Simulations and experiments of aperiodic and multiplexed gratings in volume holographic imaging systems

Abstract

A new methodology describing the effects of aperiodic and multiplexed gratings in volume holographic imaging systems (VHIS) is presented. The aperiodic gratings are treated as an ensemble of localized planar gratings using coupled wave methods in conjunction with sequential and non-sequential ray-tracing techniques to accurately predict volumetric diffraction effects in VHIS. Our approach can be applied to aperiodic, multiplexed gratings and used to theoretically predict the performance of multiplexed volume holographic gratings within a volume hologram for VHIS. We present simulation and experimental results for the aperiodic and multiplexed imaging gratings formed in PQ-PMMA at 488nm and probed with a spherical wave at 633nm. Simulation results based on our approach that can be easily implemented in ray-tracing packages such as Zemax® are confirmed with experiments and show proof of consistency and usefulness of the proposed models.

Wigner analysis of three dimensional pupil with finite lateral aperture

“…Fig. 2(i-iv) shows the 3 3 x u − planar cross sections of the 4-dimensional 3D K at various coordinates 4 x at the back plane of 3D pupil. The width of the visible slit in the 3 3 x u − space is proportional to the pupil thickness L indicating the Fourier-conjugate relationship with the width of the visible slit in the input 1 x plane due to Bragg selectivity.…”

“…Moreover, there exists an offset between the center of probing location 3 x and the maximum diffracted location 4 x in VHIS; this is because of the Braggmatching condition. For example, in case (i) of Fig.…”

“…where 4 W is calculated at the condition of 3 3 3 3 ( , ) ( ) W x u u δ = with coherent on-axis plane wave. 4 W under different recording angles s θ is plotted in Fig.…”

“…When s θ increases, 4 I decays faster and its full width at half maximum (FWHM) becomes narrower [ Figs. 6(b), 7(b)].…”

“…The use of volume holographic (VH) pupils in imaging systems includes applications such as hyper-spectral image acquisition [1], profilometric imagers [2,3], unhindered imaging capability under broadband illumination, and multi-focal microscopic imaging [4,5]. Compared to conventional 2D imaging pupils such as thin gratings and lenses, the VH pupil at a 4-f imagers' Fourier plane acts as a 3D optical element, providing unique opportunities to process the optical field in three spatial dimensions as well as wavelength [6,7].…”