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Femtosecond Laser

Recently, ultra-short femtosecond laser technology has been introduced in the market. The femtosecond laser’s smaller beam size allows the machining of very fine details, and it produces pulses that leave no thermal fingerprint on the part.   

A femtosecond is one quadrillionth, or one millionth of one billionth, of a second. In layman’s terms, a femtosecond is to a second as a second is to about 31.7 million years. It is the time taken by a ray of light to travel approximately 0.3 µm.

Femtosecond lasers are lasers with shortest pulse duration industrial marketplace.  Typically, industrial femtosecond lasers will have a pulse duration of 300-400 femtoseconds or 300-400 x 10-15 s.  When trying to produce a laser that delivers such short packets of light with sufficient pulse energy for processing materials, the peak power is so high that it would cause damage to the gain medium.  To avoid this, the pulse is usually amplified with a stretched pulse and is then later compressed. The process of chirped pulse amplification stretches the pulse by a few orders of magnitude. This reduces peak power and allows amplification to occur below the damage threshold of the medium.  After amplification, the pulse is then compressed back to its original pulse duration and beam quality. In some lasers, the initial requirement to stretch the pulse may not be required. The femtosecond laser can also be provided in different wavelengths from IR, green and UV (though UV is not available on every laser) via frequency conversion by non-linear optics.

The laser has a very short pulse duration which enables it to machine almost any type of material from glass to hardened steel and plastics.  As the pulse duration of the laser is shorter than the conduction time of the material, there is no heat signature from processing. The material removal is from solid to vapor, often referred to as “cold ablation”, which provides the highest quality machining and offer unique machining capabilities.

These disc-based femtosecond lasers offer sub-400 fs pulses, plus best-in-class beam quality and peak power. The result is in an extremely high-quality cold ablation cutting process, rather than a melt ejection process.

Therefore, the finished cut requires minimal post processing. In the past, femtosecond lasers were considered too slow for commercially viable laser cutting operations. However, recent studies that have evaluated cutting time per part and post processing steps have demonstrated that the return on investment for a disc femtosecond laser machine can be realized in as little as 12 months, especially for high-value components. 

Contact AMADA WELD TECH to find out how to implement a laser cutting system into your production process

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