A pyramidal sensor specifically developed at ONERA to measure the refractive index field is presented. This sensor can be considered as a four channel schlieren. It has a robust behavior against vibrations and can realize high resolution measurements thanks to a high level of pupil sampling. Tests have been planned in a wind tunnel to evaluate its performance in presence of a turbulent flow at subsonic Mach number. From the measured phase maps, a method has been performed to determine the optical characteristics required to respect a signal to noise ratio sufficient to ensure the quality of the measured aberrations. Preliminary results and the first reconstructed phases obtained from the tests are presented in this paper. The results are compared with those obtained with a holographic interferometer
pyramidal sensor, aero-optic effects, wavefront sensor
Born M., Wolf E. (1980). Principle of optics, Pergamon Press.
Desse J. M., Picart P. (2011). Analyse des écoulements instationnaires par interférométrie holographique numérique couleur. Photoniques, novembre/décembre, p. 43-48.
Desse J. M., Picart P., Tankam P. (2008). Digital three-color holographic interferometry for flow analysis, Optics Express, vol. 16, n° 8, p. 5471-5480.
Dessenne C. (1998), Commande modale et prédictive en optique adaptative, PHD Thèse, Université Paris VII.
Donjat D., Nicolas F., Plyer A. (2015). Study of a co-flowing hot jet: an application of direct 3DBOS technique in research wind tunnel. 10th Pacific Symposium on Flow Visualization and Imaging Processing 2015, 15-18 June, Naples, Italy.
Efimov A. (2014). Spatial coherence at the output of multimode optical fibers, Optics Express, vol. 22, n° 13, p. 15577-15588.
Goldhahn E., Seume J. (2007). The background oriented schlieren technique: sensitivity,accuracy, resolution and application to a three-dimensional density field, Journal of Experiments in Fluids, vol. 43, p. 241-249.
Noll R. J. (1976). Zernike polynomials and atmospheric turbulence. Journal Optical Society of America, vol. 66, p. 207-211.
Ragazzoni R. (1996). Pupil plane wavefront sensing with an oscillating prism. Journal of Modern Optics, vol. 43, p. 289-293.
Ragazzoni R., Farinato J. (1999). Sensitivity of a pyramidic Wave Front sensor in closed loop Adaptive Optics. Astronomy and Astrophysics, vol. 350, p. L23-L26.
Riccardi A., Bindi N., Ragazzoni R. (1998). Laboratory characterization of a “Foucault-like” wavefront sensor for Adaptive Optics, Conference on Adaptive Optical System Technologies, Kona, Hawaï, March, SPIE, vol. 3353, p. 941-951.
Rigaut F., Gendron E. (1992). Laser guide star in adaptive optics: the tilt determination problem. Astronomy and Astrophysics, vol. 261, p. 677-684.
Rodriguez O. (1984). The circular cylinder in subsonic and Transonic flow. American Institute of Aeronautics and Astronautics Journal, vol. 22, n° 12, December, p. 1713-1718