Polarimetric femtosecond-laser LiDAR for multispectral material probing

Abstract

Polarimetric LiDAR combines polarimetry and non-coherent optical ranging techniques to complement the acquisition of geometrical information with material characteristics. In recent decades, polarimetric LiDAR has been widely explored in material probing, target detection, and object identification. These approaches have so far mainly relied on implementations using a single or very few wavelengths. In this work, we propose, develop and evaluate a polarimetric femtosecond-laser LiDAR that enables extracting multispectral polarization signatures on 7 spectral channels of 40 nm spectral bandwidth and 33 spectral channels of 10 nm spectral bandwidth in the visible and near-infrared range. Multispectral polarization signatures of five material specimens (cardboard, foam, plaster, plastic, and wood board) are obtained and used as input features on a linear support vector machine classification algorithm. The results show that extending polarimetric probing to multiple spectral channels improves the classification capabilities with respect to single-wavelength approaches. The combination of different spectral signature dimensions (polarization, reflectance, and distance) that can be derived from Li-DAR measurements is also analyzed, with results indicating their capability to support challenging classification tasks.

Classification of material and surface roughness using polarimetric multispectral LiDAR

“…This relation was already used for classifying highly specular car paints and certain diffuse man-made and natural targets 25 . Our previous work on a novel polarimetric multispectral LiDAR also showed the relationship between DoLP and material specularity 26 …”

“…The polarimetric multispectral LiDAR 26 is adapted from the multispectral LiDAR prototype by setting a rotating linear polarizer (as analyzer) normalP2 in front of the probing APD. The polarization direction of the backscattered light can then be analyzed by measuring the optical intensities at the probing APD as a function of the rotation of the analyzer.…”

“…25 Our previous work on a novel polarimetric multispectral LiDAR also showed the relationship between DoLP and material specularity. 26 The physical basis for the polarimetric approaches was described and discussed by Wolff and Boult. 27 In a LiDAR system employing a linearly polarized laser source, the mechanism of light-matter interaction consists of two procedures: (1) specular reflections on the irregular surface microfacets, and (2) volume scattering of light penetrated into the target subsurface.…”

Instantaneous Material Classification Using a Polarization-Diverse RMCW LIDAR

“…Recovering polarization from received LIDAR signals can be accomplished with several methods [14,17,24], however, in this work, we use a polarization-diverse homodyne receiver, similar to the work in the digital self-homodyne receiver shown by Puttnam et al [25], but combining transmit circuit on the same chip as the receive circuit, which we call a bi-directional optical sub-assembly (BOSA).…”

Classification of material and surface roughness using polarimetric multispectral LiDAR

“…17 Our previous work on a novel polarimetric multispectral LiDAR also showed the relationship between DoLP and material specularity. 18 The physical basis for the polarimetric approaches was described and discussed by Wolff and Boult. 19 In a LiDAR system employing a linearly polarized laser source, the mechanism of light-matter interaction consists of two procedures: (1) single and multiple specular reflections on the irregular surface microfacets, and (2) volume scattering of light penetrated into the target subsurface.…”