In this paper, design, simulation and implementation of a new high accuracy Time-OfFlight range finder is presented, and various possible errors are also discussed. In this design a Q-switch Nd:YAG laser as a source and an avalanche photodiode as a detector have been used. The optics of the system, including optical filter with ZnS / MgF2 structure having quality factor of 2.53 has also been designed and implemented. Considering the transmitted power of 1.5MW, the lowest detectable optical power at the APD input, ignoring the noise, was 10nW
