What’s new?

In our last newsletter we highlighted the capabilities of the fast physical optics software VirtualLab Fusion to analyze the performance of lightguide systems. This time we address a closely related step in the design workflow: the optimization of the grating geometries used in the coupling and expansion regions of the system.

VirtualLab Fusion offers a series of powerful tools for this task: for instance, detectors that calculate fundamental merit functions like uniformity and efficiency, and moreover the possibility to implement a (custom) smooth variation of the grating parameters along a specific region of the layout. The latter approach can drastically decrease the number of free parameters in the optimization while at the same time retaining crucial flexibility. For more information, check out the examples below!

The design process of any optical system must include an investigation of the performance of the system as a crucial step. Of course, this includes lightguide devices for applications in the field of augmented and mixed reality (AR/MR), as relatively complex representatives of optical systems. Depending on the application, “performance” can be defined by different merit functions. VirtualLab Fusion provides the optical engineer with a set of helpful tools and detectors to investigate the properties of the system.

Below we demonstrate two examples centered around the performance evaluation of lightguides: an NED (“near to exe”) device with 2D pupil expansion and a human eye model in order to calculate the MTF & PSF, and another one on characterization of the lateral uniformity.

The Light Guide Toolbox of the fast physical optics software VirtualLab Fusion provides a series of tools to help the optical engineer with many of the different stages involved in the design of lightguide devices for augmented and mixed reality applications. In our recent newsletters we already covered some of the features that assist, for instance, in the determination of a sufficient layout for the lightguide and its grating regions.

Today we turn to one of the most powerful systematic design tools for gratings in lightguides: the Footprint and Grating Analysis tool. Among its many functions, which are not limited to any particular layout, it can help, for example, to visualize the interactions of the beam footprints with the grating regions for the different field-of-view modes – an important study, considering the complex propagation of light inside the lightguide. But the jewel in its crown is its capacity to perform an analysis of the grating behavior that can then be used to configure a smooth variation of the grating parameters inside a single grating region, with the aim of improving the performance of the device in terms of its uniformity and efficiency.

Learn more about it with the use cases below!

As we saw in last week’s newsletter, grating structures with various shapes are often an essential part of lightguide-based display systems for augmented and mixed reality applications. The complexity of the gratings and the manifold roles they usually play in these setups require a thorough analysis of their behavior, while the small feature size means a rigorous method is necessary to perform said analysis accurately. The fast physical optics modeling and design software VirtualLab Fusion puts several tools at your disposal to make this task easier and more user-friendly.

This time, we want to highlight the Grating Order Analyzer, which uses the rigorous Fourier Modal Method/Rigorous Coupled Wave Analysis (FMM/RCWA) for grating characterization and illustrate its application in the case of a slanted grating for lightguide incoupling.

Webinar
Advanced Modeling of Microlens Arrays with VirtualLab Fusion
23 November 2021 | 10:00 and 18:00 (CET)

Exhibition
SPIE Photonics West
25 – 27 January 2022 | San Francisco, USA
Moscone Centre | German Pavilion A #4429-15

For the purposes of in- and outcoupling light, as well as for guiding the light from a source to the intended eyebox, different kinds of surface relief or even holographic gratings are commonly used. The design of these gratings in regard to efficiency and uniformity is therefore one of the major challenges in the design process of AR/MR devices. VirtualLab Fusion provides the optical designer with a variety of different tools to investigate grating properties and an easy way to apply the designed grating structures onto the lightguide surface. This enables the detailed simulation of the whole device including all relevant effects, like polarization and coherence.

LightTrans User Meetup
Prepare for 2022 – Ask Us Your Open Questions
01 December 2021 | 10:00 – 17:45 (CET)

Online Training
Modeling Anisotropy and Crystals in VirtualLab Fusion
07 – 08 December 2021 | 08:30 – 12:00 (CET)

The design of light-guiding devices for augmented- and mixed-reality applications is famously challenging, due to the total mix-up of angular and spectral modes and a vast number of free parameters in the system, what makes a “brute-force” approach to parametric optimization pretty much an impossibility. The fast physical optics modeling and design software VirtualLab Fusion with its Light Guide Toolbox Gold Edition puts at your disposal several systematic design tools that help the optical engineer tackle the design process step by step and in a more controlled manner. These systematic design tools cover the layout of the device as well as the grating parameters in the coupling and EPE regions.

Here, we focus on two layout-related tools: k-Layout Visualization and Layout Design, applicable for devices with a separable 1D-1D pupil expansion and 1D-periodic grating structures, like Hololens 1. Take a look at the use cases below to learn more about their exciting potential!