In time-of-flight based laser scanners, measurable distance and accuracy are the most important parameters to determine performances. The optical system of the laser scanner should be optimally designed since a high intensity of measured signal increases the measurable distance and accuracy. Therefore, it is important to understand how the optical component layout affects the laser scanner performances. Optical component design for co-axial and bi-axial mechanisms are considered in the paper.
In the phase-shift based lidar system, a distance between the lidar and an object can be determined via the phase difference between the reference signal and measured signal. The maximum unambiguous range for the phase-shift based lidar is inversely proportional to the modulation frequency of the signal. When the modulation frequency is increased for high distance resolution, the unambiguous range is decreased. In this paper, we described a method to extend the unambiguous range of the lidar, which is a considerable disadvantage of the phase-shift measurement method. In addition, we propose a method for implementing dual frequencies modulation technique with two laser diodes.