The multiplexing of signals in submillimeter direct detector arrays using projections and frequency division methods

We propose a novel method of the signal multiplexing in array of receiving elements with direct detectors which are connected for this purpose in parallel in set of rows and sums of detected signals in rows are read out by one SQUID in each row. The detected signals are integrated over readout time. The image of observed radiation and the array are rotated reciprocally in their common plane fixing the array (or the image) at angle steps. The final procedure is the reconstruction of the initial image from the set of the detected signal sums gathered from all rows at all reciprocal angles using algorithms of the computer tomography. We interpret the receiving element as the direct detector and the matching antenna into which the direct detector is incorporated (coupled) at microwave (in our case - submillimeter) frequency. The array of receiving elements based, for instance, on four-slot matching antennas with double polarization is more adequate for proposed method in order not to lose the information on the difference in radiation intensity in two polarizations during reciprocal rotation of image and receiving elements array. The rotation of receiving elements relative to the image can be realized by means of the rotation of the telescope around its main optical axis. One may imagine some other methods, as optical-mechanical or electronic-optical, of rotation of image relatively to the array, what is equivalent to the rotation of the array relatively to the image.