[Paper Review] Centimeter-scale superfine three-dimensional printing with femtosecond laser two-photon polymerization

Wei Chu, Yuanxin Tan+5 more|arXiv (Cornell University)|Dec 11, 2017

Nonlinear Optical Materials Studies16 references3 citations

TL;DR

This paper presents a simultaneous spatiotemporal focusing (SSTF) technique that enables centimeter-scale, superfine three-dimensional printing using femtosecond laser two-photon polymerization (TPP), overcoming the traditional millimeter-scale size limitation. By tuning laser power, the method achieves isotropic spatial resolution from ~10 μm to ~40 μm, allowing high-resolution fabrication of complex 3D structures like a 1.3 cm-tall Terra Cotta Warrior and 0.6 cm Chinese guardian lions.

ABSTRACT

Nowadays three-dimensional (3D) printing has been widely used for producing geometrically complex 3D structures from a broad range of materials such as ceramics, metals, polymers, semiconductors, etc. Although it has been demonstrated that a fabrication resolution as high as ~100 nm can be achieved in 3D printing based on two photon polymerization (TPP), the end product size of TPP is typically on millimeter scale limited by the short working distance of high-numerical-aperture focal lens. Here we present a method based on simultaneous spatiotemporal focusing (SSTF) of the femtosecond laser pulses that enables to fabricate centimeter-scale 3D structures of fine features with TPP. We also demonstrate an isotropic spatial resolution which can be continuously tuned in the range of ~10 um and ~40 um by only varying the power of femtosecond laser, making this technique extremely flexible and easy to implement. We fabricate several Chinese guardian lions of a maximum height of 0.6 cm and a Terra Cotta Warrior of a height of 1.3 cm using this method.

Motivation & Objective

• To overcome the millimeter-scale size limitation of conventional two-photon polymerization (TPP) due to short working distance of high-NA lenses.
• To enable fabrication of centimeter-scale 3D structures with superfine features using TPP.
• To achieve isotropic spatial resolution tunable over a wide range via simple laser power adjustment.
• To demonstrate practical applicability by fabricating complex, large-scale microstructures such as cultural artifacts.

Proposed method

• The method employs simultaneous spatiotemporal focusing (SSTF) of femtosecond laser pulses to extend the depth of focus while maintaining high spatial resolution.
• SSTF enables uniform excitation over a large volume by shaping the laser beam in both time and space domains.
• The technique uses a high-numerical-aperture objective lens with a longer working distance than conventional setups, allowing larger-scale printing.
• Laser power is varied to tune the effective resolution from ~10 μm to ~40 μm, providing flexibility without changing optical components.
• The process is compatible with standard TPP materials and allows for continuous, isotropic resolution control in three dimensions.

Experimental results

Research questions

• RQ1 Can two-photon polymerization be scaled to produce centimeter-scale 3D structures without sacrificing sub-100 nm resolution?
• RQ2 Can the spatial resolution of TPP be continuously tuned over a wide range using only laser power modulation?
• RQ3 Can SSTF effectively extend the working depth while maintaining high-resolution fabrication in 3D?
• RQ4 Is it feasible to fabricate complex, large-scale microstructures with fine features using this method?

Key findings

• The method successfully produced a 1.3 cm-tall Terra Cotta Warrior with fine structural details using two-photon polymerization.
• A 0.6 cm-tall Chinese guardian lion was fabricated, demonstrating the capability for complex, large-scale microstructures.
• Isotropic spatial resolution was continuously tunable from ~10 μm to ~40 μm by adjusting the femtosecond laser power alone.
• The technique overcame the traditional millimeter-scale size limit of TPP by extending the effective working distance through SSTF.
• The fabrication process maintained high resolution across centimeter-scale volumes, enabling complex 3D printing beyond previous constraints.