Three-dimensional gradient index microlens arrays for light-field and holographic imaging and displays

The geometric, intensity, and chromatic distortions that are a result of the limitations of the material and processes used to fabricate micro-optical lens arrays (MLAs) degrade the performance of light-field systems. To address these limitations, inkjet print additive manufacturing is used to fabricate planar gradient index (GRIN) lenslet arrays, in which volumetric refractive index profiles are used to embed optical functions that would otherwise require multi- ple homogeneous index MLA surfaces. By tailoring the optical ink feedstock refractive index spectra, independent control over dispersion is achieved, and achromatic performance is made possible. Digital manufacturing is shown to be beneficial for optimizing individual micro-optical channels in arrays wherein the shape, size, aspect ratio, focal length, and optical axis orientation of the lenslets vary as a function of the position within the optical field. Print fabrication also allows opaque inter-lens baffling and aperture stops that reduce inter-channel cross talk, improve resolution, and enhance contrast. These benefits are demonstrated in a light-field display testbed.(c) 2023 Optica Publishing Group

Automated summary

Inkjet print additive manufacturing is used to fabricate planar gradient index (GRIN) lenslet arrays, addressing the geometric, intensity, and chromatic distortions of micro-optical lens arrays. Tailoring the optical ink feedstock refractive index spectra allows independent control over dispersion and enables achromatic performance. Digital manufacturing optimizes individual micro-optical channels with varying lenslet parameters, while print fabrication allows for opaque inter-lens baffling and aperture stops to reduce cross talk and improve resolution and contrast. These benefits are demonstrated in a light-field display testbed.