Fig. 2.

(a) Optical aberrations on the pupil plane of a NA=1.0 objective under 0°, 15°, 35°, 45° coverslip tilt. The linear non-aberrational components (piston, tip/tilt) are subtracted from the phase difference calculated with Eq. (20). The white dashed circle represents 0.8 NA. At 45° coverslip tilt, the pupil function is cropped to NA = 0.8 because of objective geometric constraint. The left column shows the absolute aberration in each case, and the right column shows the relative aberration with respect to that in the zero-tilt case in order to remove the spherical aberrations resulting from imaging across a glass coverslip. Color bar unit: wavelengths. (b) Cross sections of the absolute (left column) and relative (right column) aberrations. Unit: wavelength.