Principles of picosecond lasers and their applications

2021-12-27 15:55:46

     The advantages of laser excision of ultrashort laser pulses have been demonstrated in many applications, and until recently no industrial by-products of these applications have been found on the factory floor. In industrial applications, in addition to quality factors, reproducibility and cost per part are also important criteria. 

     The reliability of laser systems is of course directly linked to the laser technology used. The cost of each component is basically directly related to the repetition rate of ultrashort laser pulses. High added value, high repetition rate productivity, reliable technology, etc. All these requirements are only recently accomplished with diode-pumped picosecond lasers.

     The first application of picosecond lasers in mass production was reported at The Photonics West 2005. Pulses of 1 μJ of 20ps pulse duration are focused onto thin steel foil, and a series of concentric rings are removed in the direction of the pulsed beam. Different concentric rings form a garden disc, and the different discs of removed material form a tapered hole that acts as a nozzle for injecting ink in a professional high-quality printhead. Over the past few years, the vast majority of ultrafast laser manufacturers have focused on the development of femtosecond lasers. These lasers require a sophisticated CPA technique to maintain peak power density within an amplification step at a certain damage threshold. In this way, the pulse energy at the mJ level can be generated, but the repetition rate is limited to a few KHZ. In comparison, a high pulse energy of a few hundred μJ is advantageous for drilling or cutting thick materials. An example is the drilling of the diesel engine injection nozzle, where the 1mm thick steel sheet material has to be so precisely punched that no further cleaning process is required.