Experimental validations of simulated scan patterns of rotational Risley prisms

Abstract

Laser scanners with Risley prisms have the potential to perform a faster scanning in comparison to other twodimensional (2D) laser scanners, for example galvanometer-based. However, in contrast to the (constant speed) raster scanning produced by the latter, scan patterns of Risley prisms are highly non-linear, have intersection points, and are performed with variable speeds. The aim of this study is to build upon the novel, graphical method we have, to our knowledge, introduced for the study of these scan patterns. In contrast to complex analytical methods and to approximate ones, this graphical method is easy-to-apply and it provides exact scan patterns, respectively. In this study examples of experimental results are obtained to validate simulation results obtained using simple prisms equations and a commercially-available mechanical design program, CATIA V5 (Dassault Systemes, Paris, France). Several characteristics of the laser scanner with a pair of rotational wedges are considered, with a focus on one of Marshall’s parameters, i.e. the ratio M of the rotational speeds of the prisms. An experimental validation is demonstrated for all characteristic graphs of the scan patterns for two pairs of values, M equals 2 or -2, as well as 8 and -8. The contrast between positive and negative values of M, as well as between lower and higher absolute values can be thus observed. As this is but a step in this study, directions of current work are also pointed out.