Correction accuracy in image-based adaptive optics for nonlinear microscopy

We investigate the parameters governing the accuracy of correction in modal sensorless adaptive optics for microscopy. In this paper we focus on the case of two-photon excited fluorescence. Using analytical, numerical and experimental results, we show that using a suitable number of measurements, accurate correction can be achieved for up to 2 rad rms initial aberrations even without optimisation of the correction modes. We demonstrate that this correction can be achieved using low light levels to minimise photobleaching and toxicity, and we provide examples of such optimised correction.