In recent years, the demand for highly integrated and lightweight components has been rising sharply, especially in plastics processing. One strategy for weight-saving solutions is the development of conductive tracks and layouts directly on the polymer housing parts in order to be able to dispense with the system integration of additional printed circuit boards (PCB). This can be conducted very advantageously and flexibly with laser-based processes for functionalizing polymer surfaces. In this work, a three-step laser-based process for subsequent selective metallization is presented. Conventional injection molded components without special additives serve as the initial substrate. The Laser-Based Selective Activation (LSA) uses picosecond laser pulses to activate the plastic surface to subsequently deposit palladium. The focus is on determining the amount of deposited palladium in correlation to the laser and scan parameters. For the first time, the dependence of the metallization result on the accumulated laser fluence (Facc) is described. The treated polymer parts are characterized using optical and scanning electron microscopy as well as a contact-type profilometer.
Subsurface damage (SSD) induced during conventional manufacturing of
optics contributes mainly to a reduction in the performance and
quality of optics. In this paper, we propose the application of
full-field optical coherence tomography (FF-OCT) as a high-resolution
and nondestructive method for evaluation of SSD in optical substrates.
Both ground and polished surfaces can be successfully imaged,
providing a path to control SSD throughout the entire optics
manufacturing process chain. Full tomograms are acquired for
qualitative and quantitative analyses of both surface and SSD. The
main requirements for the detection of SSD are addressed. Data
processing allows the removal of low-intensity image errors and the
automatic evaluation of SSD depths. OCT scans are carried out on
destructively referenced glass samples and compared to existing
predictive models, validating the obtained results. Finally, intensity
projection methods and depth maps are applied to characterize crack
morphologies. The experiments highlight differences in crack
characteristics between optical glasses SF6 and HPFS7980 and
illustrate that wet etching can enhance three-dimensional imaging of
SSD with FF-OCT.
The growing interest in providing additional degrees of freedom to the design of high-end optical systems has led to an increased demand for freeform optical elements. The efficient fabrication of such elements requires a polishing process that provides high removal rates and a stable removal function while working with a relatively small spot size. Taking these constraints into consideration this paper focuses on the successful implementation of polishing processes applying the A-WPT (Advanced Wheel Polishing Tool) technology. Addressing the requirements regarding its removal characteristics as mentioned before, it represents an appropriate choice for providing an efficient pre-polishing as well as corrective polishing technique. In order to maintain perpendicularity towards the freeform surface to be polished, the A-WPT is run on a 5-axis simultaneous machining system. First investigations of the achieved surface accuracy after pre-polishing were carried out as well as an assessment of residual surface features within different spatial frequency regions. In addition, the polished surface is being checked for remaining SSD using an OCT technique.
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