This study is focused on the very high dynamic imaging field, specifically the direct observation of exoplanetary systems. The coronagraph is an essential technique for suppressing the star’s light, making it possible to detect an exoplanet with a very weak luminosity compared to its host star. Apodization improves the rejection of the coronagraph, thereby increasing its sensitivity. This work presents the apodization method by interferometry using homothety, with either a rectangular or circular aperture. We discuss the principle method, the proposed experimental setup, and present the obtained results by optimizing the free parameters of the system while concentrating the maximum of the light energy in the central diffraction lobe, with a concentration rate of 93.6% for the circular aperture and 91.5% for the rectangular geometry. The obtained results enabled scaling the various elements of the experiment in accordance with practical constraints. Simulation results are presented for both circular and rectangular apertures. We performed simulations on a hexagonal aperture, both with and without a central obstruction, as well as a segmented aperture similar to the one used in the Thirty Meter Telescope (TMT). This approach enables the attainment of a contrast of approximately 10−4 at small angular separations, specifically around 1.8λ/D. When integrated with a coronagraph, this technique exhibits great promise. These findings confirm that our proposed technique can effectively enhance the performance of a coronagraph.

Atmospheric optical parameters play a significant role in high angular resolution and adaptive optics. The single star SCIDAR (hereafter SSS) is one of the methods by which we obtain the vertical profile of these parameters such as the refractive index structural constant Cn2. This technique is based on the study of the correlation functions of atmospheric speckles using the simulation annealing (SA) minimisation algorithm to find the optimum solution. But the main disadvantage of this algorithm is that it requires time to extract the parameters (6 minutes or so per profile) and to have enough data in a reasonable time. That's why we have tested another algorithm called Active Set (AS) which is faster and allows us to get the Cn2 profile in real-time with a good accuracy. Indeed, real-time processing of atmospheric parameters and the precision of recovery are of great interest for many adaptive optical systems. The temporal resolution of the SSS using the AS algorithm (SSS-AS) is around 3 seconds and the accuracy is about 95%. The precision of this algorithm allows us to extract the Cn2 profile from autocorrelation functions of atmospheric speckles. The simulation results, real data processing and comparison with instrumented balloon data support this real-time Cn2 retrieval mode.