Laser Scanner Two-face Errors on Spherical Targets

Geometric misalignments within the construction of a laser scanner results in systematic errors in the measured point coordinates (range and angles). Many of these errors sources are sensitive to front-face back-face (two-face) measurements. We have previously investigated [1] the magnitude of two-face errors on one laser scanner using a manufacturer recommended target. Here, we expand on that work and plan on characterizing two-face behavior for different scanners using sphere targets. The ability to detect systematic errors is a critical step not only in modeling and removing these error sources but also in developing test procedures for the volumetric performance evaluation of these instruments. In this work, we plan on mounting a series of sphere targets on a vertical rail. We will then scan these targets using our laser scanner in both front face and again in the back face. We will compare the magnitude of the front-face to back-face differences to the noise limit, which we will separately determine using repeatability measurements performed on similar targets. We will then attempt to explain the nature of these two-face errors using geometric models for these instruments. We will perform similar measurements with other scanners that permit such front