Metasurface-driven full-space structured light for three-dimensional imaging

Abstract

Structured light (SL)-based depth-sensing technology illuminates the objects with an array of dots, and backscattered light is monitored to extract three-dimensional information. Conventionally, diffractive optical elements have been used to form laser dot array, however, the field-of-view (FOV) and diffraction efficiency are limited due to their micron-scale pixel size. Here, we propose a metasurface-enhanced SL-based depth-sensing platform that scatters high-density ~10 K dot array over the 180° FOV by manipulating light at subwavelength-scale. As a proof-of-concept, we place face masks one on the beam axis and the other 50° apart from axis within distance of 1 m and estimate the depth information using a stereo matching algorithm. Furthermore, we demonstrate the replication of the metasurface using the nanoparticle-embedded-resin (nano-PER) imprinting method which enables high-throughput manufacturing of the metasurfaces on any arbitrary substrates. Such a full-space diffractive metasurface may afford ultra-compact depth perception platform for face recognition and automotive robot vision applications.

Emerging low-cost, large-scale photonic platforms with soft lithography and self-assembly

“…This technology has also been investigated for use in realizing industrial-scale applications that require mass production with low-cost materials, mask-free processes, low manufacturing cost, and high production speed [49,50] . The polymers mainly used in NIL have wide applicability in optical/electronic devices such as 3D imaging [51] , solar cells [52,53] , light-emitting diodes (LEDs) [54] , and polarizers [55,56] because of their ease of manufacturing, low cost, and low reactivity. In addition, NIL has been researched for fabricating metasurfaces using metals such as gold (Au) [57] .…”

Advances in Meta-Optics and Metasurfaces: Fundamentals and Applications

“…Such OAM-carrying structured light beams have been found to have various significant applications in optics and photonics, such as optical communications [ 188 ], optical trapping [ 189 ], and image processing [ 190 ], etc. Because of their properties of ultra-compact configuration and powerful functionalities for wavefront control, metasurface-based structured-light technologies offer new opportunities for excavating the fundamentals and applications of light beams that are impossible to achieved by conventional optics [ 191 , 192 , 193 , 194 ]. As shown in Figure 7 a, Shuang Zhang et al propose multichannel metalenses via geometrical phase-based metasurfaces composed of metallic nanovoid arrays.…”

Slanted TiO2 Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

“…The typical diffraction angle of gradient metasurface is below 50°, strongly hindering their practical applications in ultracompact spectrometer, high-performance imaging, as well as virtual reality and augmented reality (VR/AR). In the field of consumer electronics and automobile engineering, [21,22] a highefficiency, large-angle beam steering facilitates the acquisition of a larger range of structural light arrays for depth perception. It is also expected to replace the scanning components in light detection and ranging (LiDAR), [23] reducing the impact of external shocks on scanning accuracy.…”