Ultrashort-pulse laser machining (original) (raw)

Ultrashort-pulse laser machining of dielectric materials

Journal of Applied Physics, 1999

There is a strong deviation from the usual 1/2 scaling of laser damage fluence for pulses below 10 ps in dielectric materials. This behavior is a result of the transition from a thermally dominated damage mechanism to one dominated by plasma formation on a time scale too short for significant energy transfer to the lattice. This new mechanism of damage ͑material removal͒ is accompanied by a qualitative change in the morphology of the interaction site and essentially no collateral damage. High precision machining of all dielectrics ͑oxides, fluorides, explosives, teeth, glasses, ceramics, SiC, etc.͒ with no thermal shock or distortion of the remaining material by this mechanism is described.

Advantages of Picosecond Laser Machining for Cutting-Edge Technologies

Physics Procedia, 2013

The demand to reduce the size, weight and material cost of modern electronic devices results in a requirement for precision micromachining to aid product development. Examples include making smaller and more powerful smartphones with brighter displays, eliminating the requirement for post-process cleaning and machining the latest bioabsorbable medical stents. The pace of innovation in high-tech industries has led to ultrafast (picosecond) industrial lasers becoming an important tool for many applications and the high repetition rates now available help to meet industrial throughput levels. This is due to the unique operating regime (megawatts of peak power) enabling clean cutting and patterning of sensitive materials and thin films used in a number of novel devices and allows micromachining of wide such as glass.

Highspeed Laser Micro Processing using Ultrashort Laser Pulses

Journal of Laser Micro / Nanoengineering

This paper discusses results obtained in highspeed laser micro processing of zirconium oxide ceramic and stainless steel. High-PRF (pulse repetition frequency) femtosecond laser systems were joined together with fast galvanometer scanner systems. A high average laser power (31.7 W) and fast scan speeds (17.1 m/s) were applied in order to increase material removal. The influence of average laser power, laser energy and repetition rate on both the volume ablation rate and the machining quality was studied. The maximum volume ablation rate for zirconium oxide was 70.3 µm³ per pulse, obtained with pulses of 5.9 µJ energy and 1.02 MHz. It is demonstrated that material removal on zirconium oxide will be strongly affected by heat. Stainless steel was irradiated with a maximum laser power of 31.7 W and various repetition rates. The maximum material removal rate was found to be 6.8 mm³ / min, achieved with laser pulses of 0.85 J/cm² fluence. The feasibility of the highspeed laser technology ...

New Method for Nanosecond Laser Machining

Journal of Laser Micro/Nanoengineering, 2012

The technique of micro-machining assisted by laser is the most recent and flexible process for the design of complex devices. To be able to micro-machine hard materials with precision it is necessary to study the parameters that control and limit the capabilities of this laser process. Several articles have shown that if it applies a lot of energy in a localized area there are hot-affected zones (HAZ), even when a femtosecond laser is used. Hence, the challenge in the laserbased micromachining is to improve the quality of machining, i.e. depleting the HAZ in the prototypes. In this work, changing the optical properties of the substrate, good quality silicon micro-machining has been obtained with a nanosecond Q-switched laser.

How to optimize ultrashort pulse laser interaction with glass surfaces in cutting regimes?

Applied Surface Science, 2015

The interaction of short and ultrashort pulse laser radiation with glass materials is addressed. Particular attention is paid to regimes which are important in industrial applications such as laser cutting, drilling, functionalization of material surfaces, etc. Different factors influencing the ablation efficiency and quality are summarized and their importance is illustrated experimentally. The effects of ambient gas ionization in front of the irradiated target are also analyzed. A possibility to enhance laser coupling with transparent solids by biwavelength irradiation is discussed.

High-PRF Ultrashort Pulse Laser Processing of Copper

2014

This paper presents results obtained in high-PRF (pulse repetition frequency) ultrashort pulse laser micro processing of copper. In the study, a variety of ultrashort pulse laser systems supplying high average laser power were applied in order to investigate the influence of the laser parameters on copper ablation. For this, laser pulses of different wavelengths (VIS, NIR) and pulse durations, ranging between 200 fs and 10 ps, were irradiated to the sample surface by raster scanning of the laser beam. The dependencies of average laser power, pulse energy, and the pulse repetition rate on the ablation rate, the ablation efficiency, and the productivity were studied. A maximum average laser power of 31.7 W was applied in this work. The pulse repetition rate was varied in the rage between 0.2 MHz and 19.3 MHz. Finally, the machining qualities obtained were evaluated by means of surface roughness measurements and SEM micrograph analysis.

Picosecond laser machining of tungsten carbide

International Journal of Refractory Metals and Hard Materials, 2020

Hard materials such as tungsten carbide (WC) are extensively used in cutting tools in high-value manufacturing, and the machining of these materials with sufficient speed and quality is essential to exploit their full potential. Over the last two decades, short (nanosecond (ns)) and ultra-short (picosecond (ps); femtosecond (fs)) pulse laser machining has been evaluated by various researchers and proposed as an alternative to the current state-of-theart machining techniques for advanced materials like WC, which include mechanical grinding and electrical discharge machining. However, most of the established/existing research on this topic is based on low power lasers, which may not be adopted in industrial production environments due to its low material removal rate. This paper presents the results of a fundamental study, on using a 300 W picosecond laser for the deep machining of tungsten carbide. The influence of various laser parameters on the geometric precision and quality (surface and sub-surface) of the ablated area was analysed, and the ablation mechanism is discussed in detail. Laser pulse frequency and scanning speed have minimal effect on ablation rate at high power levels. The surface roughness of the ablated area increases with the ablation depth. At optimal conditions, no significant thermal defects such as a recast layer, micro crack or heat affected zone were observed, even at a high average power of 300 W. The material removal rate (MRR) seems to be proportional to the average power of the laser, and a removal rate of around 45 mm 3 per minute can be achieved at 300 W power level. Edge wall taper appears to be a significant issue that needs to be resolved to enable industrial exploitation of high power ultra-short pulse lasers.

Deterministic processing of alumina with ultrashort laser pulses

Journal of Applied Physics, 2007

Ultrashort pulsed lasers can accurately ablate materials which are refractory, transparent, or are otherwise difficult to machine by other methods. The typical method of machining surfaces with ultrashort laser pulses is by raster scanning, or the machining of sequentially overlapping linear trenches. Experiments in which linear trenches were machined in alumina at various pulse overlaps and incident fluences are presented, and the dependence of groove depth on these parameters established. A model for the machining of trenches based on experimental data in alumina is presented, which predicts and matches observed trench geometry. This model is then used to predict optimal process parameters for the machining of trenches for maximal material removal rate for a given laser.