Ranging and Three-Dimensional Imaging using Time-Correlated Single-Photon Counting

摘要

Time-correlated single-photon counting techniques have been applied to time-of-flight ranging and imaging. This paper will describes recent progress in photon-counting systems performing surface mapping of non-cooperative targets. This includes systems designed for short ranges of the order of 1-50 meters, as well as measurements on distributed targets at longer ranges of the order of 100 meters up to ten kilometers. We describe the measurement approach, techniques used for scanning, as well as the signal analysis methodology and algorithm selection. The technique is fundamentally flexible: the trade-off between the integrated number of counts against range repeatability, or depth resolution allows its application in a number of diverse fields. The inherent time gating of the technique, allied to the spatial filtering provided by small active area single-photon detectors, can lead to operation under high ambient light conditions even with low average optical power pulsed sources. We have demonstrated three-dimensional imaging of meter-dimensioned objects where reverse engineering methods using cooperative targets cannot be routinely employed: e.g. mechanically delicate objects, or objects with more than one reflective surface. Using more advanced signal processing algorithms, we have been able to improve the system performance markedly, as measured by the depth resolution at short and long ranges. Furthermore, the application of these methodologies has allowed us to characterize the positions and amplitudes of multiple returns. Hence, the approach can be used for characterization of distributed non-cooperative targets at kilometer ranges, even in environments where low-light level and and/or eye-safe operation is necessary.