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Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques
Published on: March 12, 2019
Simple turbulence measurements with azopolymer thin films
Regis Barillé1, Darío G Pérez, Yohann Morille
1LUNAM Université, Université d’Angers/UMR CNRS 6200, MOLTECH-Anjou 2, Angers, France. regis.barille@univ‑angers.fr
Optics Letters
|April 3, 2013
Summary
Researchers developed a simple method using laser beams and azopolymer films to measure how turbulent media affect light propagation. This technique analyzes changes in inscribed surface relief gratings to understand beam path perturbations.
Area of Science:
- Optics and Photonics
- Materials Science
- Fluid Dynamics
Background:
- Laser beam propagation can be significantly altered by turbulent or scattering media.
- Measuring these perturbations in real-time is crucial for various applications, including remote sensing and optical communication.
- Existing methods may be complex or require multiple beams for characterization.
Purpose of the Study:
- To propose a simple, single-beam method for measuring the influence of turbid media on laser beam propagation.
- To develop a technique for analyzing perturbations in laser-induced surface relief gratings.
- To establish a method for evaluating the refractive index structure constant of the turbulent medium.
Main Methods:
- Inscription of a surface relief grating (SRG) on an azopolymer thin film using a single laser beam.
- Analysis of the perturbed grating's diffraction pattern using a CCD camera.
- Scanning probe microscopy, specifically atomic force microscopy (AFM), to analyze the inscribed SRG.
- Application of the Radon transform for detailed SRG analysis.
Main Results:
- The inscribed SRG is perturbed by the laser beam's passage through the turbulent medium.
- Perturbations in the grating are detectable and quantifiable through diffraction pattern analysis.
- AFM and Radon transform analysis provide detailed information about the inscribed SRG modifications.
- The method allows for remote inscription and detection of beam path perturbations.
Conclusions:
- The proposed method offers a straightforward approach to assess laser beam distortion caused by turbid environments.
- This technique enables remote characterization of optical perturbations using a single laser beam.
- The developed method provides a means to evaluate the refractive index structure constant, offering insights into the medium's properties.
