Figure 4
Diffraction efficiency (logarithmic scale), as represented by the far-field 1D diffraction of the lens, as a function of tilt (α) of the MLL lens. Simulations of MLLs with parallel layers (a) and with wedged layers (b) show that high NA is only achievable with the latter. (c) Measurements of diffraction from our wedged MLL. The stage used to tilt the lens was not encoded and so the tilts are only approximate. The arrow indicates the region of the pupil corresponding to the largest NA in (a). The dashed line highlights the tilt angle used for subsequent analysis. Note the difference in the range of tilts in (a).
