Note: Continuous-wave time-of-flight laser scanner using two laser diodes to avoid 2π ambiguity

Abstract

In the continuous-wave time-of-flight method, the distance traveled by light can be obtained by using the phase difference between the reference signal and the measured signal. However, when the phase difference exceeds 2π, the distance cannot be differentiated because the distance variation repeats every 2π period. In this paper, we propose a method in which low- and high-frequency signals are separately applied to two laser diodes simultaneously, and processed using two different signal processing circuits to solve the 2π ambiguity problem and achieve a high distance resolution for a longer distance measurement.