= Twin image in holography
For a uniform on-axis <plane wave> reference, choose its constant <wave phase> to be zero, so $R=A_R>0$. The reconstructed cross terms are then proportional to $O$ and its <complex conjugate> $O^*$. This pair creates the <twin image in holography>. An outgoing curved <wavefront> and its conjugate have opposite curvature: under forward propagation, one can appear to diverge from a <virtual image> while the other converges to a real image. In <in-line holography> their depths differ, but a defocused member still overlaps the other. This is the same conjugation of spatial <wave phase> used in <phase conjugation>, although a transmission <hologram> here launches both components forward rather than automatically creating a returning <phase-conjugate mirror>.
Back to article page
