Reconfigurable optical time delay array for 3D lidar scene projector.

3D lidar scene projector (LSP) plays an important role in the hardware-in-the-loop (HIL) simulation for autonomous driving system (ADS). It generates a simulated 3D lidar scene in laboratory by generating a 2D array of optical time delay signals. The reconfigurable optical time delay array (ROTDA) is crucial for LSP. However, current ROTDA solutions cannot support a LSP with a spatial resolution more than 10×10. In this paper, we proposed a novel ROTDA design based on the time slicing method. The optical signals with the same time delay but different spatial coordinates were treated as one time slice. Different time slices were superimposed into a composite image by a microlens-array-based imaging system to obtain a 3D lidar scene. And a spatial light modulator (SLM) was utilized to configure the time delay of each lidar scene pixel. We developed a ROTDA prototype with 64×64 pixels, each pixel can be reconfigured with up to 180 different time delays in one frame. The time delay resolution is 1 ns, the maximum time delay is 5000 s, and the 3D frame rate is 20Hz. The prototype can generate a continuous lidar scene with a distance span of 27 m, and can also generate up to 8 short scenes that are separated from each other along the lidar observation direction, each short scene covers a distance span of 3 m or 3.75 m. The design method proposed in this paper can also be applied to other occasions that demand a large number of time delay generators.