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J. Eur. Opt. Society-Rapid Publ. 22, 24( 2026)
Fig
. 2. Visual representation of symmetric pulse spacing( left) and asymmetric spacing( right) on an Archimedean spiral, shown at different zoom levels for the central region( top) and peripheral region( bottom). For symmetric spacing, the bubble boundary is shown as a black contour with blue fill; for asymmetric spacing, the bubble boundary is shown as a grey contour with orange fill.
asymmetric pulse spacings, respectively. Symmetric spacings refer to conditions in which spot distance( Figs. 1 and 2) along the pathway( azimuthal in rotational scanning approaches and linear in meander scanning approaches) equals the track distance( Fig. 1 and 2) across the pathway( radial in rotational scanning approaches and line-wise in meander scanning approaches), which leads to an asymmetry ratio of 1. By exclusion, asymmetric spacings refer to conditions in which spot and track distances( Figs. 1 and 2) along and across the pathway, respectively, are different, this leads to an asymmetry ratio different from 1. Geometrically it would make no difference which one is higher( yet physically and spatiotemporally), so that we only explored asymmetry ratios > 1( also as per previous publications [ 24 ]), i. e., in which the spot distance( Figs. 1 and 2) along the pathway is clearly larger than the track distance( Figs. 1 and 2) acrossthepathway.
The understanding of the underlying mechanisms of distribution of laser pulses and their impact on outcomes may help optimize refractive laser systems. Symmetric spacing produces a regular, structured pattern in which the selected spot and track distances typically yield a low to moderate energy dose, resulting in a standard dissection. In contrast, asymmetric spacing arises from a stochastic pulse distribution that, when appropriately configured, can achieve a lower effective dose and influence the characteristics of tissue separation.
In previous works we presented analytical models to optimize the laser settings of ablation processes governed by linear [ 25 ] and non-linear( multi-photon) absorption [ 26 ]. The main purpose of this paper is to extend the nonlinear absorption model and present a simple theoretical framework for identifying the optimum spatial and temporal distribution of single pulses for maximizing the cutting efficiency defined by the metrics: minimum amount of energy imparted to the tissue( i. e. minimum dose) and minimum corneal surface roughness.
Please note that this work does not aim to reduce cavitation energy to a level slightly above the threshold, as explored in previous studies [ 9, 26 ]. Instead, the objective is to provide a simplified theoretical framework for objectively determining:
the optimum total energy or dose appropriate for a given treatment or laser system, and the optimum degree of asymmetry( spatial or temporal) corresponding to that total energy / dose for the same treatment or system.