Abstract

We built a photorefractive incoherent to coherent converter¹ with a KNbO₃ crystal plate with thickness d = 0.83 mm. (see Fig, 1). Using anisotropic Bragg diffraction² and choosing the direction of the diffracted beam (λ – 632.8 nm) perpendicular to the crystal surface, a resolution of 35 linepairs per mm has been reached. Figure 2 shows 4 images after conversion. To write the hologram an Ar¹ laser beam was used at a wavelength of 514.5 nm.

© 1991 Optical Society of America