Optical mosaic gratings made by consecutive, phase-interlocked, holographic exposures using diffraction from latent...

We propose and demonstrate a method for fabricating large optical mosaic gratings, i.e., gratings made by consecutive, phase-interlocked, holographic exposures on single substrates. It takes advantage of the latent fringes generated by the preceding exposure to align the substrate for the following exposure. Good angular alignment accuracy and period consistency between the fringes recorded by consecutive exposures can be achieved by using the large-area moiré pattern produced by the latent fringes and the alignment beams. Phase-interlocking accuracy of less than 4 degrees between consecutive exposures was experimentally achieved by using the heterodyne detection technique.