corresponds to a change of the angle of the grating of 58l rad: Da ¼ Dk 5:8 10 5 rad. Consequently, 3.45lm. 10 full rotations (Dk ¼ 1000) correspond to Da ¼ 3:3 . In reality, the imaging resolution is limited by aberra- tions4 and we find experimentally FWHM exp 13 lm (see Within this range, we can approximate
