Accelerate AR Near-Eye Display Development Using the LightTools AR Waveguide Designer

Augmented reality (AR) glasses and near-eye displays (NEDs) require optical engineers to balance image uniformity, field of view (FOV), optical efficiency, compact form factor, and stray light performance while reducing design and optimization time. Developing AR waveguides can be particularly challenging because traditional workflows often require extensive manual setup of input couplers, exit pupil expanders (EPEs), output couplers, and waveguide geometries.

This application note introduces the LightTools AR Waveguide Designer, an integrated design environment that helps accelerate AR waveguide development by automating waveguide model creation, analysis, and optimization. The solution supports both geometric mirror-based waveguides and grating-based waveguides, including Surface Relief Grating (SRG) and Volume Bragg Grating (VBG) approaches.

Using an intuitive K-space diagram, optical engineers can visually define input couplers, exit pupil expanders, and output couplers. LightTools then automatically generates the corresponding waveguide model, reducing the manual model-building effort typically required during waveguide simulation development.

The application note highlights key capabilities for evaluating and improving AR near-eye display performance. Designers can analyze and optimize angular luminance uniformity and eyebox illuminance uniformity to achieve more consistent image quality across the viewing area. Integrated stray light analysis helps identify unwanted diffraction orders, rainbow artifacts, double reflections, and backside reflections earlier in the design process. Engineers can also import image files as display sources to simulate angular luminance distributions and evaluate corresponding true-color images at the eyebox.

Two example case studies demonstrate how these capabilities can be applied to practical AR waveguide design challenges. The first explores an AR smart glasses design using a Surface Relief Grating waveguide. Grating diffraction characteristics calculated in RSoft are applied through user-defined optical properties, enabling spatially varying grating parameters to be optimized for angular luminance uniformity and efficiency.

The second case study focuses on stray light in waveguide displays. K-space-based pre-analysis and image simulation are used to investigate unwanted optical paths and ghost images. The example demonstrates how optical coatings can help control ghost images and reduce potential image-quality issues before prototype fabrication.

By combining automated waveguide model generation, K-space-based design, uniformity optimization, realistic image evaluation, and stray light analysis, LightTools AR Waveguide Designer helps engineers explore AR waveguide designs more efficiently and identify potential optical performance issues earlier in development.