Andrei V. Erofeev

Micro-fractional ablative skin resurfacing with two novel erbium laser systems

Fractional ablation offers the potential benefits of full‐surface ablative skin resurfacing while minimizing adverse effects. The purpose of this study was to evaluate the safety, damage profile, and efficacy of erbium fractional lasers.

Semi-Automated method of analysis of horizontal histological sections of skin for objective evaluation of fractional devices.

The treatment of skin with fractional devices creates columns of micro‐ablation or micro‐denaturation depending on the device. Since the geometric profiles of thermal damage depend on the treatment parameters or physical properties of the treated tissue, the size of these columns may vary from a few microns to a few millimeters. For objective evaluation of the damage profiles generated by fractional devices, this report describes an innovative and efficient method of processing and evaluating horizontal sections of skin using a novel software program.

Compact 1J mid-IR Cr:ZnSe Laser

We report a record output energies of pulsed Cr:ZnSe lasers operating at 2.65 um. The maximum output energy of the Cr:ZnSe laser was demonstrated to be more than 1.1 J for 7 ms pulses.

Self-adaptation Optical Effects in Photothermal Treatment of Skin Structures

Photothermal effects form basis for many uses of optical energy to treat various medical conditions. With an increase in the optical power density, thermally induced phase transitions and chemical transformations take place and the optical properties of the tissue are affected; as a result, local intensity may become non-linear with respect to the instantaneous incident power. These nonlinearities may profoundly affect resulting patterns of the light-tissue interaction; yet they are still poorly understood due to their complexity. In this work, we briefly review the state of the art of clinically relevant nonlinear light-tissue interactions. Then, we report on investigation of the role of opto-thermal nonlinearities in one particular important case: non-ablative fractional treatment of skin. We used the Er:glass laser emitting at the wavelength of 1540 nm, the wavelength mostly absorbed by water. We have shown that propagation of optical energy in the tissue as well as the resulting temperature and damage distributions are significantly influenced by the nonlinear effects. Moreover, the observed nonlinearities led to a self-adaptation phenomenon, manifesting itself in canalization of the optical propagation pathway. Such phenomena may be used to optimize photothermal procedures.

Model of laser destruction of hard tooth tissue

A numerical combined model with movable boundary conditions having been used for the evaluation of Er-laser dental treatments is presented. This model facilitates the simulation of heat flows and temperature distribution in different kinds of human teeth caused by Er-laser irradiation with arbitrary orientation of laser beam axis. This model can be used for simulation and optimization of exposure parameters to minimize pulp overheating and procedure duration in the application of lasers for dental treatment.