Abstract We demonstrate fast, high-resolution fabrication of in-volume diffractive optical elements (DOEs) by combining galvanometric scanning with a microscope objective (NA=0. 4) and a 1 ps laser source. Carefully chosen parameters exploit nonlinear absorption in fused silica to create highly localized refractive-index modifications. Estimating the scaling laws of energy deposition, single-pulse writing becomes feasible, yielding a n 0. 5 10^{ - 2} and modification dimensions below the nominal focal spot. Using a layer-stacking scheme in z, we assemble multi-level phase masks: examples include a 4-level, 250 × 250 px DOE (2 µm pixels) and a 10-level, 416 × 416 px DOE (1. 2 µm pixels). Phase-contrast microscopy confirms the written phase structure and comparison with theoretical phase data shows strong correspondence. Optical characterization at 532 nm reproduces target intensity distributions with high fidelity (overlap >80 % against the computed discretized mask in a selected region; >66% vs. the original target). Yet, production times remain short (8–9 min for the high-resolution DOE, 60 s for the 4-level device), demonstrating that we improve trade-off between quality and speed to a level good enough for practical applications.
C. Ingenhag (Fri,) studied this question.