Fabrication of freeform optical components by fluidic shaping

Abstract

Freeform optical components enable advanced manipulation of light that is not possible with traditional optical systems. However, their fabrication relies on machining processes that are complex, time-consuming, and require significant infrastructure. Here we present the ability to shape liquid volumes and solidify them into desired freeform components, enabling rapid prototyping of freeform components with high surface quality. The method is based on controlling the minimum energy state of the interface between a curable optical liquid and an immersion liquid, by dictating a geometrical boundary constraint. We provide an analytical solution for the resulting topography given a predefined boundary and demonstrate the fabrication of freeform components with sub-nanometer surface roughness within minutes. Such a fabrication capability, that allows for rapid prototyping of high-quality components, has the potential to answer an unmet need in the optical design industry—allowing researchers and engineers to rapidly test freeform design concepts. It can be further envisioned to be expanded to an industrial scale, allowing for mold-less fabrication of freeform optics.

Gravity‐Controlled and Boundary‐Constrained High‐Throughput Fabrication of Polymeric Miniature Lens Arrays

“…Assume the shape of the hole boundary is $$ z_{\rm o}=g(\rho _b,\theta _b)$$ with $$ \rho _b$$ and $$ \theta _b$$ denoting the polar coordinates, the free energy of the deformed fluid surface can be expressed by $$\begin{equation} U=\int _{0}^{2\pi }\int _{0}^{\rho }\varphi (\rho ,\theta )\mathrm{d}\rho \mathrm{d}\theta \end{equation}$$where $$ \varphi (\rho ,\theta )$$ denotes the Lagrange equation consisting of the surface energy, body force‐induced energy, and the volume constraint. By assuming the surface form is $$ h(\rho ,\theta )$$ at an arbitrary position $$ (\rho ,\theta )$$, the Lagrange equation can be expressed by [ 26 ] $$\begin{eqnarray} &&\kern-6pt\varphi (\rho ,\theta )\nonumber\\ &&=\rho {\left[ \gamma \sqrt {1+{\left(\frac{\part...$$…”

“…where 𝜑(𝜌, 𝜃) denotes the Lagrange equation consisting of the surface energy, body force-induced energy, and the volume constraint. By assuming the surface form is h(𝜌, 𝜃) at an arbitrary position (𝜌, 𝜃), the Lagrange equation can be expressed by [26] 𝜑(𝜌, 𝜃)…”

Mold-free self-assembled scalable microlens arrays with ultrasmooth surface and record-high resolution

“…However, since their geometry is determined by control parameters such as temperature 19 , wettability 16 , liquid dose and processing time 27 , 30 , the precise control of curvature and focal length remains difficult. In this case, mould-assisted techniques are also usually introduced in the direct method to set a boundary constraint for the thermoplastic or liquid material in the self-assembly process, while the roughness is controlled by balancing the surface tension and the gravity 28 , 29 . Nevertheless, this still requires the sophisticated lithography to fabricate the mold.…”

Low-cost 3D printed lenses for brightfield and fluorescence microscopy

“…Custom techniques have been developed previously to improve the capabilities of low-cost optical printing, such as iterative learning printing algorithms which adjust grayscale pixel values throughout the print, or image pattern defocusing to smooth the lateral pixel gaps, both of which minimise the occurring staircase effect [19,20], yet still include a coating post-process step. Aside from coating techniques, liquid immersion lens moulding can produce lens geometries theoretically invariant of diameter or complexity and without the need for post-processing [21,22]. These low-cost manufacturing methods provide the opportunity to repeatably manufacture optical components with tailored uses within microscopy setups.…”