Image sensors hold a pivotal role in society due to their ability to capture vast amounts of information. Traditionally, image sensors are opaque due to light absorption in both the pixels and the read-out electronics that are stacked on top of each other. Making image sensors visibly transparent would have a far-reaching impact in numerous areas such as human-computer interfaces, smart displays, and both augmented and virtual reality. In this paper, we present the development and analysis of the first semi-transparent image sensor and its applicability as an eye-tracking device. The device consists of an 8x8 array of semi-transparent photodetectors and electrodes disposed on a fully transparent substrate. Each pixel of the array has a size of 60 x 140 {\mu}m and an optical transparency of 85-95%. Pixels have a high sensitivity, with more than 90% of them showing a noise equivalent irradiance < 10-4 W/m2 for wavelengths of 637 nm. As the semi-transparent photodetectors have a large amount of built-in gain, the opaque read-out electronics can be placed far away from the detector array to ensure maximum transparency and fill factor. Indeed, the operation and appearance of transparent image sensors present a fundamental shift in how we think about cameras and imaging, as these devices can be concealed in plain sight.

翻译：图像传感器因其能够捕获海量信息而在社会中扮演着关键角色。传统上，由于像素和堆叠在其上方的读出电子器件均吸收光线，图像传感器是不透明的。使图像传感器实现视觉透明将对人机交互界面、智能显示器以及增强现实和虚拟现实等多个领域产生深远影响。本文介绍并分析了首款半透明图像传感器的研发过程及其作为眼动追踪设备的适用性。该器件由一个8×8阵列的半透明光电探测器与电极构成，并置于全透明基底上。阵列中每个像素的尺寸为60×140微米，光学透明度达85-95%。像素具有高灵敏度，其中超过90%的像素在637纳米波长下表现出低于10^-4瓦/平方米的噪声等效辐照度。由于半透明光电探测器具有大量内置增益，不透明的读出电子器件可远离探测器阵列放置，以确保最大透明度与填充因子。事实上，透明图像传感器的运行与外观标志着我们对相机和成像认知的根本性转变——这些设备能够隐藏于众目睽睽之下。