Investigations into the accuracy of a pulsed time-of-flight ranging diagnostic sampled at discrete intervals applied...

A non-contact measurement of distance using light pulses is useful in a variety of applications. A time-of-flight measurement, where the time taken for the reflection and detection of an emitted light pulse is measured, is a conceptually simple way of determining the distance. The attainable accuracy of a time-of-flight measurement can be considered a parameter estimation problem, where the underlying parameters of the detected pulse need to be estimated from a number of measurements. The consideration of a single pulse is particularly relevant in applications such as explosively driven or high-speed impact experiments where velocities are large. This estimation problem was investigated considering a temporal Gaussian pulse sampled at fixed intervals to determine an expression for attainable uncertainty. Results are compared from maximum likelihood estimation analysis, a Monte Carlo model, and experimental measurements. The results from the different approaches are largely comparable and, furthermore, describe how the accuracy of a single-pulse time-of-flight measurement may be affected by variables such as sampling interval, pulse shape, and noise. Finally, time-of-flight measurements are conducted in a dynamic setting measuring a target moving at velocities of up to 300 m s^-1. The achieved uncertainties were similar to those predicted.