Multispectral CCD-in-CMOS Time Delay Integration imager for high resolution Earth observation

TL;DR

This paper presents a 7-band multispectral CCD-in-CMOS TDI imager with high resolution and sensitivity, designed for low-cost, high-revisit-rate Earth observation applications, featuring comprehensive performance characterization and real-world imaging demonstrations.

Contribution

Introduction of a novel 7-band multispectral TDI CMOS sensor with integrated filters and extensive performance characterization for Earth observation.

Findings

High quantum efficiency across all bands

Successful multispectral imaging of real and fake leaves

Demonstrated operation at 15 kHz for high-speed capture

Abstract

Many future small satellite missions are aimed to provide low-cost remote sensing data at unprecedented revisit rates, with a ground resolution of less than one meter. This requires high resolution, fast and sensitive line-scan imagers operating at low power consumption and ideally featuring spectral sensitivity. In this paper we present comprehensive characterization results of our 7 band Back-Side Illuminated (BSI) CCD-in-CMOS sensor with a pixel pitch of 5.4 um. We have extensively characterized the key performance parameters of our CCD-in-CMOS sensor, such as quantum efficiency (QE), full well capacity (FWC), read noise, conversion gain, non-linearity, dark current etc. Novelty of this device is the combination of 7 TDI bands on the same imager allowing simultaneous multispectral TDI capture. Glass-based broadband filters with a typical band-pass width of about 100 nm have been developed and glued together to form a filter assembly of 6 band-pass filters and one panchromatic channel. Multispectral capability of this sensor is particularly interesting for Low Earth Observation (LEO) applications such as environmental monitoring, precision agriculture, disaster detection and monitoring. To highlight its ad-vantages for use in vegetation observation, we demonstrated a fake leaf and a real leaf imaging using a 7 band BSI sensor with integrated filters operating in 7-band mode at 15 kHz.