Holo-GPC: Holographic Generalized Phase Contrast

Light shaping methods based on spatial phase-only modulation can be classified depending on whether they distribute multiple beams or shape the individual beams. Diffractive optics or holography can be classified as the former, as it spatially distributes a plurality of focal spots over a working volume. On the other hand, Generalized Phase Contrast (GPC) forms beams with well-defined lateral shapes and could be classified as the latter. To certain extents, GPC and holography can also perform both beam distribution and beam shaping. But despite the overlap in beam distribution and beam shaping, it is clear that one approach outperforms the other in one of these aspects. In this work, we introduce a hybrid of holography and GPC, coined Holo-GPC, which can efficiently control both the individual shape and the collective distribution of the resulting light beams. Hereby, Holo-GPC obtains the simplicity of GPC in forming well-defined speckle-free shapes that can be distributed over an extended 3D volume through holographic means. The combined strengths of the two photon-efficient phase-only light shaping modalities open new possibilities for contemporary laser sculpting applications.