A new system for making dimensional measurements through a rigid borescope is described. Unlike commercially available systems, the random error in the measurement is proportional to the range to the object, rather than to the square of the range. The system requires only the addition of a video cursor generator, a computer, software, and a precision translator to any standard, substantially side-looking borescope. the system is implemented so that the user can effectively interpolate between camera pixels along the axis to which the measurement is most sensitive to pointing errors. Under ideal conditions, the relative positions of object points can be located in three dimensions to within 0.1 percent of the range, and the precision to which the 3D distance between points can be determined is several times better than that. Measurements of distances under field realistic conditions are demonstrated to have a precision of 0.4 percent of the range. In all cases, the systematic error in the measurement is demonstrated to be consistent with the level of precision.

Date Published: 31 March 1998
PDF: 13 pages
Proc. SPIE 3397, Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware II, (31 March 1998); doi: 10.1117/12.305062

Published in SPIE Proceedings Vol. 3397:
Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware II
Glenn A. Geithman; Gary E. Georgeson, Editor(s)