Snapshot CMOS: The Future of Hyperspectral Imaging.

快照 CMOS：高光谱成像的未来。

• 批准号: NE/L012553/1
• 负责人: David Hall
• 金额: $ 5.21万
• 依托单位: The Open University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FL012553%2F1
• 关键词: Snapshot; CMOS; Future; Hyperspectral; Imaging.

Whilst Charge-Coupled Devices (CCDs) have been used for Hyperspectral missions for many years with great success, new developments in Complementary Metal Oxide Semiconductor (CMOS) image sensor technology offer the chance to significantly improve detectors for, and to provide higher resolution datasets in Earth observation. e2v technologies are the supplier of CCD imagers to the European Space Agency's (ESA) Sentinel missions. Future Sentinels, launched from 2013, are to carry a range of technologies from radar to Hyperspectral imaging instruments for land, ocean and atmospheric monitoring, covering a wide range of NERC environmental science themes. However, as CCD image sensors have fundamental limitations in this application which prohibit further improvements in performance, to move forwards and provide significant advances in this field one must consider the use of the newer and potentially superior technology and establish programmes for investment and development.CMOS Image Sensor (CIS) technology has many potential advantages over CCD-based systems. Firstly, each Hyperspectral image consists of many spectral lines which vary largely in intensity. A CCD must transfer all faint spectral lines through the part of the imager that has been illuminated by more intense lines, leading to cross-talk and reducing the quality of the dataset. CIS sensors do not require charge to be transferred and can therefore completely remove this cross-talk. Secondly, a CCD can only operate at one frame-rate and one sensitivity at any given time and a compromise must be made in the sensitivity and dynamic range; the difference in the brightness in an image between snow, vegetation and water can vary dramatically yet the CCD can only be optimised for one spectral band. Advanced CIS pixels offer the potential to be read and reset in any order at any time, allowing the sensitivity to be set on a line-by-line basis; high-intensity bands can be read out more frequently, dramatically increasing the dynamic range of the detector.Current CMOS image sensors are generally based around 4 or 5 transistors per pixel (4T or 5T), with 5 transistors allowing the application of a global reset or double sampling, with Correlated Double Sampling (CDS) applied off-pixel. However, a global snapshot shutter is required to ensure that all pixels are integrating over exactly the same time period and therefore the same region of the Earth's surface, removing smearing that can be present when using CCDs due to the transfer of charge. Lowest noise performance can only be achieved through the use of CDS, which must be included in the pixel to allow variable readout-rates from one spectral band to the next, therefore optimising the sensitivity across all spectral bands. However, these properties cannot be achieved simultaneously using current 5T CIS technology. In order to achieve both a global snapshot shutter and in-pixel CDS, one must develop a CIS pixel containing many more transistors. Through innovations in CIS at e2v, a new 10T pixel design has been implemented in a small-area test array. This technology is as yet unproven (currently at TRL 2) and requires thorough characterisation to determine not only the more general performance of the pixel, but the specific applicability to the field of Hyperspectral imaging. Through in-depth characterisation and optimisation of the pixel, backed up by Silvaco ATLAS simulations of the pixel performance, we aim to implement a proof-of-concept study of this new development in CIS technology for the field of Hyperspectral imaging. The programme would proceed through TRL 3 with testing of analytical and critical function, moving into testing for TRL 4 through component and breadboard validation. Only through in-depth characterisation, optimisation and simulation can the device be fully analysed and optimised, leading to the consequent developments for the design and production into a full-scale device.

虽然电荷耦合器件 (CCD) 多年来一直用于高光谱任务并取得了巨大成功，但互补金属氧化物半导体 (CMOS) 图像传感器技术的新发展提供了显着改进探测器并提供更高分辨率数据集的机会。地球观测。 e2v Technologies 是欧洲航天局 (ESA) 哨兵任务的 CCD 成像仪供应商。 “未来哨兵”于 2013 年推出，将搭载从雷达到高光谱成像仪器等一系列技术，用于陆地、海洋和大气监测，涵盖 NERC 环境科学的广泛主题。然而，由于 CCD 图像传感器在此应用中具有根本性的局限性，阻碍了性能的进一步提高，因此，为了在这一领域向前发展并取得重大进展，必须考虑使用更新的、可能更优越的技术，并制定投资和开发计划。与基于 CCD 的系统相比，图像传感器 (CIS) 技术具有许多潜在优势。首先，每张高光谱图像由许多强度变化很大的谱线组成。 CCD 必须将所有微弱的光谱线传输通过成像仪中被更强线照射的部分，从而导致串扰并降低数据集的质量。 CIS 传感器不需要传输电荷，因此可以完全消除这种串扰。其次，CCD在任何给定时间只能以一种帧率和一种灵敏度工作，必须在灵敏度和动态范围之间做出折衷；雪、植被和水之间的图像亮度差异可能会很大，但 CCD 只能针对一个光谱带进行优化。先进的 CIS 像素可以随时以任何顺序读取和重置，从而可以逐行设置灵敏度；高强度波段可以更频繁地读出，从而极大地增加了探测器的动态范围。当前的 CMOS 图像传感器通常每个像素大约有 4 或 5 个晶体管（4T 或 5T），其中 5 个晶体管允许应用全局重置或双采样，并在像素外应用相关双采样 (CDS)。然而，需要全局快照快门来确保所有像素在完全相同的时间段内积分，从而在地球表面的相同区域内积分，从而消除使用 CCD 时由于电荷转移而可能出现的拖尾现象。最低噪声性能只能通过使用 CDS 来实现，CDS 必须包含在像素中，以允许从一个光谱带到下一个光谱带的可变读出率，从而优化所有光谱带的灵敏度。然而，使用当前的 5T CIS 技术无法同时实现这些特性。为了同时实现全局快照快门和像素内 CDS，必须开发一种包含更多晶体管的 CIS 像素。通过 e2v CIS 的创新，新的 10T 像素设计已在小面积测试阵列中实现。该技术尚未得到证实（目前处于 TRL 2），需要进行彻底的表征，不仅可以确定像素的更一般性能，还可以确定其在高光谱成像领域的具体适用性。通过对像素的深入表征和优化，并以 Silvaco ATLAS 像素性能模拟为支持，我们的目标是对高光谱成像领域 CIS 技术的这一新发展进行概念验证研究。该计划将通过 TRL 3 进行分析和关键功能测试，然后通过组件和面包板验证进入 TRL 4 测试。只有通过深入的表征、优化和仿真，才能对器件进行全面分析和优化，从而将设计和生产发展为全尺寸器件。