Simple turbulence measurements with azopolymer thin films

Abstract

A simple method to measure the influence on the laser beam propagation by a turbid medium is proposed. This measurement is based on the inscription of a surface relief grating (SRG) on an azopolymer thin film. The grating obtained with a single laser beam after propagation into a turbulent medium is perturbed and directly analyzed by a CCD camera through its diffraction pattern. Later, by scanning the surface pattern with an atomic force microscope, the inscribed SRG is analyzed with the Radon transform. This method has the advantage of using a single beam to remotely inscribe a grating detecting perturbations during the beam path. A method to evaluate the refractive index constant structure is developed.

Multifractal characteristics of optical turbulence measured through a single beam holographic process

“…Finally, this work extents our previous work [11]; not only the turbulence strength is registered in the azopolymer thin films by the laser beam. Indeed, long-term multifractal characteristics of the wavefront are discovered in these gratings.…”

Instantaneous photoinduced patterning of an azopolymer colloidal nanosphere assembly

“…The material filled up in the direction parallel to the light polarization, behaving like a fluid, whereas the canal stayed empty in the direction perpendicular to the light polarization. The same phenomenon also led to the creation of nano-textures using one-beam irradiation on azopolymers [7], to the achievement of a scalable and parallel nano-texturing with a controlled complexity [8] and to new directions in metrology applications [9]. However, expanding these results to large areas, fast patterning, and a determistic nano-texturing has not been realized yet.…”