Fig. 1.

– SI-LFM illuminates samples with an axially invariant pattern generated by super-pixel diffraction. (a) The schematic drawing shows the imaging setup of SI-LFM. A DMD in the imaging path formed the grating excitation pattern, and a conventional light-field imaging path collected the sample emission. (b) The DMD pattern (top) produced a first-order diffraction pattern in Fourier space (bottom); the top-right inset of the bottom panel is a zoomed-in view of the two peaks corresponding to two symmetric plane waves. (c) The interference between these two plane waves generated a grating pattern that was invariant at different axial positions. Bottom inset: The averaged intensity profile (averaged along the x-direction, n = 50 grating cycles) of the volumetric grating pattern with lateral spatial frequency 0.1 cycle/µm retained contrast over 250 µm of depth. The non-uniformity of the tape sample induced small, but repeatable, local intensity variations. (d) The invariant imaging depth decreased as the spatial frequency of the illumination pattern increased. (e) The image reconstruction includes a light-field reconstruction step and a SIM reconstruction step.