Large-scale microlens arrays on flexible substrate with improved numerical aperture for curved integral imaging 3D display

Abstract

Curved integral imaging 3D display could provide enhanced 3D sense of immersion and wider viewing angle, and is gaining increasing interest among discerning users. In this work, large scale microlens arrays (MLAs) on flexible PMMA substrate were achieved based on screen printing method. Meanwhile, an inverted reflowing configuration as well as optimization of UV resin's viscosity and substrate's surface wettability were implemented to improved the numerical aperture (NA) of microlenses. The results showed that the NA values of MLAs could be increased effectively by adopting inverted reflowing manner with appropriate reflowing time. With decreasing the substrate's wettability, the NA values could be increased from 0.036 to 0.096, when the UV resin contact angles increased from 60.1° to 88.7°. For demonstration, the fabricated MLAs was combined to a curved 2D monitor to realize a 31-inch curved integral imaging 3D display system, exhibiting wider viewing angle than flat integral imaging 3D display system. Display technology will develop in the direction of more natural vision and more user-friendly. In the past two decades, considerable attention has been paid to extend the classical two-dimensional (2D) displays into their three-dimensional (3D) counterparts because of its stronger sense of reality 1-4. Another important research stream is flexible display, which has thin, lightweight and non-breakable characteristics. Displays with flexible form factors enable the fabrication of displays on curvilinear surfaces and allow their shapes to be transformed, providing potential applications to mobile, wearable and vehicle display. Therefore, flexible 3D displays become a major technological and application goal in the field of next-generation displays. Integral imaging is an autostereoscopic and multiscopic 3D display technology that uses double micro-lens arrays (MLAs) to capture and reproduce a light field of the target based on reversibility principle of light rays 5. It is regarded as a promising approach to realize the 3D display system due to its typical characteristics, such as glasses free, full parallax, quasi-continuous view points, eliminating visual fatigue and real 3D display. In particular, it produces real concentrations of light to optically produce 3D images that are observed without decoupling the convergence and the accommodation, avoiding the detrimental effects of the convergence-accommodation conflict. Thus, there has been substantially increasing interest in researching and implementing effective technologies for the capture, processing, and display of 3D images 6-8. It is also inferred that flexible integral imaging 3D displays could be achieved via the combination of flexible 2D display panel and flexible MLAs 9-11. MLAs have been widely used as key components in lots of optical systems 12-14 , such as integral imaging 15,16 , optical communications 17 , digital display 18 , detection 19 and far field imaging 20. In particular, MLAs with good converging performance, great uniformity of focusing...

High-resolution light field prints by nanoscale 3D printing

“…To reduce unwanted iridescence over a wide range of viewing angles, angle-insensitive structural colour pixels 53 , 54 should also be designed and fabricated. In addition, the metalenses and structural colour pixels can be fabricated on curved substrates 55 instead of flat substrates. If high NA metalenses (NA ~1) are combined with angle-insensitive structural colour pixels of 250 nm pitch, a hyper-realistic LFP that provides a ~180° range of viewing angles and an angular resolution of 0.4° can be achieved.…”

Silk Microlens Array

“…In direct methods, the lens is obtained from the base material. For example, the material directly shapes into the lens by the surface tension of the liquid or thermoplastic state of the material [2][3][4][5][6] . Although the direct methods are simple, cost-effective, and favorable for realizing super smooth curved surface of lens, it is difficult to precisely control the shape and size of the microlens as the lens geometry is determined by wettability, time, temperature, and pressure.…”

Direct Microtip Focused Electrohydrodynamic Jet Printing of Tailored Microlens Arrays on PDMS Nanofilm‐Modified Substrate

“…In recent years, microlens arrays (MLAs) have attracted extensive attention due to their wide applications in various fields such as digital displays, [ 1–3 ] light‐emitting‐diodes (LEDs), [ 4,5,6,7 ] super‐resolution imaging, [ 8,9,10 ] and artificial compound eyes. [ 11,12,13 ] The demand of MLAs with precise shaping features has increased over the last few decades.…”

“…In recent years, microlens arrays (MLAs) have attracted extensive attention due to their wide applications in various fields such as digital displays, [1][2][3] light-emitting-diodes (LEDs), [4,5,6,7] super-resolution imaging, [8,9,10] and artificial compound used to fabricate micro/nanolens arrays (M/NLAs). [13,28] Zhou et al reported that the diameters of the MLAs fabricated by E-jet printing decreased from 32.45 to 1.59 µm when the inner diameter of the nozzle decreased from 25 to 1 µm.…”