Limits...
Interaction mechanisms of cavitation bubbles induced by spatially and temporally separated fs-laser pulses.

Tinne N, Kaune B, Krüger A, Ripken T - PLoS ONE (2014)

Bottom Line: The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots.Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components.In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers.

View Article: PubMed Central - PubMed

Affiliation: Laser Zentrum Hannover e.V., Biomedical Optics Department, Hannover, Germany.

ABSTRACT
The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots. In order to get more insight into the dynamics a time-resolved photographic analysis of the interaction of cavitation bubbles is presented. Particularly, we investigated the influence of fs-laser pulses and their resulting bubble dynamics with various spatial as well as temporal separations. Different time courses of characteristic interaction effects between the cavitation bubbles were observed depending on pulse energy and spatio-temporal pulse separation. These ranged from merely no interaction to the phenomena of strong water jet formation. Afterwards, the mechanisms are discussed regarding their impact on the medical application of effective tissue cutting lateral to the laser beam direction with best possible axial precision: the mechanical forces of photodisruption as well as the occurring water jet should have low axial extend and a preferably lateral priority. Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components. In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers.

Show MeSH

Related in: MedlinePlus

Schematic depiction of the adjustment of subsequent generated cavitation bubbles.The first bubble is induced on the left side at a time defined as t1 = 0.0 µs. The second cavity is generated at t2 after a constant delay of 10.0 µs. The bubble size is characterized as its radius RCav while the distance between the focal spots amounts to Δr.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4263672&req=5

pone-0114437-g002: Schematic depiction of the adjustment of subsequent generated cavitation bubbles.The first bubble is induced on the left side at a time defined as t1 = 0.0 µs. The second cavity is generated at t2 after a constant delay of 10.0 µs. The bubble size is characterized as its radius RCav while the distance between the focal spots amounts to Δr.

Mentions: A schematically depiction of the experimental scenario is shown in Fig. 2: The laser was scanned from left to right in each of the following pictures of the interaction mechanisms between a cavitation bubble and a subsequent laser pulse or even its cavitation bubble. Furthermore, the laser light was focused from below. The first cavitation bubble on the left side was created at a time defined as t1: = 0.0 µs and its radius is RCav(t). At a time t2, which was always t2 = 10.0 µs in this analysis, the second pulse was focused at a certain spatial distance Δr of the first focus.


Interaction mechanisms of cavitation bubbles induced by spatially and temporally separated fs-laser pulses.

Tinne N, Kaune B, Krüger A, Ripken T - PLoS ONE (2014)

Schematic depiction of the adjustment of subsequent generated cavitation bubbles.The first bubble is induced on the left side at a time defined as t1 = 0.0 µs. The second cavity is generated at t2 after a constant delay of 10.0 µs. The bubble size is characterized as its radius RCav while the distance between the focal spots amounts to Δr.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263672&req=5

pone-0114437-g002: Schematic depiction of the adjustment of subsequent generated cavitation bubbles.The first bubble is induced on the left side at a time defined as t1 = 0.0 µs. The second cavity is generated at t2 after a constant delay of 10.0 µs. The bubble size is characterized as its radius RCav while the distance between the focal spots amounts to Δr.
Mentions: A schematically depiction of the experimental scenario is shown in Fig. 2: The laser was scanned from left to right in each of the following pictures of the interaction mechanisms between a cavitation bubble and a subsequent laser pulse or even its cavitation bubble. Furthermore, the laser light was focused from below. The first cavitation bubble on the left side was created at a time defined as t1: = 0.0 µs and its radius is RCav(t). At a time t2, which was always t2 = 10.0 µs in this analysis, the second pulse was focused at a certain spatial distance Δr of the first focus.

Bottom Line: The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots.Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components.In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers.

View Article: PubMed Central - PubMed

Affiliation: Laser Zentrum Hannover e.V., Biomedical Optics Department, Hannover, Germany.

ABSTRACT
The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots. In order to get more insight into the dynamics a time-resolved photographic analysis of the interaction of cavitation bubbles is presented. Particularly, we investigated the influence of fs-laser pulses and their resulting bubble dynamics with various spatial as well as temporal separations. Different time courses of characteristic interaction effects between the cavitation bubbles were observed depending on pulse energy and spatio-temporal pulse separation. These ranged from merely no interaction to the phenomena of strong water jet formation. Afterwards, the mechanisms are discussed regarding their impact on the medical application of effective tissue cutting lateral to the laser beam direction with best possible axial precision: the mechanical forces of photodisruption as well as the occurring water jet should have low axial extend and a preferably lateral priority. Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components. In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers.

Show MeSH
Related in: MedlinePlus