation results are presented.