A thermoplastic device, which used corona wires with grids to aim at a uniform charging over the surface of a thermoplastic and a sheet couple to make a temperature measurement for the purpose of stopping heat at a optimum developing time, is described. This device made it easy to construct a matched filtering system with a quasi real-time input element. The diffraction efficiency of the thermoplastic as a function of signal intensity with a parameter of reference beam intensity was measured. This result suggested a easier method of making a matched filter than using a photographic material. With a BSO device, a matched filtering system was constructed and a matched filtering for character reading was carried out.