Deep 3D laser engraving technology
The technology can be applied for various materials processing. During the preparation stage, the 3D object drawing is divided to individual layers. Afterwards, layer by layer material ablation is introduced. The use of ultrafast laser pulses for processing ensures high processing quality and speed. Compared to nanosecond lasers, the short pulse – matter interaction time significantly reduces the thermal effects. The laser induced heat diffusion is limited at such pulse durations. Therefore, melt formation and oxidation of the surface are significantly reduced. Also burr formation is much lower compared to nanosecond laser processing. In the case of copper, 6 mm 3/min ablation rate is achieved. Materials: metals, semiconductors, ceramics, glass, polymers. 50 μm ablation precision is achieved.
FEMTOSECOND LASER INDUCED CHEMICAL ETCHING OF FUSED SILICA
During the past decades, the femtosecond lasers become a unique tool for 3D structures fabrication in different optical materials. Femtosecond lasers can space-selectively induce local modifications in any transparent materials due the strong nonlinear absorption. These internal modifications in fused silica cause the structural and chemical changes that can be selectively removed by immersing the samples to aqueous solutions of etchant such as hydrofluoric acid (HF) or potassium hydroxide (KOH) resulting in direct fabrication of the true 3D micro-devices inside transparent materials. The transparent materials plays crucial role due the ability of confined internal modifications and selective modified zone removing by chemical etching.
The processing of transparent materials such as fused silica or sapphire with conventional fabrication techniques or direct laser ablation have a limitation due the structure size and material thickness. The taper is involved and surface chipping due the accumulated stresses limits the quality of the final sample. The technology combining femtosecond lasers with chemical etching (Selective Laser Etching SLE) involves avoiding all mentioned drawbacks during the fabrication of high resolution structures in transparent materials. The etching selectivity from 100:1 to 10000:1 can be achieved depending on the transparent material and etchant used. That involves formation of high aspect ratio (>50:1) taper less holes, 2D free shape structures according the imported CAD drawing and embedded 3D microsystems involving optical, mechanical and fluid transportation properties in the single device.
SYNTHETIC DIAMOND OR CERAMIC MECHANICAL TOOLS TREATMENT
The laser processing of composite materials as well as cutting edge generation technology based on ultrashort laser pulses has drawn a lot of attention in the past few years. Ultra-hard materials processing such as polycrystalline diamond, natural diamond, tungsten carbide, and CERMET with picosecond pulses makes new opportunities in industrial world. The key parameters that are critical for industrial applications are processing time and processing quality.
Laser manufacturing is done with five axis CNC machine and scanner for beam translation with high speed and ultrashort ps laser source with high repetition rate. The cutting tools and cuttings inserts from Tungsten Carbide and CERMET materials were processed. To reach required 3D shape geometry the different scanning algorithms consisting of sliced structure were designed for investigate the both: optimised processing time and quality.
By varying the laser pulse energy, pulses overlap and layers count, different material removing rates can be achieved from 0.3 μm/layer to ~ 18 μm/layer. In such a way the depth of structures can be controlled with a high precision. The surface quality strongly depends on the used pulse energy and scanning parameters. It was shown that by adjusting processing parameters rough and smooth surfaces can be processed.