Aberration-free large-area stitch-free 3D nano-printing based on binary holography

Abstract

Direct laser writing (DLW) has been widely used in a variety of engineering and research applications. However, the fabrication of complex and robust three-dimensional (3D) structures at submicron-level resolution by DLW is still largely limited by the laser focus quality, i.e., point spread function (PSF), laser dose, precision of mechanical scanners, and printing trajectory. In this work, we present a two-photon polymerization (TPP)-based DLW system based on a digital micromirror device (DMD) and binary holography to realize aberration-free large-area stitch-free 3D printing as well as 3D random-access scanning. First, the binary holograms, which control the amplitude, phase, and position of the laser focus, are optimized by the sensorless adaptive optics algorithm to correct the distorted wavefront in the DMD work field. Next, the DMD is synchronized to a continuously moving sample stage to eliminate stitching errors, i.e., the sample positioner simultaneously moves with the scanning focus until the structure is completed. We have fabricated large-area complex 3D structures, e.g., metamaterial structures, and micro-lenses, and 2D gray level diffractive optical elements (DOEs) with better than 100 nm resolution and optimal scanning trajectories. Notably, the variation of the scanning trajectory, laser power (dose), and voxel sizes can be realized without affecting the scanning speed, i.e., 22.7 kHz, which is equivalent to the DMD pattern rate.

Recent Advances on High‐Speed and Holographic Two‐Photon Direct Laser Writing

“…Reproduced with permission. [216] Copyright 2021, Optical Society of America under the terms of the OSA Open Access Publishing Agreement.…”

“…[215] Most of the compensation methods described so far aim for global average correction over the entire workspace, although aberrations related to modulation devices are typically local in nature and not uniform over the active area. Through a local correction, obtained by evaluating the distortion induced by separate subregions of a DMD, Ren et al [216] achieved efficient voxel optimization and uniformity over the fabrication FOV, resulting in aberration-free large-area stitch-free 3D structures with total dimensions of hundreds of micrometers (Figure 8F).…”

3D printing of optical materials by processes based on photopolymerization: materials, technologies, and recent advances

“…In this context, several approaches based on two-photon absorption have been proposed such as multi-focus two-photon printing [96] or two-photon printing with an ultrafast random-access digital micromirror device (DMD) scanner [97]. Binary holography was also proposed to realize aberration-free large-area stitch-free 3D printing [98]. These techniques allow the fabrication of large-area complex 3D structures such as metamaterial structures, micro-lenses, and 2D gray level diffractive optical elements (DOEs) with better than 100 nm resolution and they have competitive DMD pattern rates, which reinforces the interest of approaches based on biphotonic absorption.…”

Fabrication of large-scale scaffolds with microscale features using light sheet stereolithography

“…However, the magnification or resolution dependence of DLP due to the projection optics and digital micromirror devices (DMDs) hinder the scaling-up capabilities of rapid and high-resolution 3D printing (e.g., down to several millimeters in size)[ 38 , 39 , 44 - 46 ], making its implementation impractical in large surface-to-volume ratio constructs found in wound dressing applications[ 30 , 46 - 48 ]. Furthermore, although stitching methods have been proposed to fabricate larger areas in state-of-the-art, the printed structures exhibit inaccuracies, surface defects, and mechanical deformations that may affect the performance of the scaffolds[ 38 , 47 , 49 ]. It is worth mentioning that more research must be carried out on the stitching effects of biomaterials on scaffold fabrication.…”