An Optical Journey into AR/VR Realms

In the vast and ever-evolving world of optical engineering, few quests are as challenging — or as rewarding — as designing cutting-edge components for augmented and virtual reality headsets. This is the tale of one of my most fullfilled journey through the labyrinth of light and glass, where I sought to tame a freeform prism that would unlock new realms of visual magic, while respecting the constraints imposed by the weird and intrusive Wizard (aka my curiosity about AR/VR technologies).

The Call to Adventure

The call came from the future — a demand for compact (10 mm thickness), lightweight, and high-performance optics that could bring immersive AR/VR experiences to life. A legend said that upgrading the performance to an 80°×80° field of view and a 15 mm eyebox led the innocent to a more peaceful life. But the true mastery lay in pushing the angular resolution beyond 60 pixels per degree, securing an eye relief of 12 to 14 mm, and keeping distortion under 1% for both virtual imagery and real-world views — the trifecta of clarity, comfort, and realism that turned dreams into seamless reality. The expectations exhibits a clear definition of how walking through Hell should be…
At the heart of this challenge was a freeform prism, a shape as mysterious and complex as the legendary Rings of Power. Unlike simple lenses or mirrors, this prism needed to bend and fold light with precision, preserving field of view, clarity, and alignment — all inside a tiny headset. I started to lose my breathe, even before starting.

I began my journey armed with little more than vague specifications and a rough pre-design CAD model. From these humble beginnings, I set forth into the intricate world of optical design, ready to shape light itself into a new realm of immersive experience.

The first CAD design — where the prism was forged to lie in harmony with the glass frame’s ancient curves.

Crossing the Threshold

Armed with my trusted and old friend companion, Zemax OpticStudio, I ventured into the unknown, unpaved path. I chose the most-well one for cubesat spectrometers: a dusty book showed me a folded multidimensionnal approach, where the optical path is reflected multiple times in a tiny space. The first trials were daunting. Freeform surfaces, by their nature, resist easy understanding. Their curves twist and turn in ways that defy simple equations, demanding careful simulation and endless iterations.

First draft of the demonish folded freeform mirrors — the curved beast defied me. I tried to bend it, but the mission was avorted.

I began by defining the optical path, folding the light beam with finesse. Each parameter was a riddle — angles, refractive indices, aspheric coefficients — all had to harmonize perfectly. The challenge: maintain image quality across a wide field while keeping the system compact enough to fit into the sleek form factor demanded by AR/VR designers.

Trials of Optimization

Much like the fellowship facing dark forests and treacherous mountains, I wrestled with aberrations and distortions that threatened to blur the vision. Ghost reflections, chromatic shifts, and mechanical constraints loomed like ugly — but determined — orcs blocking the path.

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But Zemax was my sword and Hope, my shield. Through meritricous use of optimization algorithms and merit functions, I refined the freeform surfaces by spreading the dimensions. Iteration after iteration, the optical performance improved — sharpness sharpened, distortions faded, and the field of view blossomed into life.

Exploring another path, I forged onward to a first pre-prototype — yet the journey veered, and the project was cast into a wholly different realm.

The Light Revealed

Another path to follow... Another design version to imagine... Some precious companions sacrified for a more transcendental dream… Finally, after long hours of simulation (meaning weeks) and adjustments, the prism’s shape emerged from the shadows — a perfectly folded relay system that preserved alignment and clarity with minimal elements. Its surfaces, sculpted by careful mathematics, channeled light flawlessly into the eye box, delivering crisp images with wide fields of view.

This was no ordinary lens; it was a crafted artifact, a key to unlocking immersive worlds where virtual and real coexist.

The Return Home

With the design completed, I transitioned from optical wizardry to practical reality — preparing the model for mechanical integration and manufacturing. Each curve, each angle was now a blueprint for production, destined to be realized in precision glass or plastic.

…The journey continues, the mountains to be climbs still unumbered, but this chapter closes with a sense of accomplishment. The freeform prism, born from a blend of art, science, and relentless optimization, stands ready to enhance the next generation of AR/VR devices.

Behold the first draft of my design: a form forged beneath 10 millimeters, crafting a helmet both compact and light for the bravest knights.

Using high-index COC material helps reduce thickness and weight without compromising optical quality. The MTF (Modulation Transfer Function) still requires further optimization to ensure crisp, clear images across the entire field of view. This design lays the foundation for a sleek, efficient optical relay that will bring immersive AR/VR experiences closer to reality.

To Be Continued

Here was my story about my daily work as optical designer — always epic and full of fun and discovery. There is always an endless road to follow and a new feature to use that help you to fight or domesticate the most impressive dragon! :)