Optimization of Coupling Gratings for AR & MR Lightguide Devices
In last week’s newsletter, we highlighted some of the challenges for the analysis of lightguide-based augmented- and mixed-reality (AR & MR) devices. This week, we want to continue diving into this topic and have a look at the optimization of coupling gratings for lightguide systems. Due to their small feature sizes and the high number of free parameters, these tasks are famously challenging.
The fast physical optics software VirtualLab Fusion offers, with its Light Guide Toolbox, a series of convenient tools to help the optical engineer in the design process, such as user-friendly workflows for the configuration of the grating structure, the rigorous Fourier modal method (FMM) for grating analysis, as well as a parametric optimization method and several systematic design approaches specific to lightguides.
In the examples below you can see some of these tools in action:
Optimization of Lightguide with Continuously Modulated Grating Regions
An Lightguide sytem for AR - MR devices is shown an how to optimize the grating for reaching the best results in the optical design process.
This use case demonstrates how to optimize a lightguide with continuously varying fill factor of the gratings in the EPE and outcoupler regions to achieve adequate lateral uniformity in the eyebox.
Optimization of Lightguide Coupling Grating for Single Incidence Direction
We demonstrate the design workflow for optimizing a rectangular grating for one specific incidence direction to obtain maximum efficiency for a specific diffraction order.
