1 / 16

Adaptive optics

Adaptive optics. Using Ferro-fluids Mathieu De Goer-de Herve and Raphael-David Lasseri (ENS Cachan). Resolution in optics. Two limitant factors : → Diffraction → Atmosphere turbulences : speckle patterns. . Characteristic length D Airy disc : Ø = λx f/D. D.

lamar-tate
Download Presentation

Adaptive optics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Adaptiveoptics UsingFerro-fluids Mathieu De Goer-de Herve and Raphael-David Lasseri (ENS Cachan)

  2. Resolution in optics • Two limitant factors : → Diffraction → Atmosphere turbulences : speckle patterns. Characteristic length D Airy disc : Ø=λxf/D D Characteristic length dc (correlation) dc~10cm Disc : Ø=λxf/dc Ø

  3. What solution? • High places • Adaptive optics

  4. How? • Mechanics deformation of a “usual” mirror using piezoelectric devices

  5. How? • Mechanics deformation of a “usual” mirror using piezoelectric devices • Shack-Hartmann wavefront sensor

  6. Ferrofluids • General definition: Colloidal suspensions of magnetic nanoparticles conferring super-paramagnetic properties to the fluid. When a magnetic field is applied to the system their magnetic moments tend to align along the applied field, leading to a net magnetization.

  7. Field of the study

  8. Rosenweig instability • Domain of the RW Instability “Hedgehog surface” • Domain of Stability “Smooth surface” B>Bc B<Bc

  9. MHD Fundamentals Equations Approximations : We will neglect the influence of the capillary forces in this stable domain, 3 Major Factors: - Gravity • Magnetostrictive Pressure • Laplace Forces When the Equilibrium is reached -> Bernouilli Generalised Equation (1)

  10. Numerical Resolution • Finite Element Method applied to model the interaction of the field and the fluid. Field of a cylindric shaped magnet Height of the ferrofluid sample (From Top)

  11. Experiment VS Theory Numerical approach Physical Experiment • Deformation of the fluid above the magnet • Ferrofluid sample subjected to a strong magnet

  12. Validation of the model

  13. Classic methods • Mechanics deformation of a “usual” mirror using piezoelectric devices

  14. Applications to adaptive optics • Generic principle of adaptive optics

  15. Some examples • Results using classic adaptive Final Results (NGC 7469 Galaxy)

  16. Liquid Mirror • A well-know Patent (Ernesto Capocci -1856)

More Related