High-Resolution waveform acquisition and analysis for pulsed laser

In this paper we describe investigations for digital recording ofreceived laser pulses and a detailed analysis of the pulse waveform.An experimental system was constructed using an airborne laser scanningsystem and a receiver unit with a high-resolution sampling rate, which is above the sampling rate of current commercial lasersystems. Capturing the temporal waveform by simultaneous scanning of the scene delivers a data volume (space-time cube). Sucha data cube of the received signals allows exploiting different features without selecting a special feature or a measuring techniquein advance. For the main investigation a ground based sensor platform is used to measure the urban scene. Surface variations withinthe spatial beam width result in special waveforms. We explored the capabilities of analyzing the shape of the waveform forsurface features in form of distance, roughness, and reflectancefor each backscattered pulse. An iterative estimation algorithm (Gauss-Newtonmethod) is proposed to get a parametric description of the original waveform by a Gaussian. Single responses and morethan one response (multiple pulses) are investigated. Additionally, the data cube opens the possibility of considering neighborhoodrelations for space-time filtering or segmentation. Image slices extracted from the data cube were processed to estimateline segments for surface features. This has a significantadvantage: the estimated lines are not based on single range pointsreceived from a pulse detector which delivers more or less accurate range values, but they are based directly on the intensitydistribution of the backscattered signal. Since many values of theintensity distribution have contributed to each line segment, theaccuracy of location can be much better than the pixel dimensionof the image slice.     «

In this paper we describe investigations for digital recording ofreceived laser pulses and a detailed analysis of the pulse waveform.An experimental system was constructed using an airborne laser scanningsystem and a receiver unit with a high-resolution sampling rate, which is above the sampling rate of current commercial lasersystems. Capturing the temporal waveform by simultaneous scanning of the scene delivers a data volume (space-time cube). Sucha data cube of the received signals allows exp...     »