Comparison of Transmission and the 90-Degree Holographic Recording Geometry

We compare the system performances of two holographic recording geometries using iron-doped lithium niobate: the 90-degree and transmission geometry. We find that transmission geometry is better because the attainable dynamic range (M /#) is much higher. The only drawback of transmission geometry is the buildup of fanning, particularly during readout. Material solutions that reduce fanning such as doubly-doped photorefractive crystals make transmission geometry the clear winner.