Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Please note that all times are shown in the time zone of the conference. The current conference time is: 4th Aug 2021, 02:38:39am CEST

Program for LiM 2021
Micro: Processing of Transparent Materials 2
Thursday, 24/June/2021:
2:45pm - 4:00pm

Session Chair: Dr. Kristian Cvecek, Institute of Photonic Technologies (LPT), Germany
Location: Room 3
ICM Ground Floor 125

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2:45pm - 3:00pm

Deep engraving of fused silica glass using bursts of femtosecond pulses with intra-burst frequencies in the range of 25 - 100 GHz

Simas Butkus1,2, Martynas Barkauskas1,2, Aurimas Augus1, Martynas Kojelis1, Jonas Pocius1, Linas Giniūnas1

1Light Conversion, Lithuania; 2Laser Research Center, Vilnius University, Lithuania

Due to the high precision offered by ultrashort pulse micromachining, femtosecond laser systems are applied in both industrial and scientific fields. To accompany the needs of the industry, a trend towards high average power (>100 W) femtosecond laser systems for micromachining has become apparent. However, upscaling the micromachining throughput is not straightforward and typically results in a decrease in the micromachining quality. To this end, new ideas are sought to increase the efficiency of an ablation-based process.

In this work we present data on deep engraving of fused silica glass using burst of femtosecond pulses with a custom-built laser capable of tuning the intra-burst temporal gap producing a variable effective repetition rate of 25 – 100 GHz. By adjusting the average power, number of sub-pulses within the burst and the intra-burst gap it was found that the ablation efficiency can be increased by several-fold as compared to the convention single-pulse regime.

3:00pm - 3:15pm

Fully reflective Bessel beam generation with constant energy distribution over the propagation axis for complex glass cutting

Siddharth Sivankutty, Antonin Billaud, Gwenn Pallier, Pu Jian, Olivier Pinel, Guillaume Labroille

Cailabs, France

Glass cutting with femtosecond lasers is spreading led by the touch panel displays development. Bessel beams are very efficient and precise way to process glass thanks to their extended depth of focus 100 times longer than a standard Gaussian beam and their central beam which can be smaller than the diffraction limit.

High quality glass cutting with a reflective axicon has already been demonstrated with no oscillations leading to cleaner cuts and faster processes. The beam is able to propagate through a galvo-scanner and a F-theta lens. The reflective design is compatible with extreme high peak and average power.

Here we describe the generation of a complex Bessel beam profile flatter over the propagation axis based on a reflective design. The tail of this profile is five times sharper compared to standard Bessel beams paving the way to complex glass cutting such as multi-layer glasses.

3:15pm - 3:30pm

Optical coherence tomography for 3D weld seam localization in absorber-free laser transmission welding

Frederik Maiwald1, Clemens Roider2, Michael Schmidt2,3, Stefan Hierl1

1Ostbayerische Technische Hochschule Regensburg, Labor Lasermaterialbearbeitung, Technologie Campus Parsberg-Lupburg, Am Campus 1, 92331 Parsberg, Germany; 2Institute of Photonic Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052 Erlangen, Germany; 3Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Str. 6, 91052 Erlangen, Germany

Thulium fibre lasers emit in the intrinsic absorption spectrum of polymers and enable welding of transparent parts without absorbent additives. Focusing with high NA provides large intensity gradients inside the workpiece, enabling selective fusing of the joining zone without affecting the surface. Therefore, absorber-free laser transmission welding is well suited to fulfil the high demands on quality and reliability in manufacturing of optical and medical devices. However, monitoring the welding process is required, since seam size and position are crucial for quality.

The aim of this work is the volumetric acquisition of the weld seam’s location and size using optical coherence tomography. Due to the change of the optical properties during melting, the seam can be distinguished from the base material. The results coincide with microscopic images of microtome sections and demonstrate that weld seam localization in polyamide 6 is possible with an accuracy better than a tenth of a millimetre.

3:30pm - 3:45pm

Laser-manufactured glass microfluidic devices with embedded sensors

Krystian L. Wlodarczyk1,2, William N. MacPherson2, Duncan P. Hand2, M. Mercedes Maroto-Valer1

1Research Centre for Carbon Solutions, School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK; 2Applied Optics and Photonics group, School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK

Recently, we have developed a laser process that enables the rapid fabrication of microfluidic devices using widely-available borosilicate glass slides. In contrast to conventional manufacturing techniques, there is no requirement for projection masks and hazardous glass etchants, such as hydrofluoric acid. Instead, a single item of equipment, i.e. an ultrashort pulsed picosecond laser (Trumpf TruMicro 5x50), is used to: (a) write microfluidic patterns directly onto the glass surface by ablating the material and (b) permanently enclose the microfluidic structure from the top by welding this glass substrate to another glass slide that typically contains inlet/outlet ports. In this work, we demonstrate that this process also allows us to manufacture customised glass microfluidic devices with embedded sensors, which enable local, real-time monitoring of various parameters, such as pressure and pH, inside the microfluidic patterns.

3:45pm - 4:00pm

Ultrashort pulse laser cutting of colorless polyimide and hard coat film stacks for flexible OLED displays

Jim Bovatsek, Terence Hollister

MKS Spectra-Physics, United States of America

New mobile devices include flexible and foldable OLED displays which require new protective cover materials. Options for this include ultrathin glass (UTG) as well as a new type of colorless polyimide (CPI), which is transparent at visible wavelengths. The CPI is combined with a scratch resistant hard coat (HC) layer and a final PET (polyethylene terephthalate) protective film. Here we present results for cutting thick CPI/HC/PET layered stacks using high power UV ultrashort pulse lasers. Ablation thresholds were found to vary by almost a factor of ten, and a layer-optimized cutting approach was used. The optimized cutting process is of high quality and throughput, with heat-affect zone (HAZ) of <10 µm and cutting speed of >400 mm/s. These results are comparable to that for individual sheets of polymers used in OLED display manufacturing.

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