Optical calculator for determining the Fourier transform of a function represented by a time-variable signal and locating system comprising such a calculator

摘要

An optical calculator for producing the Fourier transform of a time function represented by a signal comprises at least one light source 40, an integrator screen 46 and a mask 42 with variable transparency in its plane interposed between the source and the screen. The emission point 43 of the source is variable in a direction parallel to the mask and the intensity of this source varies as a function of time in such a way as to carry out modulation of the intensity of the emission point in space in correspondence with the value of the signal to be processed in time. The transparency of the mask 42 is spatially modulated according to a periodic function parallel to the trajectory of the emission point. The illumination of all of the points of the screen represents at least one term of the Fourier transform of the signal modulating the intensity of the source. Application to systems for locating aircraft with the aid of antennae systems whose position is variable in time. IMAGE