solutions 1/2008 – Additional informations

Source: SCHOTT/W. Feldmann
Special manufacturing of micro-lenses

The many individual emitters arranged on a single component of a diode laser deliver a beam that is highly divergent. In order to align them in a parallel manner, aspherical lenses made of specialized optical glass are used. These FAC (Fast Axis Collimation) lenses represent the first optical interface between the laser and the application process. They influence the beam quality that is extremely important to material processing and must, therefore, offer excellent optical characteristics.

For this reason, SCHOTT researchers have developed a reproducible manufacturing technology that is completely unique in the world today. The micro-rod lenses are produced in large volumes using a special precision glass molding. Rather than drawing them as usual from a long, drawn-out glass fiber and then cutting them, they are embossed in heated glass plates and sawed out, once they have cooled off. The starting materials are highly refractive, low Tg glasses with a maximum transformation temperature (Tg) of 550 degrees Celsius. These allow for significantly lower temperatures during pressing, the pressing molds that are exposed to considerable stress last longer and the process intervals can be shortened. In this way, products that offer the same constantly high quality can be produced. In addition, holding clamps made of glass make it easier to mount the lenses that can be inserted rather easily. ”Due to the fact that virtually no production tolerance exists in lens manufacturing, very few readjustments need to be made. Laser manufacturers save time and money,” assures Steffen Reichel, Manager for New Products at schott Advanced Optics.