ZEMAX NON SEQUENTIAL OPTIMIZATION CODE
ZEMAX NON SEQUENTIAL OPTIMIZATION WINDOWS

For every sampling zone the assumption of a planar grating holds if the grating vector is slowly varying. In order to simulate non-planar gratings the hologram plane is split into a large number of sampling zones. In Ref aperiodic and multiplexed VHG are analyzed based on the coupled-wave theory within Zemax®. A suitable description of highly efficient (planar) VHG is given by Kogelnik’s coupled-wave theory. As in display technologies high diffraction efficiencies are favourable, simulations based on the Born approximation lead to inaccurate results. This approximation assumes a weak interaction of the lightfield with the VHG. In Ref the Born approximation is used to estimate the diffraction efficiency. There have been different approaches to overcome this problem. Unfortunately, most of the commercially available optic simulation tools like Zemax® OpticStudio don’t provide this possibility. In order to avoid disturbing stray light paths it is crucial to simulate VHG and their diffraction efficiencies during the design process. Additionally, holographic optical systems tend to suffer from stray light due to reflections at glass-air boundaries and multiple interactions with the VHG. On the other hand their strong dependency on wavelength and incidence angle can be problematic if a robust and reliable optical design is required. VHG have several advantages compared to conventional optics: they can be space-saving, lightweight and they offer a high degree of freedom in the optical design process. Recently, new display technologies using holographic approaches have been reported.

ZEMAX NON SEQUENTIAL OPTIMIZATION CODE

The implemented C++ code enables the user to simulate VHG and its diffraction efficiency within Zemax® Optic Studio. Especially the simulation of VHG in non-sequential mode can be helpful in order to identify possible stray light paths. This allows the fast, easy and reliable simulation of optical systems which include holograms or holographic optical elements, e.g. The aforementioned DLL enables the simulation of planar and arbitrarily spherical curved VHG and their diffraction efficiency within Zemax® OpticStudio.

ZEMAX NON SEQUENTIAL OPTIMIZATION WINDOWS

The C ++ code is compiled and linked into Zemax® using the Windows Dynamic Link Library (DLL). Furthermore, its diffraction efficiency is defined according to Kogelnik’s coupled-wave theory. Based on the k-sphere formalism the propagation direction of the diffracted light is determined. The C ++ code calculates the grating vector for every single ray traced. To solve this problem we implemented a C ++ code for each raytracing mode of Zemax®, namely the sequential and non-sequential. The latter is not supported by the current version of Zemax® OpticStudio 17, one of the most popular optic simulation tools. This especially includes the correct behaviour of the volume holographic grating (VHG) in terms of its optical function and its diffraction efficiency. In the development process of holographic displays like holographic Head-Mounted Displays (hHMD) the simulation of the complete optical system is strongly required.

Zemax non sequential optimization