Optical elements containing semitransparent wavelike films

Abstract

Novel optical elements containing semitransparent wavelike films embedded into the bulk of transparent material, which form a reflection image without transmitted light distortion, are studied. The dynamic theory of light diffraction by a locally periodic multilayer semitransparent wavelike film is developed. A simple analytical formula for near Bragg diffraction order intensity is obtained for the case when only one diffraction order lies within the hologram angular selectivity. The phase modulation of light transmitted through the optical element containing wavelike films is estimated for single-layer and multilayer wavelike films with an arbitrary shape of surface. The restrictions on the structure parameters for which transmitted light distortions would be negligible are obtained. A new type of high quality color hologram is proposed and shown to be feasible by calculation of hologram diffraction efficiency and spectral selectivity for three colors. Other possible applications, such as monochrome and color head-up and head-mounted displays, and imaging on spectacle lenses, are discussed.

See-through reflective optical elements with embedded wavelike films.

“…For investigation of the OE feasibility let us estimate the maximum phase modulation of transmitted light. We will use the expression (38) from [1] for phase modulation δ of transmitted wave for a beam normally incident onto the OE containing a single-layer WF with a sinusoidal shape:…”

“…where S 1 is the amplitude of the 1-st order of diffraction by the wavelike structure, c R and c 1 are cosines of the reconstructing beam and the 1-st diffraction order to the direction of the optical axis, the asterisk means complex conjugation. We used the expression from [1] for the case of pure dielectric multilayer structure:…”

“…There are, for instance, head-up and head mounted displays (HUD and HMD, respectively). The reduction of this distortion can be done by using novel OEs containing semitransparent wavelike films (WFs) embedded into the transparent material that were analyzed in our previous paper [1].…”

“…However, as far as we know, the distortion of light passing through an OE containing holographic and chaotic diffuse WFs was not especially investigated before our publication [1]. It was obvious that it was necessary to apply some restrictions on the parameters of the WF, including its thickness, in order to ensure an acceptably low level of phase modulation of the transmitted light.…”

“…It was important to understand what values of the diffraction efficiency of the wavelike hologram and its spectral selectivity can be achieved under these constraints. In [1], we evaluated the phase modulation of light transmitted through OEs containing various types of WFs and developed a dynamic theory of light diffraction for a multilayer wavelike hologram.…”