<p>A photo-to-photo transducer (12a) is composed by laminating a photoconductive layer member (16) and a photo-modulation layer member (20a) including liquid crystals of scattering type each other and disposing the members (16 and 20a) between two transparent electrodes (14 and 22). The transducer (12a) is operated as follows: a specified voltage is applied across the electrodes (14 and 22) to operate the photo-modulation layer member (20a) in the vicinity of operation threshold level thereof; an electro-magnetic radiation beam for writing information is projected onto the photoconductive layer member (16) through the electrode (14) at the side thereof; and an electro-magnetic radiation beam for reading the information is projected onto the photo-modulation layer member (20a) through the electrode (22) at the side thereof, thus the electro-magnetic radiation beam for reading the information is modulated accordingly with intensity of the electro-magnetic radiation beam for writing the information.</p>
