Calibration of CONICA static aberrations by phase diversity

CONICA is the first AO equipped multimode near infrared camera which saw first light at the VLT in the end of 2001. A technique will be described to benefit of the AO system NAOS to correct not only for atmospheric turbulence but also for the internal optical aberrations of the high resolution camera. The aberrant optical components in the light path of CONICA are outside of the AO loop and therefore no self-acting correction is possible. Independently of the AO wave front sensor, a separate measurement of these minor aberrations using a method called phase diversity allows to predict for the variety of camera configurations the corresponding aberrations. They are quantified by sets of Zernike coefficients which are rendered to the adaptive optics. This technique turns out to be very flexible and results into a further improvement of the optical overall performance.

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