Verification of wide-angle beam steering based on two- dimensional translation of objective lens, and design of relay optics to improve optical performances

Studies on light detection and ranging (LiDAR) sensors that minimize the movement of the driving unit and facilitate the realization of a wider field of view (FoV) have been actively developed. This study first confirmed possibility of a beam steering angle above 175 degrees being achieved through the biaxial movement of the objective lens via static optical experiments using a commercial fisheye lens with an image diameter of 4 mm in an optical setup without a relay optical system. In addition, the detection possibility of a signal from an object, either a reflector or a scattering object, using the same light path as the beam steering optical path was verified. Thereafter, an attempt was made to design relay optics capable of reducing divergence angle and deviation in light transmission efficiency over the entire range of beam steering angles. The proposed design with an FoV of 170 degrees, resulted in a reduction of the divergence angles and deviation in light transmission efficiency less than 0.05 degrees and 1 %, respectively. Finally, using the designed optical system, a non-sequential ray-tracing-based return signal strength simulation was performed to verify the ability of the designed optics in properly detecting shape and object distance of a vehicle model placed 100 m ahead of the sensor, over the entire range of beam steering angles.

Automated summary

This study confirmed the possibility of achieving a beam steering angle above 175 degrees through the biaxial movement of the objective lens, without the use of a relay optical system. It also verified the detection possibility of a signal from an object using the same light path as the beam steering optical path. A relay optics design was then proposed to reduce divergence angle and deviation in light transmission efficiency, resulting in improved performance. Finally, ray-tracing simulations were performed to verify the ability of the designed optics in properly detecting shape and object distance.