Super Field-of-View Lensless Camera by Coded Image Sensors.

Tomoya Nakamura,Shiho Torashima,Masahiro Yamaguchi,Keiichiro Kagawa

doi:10.3390/s19061329

Abstract

A lensless camera is an ultra-thin computational-imaging system. Existing lensless cameras are based on the axial arrangement of an image sensor and a coding mask, and therefore, the back side of the image sensor cannot be captured. In this paper, we propose a lensless camera with a novel design that can capture the front and back sides simultaneously. The proposed camera is composed of multiple coded image sensors, which are complementary-metal-oxide-semiconductor (CMOS) image sensors in which air holes are randomly made at some pixels by drilling processing. When the sensors are placed facing each other, the object-side sensor works as a coding mask and the other works as a sparsified image sensor. The captured image is a sparse coded image, which can be decoded computationally by using compressive sensing-based image reconstruction. We verified the feasibility of the proposed lensless camera by simulations and experiments. The proposed thin lensless camera realized super-field-of-view imaging without lenses or coding masks and therefore can be used for rich information sensing in confined spaces. This work also suggests a new direction in the design of CMOS image sensors in the era of computational imaging.

Highlights

Computational imaging is an imaging method based on a combination of optical encoding and computational decoding [1]
We proposed a novel architecture for a lensless camera that can capture the front and back scene at once
The merit of the proposed camera is the capability of super-FOV imaging by a thin and compact optical hardware constructed only by image sensors

Summary

Introduction

Computational imaging is an imaging method based on a combination of optical encoding and computational decoding [1]. A computational lensless camera is a lensless camera that works on the basis of computational imaging instead of lens-based optical imaging [2]. The lensless imaging frees the camera from the need of optical focusing. This allows the camera to be implemented with ultra-thin, miniature hardware [3]. A lens system is typically replaced with a coded aperture such as a coding mask, which makes the inverse problem numerically invertible. Amplitude masks [4,5,6] or phase-modulation optics [7,8,9,10] have been installed in front of the image sensor. The inverse problem of coded sensing is solved by signal processing

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