OPTICAL PRODUCT High-precision grayscale lithography without multiple lithography or alignment steps. For example, hybrid microlenses designed for aberration-corrected imaging can be printed in a single printing step from grayscale input data, preserving design fidelity and ensuring high surface accuracy.
Figure 5: High-precision optics developed for a miniature endomicroscope. The stacked freeform lenses are 3D-printed by Two-Photon Grayscale Lithography. The three lenses are supported by a textured scaffold avoiding back-reflexes. All three freeform lenses have optical-grade surfaces on the top and bottom, integrating diffractive and refractive elements into one optical system and are printed in one pass. Lens design by Printoptix, manufacturing by Nanoscribe.
material processing, and structured light generation for 3D sensing. Their compact form factor and design flexibility make them especially valuable in systems where conventional refractive optics are limited by size, weight, or complexity. Two-Photon Grayscale Lithography is well suited for the fabrication of multi-level and quasi-continuous DOEs, which require precise 2.5D surface topographies to encode phase functions. The technology offers the lateral and axial resolution needed to create DOE features with submicron precision and offers high shape accuracy and printing performance to print DOEs in reasonable time. One example is a 256-level Moiré lens fabricated by 2GL with a lateral pixel size of 500 nm. Complex freeform DOEs, such as quasi-continuous DOEs shown in figure 4, further demonstrate 2GL’ s capability to produce highly accurate surface profiles that are essential for ensuring optical performance in far-field beam shaping or phase control applications.
HYBRID OPTICS 2GL enables the fabrication of hybrid micro-optics that combine refractive and diffractive features into one, continuous topography. This is particularly relevant for applications where complex wavefront shaping or chromatic aberration correction is required. While refractive elements offer high focusing efficiency, diffractive structures can compensate for dispersion or introduce precise phase control. Thus, combining both allows for compact, highly functional optical components. 2GL supports the direct fabrication of such hybrid elements with its ability to produce freeform 2.5D topographies at submicron resolution
CONCLUSION AND OUTLOOK Two-Photon Grayscale Lithography builds on the principle of Two- Photon Polymerization by enabling the fabrication of high-precision 2.5D micro-optics. Through dynamic voxel size modulation, 2GL produces freeform surfaces with optical-grade smoothness and submicron resolution, ideal for beam shaping, imaging, and light modulation applications. The 2GL process integrates seamlessly into microfabrication workflows: from rapid design iteration based on grayscale input data to high-precision printing. Furthermore, 2GL can be combined with subsequent replication via nanoimprint lithography, hot embossing, or injection molding. This makes 2GL a viable bridge between prototyping and scalable manufacturing. Looking forward, the optimization of printing material properties is enabling the development of photoresins tailored for specific applications. This advancement will continue to enhance the functionality of printed structures and improve their stability, both during integration into optical modules and throughout their operational lifetime. In addition, automated processes will further increase throughput and improve process repeatability. While originally developed for 2.5D structures, the underlying grayscale modulation principle also enables the fabrication of complex 3D micro-optics. Three-dimensional geometries, such as stacked freeform lenses for microendoscopy( figure 5) illustrate how 2GL has evolved toward fully 3D optical components for next-generation applications in sensing, communications, displays, and integrated photonics.
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