Ultra-fast laser in micromachining have a reputation of highest precision and quality, which justifies additional invest in numerous applications. However, deficits in the synchronization of the positioning of beam deflection device and laser triggering -in particular at high repetition rates- still lead to defects like overtreatment due to the inertia of the mirrors of galvanometer scanners or path deviations at complex shapes. This in turn has led to an increasing demand of advanced pulse to pulse control for precise laser energy deposition. Two recent innovations have the potential to overcome these current limitations. Firstly, the scan ahead feature allows to calculate the actual beam position in acceleration and deceleration mode. According to the precise position feedback the control needs to adjust the repetition rate of the laser source e.g. at rectangular corners of a scan trajectory. Therefore, the pulse on demand feature at the laser interface is obligatory to dynamically adjust the pulse to pulse delay in order to accomplish constant energy deposition at any programmed scan pattern. We have put these two innovations to a test by combining an Excelliscan from Scanlab with an UV Tangor laser from Amplitude to validate the synchronization and constant pulse separation at various scan speeds and geometrical patterns. Applications trials like engraving with scan speed are presented in comparison to conventional scanning techniques to demonstrate the benefit of the fast synchronization and pulse on demand technologies.
Ultra-short pulse laser (UPL) industry is counting on high power P sources (100W class) to increase the throughput of a wide variety of industrial fabrication process. Nevertheless, this poses the challenge to overcome heat accumulation phenomena observed when P exceeds few tens of Watts compromising the machining quality. Novel beam engineering strategies are required to tackle this issue and guarantee high throughput with the high, distinctive, UPL machining quality. Here a study is reported on a variety of laser processes carried out with 100W class femtosecond lasers following two possible beam engineering strategies i.e. beam scanning with high speed (both a 100 m/s polygon scanner head and a 2D, 20 m/s fast, galvo-head) and parallel processing with multiple beams (obtained with both a DOE and an SLM head). Results show that by increasing P from few to 100 W also the throughput increases by nearly a factor 10 for micro-cutting (with galvo head and DOE) and even higher for surface texturing (with polygon scanner) while the machining quality is kept unchanged. Furthermore, we optimised the use of an SLM head for precise micro drilling of matrix holes showing the benefit of this technological approach in term of throughput. A full characterisation of the results carried out via optic and electronic microscopy will be also reported. We believe that all these results further increase the USP laser technology effectiveness level which is primed for industrial applications.
Femtosecond lasers have been proved to be an effective fabrication tool to process with high machining quality and negligible thermal effects a wide variety of materials. However, the system technology enabling fast and precise scanning on the workpiece, currently limits the average power of these laser sources to less than 10 Watts of average power in most industrial application. To overcome this limitation, a proportional up-scaling of both, the laser repetition rate and scan speed is needed, demanding for faster scanning technologies. Recently, rugged, femtosecond lasers delivering pulses with repetition rates of several MHz and pulse energy up to some hundreds of μJ have been introduced to the market. In parallel, the development and commercialization of novel galvanometric scanner heads, enabling scan speeds well above 10 m/s is ongoing. Here we explored the capabilities of a novel set-up consisting of an industrial femtosecond laser delivering 100 W with a repetition rate up to 13 MHz coupled with an innovative galvanometric scanner head enabling scan speeds up to 30 m·s-1. On stainless steel, we carried out engraving tests with both single line grooving and multiple surface raster scanning. By systematic variation of repetition rate and pules overlap we investigate how the machining quality and the ablation rate depend on the average laser power at different fluence levels. Heat accumulation effects are evaluated via Scanning Electron Microscope. Finally, we show how to scale-up the cutting of a 500 μm thick stainless-steel part varying the scan speed from 1 m·s-1 to 20 m·s-1.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.