Gray-scale image fidelity and enhancement in photorefractive volume memory recorded with a pulsed signal beam

We present, for the first time to our knowledge, a gray-level image recording method in photorefractive volume memory, in which the image to be recorded is illuminated periodically by a pulse while the reference beam interacts the medium continuously until the steady state is reached. By adjusting the duty cycle of the exposure of the image in recording, high fidelity can be maintained in image reconstruction for pixels of different gray-scale intensities. Furthermore, due to multiple beam coupling the weak input image can be greatly enhanced without the loss of fidelity.