It is now ten years since Rofin-Baasel Lasertech invented the sweet spot resonator®, and in doing so set a new standard in the development of solid state laser sources.
This patented resonator technology provides excellent pulse-to-pulse stability combined with a large depth of field. Today, a new third generation system now extends the sweet spot resonator technology into the 200 W average power range.
First- Pulse Effect Eliminated
Excess heat inside a YAG rod which is water cooled on the outside (a standard feature of Nd:YAG lasers), creates a “thermal lens” which is influenced by the average power level. This induced thermal lens changes the divergence of the laser beam which can lead to a variation in spot size and penetration depth during the course of a seam weld. ROFIN's patented sweet spot resonator® ensures that the characteristics of the first laser pulse are the same as the last thus eliminating any variation in weld penetration depth and creating a more even weld profile.
Consistent and Predictable Manual Welding
The pulse-to-pulse stability and large depth of field, both key features of the sweet spot technology, enable excellent results to be obtained in manual welding applications. The extraordinary beam quality produced by this technology means that the weld quality is not wholly dependent upon exact positioning of the part within the focal point of the beam - a decisive advantage for hand welding applications. Another area where the sweet spot resonator® technology has proved to be especially effective is in the field of processing highly reflective materials such as copper, gold and silver. These materials are commonly used in jewellery production and the dental industry, where laser welding is fast becoming the preferred method of joining. In addition, Rofin’s sweet spot resonator® technology allows processing of the finest and most delicate components with weld spot diameters smaller than 100 μm using Rofin’s MicroWeldTM function.
Sweet Spot Resonator® Benefits Extend to New Application Areas
Seam welding applications on sheet metal is one area where the advantages of the sweet spot resonator® can be clearly seen. The consistency and predictability of the process, achieved from the excellent beam quality, vastly reduces the setup and development times normally associated with welding on thin metal components. The high pulse-to-pulse stability produced also ensures process reliability. This is particularly important on components such as medical devices and implants where fine tolerances and high quality must be achieved on each and every part.
This latest extension of the sweet spot resonator technology into the 200 W power range means that it can now be applied to many new areas. Applications such as aluminium welding or sealed membrane welding of pressure sensors will now benefit from the sweet spot resonator® technology, variable pulse shaping and extremely precise parameter adjustment. In addition, the availability of 200 W of power will be highly beneficial in high volume production applications.
The efficiency of this technology enables 200 W of laser power to be produced using one single, new generation, flashlamp which also offers a considerably longer life time. This is also highly beneficial for the ongoing maintenance of the system as only one lamp has to be replaced, thus reducing operating costs in comparison to the more commonly used two lamp resonators in this class of laser.
StarWeld Integral Includes Sweet Spot Resonator®
The new StarWeld Integral provides 200 W average laser power with all benefits of the new sweet spot resonator® technology. The StarWeld Integral system offers a unique and innovative welding concept - the ability to be used in three distinct operational modes:
• As a manual welding laser having excellent ergonomic design
• As a joystick-controlled deposit welding laser
• As a high-precision CNC laser welding system
Incorporating up to four high-precision positioning axes, with short set-up times and easy CNC programming, users can select as much automation as they desire, and perform the minimum of programming necessary. The large working chamber provides space for objects with an edge length of up to 500 mm. Motorised X,Y and Z axes are designed to move work pieces with a maximum weight of up to 500 kg quickly and precisely in all three planes, allowing rapid and accurate positioning of parts, from the most delicate to a heavy load. In addition, a patented optical system can be swivelled around two axes to enable processing of vertical surfaces, undercuts or deep grooves without the need to swivel or tilt the work-piece.
This wide range of features combined with its flexibility of operation make the Integral ideally suited to practically all laser welding applications in precision engineering, electronics, thin sheet processing and the tool and mould industry.