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The use of lasers in the processing of solar cell structures has been known for many years both for c-Si and thin-film solar technologies. The maturity of the laser technology, the increase in scale of solar module production and the pressures to drive down cost of ownership and increase cell efficiencies have all contributed to the adoption of laser processes in industrial manufacturing. Today laser systems are the tool of choice in thin-film module manufacturing both for scribing the cell interconnects and for the module edge isolation. For c-Si solar cells the primary laser application today is edge isolation and this is well-established in industrial production of most types of waferbased cells. Other laser processes are used in the production of advanced high-efficiency c-Si cell designs such as laser grooved buried contacts, emitter wrap-through or metal wrap-through interconnects, selective emitters and laser fired contacts. In the mission of the solar industry to reduce the cost of electricity generation there are increasing opportunities for laser processing to contribute to the goal of low cost of ownership in industrial manufacturing through improved module efficiencies, higher throughput and reduced process costs.

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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