Bachar Wehbe

PhD Student

Atmospheric Dispersion Correction for High Resolution Astronomical Instruments

Adaptive Optics -- Spectroscopy -- Exoplanets

Current Research Summary:

Astronomical observations with ground based telescopes are affected by differential atmospheric dispersion, a consequence of the wavelength-dependent index of refraction of the atmosphere. Even if telescope pointing and guiding is perfect at a given reference wavelength, atmospheric dispersion will shift the image of the object at different wavelengths. Moreover such effect will vary during exposure with the observation zenital angle. In high resolution astronomical instruments, an Atmospheric Dispersion Corrector (ADC) is thus mandatory to avoid wavelength dependent losses. My work research is focused on the following aspects:

• Study of the atmospheric dispersion phenomena by analyzing different atmospheric dispersion models
• Analysis of different ADC configurations, and focusing on the rotating ADC concept
• Development of an ADC optical design tool
• ADC implementation using as case studies ESPRESSO, NIRPS, and the future HIRES on the ELT

As an outcome of this work, it is expected that we advance on the knowledge of the impact of the dispersion correction in high resolution spectrographs and its scientific applications.

Prior Research:

Master's degree at Notre Dame University - Louaize, Lebanon (2011-2014)