Satoshi Shiraga | Cellid: How do light engine type and field of view change AR display module efficiency in nit per watt?

Why do eyepieces dominate over 40% of AR glasses weight, and what design balance does that force?

For everyday consumer AR glasses, the weight must stay under 50 grams. The reference design created with Foxconn breaks down that budget in an exploded view: the frame weighs 27 grams, the eyepiece 30 grams, the PCB 4 grams, the battery 5 grams, and other parts just under 5 grams. Eyepieces alone occupy more than 40% of the total weight, making the optics the single largest mass contributor in the assembly.

To overcome the trade-off between functionality and form factor, the eyepiece weight must come down and more of the budget must be reallocated to the battery. That is the core design tension: every gram removed from the optics can be redirected toward energy storage, but only if the optical performance does not collapse. The reference design shows just how tight the remaining margin is once frame, PCB, battery and other parts are accounted for.

Managing power consumption is the key to pushing for higher performance while keeping the battery compact. If the eyepiece can be made lighter, the freed weight can go into a larger battery, but that only helps if the light engine and drive electronics do not burn the extra capacity. Higher performance and a compact battery therefore pull against each other unless power is managed aggressively across the system.

In this short video, you can learn:
* Everyday consumer AR glasses must weigh under 50 grams, a hard constraint on the whole bill of materials.
* In the Foxconn reference design, the eyepiece at 30 grams exceeds 40% of total weight, versus a 27 gram frame, 5 gram battery, 4 gram PCB and just under 5 grams of other parts.
* Reducing eyepiece weight frees mass for the battery, but managing power consumption is what allows higher performance to coexist with a compact battery.

📋 **Clip Abstract** A Foxconn reference design for everyday consumer AR glasses puts the eyepiece at 30 grams, over 40% of total weight, versus a 27 gram frame. To balance functionality and form factor, eyepiece weight must drop and the saved mass go to the battery, with power consumption management as the key enabler.

About the speaker:
* Speaker: Satoshi Shiraga
* Company: Cellid
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven

What wafer size roadmap and optical uniformity trade-offs define production-ready waveguides?

Mass production has used six-inch polymer wafers, with a transition to eight-inch by the end of this year and twelve-inch next year. Glass wafers will use twelve-inch now. Optical requirements include transmittance above 92%, a grading area of minus 1%, making grading detection difficult, and rainbow-effect suppression as a priority. MTF is remarkably high, more than 60% at 10 line pairs per degree.

Uniformity is a trade-off with efficiency. Prioritizing full-color uniformity achieves delta U'V' 0.015 now. If efficiency is prioritized instead, the result is nine-k nits per lumen, but uniformity is lost. That trade-off sits alongside waveguide-level requirements for high transmittance, low rainbow effect, and high MTF, so the production choice is not a single optical number but a balance between color fidelity and luminous output.

The wafer roadmap therefore has two tracks: polymer moves from six-inch to eight-inch by year-end and twelve-inch next year, while glass uses twelve-inch now. Performance metrics remain tight: transmittance above 92%, grading area of minus 1%, rainbow suppression, and MTF above 60% at 10 line pairs per degree. The measured trade-off is explicit: full-color uniformity reaches delta U'V' 0.015, or efficiency reaches nine-k nits per lumen with uniformity sacrificed.

In this short video, you can learn:
* Polymer waveguide mass production is moving from six-inch to eight-inch wafers by the end of this year and to twelve-inch next year, while glass wafers use twelve-inch now.
* The optical target includes transmittance above 92%, a grading area of minus 1%, rainbow-effect control, and MTF above 60% at 10 line pairs per degree.
* Full-color uniformity reaches delta U'V' 0.015 when prioritized, while efficiency priority gives nine-k nits per lumen at the cost of uniformity.

📋 **Clip Abstract** This clip summarizes production requirements and wafer roadmap for lightweight high-performance waveguides. It reports six-inch polymer wafers moving to eight-inch by year-end and twelve-inch next year, twelve-inch glass now, transmittance above 92%, grading area minus 1%, MTF above 60% at 10 line pairs per degree, and a uniformity-versus-efficiency trade-off: delta U'V' 0.015 for uniformity or nine-k nits per lumen for efficiency.

About the speaker:
* Speaker: Satoshi Shiraga
* Company: Cellid
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven

What refractive index, density and thickness trade-offs separate polymer from glass waveguides?

Two substrate materials are proposed for waveguides. The polymer waveguide is lightweight and robust, with refractive index above 1.7, density of 1.4 grams per cubic centimetre, and minimum thickness of 500 micrometres. The glass waveguide targets wide field of view and high optical performance use cases, with refractive index above 2.0, minimum density of 3.5 grams per cubic centimetre, and minimum thickness of 300 micrometres. These values frame the polymer-versus-glass trade-off.

Conventional DOE waveguides require an air gap on both sides, provided by covers and spacers. The proposal successfully eliminates the air gap on the right side by applying coating on top of gratings. These coatings make it possible to reduce covers and improve brightness, thickness thinness, robustness, and reliability. A full laminated layer structure improves durability, reduces the number of covers, and lowers weight, but it involves a trade-off with performance.

Combining two base materials and two layer structures forms four waveguides. A polymer fully laminated waveguide prioritizes form factor. A polymer air gap waveguide offers mid-high form factor and mid-range optical performance. A glass fully laminated waveguide delivers mid-high performance. A glass air gap waveguide prioritizes performance. Other requirements are also summarised: transmittance is more than 92% or higher.

In this short video, you can learn:
* Polymer waveguides use refractive index above 1.7, density 1.4 g/cc, and 500 µm minimum thickness.
* Glass waveguides use refractive index above 2.0, density at least 3.5 g/cc, and 300 µm minimum thickness.
* Coating on top of gratings removes one air gap, enabling fewer covers and a full laminated stack with a performance trade-off.

📋 **Clip Abstract** The clip compares polymer and glass waveguide substrates using refractive index, density, and thickness, then describes air-gap and fully laminated layer structures. It lists four resulting waveguides, from polymer fully laminated for form factor to glass air gap for performance, plus transmittance above 92%.

About the speaker:
* Speaker: Satoshi Shiraga
* Company: Cellid
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven