The laser is delivered to the workstation by means of a flexible fiber optic cable or fixed mirrors. Typically the laser is delivered to the work piece at a low power density which requires focusing to enable materials processing. The focus is the tool which takes the “raw” laser beam and focuses to a small diameter typically less than 0.04” down to 0.0005”.
For Nd:YAG and fiber lasers there are a number of different types of focusing heads. Below shows a few options, including a schematic of a 90 degree focus head, showing the collimating lens, the 45˚ reflector, focusing lens and cover slide; a 90˚ focus head; and an in-line focusing head. Selection will be based on the application, space and budget.
A great benefit of using Nd:YAG and fiber lasers is that an in-line camera can be mounted to the focus head, providing a view of the weld area. This enables the operator to view the weld, provide a means for suing vision systems and can confirm that the laser is in focus on the part.