Laser ranging and three-dimensional imaging systems based on the differential optical path method

In order to suppress the effects of common-mode noise, laser ranging and three-dimensional imaging systems based on the differential optical-path method (DOPM) are proposed. Compared with the traditional method based on single receiver, DOPM uses two receivers which have different optical-paths. Based on DOPM, we developed the laser ranging and three-dimensional (3D) imaging systems and carried out ranging and three-dimensional imaging experiments to research DOPM for practical application. In ranging experiments, the root-mean-square (RMS) of ranging error decreases from 95 to 70 mm; as a result the error could be decreased to 74% of the method based on a single receiver. Meanwhile, the system obtains the highest sensitivity when differential distance is multiplied by light speed and receiving pulse width. In 3D imaging experiments, compared with the traditional method, the mean RMS of 64 channels based on DOPM decreases from 99 to 65 mm, which decreases to 66%. Meanwhile, DOPM improves the range resolution and could distinguish two targets with height difference of 80 mm.