Fast differential discrimination approach to improve time resolution with multiple returns for time-of-flight system

A differential discrimination approach has been proposed in this paper to make fast discrimination from multi-returns in time-of-flight (TOF) systems. The time resolution of classical direct discrimination in a laser TOF system has been analyzed. A theoretical model of the differential discriminator has been established. As theoretical calculations and numerical simulations have shown, time resolution can be improved by using a differential discriminator instead of a classical direct discriminator, especially with large-amplitude signals. However, the relationship between the time resolution and the amplitude is not monotonic. The time resolution decreases as the amplitude decreases when the signals are small. But, through further analysis and simulations, a method to find an appropriate parameter, which can optimize the relationship curve, has been proposed. The theory and the simulations were verified by electrical circuit experiments, and the optical circuit experiments taken with two close targets of about 8.3 m. The FWHM of the laser is about 1.9 ns. The measured time resolution was better than 2.2 ns when the amplitude is 30 mV.