Laser Cutting of CFRP with a Fibre Guided High Power Nanosecond Laser Source – Influence of the Optical Fibre Diameter on Quality and Efficiency

Abstract In this manuscript we present a true pulse-on-demand laser design concept using two different approaches. First, we present a fiber master oscillator power amplifier (MOPA) based quasi-continuous wave (CW) laser, working at high modulation bandwidths, for generation of nanosecond pulses. Second, we present a hybrid chirped pulse amplification (CPA)-based laser, combining a chirped-pulse fiber amplifier and an additional solid-state amplifier, for generation of femtosecond pulses. The pulse-on-demand operation is achieved without an external optical modulator/shutter at high-average powers and flexible repetition rates up to 40 MHz, using two variants of the approach for near-constant gain in the amplifier chain. The idler and marker seed sources are combined in the amplifier stages and separated at the out using either wavelength-based separation or second harmonic generation (SHG)-generation-based separation. The nanosecond laser source is further applied to high throughput processing of thin film materials. The laser is combined with a resonant scanner, using the intrinsic pulse-on-demand operation to compensate the scanner’s sinusoidal movement. We applied the setup to processing of indium tin oxide (ITO) and metallic films on flexible substrates.

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Applicability of various beam sources for high power laser cutting of non-oriented electrical steel

10.1117/12.907832 ◽

2012 ◽

Author(s):

René Siebert ◽

Harry Thonig ◽

Andreas Wetzig ◽

Eckhard Beyer

Keyword(s):

High Power ◽

Laser Cutting ◽

Electrical Steel ◽

High Power Laser ◽

Power Laser

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Laser Lock-In Thermography for Fatigue Crack Detection

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.558.76 ◽

2013 ◽

Vol 558 ◽

pp. 76-83 ◽

Cited By ~ 1

Author(s):

Yun Kyu An ◽

Ji Min Kim ◽

Hoon Sohn

Keyword(s):

Fatigue Crack ◽

Heat Source ◽

High Power ◽

Crack Detection ◽

Laser Source ◽

Cw Laser ◽

Laser Heat ◽

Laser Heat Source ◽

Fatigue Crack Detection ◽

Lock In

This study proposes a new nondestructive evaluation methodology named laser lock-in thermography (LLT) for fatigue crack detection. LLT utilizes a high power continuous wave (CW) laser as a heat generation source for lock-in thermography instead of commonly used flash and halogen lamps. The advantages of the proposed LLT method are that (1) the laser heat source can be positioned at an extended distance from a target structure thank to the directionality and low energy loss of the laser source, (2) thermal image degradation due to surrounding temperature disturbances can be minimized because of high temperature gradient generated by the laser source and (3) a large target surface can be inspected using a scanning laser heat source. The developed LLT system is composed of a modulated high power CW laser, galvanometer and infrared camera. Then, a holder exponent-based data processing algorithm is proposed for intuitive damage evaluation. The developed LLT is employed to detect a micro fatigue crack in a metal plate. The test result confirms that 5 μm (or smaller) fatigue crack in a dog-bone shape aluminum plate with a dimension of 400 x 140 x 3 mm3 can be detected.

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Improvement of cutting performance for thick stainless steel plates by step-like cutting speed increase in high-power fiber laser cutting

Optics & Laser Technology ◽

10.1016/j.optlastec.2018.01.054 ◽

2018 ◽

Vol 103 ◽

pp. 311-317 ◽

Cited By ~ 6

Author(s):

Sangwoo Seon ◽

Jae Sung Shin ◽

Seong Yong Oh ◽

Hyunmin Park ◽

Chin-Man Chung ◽

...

Keyword(s):

Stainless Steel ◽

Fiber Laser ◽

High Power ◽

Laser Cutting ◽

Cutting Speed ◽

Cutting Performance ◽

Steel Plates ◽

Speed Increase

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Characteristics of Nanopatterns and the Associated Thermal Mechanisms During Near Field Laser-Material Interaction of Nanosecond Laser on Different Targets

Volume 3: Combustion, Fire and Reacting Flow; Heat Transfer in Multiphase Systems; Heat Transfer in Transport Phenomena in Manufacturing and Materials Processing; Heat and Mass Transfer in Biotechnology; Low Temperature Heat Transfer; Environmental Heat Transfer; Heat Transfer Education; Visualization of Heat Transfer ◽

10.1115/ht2009-88225 ◽

2009 ◽

Cited By ~ 1

Author(s):

Vijay M. Sundaram ◽

Sy-Bor Wen

Keyword(s):

Near Field ◽

Target Material ◽

Optical Microscope ◽

Laser Source ◽

Nanosecond Laser ◽

Metallic Surfaces ◽

Experimental Conditions ◽

Laser Material ◽

Material Conditions ◽

Material Interaction

Nano-patterns are generated on semiconducting and metallic surfaces through coupling an apertured near field scanning optical microscope (NSOM) with a pulsed laser source in this study. To understand the dominant mechanisms for the generation of the nano-patterns, a series of experimental measurement of the size and shape of nano-patterns generated on targets under different experimental conditions with different targets is conducted. The characteristic dimensions of nano-patterns show dependence on optical properties of the target material. The qualitative trend of the variation of nano-patterns as a function of laser and material conditions indicates that the dominant mechanisms for the generation of nano-patterns through a combination of nanosecond laser and an apertured NSOM under different conditions studied is near field laser-material interaction.

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