The ASTM E57.02 Test Methods Subcommittee is developing a test method to evaluate the ranging performance of a 3D imaging system. The test method will involve either measuring the distance between two targets or between an instrument and a target. The first option is necessary because some instruments cannot be centered over a point and will require registration of the instrument coordinate frame into the target coordinate frame. The disadvantage of this option is that registration will introduce an additional error into the measurements. The advantage of this option is that this type of measurement, relative measurement, is what is typically used in field applications. A potential target geometry suggested for the test method is a planar target. The ideal target material would be diffuse, have uniform reflectivity for wavelengths between 500 nm to 1600 nm (wavelengths of most commercially-available 3D imaging systems), and have minimal or no penetration of the laser into the material. A possible candidate material for the target is Spectralon1. However, several users have found that there is some penetration into the Spectralon by a laser and this is confirmed by the material manufacturer. The effect of this penetration on the range measurement is unknown. This paper will present an attempt to quantify the laser penetration depth into the Spectralon material for four 3D imaging systems.

Date Published: 19 January 2009
PDF: 10 pages
Proc. SPIE 7239, Three-Dimensional Imaging Metrology, 723909 (19 January 2009); doi: 10.1117/12.804929

Published in SPIE Proceedings Vol. 7239:
Three-Dimensional Imaging Metrology
J. Angelo Beraldin; Geraldine S. Cheok; Michael McCarthy; Ulrich Neuschaefer-Rube, Editor(s)