Simultaneous distance and vibration mapping of FMCW-LiDAR with akinetic external cavity diode laser

In this study, the simultaneous distance and vibration mapping of frequency-modulated continuous-wave light detection and ranging (FMCW-LiDAR) is performed using an electro-optical external cavity diode laser (ECDL). Owing to the akinetic operation regime of the ECDL, a uniform (R2 = 1.0000) interference signal can be generated over a bandwidth of 1 GHz at an optical frequency sweep rate of 10 kHz without any postprocessing or system for linearization. Furthermore, the proposed ECDL exhibits a high optical frequency sweep rate of 200 kHz with a considerable linearity of R2 = 0.99975. Based on a point sensing experiment using the FMCW-LiDAR system, three measurands, namely, distance, vibration frequency, and vibration velocity change, are demonstrated with a highly linear relationship between the beat frequency and amplitude of each individual parameter. Furthermore, temporal variations in multiple targets with rapidly frequency-varying vibrations, such as those occurring in music or voice sounds, can be successfully acquired by tracking the temporal change in the beat frequency of each target. Moreover, three-dimensional (3D) mapping of distance, vibration frequency, and vibration velocity change is simultaneously implemented in the same 3D space. The results show that the proposed FMCW-LiDAR system can be used for the 3D visualized display of various measurands within the same space frame.