Image Blurring In Display Holograms And In Holographic Optical Elements

A review is given of image blurring mechanisms in reflection and transmission holograms for both monochromatic and white-light replay. A theoretical model based on ray-tracing and locally-planar grating 2-beam coupled-wave theory is used to analyse dispersion blurring in white-light holograms as a function of wavelength in terms of the angular blur of an image-point seen by an observer. Methods of minimizing the blur are given, and the significant reduction achieved by recording reflection holograms with a tilt is explained and illustrated by experimental results. The use of a thick recording material is proposed as a method of producing full-parallax transmission holograms which can be replayed with white-light without dispersion compensation, and some preliminary results are given. The theoretical model used can also be applied to the analysis of the imaging properties of holographic optical elements.