We propose and demonstrate an overall nonmechanical spectrally steered laser rangefinder using the dispersion-tuned swept laser (DTSL) and a passive diffractive element. The DTSL has no mechanical moving parts, making it possible to achieve an inertial-free high wavelength sweeping speed. The inherent intensity-modulation characteristic of the DTSL allows the modulation phase-shift method to be applied, similar to that used for an amplitude-modulated continuous-wave (AMCW) rangefinder. Since the pulse repetition rate of the DTSL is chirped, standard signal processing techniques for AMCW are not applicable. In this paper, we propose a novel chirped amplitude-modulated phase-shift (CAMPS) method with a signal processing technique to obtain the phase-shift information from a chirped amplitude-modulated signal. As a proof of concept, we demonstrated the CAMPS LiDAR with an axial ranging resolution of ~50 μm at a scanning speed of 10 kHz.
I. INTRODUCTIONLaser detection and ranging (LiDAR) is a laser-based technology for distance measurement with the reflected light from the object under measurement [1], [2]. In recent years, with the advent of Industry 4.0, LiDAR that can measure the distance as well as the surface shape of the objects has attracted significant research interests as a promising technology for emerging 3D imaging applications such as autonomous driving [3]-[6], intelligent mobile robot navigation [7]-[9], and smart factory [10], [11]. Amongst the demanding requirements on the range, spatial resolution, compactness, and cost, the LiDAR beam scanner is an essential part of expanding a single-point range-finding measurement to a multi-dimensional mapping by steering the beam to the direction of interests. Most of the current LiDAR systems are based on optical elements driven by electromechanical devices, such as galvo scanners [12], polygon mirrors [13], Risley prisms [14], [15], or Microelectromechanical systems (MEMS) [16], [17]. These mechanical devices have limited steering speeds due to inertia, and are usually costly, bulky,
