About LightTrans

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.