the construction of phase holograms and their reading in real time this crystal is illuminated by a reference wave from the semitransparent plate 2 after passing through a lens 6 which focuses the radiation which it receives on the intake face of a monomodal optical fibre 7 the radiation emerging from this beam is transmitted to a lens 10 which forms a plane wave front u03c3 r for interfering with the wave front u03c3 o emerging from the object in the photosensitive electrooptical crystal 8 the device also has a plane mirror 11 which is parallel to the reference wave front u03c3 r and which serves to retransmit to the crystal 8 that part of the reference beam which is not absorbed by the crystal 8 during recording this arrangement makes it possible to form a reading wave front which is phase conjugate with the reference wave front and therefore makes it possible to generate in real time a restored wave front which is conjugate with the incident object wave front the real image formed by this wave front is separated from the real object by means of a separating plate 12 thus this image is formed in an image plane and a photosensitive support 13 is placed in that plane for recording the image an appropriately oriented polarizer 14 makes it possible to insulate the photosensitive support from the noise thus the polarization state of the beam.