Outputs (15)

PEPITO: atmospheric Profiling from short-Exposure focal Plane Images in seeing-limiTed mOde (2019)
Journal Article
Beltramo-Martin, O., Bharmal, N. A., & Correia, C. (2019). PEPITO: atmospheric Profiling from short-Exposure focal Plane Images in seeing-limiTed mOde. Monthly Notices of the Royal Astronomical Society, 486(2), 2032-2041. https://doi.org/10.1093/mnras/stz979

Atmospheric profiling is a requirement for controlling wide-field Adaptive Optics (AO) instruments, analyzing the AO performance with respect to the observing conditions and predicting the Point Spread Function (PSF) spatial variations. We present PE... Read More about PEPITO: atmospheric Profiling from short-Exposure focal Plane Images in seeing-limiTed mOde.

Origin of the asymmetry of the wind driven halo observed in high-contrast images (2018)
Journal Article
Cantalloube, F., Por, E., Dohlen, K., Sauvage, J., Vigan, A., Kasper, M., …Fusco, T. (2018). Origin of the asymmetry of the wind driven halo observed in high-contrast images. Astronomy & Astrophysics, 620, Article L10. https://doi.org/10.1051/0004-6361/201834311

The latest generation of high-contrast instruments dedicated to exoplanets and circumstellar disk imaging are equipped with extreme adaptive optics and coronagraphs to reach contrasts of up to 10−4 at a few tenths of arcseconds in the near-infrared.... Read More about Origin of the asymmetry of the wind driven halo observed in high-contrast images.

Calibration of quasi-static aberrations in high-contrast astronomical adaptive optics with a pupil-modulated point-diffraction interferometer (2018)
Journal Article
Dubost, N., Bharmal, N., & Myers, R. M. (2018). Calibration of quasi-static aberrations in high-contrast astronomical adaptive optics with a pupil-modulated point-diffraction interferometer. Optics Express, 26(9), 11068-11083. https://doi.org/10.1364/oe.26.011068

The direct detection and imaging of exoplanets requires the use of high-contrast adaptive optics (AO). In these systems quasi-static aberrations need to be highly corrected and calibrated. In order to achieve this, a high-sensitivity wavefront sensor... Read More about Calibration of quasi-static aberrations in high-contrast astronomical adaptive optics with a pupil-modulated point-diffraction interferometer.

Projected Pupil Plane Pattern: an alternative LGS wavefront sensing technique (2018)
Journal Article
Yang, H., Bharmal, N. A., & Myers, R. M. (2018). Projected Pupil Plane Pattern: an alternative LGS wavefront sensing technique. Monthly Notices of the Royal Astronomical Society, 477(4), 4443-4453. https://doi.org/10.1093/mnras/sty926

We have analysed and simulated a novel alternative Laser Guide Star (LGS) configuration termed Projected Pupil Plane Pattern (PPPP), including wavefront sensing and the reconstruction method. A key advantage of this method is that a collimated beam i... Read More about Projected Pupil Plane Pattern: an alternative LGS wavefront sensing technique.

Estimating stochastic noise using in-situ measurements from a linear wavefront slope sensor (2016)
Journal Article
Bharmal, N., & Reeves, A. (2016). Estimating stochastic noise using in-situ measurements from a linear wavefront slope sensor. Optics Letters, 41(2), 428-431. https://doi.org/10.1364/ol.41.000428

It is shown how the solenoidal component of noise from the measurements of a wavefront slope sensor can be utilized to estimate the total noise: specifically, the ensemble noise variance. It is well known that solenoidal noise is orthogonal to the re... Read More about Estimating stochastic noise using in-situ measurements from a linear wavefront slope sensor.