Improving Lidar Depth Resolution with Dither

Using detector arrays can speed up lidar systems by parallelizing acquisition. However, current SPAD arrays have time bins longer than typical laser pulse durations, resulting in measurement errors dominated by quantization. We propose an optical time-of-flight system that uses subtractive dither to improve image depth resolution. Modeling the measurement noise with a generalized Gaussian distribution further improves estimation error in simulations, although model mismatch prevents the same advantage for our experimental data. Experimental results with the ratio of laser pulse standard deviation to quantization bin duration equal to 0.15 and using an average of 267 photons per pixel show a reduction in RMS error as large as 9-fold over estimates from coarsely quantized data.