High-precision grayscale lithography OPTICAL PRODUCT
2PP is widely used for fabricating microoptics with high spatial resolution, optical-quality surfaces, and high shape accuracy. However, the printing process requires splitting of the structure design into numerous closely spaced layers to avoid staircasing effects and achieve smooth surfaces. As a result, fabricating micro-optical elements often implies long print times.
TWO-PHOTON GRAYSCALE LITHOGRAPHY: COMBINING PRECISION AND PRINT PERFORMANCE Two-Photon Grayscale Lithography builds on the established principle of two-photon polymerization( 2PP), extending it with dynamic voxel size control to significantly improve printing speed. Unlike conventional layer-by-layer fabrication, 2GL continuously modulates the laser power during exposure to produce spatially varying voxel heights within a single scanning
Figure 1: Densely packed microoptics in random microlens array for diffuser applications. The microlens array was fabricated by Two-Photon Grayscale Lithography and features a fill factor of 100 %.
plane. A grayscale image serves as the input, translating into spatial variations in exposure dose. This allows 2.5D structures to be printed in one step, drastically reducing the number of layers and substantially shortening overall fabrication time by up to two orders of magnitude.
2GL offers broad design flexibility for freeform micro-optics, enabling the fabrication of complex refractive elements, sharp-edged geometries, and hybrid components that combine refractive and diffractive elements. The process produces smooth surfaces without slicing artifacts or voxel-induced distortions, making it well-suited for high-precision optical applications. 2GL provides a means to iterate and produce functional prototypes with optical-grade quality much faster than conventional Two-Photon Polymerization, and without the need for time-intensive mask fabrication. The combination of speed, submicron resolution, and design flexibility makes 2GL a practical approach for both rapid development and scalable manufacturing of advanced microoptical components. In addition, the ability to fabricate 2.5D nano- and microstructured patterns supports wafer-level production and the creation of master templates for subsequent
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