This experimental study tests image-mode spatial light modulation as a way to increase two-photon polymerization throughput by projecting patterns to fabricate several microstructures together. A 515 nm femtosecond laser and modified OrmoComp photoresin produced pillar arrays, square boxes and rings; pulse energy and exposure time controlled lateral dimensions and heights while the focal z position remained fixed. The measured processing window included smooth pillars 0.6–1.2 micrometres in diameter and structure heights of 0.25–1.5 micrometres. Excessive irradiation produced irregular edges a

One beam. Many tiny structures. A different way to write with light.

A spatial light modulator turns a laser into a pattern. This study explores how projecting that pattern into resin can make microstructures together—and how exposure shapes what survives.

515 nm Visible femtosecond laser

0.6–1.2 µm Smooth, uniform pillar diameters

Fixed focal z Exposure changes voxel dimensions

Let light do several jobs at once.

In two-photon polymerization, tightly focused light triggers a reaction inside a small volume of resin. That solidified volume is a voxel : a three-dimensional pixel.

A small voxel gives exquisite resolution, but writing an entire structure point by point takes time. Here, a spatial light modulator (SLM) shapes the beam into an image, creating several features in a single exposure. Changing the dose grows the voxels while the focus stays at the same height.

Same pattern. Different dose.

Choose a pattern, tune the exposure, then wash away the uncured resin. What will your light leave behind?

Cross · 5 pillars

Five smooth pillars, exposed together.

Dose combines pulse energy, repetition rate and exposure time. This relative slider explores the trend; intermediate geometry is conceptual.

Separate, smooth pillars. Dose controls size while the projected pattern stays the same.

Figure 6 reference: ~1.1 µm diameter

The useful window matters. Too little exposure can leave pillars that fall during development. Too much can grow irregular edges and bridges between neighbours.

From light to evidence.

The experiment’s actual images reveal how dose, shape and repeatability fit together.

More exposure changes more than size.

In the pillar experiments, diameter increased from 0.6 to 3.5 µm. Smooth, circular pillars occupied the 0.6–1.2 µm range; larger doses produced irregular edges and, in severe cases, connections between neighbours.

A route toward surfaces that shape light.

Rings, pillars and boxes can act as building blocks— meta-atoms —for optical metasurfaces. Their geometry helps determine how a designed surface interacts with light.

Patterns replace repeated writing.

Projecting a pattern fabricates several microstructures in one exposure, offering a way to improve throughput while preserving fine features.

Dose adds a vertical dimension.

The focus remains fixed while exposure controls voxel height. Reported square structures span 0.25–1.5 µm in height, offering a route toward single-scanning-layer 3D metasurfaces.

Geometry stays repeatable.

Across a 20 × 20 mm² sample, printed pillars had a mean diameter of 3.16 µm and a standard deviation of 0.35 µm. Rings and square boxes also retained similar shapes and sizes.

Enhancing Two-Photon Polymerization Productivity: Beam Shaping and Parallelization via Spatial Light Modulators

Jaime Cuartero · Nerea Otero · Francisco Gontad

Journal of Manufacturing and Materials Processing · 2026 · 10(6), 182

The apparatus uses a 515 nm laser with pulses below 200 fs at 1–5 MHz, an SLM operated in image mode, and a ×40 microscope objective with numerical aperture 0.95. Patterns are projected into OrmoComp resin with 2% Irgacure OXE02 photoinitiator, on a glass substrate.

Pulse energy and exposure time control voxel dimensions at a fixed focal z. Unpolymerized resin is removed during development, and the structures are characterized using 3D optical profiling and scanning electron microscopy.

The visual lab uses a relative dose scale; intermediate shapes illustrate the trends in Figures 3–6.

Explore the science. Follow the light.

Figure 6 · Cuartero et al. (2026) · CC BY 4.0 · Resized; content unchanged.