Fig. 2.

Calibration of the accuracy of the spatially resolved aberration measurement. (a), example of test sample used for calibration (fixed, stained pine root slice). The green rectangles indicate the locations of the smaller regions over which aberrations were measured iteratively. Scale bar, 100μm. (b), aberration map obtained on the sample in (a) for astigmatism (z=5, see Appendix A). The green rectangles mark the same location as in (a), and delimitate the region over which the aberration map was averaged to compare the spatially-resolved measurement with the iterative result. (c), Error in the spatially resolved measurements as a function of the total amount of aberrations in the 11 Zernike modes under investigation (z=5 to 15, see Appendix A), estimated as the difference between the spatially-resolved value at a given location and the iterative (accurate) local measurement at the same location (green rectangles in (a) and (b)). Both axes are expressed in terms of rms value of the phase profile, or equivalently of the norm of the Zernike coefficient vector. Results for each sample are plotted with a different symbol and colour. The black line is a quadratic fit to the data [9].