Keller P E, Gmitro A F
Appl Opt. 1993 Mar 10;32(8):1304-10. doi: 10.1364/AO.32.001304.
For optical neural networks implemented with computer-generated planar holograms the spacebandwidth product of the hologram is a major consideration. Off-axis holograms can be fabricated with a single binary transmission mask. However, the carrier frequency greatly increases the space-bandwidth product. On axis-holograms use a lower space-bandwidth product to encode interconnections but require a multilevel phase transmission profile. Significant errors can result during the fabrication of multilevel phase structures. With modification of the on-axis geometry the effects of the fabrication errors can be reduced while a lower space-bandwidth product per interconnection is retained. The interconnection accuracy, the diffraction efficiency, the and sensitivity to fabrication errors are compared for the off-axis, the on-axis, and the modified on-axis diffraction geometries.
对于用计算机生成的平面全息图实现的光学神经网络，全息图的空间带宽积是一个主要考虑因素。离轴全息图可以用单个二元透射掩模制造。然而，载波频率会大大增加空间带宽积。同轴全息图使用较低的空间带宽积来编码互连，但需要多级相位透射轮廓。在制造多级相位结构时可能会产生重大误差。通过修改同轴几何结构，可以减少制造误差的影响，同时保留每个互连较低的空间带宽积。比较了离轴、同轴和修改后的同轴衍射几何结构的互连精度、衍射效率和对制造误差的敏感度。
