Achromatization in Optical Reconstruction of Computer Generated Color Holograms

In optical reconstruction of time-multiplexed color holography, three types of chromatic aberrations exist: magnification chromatic aberration (MCA), lateral chromatic aberration (LCA), and axial chromatic aberration (ACA). MCA is due to wavelength change of light source for reconstruction of different color components. In order to compensate for MCA, a different number of pixels for each color component is suggested and demonstrated. LCA causes mismatch of image centers for the three-color components. The use of digital blazed gratings superposed on the computer-generated hologram (CGH) is demonstrated as an effective way to correct for LCA. The error due to non-integer period is analyzed, and the maximum red wavelength is deduced in use based on the critical value of resolving power of human eyes. For ACA, where the images of the three reconstructing wavelengths focus at different planes, adding specific phase values for digital achromatization is proposed. The image quality is numerically evaluated by the mean square error. The techniques summarized in this paper are used during generation of the CGH and thus avoids mechanical complexity.