Ultra-fast 3D printing of assembly—free complex optics with sub-nanometer surface quality at mesoscale

Key words: 
• tomographic volumetric printing /
• meniscus equilibrium post-curing methods /
• spherical lens sub-nanometric roughness

Abstract: 

Complex-shaped optical lenses are of great interest in the areas of laser processing, machine vision, and optical communications. Traditionally, the processing of complex optical lenses is usually achieved by precision machining combined with post-grinding or polishing, which is expensive, labor-intensive and difficult in the processing of ultra-complex optical lenses. Additive manufacturing is an emerging technology that provides significant advantages in producing highly intricate optical devices. However, the layer-by-layer method employed in such manufacturing processes has resulted in low printing speeds, as well as limitations in surface quality. To address these challenges, we apply tomographic volumetric printing (TVP) in this work, which can realize the integrated printing of complex structural models without layering. By coordinating the TVP and the meniscus equilibrium post-curing methods, ultra-fast fabrication of complex-shaped lenses with sub-nanometric roughness has been achieved. A 2.5 mm high, outer diameter 9 mm spherical lens with a roughness value of RMS = 0.3340 nm is printed at a speed of 3.1 × 10⁴ mm³ h^-1. As a further demonstration, a complex-shaped fly-eye lens is fabricated without any part assembly. The designed spherical lens is mounted on a smartphone’s camera, and the precise alignments above the circuit board are captured. Upon further optimization, this new technology demonstrates the potential for rapid fabrication of ultra-smooth complex optical devices or systems.