Because of its high range and resolution, light detection and ranging (LIDAR) is a significant technology for numerous applications, such as autonomous vehicles, robotics, aerial or terrestrial mapping, and atmospheric research. Current lidar market is mainly occupied by conventional pulsed time of flight lidars. However, recently emerging companies are utilizing frequency modulated continuous wave lidars for improved and robust range resolution, dynamic range, sensitivity and simultaneous velocity measurement. Here, we propose and demonstrate multi-tone modulated continuous wave (MTCW) lidar system made of a CW laser with multiple fixed RF tones for a high precision range finding and velocimetry. In the proposed approach, the interference of the scattered light with the reference is detected by a PIN photodiode to extract the modulation information. Since, the acquired light is traveled all the way to the target and back to the beam splitter, it carries the range and velocity information about the target as phase and frequency shift, respectively, on the RF modulation tones. We use 1550nm light source and multiple RF tone modulations ranging from 50 MHz to 6 GHz to demonstrate proof of principle for range finding. We also provide sine fitting algorithms on the measured RF tones to extract the range and velocity information in a single shot RF measurement. We show that the precision and range information are scaled by the selection of RF tones. By an engineered selection of RF tones and a laser source, the measurement precision can be increased without compromising the range.
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