Laser beam shaping and its effects in medical applications

Abstract

Summary form only given. For many medical and industrial laser applications, a particular irradiance distribution (beam shape) is required. The intra- or extra cavity laser beam shaping-LBS methods can be employed to alter the output beam characteristics. A novel design is presented to convert a semi Gaussian beam produced by usual commercial lasers into a high quality flat-top beam. Furthermore, it will be demonstrated that by changing some simple parameters related to characteristics of optical elements (mirrors and beam-splitter with particular dielectric coating) used in this design, we can easily improve the shape of any arbitrary laser beam distribution and its related standard parameters (M2 and k). Considering the significance of laser beams in medical applications especially in surgery and dermatology and to show the validation of this design, the effects of laser beam shapes in treatments of vascular malformation is presented here. Before clinical treatments, the Monte-Carlo method is used to model and simulate the energy deposition in a true skin anatomy for different beam shapes, wavelengths and powers. We have used a 12 watts copper vapor laser (having 511 nm and 578 nm wavelengths) with semi-Gaussian output beam distribution. The results are repeated using a multimode KTP (532 nm) of similar power. Finally, a comparison between the results of laser treatments with and without LBS facilities on patients having Port Wine Stains (malformation of vascular tissues) of various sizes and depths are presented and a significant improvement in treatments of PWS of different sizes using the beam homogenizer are seen.