Nonlinear absorption: intraocular microsurgery and laser lithotripsy

Vogel, Alfred

doi:10.1088/0031-9155/42/5/011

Cited by 115 publications

(74 citation statements)

References 85 publications

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“…The influence of medium (ionization energy, impurity level and absorption) as well as beam (wavelength, pulse width, spot size, and polarization) characteristics on irradiance threshold has been the subject of several theoretical as well as experimental studies [11][12][13][14][15][16]. These investigations were primarily motivated to produce the same surgical effect in ophthalmic laser surgery applications at lower pulse energies and with less collateral tissue damages [17][18][19][20] and therefore have so far concentrated predominantly on transparent and low absorbing tissues.…”

Section: Discussionmentioning

confidence: 99%

“…However, to the best of our knowledge, laser induced thermal breakdown as an independent process was not analyzed in any of the previously published models. An empirical justification for this approach is that the optical breakdown thresholds in water and in transparent tissues such as cornea were found to be very similar for laser wavelengths exhibiting small linear absorption in those tissues [22]. However, for laser wavelengths that are highly absorbed in tissues, the dynamics of laser induced breakdown is completely different.…”

Section: Discussionmentioning

confidence: 99%

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Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

Varghese

Bonito

Jurna

et al. 2015

Biomed. Opt. Express

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Abstract:We investigated the influence of thermal initiation pathway on the irradiance threshold for laser induced breakdown in transparent, absorbing and scattering phantoms. We observed a transition from laserinduced optical breakdown to laser-induced thermal breakdown as the absorption coefficient of the medium is increased. We found that the irradiance threshold after correction for the path length dependent absorption and scattering losses in the medium is lower due to the thermal pathway for the generation of seed electrons compared to the laser-induced optical breakdown. Furthermore, irradiance threshold gradually decreases with the increase in the absorption properties of the medium. Creating breakdown with lower irradiance threshold that is specific at the target chromophore can provide intrinsic target selectivity and improve safety and efficacy of skin treatment methods that use laser induced breakdown. Phys. 64(4), 1549-1554 (1976). 11. P. K. Kennedy, "A first-order model for computation of laser-induced breakdown thresholds in ocular and aqueous media. I. Theory," IEEE J. Quantum Electron. 31(12), 2241-2249 (1995). 12. D. X. Hammer, R. J. Thomas, G. D. Noojin, B. A. Rockwell, P. P. Kennedy, and W. P. Roach, "Experimental investigation of ultrashort pulse laser-induced breakdown thresholds in aqueous media," IEEE J. Quantum Electron. 32(4), 670-678 (1996). calculation of thresholds, absorption coefficients, and energy density," IEEE J. Quantum Electron. 35(8), 1156-1167 (1999

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

Varghese

Bonito

Jurna

et al. 2015

Biomed. Opt. Express

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“…8,12,16,[20][21][22] Some of these reports have shown images of small residual effects of the bubble collapse behind the fiber tip. 12,19 This is presumably due to a collapsing bubble-induced pressure wave propagating in the axial direction of the fiber, both toward and away from the fiber tip.…”

Section: Discussionmentioning

confidence: 99%

Fiber-optic manipulation of urinary stone phantoms using holmium:YAG and thulium fiber lasers

et al. 2013

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Abstract. Fiber-optic attraction of urinary stones during laser lithotripsy may be exploited to manipulate stone fragments inside the urinary tract without mechanical grasping tools, saving the urologist time and space in the ureteroscope working channel. We compare thulium fiber laser (TFL) high pulse rate/low pulse energy operation to conventional holmium:YAG low pulse rate/high pulse energy operation for fiber-optic suctioning of plaster-ofparis (PoP) stone phantoms. A TFL (wavelength of 1908 nm, pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rate of 10 to 350 Hz) and a holmium laser (wavelength of 2120 nm, pulse energy of 35 to 360 mJ, pulse duration of 300 μs, and pulse rate of 20 Hz) were tested using 270-μm-core optical fibers. A peak drag speed of ∼2.5 mm∕s was measured for both TFL (35 mJ and 150 to 250 Hz) and holmium laser (210 mJ and 20 Hz). Particle image velocimetry and thermal imaging were used to track water flow for all parameters. Fiber-optic suctioning of urinary stone phantoms is feasible. TFL operation at high pulse rates/low pulse energies is preferable to holmium operation at low pulse rates/high pulse energies for rapid and smooth stone pulling. With further development, this novel technique may be useful for manipulating stone fragments in the urinary tract. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…> 0.9, which can provide a rapid decrease gradient of photon density along with the distance from the focus center and thus greatly protect cells out of the laser focus. Generally, according to theoretical and experimental studies [95,96], the nonlinear and thermal effect can be well confined inside the short pulse and the focus volume to femtosecond pulses, especially to pulses shorter than 150 fs, with a repetition rate at less than MHz level. In this regard, the photostimulation by tightly-focused femtosecond laser holds a precise spatial and temporal resolution, and is relatively safe to cells.…”

Section: Physical Effects Of Femtosecond Laser To Cellsmentioning

confidence: 99%

Regulation of Cellular Molecular Signaling by Light (Invited Paper)

Cheng¹,

Zhu²,

He³

2015

PIER

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Abstract-Laser technology has been promoting various microscopy methods and thus making great progresses in life science. Further than contribution to "seeing is believing", lasers have also demonstrated their capacity of manipulating cells and even molecular signaling. Specifically, with advances of lasers and combination with other techniques, recent reports show that cell calcium ion, a universal intra-and inter-cellular messenger, can be modulated by lasers at different levels of biological organization from organelle to tissue. It is very encouraging that laser irradiation can activate or control plenty of corresponding cell processes and functions by regulating cell calcium signaling pathways, with promising potential in both scientific research and clinical application. In this paper, optical techniques for regulation of cell calcium signaling are specifically reviewed. Most methods need exogenous chemicals or genetic materials to convert incident photon into stimulation that cells can response with specific molecular dynamics. The only all-optical approach is achieved by nonlinear excitation with femtosecond laser, despite lack of specificity and controllability, providing possibility of a totally noninvasive method without any biochemical materials and thus further potential clinical application in human beings. The developments and techniques of those methods are introduced and explained, with analysis on their properties and current challenges. Potential applications and prospective development are also discussed. Researchers on biophotonics and related biological fields can benefit from this review. It also provides a systematic reference to doctors and researchers who are working on practical application of those methods.

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Nonlinear absorption: intraocular microsurgery and laser lithotripsy

Cited by 115 publications

References 85 publications

Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

Fiber-optic manipulation of urinary stone phantoms using holmium:YAG and thulium fiber lasers

Regulation of Cellular Molecular Signaling by Light (Invited Paper)

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