High-speed, high-resolution time-delay and integration (TDI) image sensor for use in airborne reconnaissance applications

A 2048 X 96 time-delay and integration (TDI) CCD image sensor has been designed which has been optimized for the high speed (13,000 lines/s) scanning typically found in airborne reconnaissance. The image sensor incorporates an imaging area size selection mechanism which, in conjunction with the TDI architecture, extends the response of the sensor over a wide range of incident light intensities. At high signal levels as found in airborne reconnaissance, the dynamic range of the output signal is limited by shot noise of the image rather than device noise. The pixel spacing is 13 micrometers , giving the sensor excellent spatial resolution. The MTF of the sensor at the Nyquist frequency is 50%. The device is fabricated using an NMOS process using three polysilicon layers and buried channel CCD registers to reduce image lag.