How to double the spatial resolution of a push-broom instrument

Within the preliminary studies for the definition of the next generation of SPOT satellites, a new concept has been proposed to enhance the spatial resolution of future instruments. This concept is called HIPERMODE (High PERformances by Mid Overlap and DEconvolution). The SPOT optical remote sensing satellites of the first generation include a 10 meter panchromatic band. SPOT5 will offer 5 m resolution images obtained by reducing the size of the CCD elementary detectors (6.5 microns instead of 13) without changing the telescope. But even this resolution is not sufficient for many applications, such as high precision cartography. With the HIPERMODE concept it would be possible to achieve a 2.5 meter resolution instrument. With the same telescope as SPOT1, and with 6.5 μm detectors. The images obtained by this method have a low modulation transfer function (with a value of zero at the sampling frequency), but nearly no aliasing. The images can be easily enhanced by deconvolution techniques, provided the level of noise is low. Accurate simulations of the images given by an HIPERMODE instrument are presented and compared to classical push-broom images: the gain of information is surprising