High performance multispectral TDI CCD image sensors

Abstract

We developed a Time Delay Integration (TDI) CCD image sensor that consists of four multispectral bands (B1-B4 zone) and one panchromatic band (P zone) in an integrated, compact package. The B zones have a horizontal resolution of 3k columns, with a pixel size of 28 μm x 28 μm. The P zone has a horizontal resolution of 12k columns, with a pixel size of 7 μm x 7 μm. The large pixel size of B zones provides excellent colour differentiation even under extremely low light intensity, while the small pixel size and the large pixel number of broad band zone (P zone) provides high resolution images within a wide spectrum range. By utilizing a particularly designed hybrid optical filter, the sensor is able to collect blue, green, red, and near infrared images with only negligible optical crosstalk. The sensor uses selectable outputs and data rate: 2 or 1 outputs running at 16.5 MHz (B1-B4 Zone) per output, and 8 or 4 outputs running at 33 MHz (P Zone) per output. Special design features minimize optical crosstalk between the image zones, and achieve a low signal noise: ≤ 85 e- in B zone, and ≤ 35 e- in P zone. To acquire spectral reflectance signatures with good fidelity, the image sensor must be very sensitive to weak light in some spectral bands and cannot be over exposed to light in other spectral bands. To fulfil this requirement, the sensor is designed to show a balanced responsivity in all the image zones. Over all, the sensor demonstrates outstanding performance, providing exceptional images that are crucial for remote sensing applications.