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

Kraft, Sebastian; Schille, Joerg; Löschner, Udo; Krüger, Jörg

doi:10.1007/s00339-023-06440-4

Cited by 4 publications

(1 citation statement)

References 41 publications

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“…Most of the experimental studies on the emission of ionizing radiation from laser-produced plasmas were already carried out in the 1980s under high vacuum conditions [ 9 , 10 , 11 , 12 , 13 , 14 ], resulting in only a few publications considering industrial conditions [ 7 , 15 , 16 , 17 , 18 ]. With the increase in available power of recent ultrafast lasers, the topic is gaining interest in the area of industrial laser material processing, which has lead to the latest investigations about the influence of high pulse repetition rates [ 19 ], different materials [ 20 ] and the pulse duration [ 21 ] on the X-ray emission. There are several important differences between the two conditions, one being the air breakthrough (ionization of the gas atmosphere) at high intensities [ 22 ] when working in standard atmosphere, leading to defocusing of the incident laser beam and thereby reducing the local irradiance on the workpiece.…”

Section: Introductionmentioning

confidence: 99%

Self-Shielding of X-ray Emission from Ultrafast Laser Processing Due to Geometrical Changes of the Interaction Zone

Holland,

Hagenlocher,

Weber

et al. 2024

Materials

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Materials processing with ultrashort laser pulses is one of the most important approaches when it comes to machining with very high accuracy. High pulse repetition rates and high average laser power can be used to attain high productivity. By tightly focusing the laser beam, the irradiances on the workpiece can exceed 1013 W/cm2, and thus cause usually unwanted X-ray emission. Pulsed laser processing of micro holes exhibits two typical features: a gradual increase in the irradiated surface within the hole and, with this, a decrease in the local irradiance. This and the shielding by the surrounding material diminishes the amount of ionizing radiation emitted from the process; therefore, both effects lead to a reduction in the potential X-ray exposure of an operator or any nearby person. The present study was performed to quantify this self-shielding of the X-ray emission from laser-drilled micro holes. Percussion drilling in standard air atmosphere was investigated using a laser with a wavelength of 800 nm a pulse duration of 1 ps, a repetition rate of 1 kHz, and with irradiances of up to 1.1·1014 W/cm. The X-ray emission was measured by means of a spectrometer. In addition to the experimental results, we present a model to predict the expected X-ray emission at different angles to the surface. These calculations are based on raytracing simulations to obtain the local irradiance, from which the local X-ray emission inside the holes can be calculated. It was found that the X-ray exposure measured in the surroundings strongly depends on the geometry of the hole and the measuring direction, as predicted by the theoretical model.

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Section: Introductionmentioning

confidence: 99%

Self-Shielding of X-ray Emission from Ultrafast Laser Processing Due to Geometrical Changes of the Interaction Zone

Holland,

Hagenlocher,

Weber

et al. 2024

Materials

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Impact of repetitive, ultra-short soft X-ray pulses from processing of steel with ultrafast lasers on human cell cultures

Holland,

Lungu,

Weber

et al. 2024

Appl. Phys. A

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Ultrafast lasers, with pulse durations below a few picoseconds, are of significant interest to the industry, offering a cutting-edge approach to enhancing manufacturing processes and enabling the fabrication of intricate components with unparalleled accuracy. When processing metals at irradiances exceeding the evaporation threshold of about 1010 W/cm² these processes can generate ultra-short, soft X-ray pulses with photon energies above 5 keV. This has prompted extensive discussions and regulatory measures on radiation safety. However, the impact of these ultra-short X-ray pulses on molecular pathways in the context of living cells, has not been investigated so far. This paper presents the first molecular characterization of epithelial cell responses to ultra-short soft X-ray pulses, generated during processing of steel with an ultrafast laser. The laser provided pulses of 6.7 ps with a pulse repetition rate of 300 kHz and an average power of 500 W. The irradiance was 1.95 ×1013 W/cm2. Ambient exposure of vitro human cell cultures, followed by imaging of the DNA damage response and fitting of the data to a calibrated model for the absorbed dose, revealed a linear increase in the DNA damage response relative to the exposure dose. This is in line with findings from work using continuous wave soft X-ray sources and suggests that the ultra-short X-ray pulses do not generate additional hazard. This research contributes valuable insights into the biological effects of ultrafast laser processes and their potential implications for user safety.

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Mode-locked thulium-holmium doped fiber laser using Bi₂Se₃ saturable absorber deposited onto arc-shaped and side-polished fibers via airbrush spraying technique

Ahmad,

Rusni,

Samion

et al. 2024

Mater. Res. Express

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In this paper, the mode-locking performance using bismuth selenide (Bi2Se3) as a saturable absorber in a thulium-holmium-doped fiber laser (THDFL) was demonstrated for the first time. The saturable absorber (SA) was coated using an airbrush spraying technique onto two different hosts, arc-shaped and side-polished fibers. The airbrush was used to provide an even and uniform coating onto these two hosts. The generated mode-locked pulses of the arc-shaped fiber have a center wavelength of 1913.5 nm and a 3-dB bandwidth of 3.11 nm. The optical output has a repetition frequency of 13.9 MHz and an optical pulse width of 1.33 ps. In the case of the side-polished fiber, it has a center wavelength of 1918.55 nm and a 3-dB bandwidth of 2.60 nm. The output pulse has a repetition frequency of 12.16 MHz and an optical pulse width of 1.43 ps. This demonstration indicates that the arc-shaped fiber host has a better performance in terms of shorter pulse width, which is essential for a 2 µm laser in tissue ablation procedures for medical applications.

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

Cited by 4 publications

References 41 publications

Self-Shielding of X-ray Emission from Ultrafast Laser Processing Due to Geometrical Changes of the Interaction Zone

Self-Shielding of X-ray Emission from Ultrafast Laser Processing Due to Geometrical Changes of the Interaction Zone

Impact of repetitive, ultra-short soft X-ray pulses from processing of steel with ultrafast lasers on human cell cultures

Mode-locked thulium-holmium doped fiber laser using Bi₂Se₃ saturable absorber deposited onto arc-shaped and side-polished fibers via airbrush spraying technique

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

Cited by 4 publications

References 41 publications

Self-Shielding of X-ray Emission from Ultrafast Laser Processing Due to Geometrical Changes of the Interaction Zone

Self-Shielding of X-ray Emission from Ultrafast Laser Processing Due to Geometrical Changes of the Interaction Zone

Impact of repetitive, ultra-short soft X-ray pulses from processing of steel with ultrafast lasers on human cell cultures

Mode-locked thulium-holmium doped fiber laser using Bi2Se3 saturable absorber deposited onto arc-shaped and side-polished fibers via airbrush spraying technique

Contact Info

Product

Resources

About

Mode-locked thulium-holmium doped fiber laser using Bi₂Se₃ saturable absorber deposited onto arc-shaped and side-polished fibers via airbrush spraying technique