Potential hazards and mitigation of X-ray radiation generated by laser-induced plasma from research-grade laser systems

Mosel, Philip; Sankar, Pranitha; Zulqarnain, Zulqarnain; Appi, E.; Jusko, Christoph; Zuber, David; Kleinert, Sven; Düsing, Jan Friedrich; Mapa, Jose; Dittmar, Günter; Püster, Thomas; Böhmer-Brinks, Petra; Vahlbruch, Jan-Willem; Morgner, Uwe; Kovačev, Milutin

doi:10.1364/oe.468135

Cited by 6 publications

(3 citation statements)

References 37 publications

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“…Several investigations were performed to analyze the X-ray emission for different laser and process parameters during ultrashort pulse laser machining of various technical materials [5][6][7][8][9][10][11][12][13][14][15][16][17]. Recently, possibly harmful X-ray emission was observed already at laser irradiances below 10 13 W cm −2 [18,19]. Especially the burst modes of laser machines were identified as a configuration that can lead to very high dose rates in the ultrashort laser pulse processing of metals [20,21].…”

Section: Introductionmentioning

confidence: 99%

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

et al. 2022

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Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 1013 W cm−2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 μm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances I0 ranging from 7.3 × 1013 W cm−2 up to 3.0 × 1014 W cm−2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 1014 W cm−2.

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Section: Introductionmentioning

confidence: 99%

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

et al. 2022

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“…A few recent studies have reported that X-ray radiation can be induced at peak intensities above 10 13 W cm À2 . [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In the meantime, more than 20 influencing factors have been identified for significantly affecting the X-ray dose rate induced during usp laser processing. Thereby, the peak intensity of the laser pulses is one of the most influencing factors, as doubling the peak intensity can increase the X-ray dose rate by a factor of 10.…”

Section: Introductionmentioning

confidence: 99%

Influence of Laser Process Factors on Laser‐Induced X‐Ray Emission in High‐Repetition Laser Processes

Kraft,

Schille,

Backe

et al. 2024

Physica Status Solidi (a)

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Lasers have established themselves as a versatile tool that generates innovations in a wide range of fields, from automotive to surface engineering, medical applications, etc. A current research field for lasers is surface texturing in biomimetic, which aims to mimic nature‐inspired functionalities and mechanisms, for example, to tailor and control wetting, adhesion/friction, or optical properties of technical surfaces. Therefore, ultrashort pulse lasers are often the right choice to alter surface structures at microscopic scale. Moreover, the ongoing trend toward high‐average power lasers reaching “kilowatt class” levels even for ultrashort pulse lasers seems to be beneficial to increase throughput of this powerful laser technology for industrial production. However, several recent studies are reported on harmful X‐ray emissions arising from high‐intense ultrashort laser pulses which must be considered as a secondary laser beam hazard in risk assessment. Shining light on this topic, this article reports on a set of experiments investigating X‐rays emission induced by ultrashort pulse laser processing of different laser‐pretreated stainless steel sheets. The X‐ray measurements show the effect of roughness and scan number on the laser‐induced X‐ray emission dose. In addition, the dependency of X‐ray emission on the scan direction relatively to the laser beam polarization state is discussed.

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“…While the usp laser-induced hazard has been studied during the last years for various inorganic materials such as metals and glasses [15,16,[19][20][21], and for numerous laser irradiation parameters and processing strategies [22][23][24] in the peak intensity range exceeding 10 13 W/cm 2 , a study of laser-induced X-ray dose rates upon ultrashort pulsed laser processing of biological materials is widely missing. Just very few publications are available, e.g., pointing to the enhancement of the characteristic radiation in X-ray spectra through the additional presence of alkali metal chlorides in aqueous solutions at peak intensities in the range of 2•10 15 W/cm 2 [25].…”

Section: Introductionmentioning

confidence: 99%

X-ray emission during the ablative processing of biological materials by ultrashort laser pulses

et al. 2023

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The ablative laser processing with ultrashort pulsed laser beams may cause secondary emission of hazardous X-rays. While the effect has recently been proven to be considered in working safety regulations when processing technical materials, such as metals, the X-ray emission rates during the ablative processing of biological tissue materials are widely unexplored yet. Therefore, biological materials like water, isotonic saline solution, pig eyes, and human teeth were ablated with ultrashort laser pulses of 1030 nm wavelength, 600 fs pulse duration and 5 kHz pulse repetition rate, aiming to mimic typical surgery situations. Simultaneously, in-situ X-ray dose rate measurements were performed at a short distance from the plasma to display potential X-ray emission. For all four studied biological materials, our measurements prove the secondary emission of laser-induced X-rays.

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Potential hazards and mitigation of X-ray radiation generated by laser-induced plasma from research-grade laser systems

Cited by 6 publications

References 37 publications

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

Influence of Laser Process Factors on Laser‐Induced X‐Ray Emission in High‐Repetition Laser Processes

X-ray emission during the ablative processing of biological materials by ultrashort laser pulses

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