Estimating laser scanner’s effective laser beam footprint using line spread function

Abstract. Accurate characterization of the terrestrial laser scanner (TLS) beam footprint is essential for understanding the stochastic behavior of the scanner. Estimating the laser footprint is crucial for determining the correlation length between neighboring observations, and thus for providing a realistic estimation of the correlation elements within the variance-covariance matrix quantifying the measurement uncertainties. In this contribution, an intensity-based workflow is introduced to estimate the effective laser beam footprint by deriving the line spread function (LSF) from the edge spread function (ESF). This effective laser beam footprint depends on the dynamic surface response over the interaction region between the emitted laser beam and the surface. The proposed method applies no assumptions regarding the geometric or physical behavior of the beam, allowing the footprint to be determined directly from the measured intensity values. Using the BOTA8 target, the Z+F Imager 5016A was investigated at two different distances and two scanning rates with varying mirror rotation speeds. The results provide insights into the influence of distance and scanning rate on the effective laser beam footprint.