Freeform beam shaping in optical systems of high-power lasers

Abstract

Control of irradiance distribution in complex optical systems of modern high-power lasers is of great importance to increase efficiency of optical techniques used to reach high power levels. For example, flat-top or super-Gaussian irradiance profiles are optimum for amplification in MOPA lasers and for reduction of thermal effects in crystals of solid-state ultra-short pulse lasers when pumping by an external multimode laser. Specific requirements to beam shaping optics in these laser systems are providing variable irradiance distributions, saving of beam consistency and flatness of phase front, capability to work with TEM 00 and multimode lasers, resistance to high peak power radiation. Among various refractive and diffractive beam shaping techniques only refractive field mapping beam shapers like Shaper meet these requirements. The operational principle of these devices presumes almost lossless transformation of laser beam irradiance from Gaussian to flat-top, super-Gauss or inverse-Gauss through controlled wavefront manipulation inside a beam shaper using lenses with smooth optical surfaces. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in optical systems of high-power lasers. Examples of real implementations and experimental results will be presented as well.

Implementation of uniform beam shape of medical picosecond laser for effective treatment

“…In particular, it is very important to uniformly irradiate the laser to the desired area for effective treatment. Various methode such as beam shaper [4], vacuum ARM [5], MLA or DOE Lens and vesious types of lens design [6] are being developed to create a uniform laser beam. However, the shorter the pulse duration and the higher power, the more damage to the optical system and air break-down occur, limiting the application of methods used in longer pulser laser.…”