Wide field-of-view imaging with a metalens

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A research group from Nanjing University has published a new paper titled "Planar wide-angle-imaging camera enabled by metalens array" in the recent issue of Optica.

Wide-angle imaging is an important function in photography and projection, but it also places high demands on the design of the imaging components of a camera. To eliminate the coma caused by the focusing of large-angle incident light, traditional wide-angle camera lenses are composed of complex optical components. Here, we propose a planar camera for wide-angle imaging with a silicon nitride metalens array mounted on a CMOS image sensor. By carefully designing proper phase profiles for metalenses with intentionally introduced shifted phase terms, the whole lens array is capable of capturing a scene with a large viewing angle and negligible distortion or aberrations. After a stitching process, we obtained a large viewing angle image with a range of >120 degrees using a compact planar camera. Our device demonstrates the advantages of metalenses in flexible phase design and compact integration, and the prospects for future imaging technology.

Metalens array mounted directly on a CMOS camera

Schematic diagram of the principle and device architecture. (a) Schematics of wide-angle imaging by MIWC. Zoom-in figure shows the imaging principle with each part of the wide-angle image clearly imaged separately by each metalens. (b) Photograph of MIWC. The metalens array can be seen in the middle of the enlarged figure on the right. (c) Architecture of MIWC. The metalens array is integrated directly on the CMOS image sensor (DMM 27UJ003-ML) and fixed by an optically clear adhesive (OCA) tape (Tesa, 69402).

Experimental wide-angle imaging results by MIWC. (a) Projected “NANJING UNIVERSITY” on the curved screen covers a viewing angle of 120° and then is imaged by MIWC. (b) Imaging results and corresponding mask functions of lenses with designed angles of −57.5∘, 0°, 57.5°. (d) Imaging result of a traditional metalens showing limited field of view. (e) Final imaging result of MIWC by processing with mask functions and sub-images, which shows three times larger FOV compared with the traditional lens.

Press release: https://phys.org/news/2022-04-miniature-wide-angle-camera-flat-metalenses.html

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