Automatic calibration of a scanner-based laser welding system

Abstract

In precision engineering scanners are widely used for laser beam positioning. Equipped with cameras, scanners enable process monitoring or even position recognition of the parts to be welded. To allow precise welding or position recognition, it is essential to calibrate a welding system. Instead of calibrating the whole system, most approaches only help to adjust the laser beam position. Consequently, the varying lateral offset between the laser's focus point and the camera's field of view, due to chromatic aberration of the scanner optics. cannot be compensated. Furthermore, these approaches require manual microscopic measurement of weld seams. which comes along with several downsides. This paper proposes two techniques for automatic calibration without these downsides by use of the system-incorporated camera. The first technique is the calibration at laser wavelength. To this end, the system automatically creates laser spots, evaluates their positions and possible offsets, and finally fits an affine model for compensation. The second technique is based oil a specially coded test pattern, which is used for calibration at camera wavelengths. Experimental results confirm the accuracy of the calibration obtained

A novel method for error verification of a handy laser scanner

“…Many industrial applications require accurate and rapid measurement of the 3D shapes of objects. The optical techniques for 3D shape measurement have been extensively studied and play an increasingly important role for various applications [1,2], such as quality control, archeology, virtual reality, industrial inspection, reverse engineering, etc. A predominant number of shape measurement equipment used in industry are contact based.…”

“…The requirement of physical contact leads to the following disadvantages [5,7]: (1) a high-resolution measurement of a large surface with a complex shape can be time consuming since it takes a long time for the probe to walk along the surfaces. (2) In cases that the surface of the object being measured is soft, fragile or easily scratched, contactbased techniques will not work or are not desired. (3) Contactbased techniques are indirect measurement.…”