Erin McDowell

Bridging the gap: Push-pull lenses, pixelated dimming, and the future of AR optics

The Augmented Reality industry is pursuing the goal of providing a device that has the form factor of a pair of glasses, and can provide an AR image experience that is ‘indistinguishable from reality’. This goal has proven to be challenging with existing optical components. Optics is all about trade-offs, and the trade-off for great images is generally at the cost of form factor, weight and cost.

Unlocking see-through AR’s potential depends, among other things, on solving the challenge of keeping the virtual image consistent and clear against the backdrop of the real-world, where focal distance and brightness levels can change rapidly.

FlexEnable has designed flexible liquid crystal (LC) optics for AR that are ultra-thin and light. They are built on plastic and can provide a multitude of optical enhancements for AR (and VR) devices, increasing visual comfort whilst adding near zero thickness and weight.

In this talk, we will outline two such LC technologies: ambient and pixelated dimming films that can enhance image contrast and occlusion for AR, and tunable lenses for both AR and VR, that can adjust focus in milliseconds.

Firstly, we will review the ultimate goals for an AR device, before looking at how the industry is taking steps towards these every day, particularly the drive for reduction in weight and size.

We will discuss how most current binocular see-through AR devices use fixed-focus lenses. In these cases, the AR image is set at a fixed plane which can limit the feeling of immersion – especially in use cases where objects or user focus move between focal distances (for example, bringing a virtual object closer to inspect it), vergence-accommodation conflict (VAC) may arise resulting in user discomfort. Additional focal planes/waveguides could alleviate this, but would add weight, bulk and expense to the device.

We will show how liquid crystal push-pull lenses can solve these issues by bringing dynamic focus to see-through AR, allowing the focal length of virtual objects to be adjusted without affecting the appearance of the real world.

We will then discuss the importance of real-world light management for see-through AR – and summarise existing and new methods, comparing benefits and drawbacks: from clip-on plastic covers to brute force with high-brightness light engines, through to glass-based electrochromic and segmented dimming methods.

Next, we will describe liquid crystal dimmers and how, when combined with organic transistors, they can enable pixellated dimming to maximise visual performance, object occlusion and perceived contrast when blending the virtual world with the real world.

Finally, we will show how both tunable push-pull lenses and pixelated dimmers can be built on lightweight, ultrathin flexible bioplastic that can biaxially conform to almost any surface, bringing both technologies to future devices with no compromise on weight, power consumption or form factor – a key part of improving device adoption, user comfort, and bringing the industry another step closer to the AR device end goal of all-day wearability.

Erin McDowell is Chief Revenue Officer at FlexEnable. She has over 25 years of experience in corporate and start-ups, with responsibilities in business development, product development, licensing and sales growth. Prior to FlexEnable, Erin grew 3M’s ARVR business, providing key optical components to consumer electronics OEMs and supply chain companies. Erin has a degree in Electrical Engineering from Washington University in St. Louis and is a co-inventor on over 40 patents in optical components.