Non-diffracting beam based probe technology for measuring coordinates of hidden parts

A probe technique based on non-diffracting beam was proposed. The probe was combined with a total station or a laser tracker to form a combined measuring system that realized the coordinate measurement of hidden parts in large spaces. In the combined measurement system, the probe stylus was first set to touch the point of measurement, and the optical system of the probe was targeted by the total station or the laser tracker. This was used to measure the spatial coordinates of the probe. The probe transformed the laser that was used to measure distance into a non-diffracting beam through the axicon lens, and non-diffracting images were produced in CCD plane. The center of the non-diffracting beam mapped one to one to the incident direction of the laser, and the horizontal angle the probe were obtained via center fitting of the non-diffracting images. The inclinometer was used to measure the rolling angle and the pitching angle of the probe. Finally, all the measured attitude angles and position coordinates were combined and coordinate transformation was used to calculate the spatial coordinates of the measured point. Our results show that the probe could achieve milliradian-level precision when measuring the attitude angles, demonstrating more flexibility and reliable precision during combined measurement. (C) 2012 Elsevier Ltd. All rights reserved.