The concept for an imaging spectral sensor is presented. The starting point is an advanced raster scanning with multiplexing in spatial terms. The essential components are an entrance array, an imaging grating and a detector array -- a double array architecture. A programmable micro slit matrix is used as a two-dimensional HADAMARD-mask. It scans the two- dimensional images to be processed in a one-dimensional spectrometer. A multiplexing in spatial terms and simultaneously in spectral terms is possible. The spectra recorded by a commercial detector array spectrometer. At the present state the multiplexing of more than 100 spatial pixels within the quality of spectrometry is demonstrated. The concept provides a HADAMARD or multiplex advantage resulting from the micro slit matrix (increase of SNR by (root)n/2, n- number of imaging pixels) and a multidetector advantage resulting from the linear detector array of the spectrometer (increase of SNR by (root)N, N-number of detector elements). Experiments reported on a further paper.